PCM not letting heat/AC blower blow?
Guest
Posts: n/a
Re: PCM not letting heat/AC blower blow?
"Carl K" <carl@personnelware.com> wrote in message
news:LqWdne-5K4JAdiPZnZ2dnUVZ_qmdnZ2d@comcast.com...
> Mike wrote:
>> "Carl K" <carl@personnelware.com> wrote in message
>> news:Ad-dnScCL541OCPZnZ2dnUVZ_qWdnZ2d@comcast.com...
>>> Mike wrote:
>>>> "Carl K" <carl@personnelware.com> wrote in message
>>>> news:pOydnfaDzraa6iPZnZ2dnUVZ_radnZ2d@comcast.com. ..
>>>>> Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>>>> to the library to confirm - Haynes wiring didn't have it.)
>>>>>
>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>> Powertrain Control Module -- Battery(-)
>>>>>
>>>>> the == is 4 wires, 1 for each speed
>>>>>
>>>>> If I hook the far side of the relay to ground, the blower blows. The
>>>>> relay is controlled by both ignition and vent selector, so just making
>>>>> a permanent connection to ground would leave me with a fully
>>>>> functional system.
>>>>>
>>>>> But before I go with that hack, wondering if I am missing something?
>>>>>
>>>>> The PCM is $480+installation required to program it.
>>>>>
>>>>> Will a "diagnostic code reader" ($99 from local auto store) tell me if
>>>>> the PCM is not letting the blower blow?
>>>>>
>>>>> Also, $99 gets me "just numeric codes for '96 and up" but $250 get a
>>>>> 'delux' that works on "all cars" and gives descriptions. the 97 is
>>>>> the only car I have that has any sort of diag system (like it will do
>>>>> my 68 pickup any good) - and I somehow doubt the delux will really
>>>>> tell me everything I need to know anyway. any comments?
>>>>>
>>>>>
>>>>> Carl K
>>>> The PCM has nothing to do with your blower motor. What type of heat/
>>>> A/C controls do you have ? There are two choices, ATM ( Automatic temp
>>>> control ) or manual control. The wiring is totally different depending
>>>> on which one you have.
>>> Manual switches.
>>>
>>> I have a 97, this is for a 98:
>>>
>>> "The PCM manages air-conditioning compressor and coolant-fan operation,
>>> but it has to see the correct incoming signals before sending outgoing
>>> commands. When the climate-control head is switched to A/C-on mode, a
>>> signal is sent to the PCM. The PCM must also receive a signal from the
>>> A/C low- and high-prcoolant-fan operationessure switches before it turns
>>> on the compressor and/or coolant fan. These switches prevent damage to
>>> the system. I'm not sure what method you used to check for a sufficient
>>> charge of R-134a refrigerant, but a low charge will kill the signal from
>>> the low-pressure switch and therefore prevent the system from working.
>>> It could be a low refrigerant charge, defective PCM, faulty
>>> climate-control head, one of the pressure switches on the blink, a break
>>> in related power, or an issue with the ground circuit wiring."
>>
>>
>> The above info is in reference to an ATC system not a manual system.
>> The wiring is completely different from one to the other. Also, it talks
>> about the PCM controlling the A/C compressor and the coolant fan. That is
>> all the PCM controls and it is the same with either system.
>>
>>
>>> http://trucktrend.com/features/advic...rd_ranger.html
>>>
>>> Isn't the "coolant-fan operation" the "blower motor" ?
>>
>>
>> No. The coolant fan motor is the radiator fan.
>
> ah - I was wondering why it was called something other than "blower
> motor."
>
>>
>>> I am hoping for something else besides the PCM between the relay and the
>>> Battery(-), like an relay or some other $20 part.
>>> C
>>
>> The PCM does not have anything to do with the blower motor.
>>
>> From what you stated above:
>>
>> "Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>> to
>>>>> the library to confirm - Haynes wiring didn't have it.)
>>>>>
>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>> Powertrain Control Module -- Battery(-)
>>>>>
>>
>> That's fairly close. It is actually alot simpler. Bat + -- 40A
>> fuse -- blower motor -- resistor pack -- switch -- Ground.
>>
>> The blower motor switch uses the resistor pack to vary the resistance
>> on the ground side of the blower motor to change speeds. For high speed
>> the resistor is bypassed comepletely.
>>
>>
>> From your other post, so this is easier to follow. You stated :
>>
>>>> If I hook the far side of the relay to ground, the blower blows.
>>
>> and I can control the speed with the switch.
>>
>> Good Q - how did that happen?
>
>> The wiring diagram shows no relay in the circuit at all. Are you shure
>> that you have a relay ? Were is this relay located ?
>>
>>
>
> Whoops.
> Good Q - how did that happen?
>
>
> Bat+ -- 40A fuse -- blower motor -- resistor pack == switch --x- relay
> switch -y-- PCM? -- Ground.
>
> The relay coil side is driven by the ignition switch and the air flow
> control switch (off and 7 on's: max, norm, bi, vent, heat, heat/def, def)
>
> If I ground X, the blower blows and I can adjust the speed with the speed
> switch: low to high (no off).
>
> If I ground Y, the blower only blows when the relay is engaged: ignition
> and air flow control switch on.
>
> If the far side of the relay was just going to ground, where would the
> wire terminate?
>
> The relay is mounted inside the box that the 3 controls are in: fan speed,
> air flow and hot/cold. if you look at the back of the box, you can see
> the 4 connectors, you have to disassemble the box to pull the relay out.
>
> I am hung up on it going to the PCM just because of the XJ wiring diagram
> I have. but it is significantly different (like the relay is between the
> 40A fuse and the motor) , so it won't surprise me if it just goes to
> ground.
>
> Carl K
>
Carl
I have a wiring diagram and it is not showing a relay in the blower motor
circuit. It also is not connected to the PCM. Are you sure what you are
calling a relay is not part of the A/C switch ? I believe that is what you
are grounding. From what you are saying it soumds like you have a bad blower
motor switch. It appears that the ground for the blower switch is opened
inside the switch. I can send you a copy of the wiring diagram if you have a
valid email address.
Guest
Posts: n/a
Re: PCM not letting heat/AC blower blow?
"Carl K" <carl@personnelware.com> wrote in message
news:LqWdne-5K4JAdiPZnZ2dnUVZ_qmdnZ2d@comcast.com...
> Mike wrote:
>> "Carl K" <carl@personnelware.com> wrote in message
>> news:Ad-dnScCL541OCPZnZ2dnUVZ_qWdnZ2d@comcast.com...
>>> Mike wrote:
>>>> "Carl K" <carl@personnelware.com> wrote in message
>>>> news:pOydnfaDzraa6iPZnZ2dnUVZ_radnZ2d@comcast.com. ..
>>>>> Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>>>> to the library to confirm - Haynes wiring didn't have it.)
>>>>>
>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>> Powertrain Control Module -- Battery(-)
>>>>>
>>>>> the == is 4 wires, 1 for each speed
>>>>>
>>>>> If I hook the far side of the relay to ground, the blower blows. The
>>>>> relay is controlled by both ignition and vent selector, so just making
>>>>> a permanent connection to ground would leave me with a fully
>>>>> functional system.
>>>>>
>>>>> But before I go with that hack, wondering if I am missing something?
>>>>>
>>>>> The PCM is $480+installation required to program it.
>>>>>
>>>>> Will a "diagnostic code reader" ($99 from local auto store) tell me if
>>>>> the PCM is not letting the blower blow?
>>>>>
>>>>> Also, $99 gets me "just numeric codes for '96 and up" but $250 get a
>>>>> 'delux' that works on "all cars" and gives descriptions. the 97 is
>>>>> the only car I have that has any sort of diag system (like it will do
>>>>> my 68 pickup any good) - and I somehow doubt the delux will really
>>>>> tell me everything I need to know anyway. any comments?
>>>>>
>>>>>
>>>>> Carl K
>>>> The PCM has nothing to do with your blower motor. What type of heat/
>>>> A/C controls do you have ? There are two choices, ATM ( Automatic temp
>>>> control ) or manual control. The wiring is totally different depending
>>>> on which one you have.
>>> Manual switches.
>>>
>>> I have a 97, this is for a 98:
>>>
>>> "The PCM manages air-conditioning compressor and coolant-fan operation,
>>> but it has to see the correct incoming signals before sending outgoing
>>> commands. When the climate-control head is switched to A/C-on mode, a
>>> signal is sent to the PCM. The PCM must also receive a signal from the
>>> A/C low- and high-prcoolant-fan operationessure switches before it turns
>>> on the compressor and/or coolant fan. These switches prevent damage to
>>> the system. I'm not sure what method you used to check for a sufficient
>>> charge of R-134a refrigerant, but a low charge will kill the signal from
>>> the low-pressure switch and therefore prevent the system from working.
>>> It could be a low refrigerant charge, defective PCM, faulty
>>> climate-control head, one of the pressure switches on the blink, a break
>>> in related power, or an issue with the ground circuit wiring."
>>
>>
>> The above info is in reference to an ATC system not a manual system.
>> The wiring is completely different from one to the other. Also, it talks
>> about the PCM controlling the A/C compressor and the coolant fan. That is
>> all the PCM controls and it is the same with either system.
>>
>>
>>> http://trucktrend.com/features/advic...rd_ranger.html
>>>
>>> Isn't the "coolant-fan operation" the "blower motor" ?
>>
>>
>> No. The coolant fan motor is the radiator fan.
>
> ah - I was wondering why it was called something other than "blower
> motor."
>
>>
>>> I am hoping for something else besides the PCM between the relay and the
>>> Battery(-), like an relay or some other $20 part.
>>> C
>>
>> The PCM does not have anything to do with the blower motor.
>>
>> From what you stated above:
>>
>> "Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>> to
>>>>> the library to confirm - Haynes wiring didn't have it.)
>>>>>
>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>> Powertrain Control Module -- Battery(-)
>>>>>
>>
>> That's fairly close. It is actually alot simpler. Bat + -- 40A
>> fuse -- blower motor -- resistor pack -- switch -- Ground.
>>
>> The blower motor switch uses the resistor pack to vary the resistance
>> on the ground side of the blower motor to change speeds. For high speed
>> the resistor is bypassed comepletely.
>>
>>
>> From your other post, so this is easier to follow. You stated :
>>
>>>> If I hook the far side of the relay to ground, the blower blows.
>>
>> and I can control the speed with the switch.
>>
>> Good Q - how did that happen?
>
>> The wiring diagram shows no relay in the circuit at all. Are you shure
>> that you have a relay ? Were is this relay located ?
>>
>>
>
> Whoops.
> Good Q - how did that happen?
>
>
> Bat+ -- 40A fuse -- blower motor -- resistor pack == switch --x- relay
> switch -y-- PCM? -- Ground.
>
> The relay coil side is driven by the ignition switch and the air flow
> control switch (off and 7 on's: max, norm, bi, vent, heat, heat/def, def)
>
> If I ground X, the blower blows and I can adjust the speed with the speed
> switch: low to high (no off).
>
> If I ground Y, the blower only blows when the relay is engaged: ignition
> and air flow control switch on.
>
> If the far side of the relay was just going to ground, where would the
> wire terminate?
>
> The relay is mounted inside the box that the 3 controls are in: fan speed,
> air flow and hot/cold. if you look at the back of the box, you can see
> the 4 connectors, you have to disassemble the box to pull the relay out.
>
> I am hung up on it going to the PCM just because of the XJ wiring diagram
> I have. but it is significantly different (like the relay is between the
> 40A fuse and the motor) , so it won't surprise me if it just goes to
> ground.
>
> Carl K
>
Carl
I have a wiring diagram and it is not showing a relay in the blower motor
circuit. It also is not connected to the PCM. Are you sure what you are
calling a relay is not part of the A/C switch ? I believe that is what you
are grounding. From what you are saying it soumds like you have a bad blower
motor switch. It appears that the ground for the blower switch is opened
inside the switch. I can send you a copy of the wiring diagram if you have a
valid email address.
Guest
Posts: n/a
Re: PCM not letting heat/AC blower blow?
"Carl K" <carl@personnelware.com> wrote in message
news:LqWdne-5K4JAdiPZnZ2dnUVZ_qmdnZ2d@comcast.com...
> Mike wrote:
>> "Carl K" <carl@personnelware.com> wrote in message
>> news:Ad-dnScCL541OCPZnZ2dnUVZ_qWdnZ2d@comcast.com...
>>> Mike wrote:
>>>> "Carl K" <carl@personnelware.com> wrote in message
>>>> news:pOydnfaDzraa6iPZnZ2dnUVZ_radnZ2d@comcast.com. ..
>>>>> Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>>>> to the library to confirm - Haynes wiring didn't have it.)
>>>>>
>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>> Powertrain Control Module -- Battery(-)
>>>>>
>>>>> the == is 4 wires, 1 for each speed
>>>>>
>>>>> If I hook the far side of the relay to ground, the blower blows. The
>>>>> relay is controlled by both ignition and vent selector, so just making
>>>>> a permanent connection to ground would leave me with a fully
>>>>> functional system.
>>>>>
>>>>> But before I go with that hack, wondering if I am missing something?
>>>>>
>>>>> The PCM is $480+installation required to program it.
>>>>>
>>>>> Will a "diagnostic code reader" ($99 from local auto store) tell me if
>>>>> the PCM is not letting the blower blow?
>>>>>
>>>>> Also, $99 gets me "just numeric codes for '96 and up" but $250 get a
>>>>> 'delux' that works on "all cars" and gives descriptions. the 97 is
>>>>> the only car I have that has any sort of diag system (like it will do
>>>>> my 68 pickup any good) - and I somehow doubt the delux will really
>>>>> tell me everything I need to know anyway. any comments?
>>>>>
>>>>>
>>>>> Carl K
>>>> The PCM has nothing to do with your blower motor. What type of heat/
>>>> A/C controls do you have ? There are two choices, ATM ( Automatic temp
>>>> control ) or manual control. The wiring is totally different depending
>>>> on which one you have.
>>> Manual switches.
>>>
>>> I have a 97, this is for a 98:
>>>
>>> "The PCM manages air-conditioning compressor and coolant-fan operation,
>>> but it has to see the correct incoming signals before sending outgoing
>>> commands. When the climate-control head is switched to A/C-on mode, a
>>> signal is sent to the PCM. The PCM must also receive a signal from the
>>> A/C low- and high-prcoolant-fan operationessure switches before it turns
>>> on the compressor and/or coolant fan. These switches prevent damage to
>>> the system. I'm not sure what method you used to check for a sufficient
>>> charge of R-134a refrigerant, but a low charge will kill the signal from
>>> the low-pressure switch and therefore prevent the system from working.
>>> It could be a low refrigerant charge, defective PCM, faulty
>>> climate-control head, one of the pressure switches on the blink, a break
>>> in related power, or an issue with the ground circuit wiring."
>>
>>
>> The above info is in reference to an ATC system not a manual system.
>> The wiring is completely different from one to the other. Also, it talks
>> about the PCM controlling the A/C compressor and the coolant fan. That is
>> all the PCM controls and it is the same with either system.
>>
>>
>>> http://trucktrend.com/features/advic...rd_ranger.html
>>>
>>> Isn't the "coolant-fan operation" the "blower motor" ?
>>
>>
>> No. The coolant fan motor is the radiator fan.
>
> ah - I was wondering why it was called something other than "blower
> motor."
>
>>
>>> I am hoping for something else besides the PCM between the relay and the
>>> Battery(-), like an relay or some other $20 part.
>>> C
>>
>> The PCM does not have anything to do with the blower motor.
>>
>> From what you stated above:
>>
>> "Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>> to
>>>>> the library to confirm - Haynes wiring didn't have it.)
>>>>>
>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>> Powertrain Control Module -- Battery(-)
>>>>>
>>
>> That's fairly close. It is actually alot simpler. Bat + -- 40A
>> fuse -- blower motor -- resistor pack -- switch -- Ground.
>>
>> The blower motor switch uses the resistor pack to vary the resistance
>> on the ground side of the blower motor to change speeds. For high speed
>> the resistor is bypassed comepletely.
>>
>>
>> From your other post, so this is easier to follow. You stated :
>>
>>>> If I hook the far side of the relay to ground, the blower blows.
>>
>> and I can control the speed with the switch.
>>
>> Good Q - how did that happen?
>
>> The wiring diagram shows no relay in the circuit at all. Are you shure
>> that you have a relay ? Were is this relay located ?
>>
>>
>
> Whoops.
> Good Q - how did that happen?
>
>
> Bat+ -- 40A fuse -- blower motor -- resistor pack == switch --x- relay
> switch -y-- PCM? -- Ground.
>
> The relay coil side is driven by the ignition switch and the air flow
> control switch (off and 7 on's: max, norm, bi, vent, heat, heat/def, def)
>
> If I ground X, the blower blows and I can adjust the speed with the speed
> switch: low to high (no off).
>
> If I ground Y, the blower only blows when the relay is engaged: ignition
> and air flow control switch on.
>
> If the far side of the relay was just going to ground, where would the
> wire terminate?
>
> The relay is mounted inside the box that the 3 controls are in: fan speed,
> air flow and hot/cold. if you look at the back of the box, you can see
> the 4 connectors, you have to disassemble the box to pull the relay out.
>
> I am hung up on it going to the PCM just because of the XJ wiring diagram
> I have. but it is significantly different (like the relay is between the
> 40A fuse and the motor) , so it won't surprise me if it just goes to
> ground.
>
> Carl K
>
Carl
I have a wiring diagram and it is not showing a relay in the blower motor
circuit. It also is not connected to the PCM. Are you sure what you are
calling a relay is not part of the A/C switch ? I believe that is what you
are grounding. From what you are saying it soumds like you have a bad blower
motor switch. It appears that the ground for the blower switch is opened
inside the switch. I can send you a copy of the wiring diagram if you have a
valid email address.
Guest
Posts: n/a
Re: PCM not letting heat/AC blower blow?
Mike wrote:
> "Carl K" <carl@personnelware.com> wrote in message
> news:LqWdne-5K4JAdiPZnZ2dnUVZ_qmdnZ2d@comcast.com...
>> Mike wrote:
>>> "Carl K" <carl@personnelware.com> wrote in message
>>> news:Ad-dnScCL541OCPZnZ2dnUVZ_qWdnZ2d@comcast.com...
>>>> Mike wrote:
>>>>> "Carl K" <carl@personnelware.com> wrote in message
>>>>> news:pOydnfaDzraa6iPZnZ2dnUVZ_radnZ2d@comcast.com. ..
>>>>>> Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>>>>> to the library to confirm - Haynes wiring didn't have it.)
>>>>>>
>>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>>> Powertrain Control Module -- Battery(-)
>>>>>>
>>>>>> the == is 4 wires, 1 for each speed
>>>>>>
>>>>>> If I hook the far side of the relay to ground, the blower blows. The
>>>>>> relay is controlled by both ignition and vent selector, so just making
>>>>>> a permanent connection to ground would leave me with a fully
>>>>>> functional system.
>>>>>>
>>>>>> But before I go with that hack, wondering if I am missing something?
>>>>>>
>>>>>> The PCM is $480+installation required to program it.
>>>>>>
>>>>>> Will a "diagnostic code reader" ($99 from local auto store) tell me if
>>>>>> the PCM is not letting the blower blow?
>>>>>>
>>>>>> Also, $99 gets me "just numeric codes for '96 and up" but $250 get a
>>>>>> 'delux' that works on "all cars" and gives descriptions. the 97 is
>>>>>> the only car I have that has any sort of diag system (like it will do
>>>>>> my 68 pickup any good) - and I somehow doubt the delux will really
>>>>>> tell me everything I need to know anyway. any comments?
>>>>>>
>>>>>>
>>>>>> Carl K
>>>>> The PCM has nothing to do with your blower motor. What type of heat/
>>>>> A/C controls do you have ? There are two choices, ATM ( Automatic temp
>>>>> control ) or manual control. The wiring is totally different depending
>>>>> on which one you have.
>>>> Manual switches.
>>>>
>>>> I have a 97, this is for a 98:
>>>>
>>>> "The PCM manages air-conditioning compressor and coolant-fan operation,
>>>> but it has to see the correct incoming signals before sending outgoing
>>>> commands. When the climate-control head is switched to A/C-on mode, a
>>>> signal is sent to the PCM. The PCM must also receive a signal from the
>>>> A/C low- and high-prcoolant-fan operationessure switches before it turns
>>>> on the compressor and/or coolant fan. These switches prevent damage to
>>>> the system. I'm not sure what method you used to check for a sufficient
>>>> charge of R-134a refrigerant, but a low charge will kill the signal from
>>>> the low-pressure switch and therefore prevent the system from working.
>>>> It could be a low refrigerant charge, defective PCM, faulty
>>>> climate-control head, one of the pressure switches on the blink, a break
>>>> in related power, or an issue with the ground circuit wiring."
>>>
>>> The above info is in reference to an ATC system not a manual system.
>>> The wiring is completely different from one to the other. Also, it talks
>>> about the PCM controlling the A/C compressor and the coolant fan. That is
>>> all the PCM controls and it is the same with either system.
>>>
>>>
>>>> http://trucktrend.com/features/advic...rd_ranger.html
>>>>
>>>> Isn't the "coolant-fan operation" the "blower motor" ?
>>>
>>> No. The coolant fan motor is the radiator fan.
>> ah - I was wondering why it was called something other than "blower
>> motor."
>>
>>>> I am hoping for something else besides the PCM between the relay and the
>>>> Battery(-), like an relay or some other $20 part.
>>>> C
>>> The PCM does not have anything to do with the blower motor.
>>>
>>> From what you stated above:
>>>
>>> "Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>> to
>>>>>> the library to confirm - Haynes wiring didn't have it.)
>>>>>>
>>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>>> Powertrain Control Module -- Battery(-)
>>>>>>
>>> That's fairly close. It is actually alot simpler. Bat + -- 40A
>>> fuse -- blower motor -- resistor pack -- switch -- Ground.
>>>
>>> The blower motor switch uses the resistor pack to vary the resistance
>>> on the ground side of the blower motor to change speeds. For high speed
>>> the resistor is bypassed comepletely.
>>>
>>>
>>> From your other post, so this is easier to follow. You stated :
>>>
>>>>> If I hook the far side of the relay to ground, the blower blows.
>>> and I can control the speed with the switch.
>>>
>>> Good Q - how did that happen?
>>> The wiring diagram shows no relay in the circuit at all. Are you shure
>>> that you have a relay ? Were is this relay located ?
>>>
>>>
>> Whoops.
>> Good Q - how did that happen?
>>
>>
>> Bat+ -- 40A fuse -- blower motor -- resistor pack == switch --x- relay
>> switch -y-- PCM? -- Ground.
>>
>> The relay coil side is driven by the ignition switch and the air flow
>> control switch (off and 7 on's: max, norm, bi, vent, heat, heat/def, def)
>>
>> If I ground X, the blower blows and I can adjust the speed with the speed
>> switch: low to high (no off).
>>
>> If I ground Y, the blower only blows when the relay is engaged: ignition
>> and air flow control switch on.
>>
>> If the far side of the relay was just going to ground, where would the
>> wire terminate?
>>
>> The relay is mounted inside the box that the 3 controls are in: fan speed,
>> air flow and hot/cold. if you look at the back of the box, you can see
>> the 4 connectors, you have to disassemble the box to pull the relay out.
>>
>> I am hung up on it going to the PCM just because of the XJ wiring diagram
>> I have. but it is significantly different (like the relay is between the
>> 40A fuse and the motor) , so it won't surprise me if it just goes to
>> ground.
>>
>> Carl K
>>
>
> Carl
>
> I have a wiring diagram and it is not showing a relay in the blower motor
> circuit. It also is not connected to the PCM. Are you sure what you are
> calling a relay is not part of the A/C switch ?
well, it is a relay that is part of the AC/air control assembly
picture of the relay, in it's socket (or whatever you call the place it plugs into)
http://pictures.personnelware.com/ga...g2_itemId=2003
do prev/next to see a bunch of pictures of that assembly.
> I believe that is what you
> are grounding.
I did ground everything on the ground side of the blower :)
> From what you are saying it soumds like you have a bad blower
> motor switch.
except that when I ground 'something' the blower switch functions correctly. I
am not sure a faulty switch would 'work' under some other configuration. Maybe
if the thing was so broken that 2 contacts had a bridge between them it would
get the blower to go, but the low, m1, m2, high wouldn't all work as expected.
> It appears that the ground for the blower switch is opened
> inside the switch. I can send you a copy of the wiring diagram if you have a
> valid email address.
>
>
carl@personnelware.com
Thanks.
> "Carl K" <carl@personnelware.com> wrote in message
> news:LqWdne-5K4JAdiPZnZ2dnUVZ_qmdnZ2d@comcast.com...
>> Mike wrote:
>>> "Carl K" <carl@personnelware.com> wrote in message
>>> news:Ad-dnScCL541OCPZnZ2dnUVZ_qWdnZ2d@comcast.com...
>>>> Mike wrote:
>>>>> "Carl K" <carl@personnelware.com> wrote in message
>>>>> news:pOydnfaDzraa6iPZnZ2dnUVZ_radnZ2d@comcast.com. ..
>>>>>> Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>>>>> to the library to confirm - Haynes wiring didn't have it.)
>>>>>>
>>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>>> Powertrain Control Module -- Battery(-)
>>>>>>
>>>>>> the == is 4 wires, 1 for each speed
>>>>>>
>>>>>> If I hook the far side of the relay to ground, the blower blows. The
>>>>>> relay is controlled by both ignition and vent selector, so just making
>>>>>> a permanent connection to ground would leave me with a fully
>>>>>> functional system.
>>>>>>
>>>>>> But before I go with that hack, wondering if I am missing something?
>>>>>>
>>>>>> The PCM is $480+installation required to program it.
>>>>>>
>>>>>> Will a "diagnostic code reader" ($99 from local auto store) tell me if
>>>>>> the PCM is not letting the blower blow?
>>>>>>
>>>>>> Also, $99 gets me "just numeric codes for '96 and up" but $250 get a
>>>>>> 'delux' that works on "all cars" and gives descriptions. the 97 is
>>>>>> the only car I have that has any sort of diag system (like it will do
>>>>>> my 68 pickup any good) - and I somehow doubt the delux will really
>>>>>> tell me everything I need to know anyway. any comments?
>>>>>>
>>>>>>
>>>>>> Carl K
>>>>> The PCM has nothing to do with your blower motor. What type of heat/
>>>>> A/C controls do you have ? There are two choices, ATM ( Automatic temp
>>>>> control ) or manual control. The wiring is totally different depending
>>>>> on which one you have.
>>>> Manual switches.
>>>>
>>>> I have a 97, this is for a 98:
>>>>
>>>> "The PCM manages air-conditioning compressor and coolant-fan operation,
>>>> but it has to see the correct incoming signals before sending outgoing
>>>> commands. When the climate-control head is switched to A/C-on mode, a
>>>> signal is sent to the PCM. The PCM must also receive a signal from the
>>>> A/C low- and high-prcoolant-fan operationessure switches before it turns
>>>> on the compressor and/or coolant fan. These switches prevent damage to
>>>> the system. I'm not sure what method you used to check for a sufficient
>>>> charge of R-134a refrigerant, but a low charge will kill the signal from
>>>> the low-pressure switch and therefore prevent the system from working.
>>>> It could be a low refrigerant charge, defective PCM, faulty
>>>> climate-control head, one of the pressure switches on the blink, a break
>>>> in related power, or an issue with the ground circuit wiring."
>>>
>>> The above info is in reference to an ATC system not a manual system.
>>> The wiring is completely different from one to the other. Also, it talks
>>> about the PCM controlling the A/C compressor and the coolant fan. That is
>>> all the PCM controls and it is the same with either system.
>>>
>>>
>>>> http://trucktrend.com/features/advic...rd_ranger.html
>>>>
>>>> Isn't the "coolant-fan operation" the "blower motor" ?
>>>
>>> No. The coolant fan motor is the radiator fan.
>> ah - I was wondering why it was called something other than "blower
>> motor."
>>
>>>> I am hoping for something else besides the PCM between the relay and the
>>>> Battery(-), like an relay or some other $20 part.
>>>> C
>>> The PCM does not have anything to do with the blower motor.
>>>
>>> From what you stated above:
>>>
>>> "Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>> to
>>>>>> the library to confirm - Haynes wiring didn't have it.)
>>>>>>
>>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>>> Powertrain Control Module -- Battery(-)
>>>>>>
>>> That's fairly close. It is actually alot simpler. Bat + -- 40A
>>> fuse -- blower motor -- resistor pack -- switch -- Ground.
>>>
>>> The blower motor switch uses the resistor pack to vary the resistance
>>> on the ground side of the blower motor to change speeds. For high speed
>>> the resistor is bypassed comepletely.
>>>
>>>
>>> From your other post, so this is easier to follow. You stated :
>>>
>>>>> If I hook the far side of the relay to ground, the blower blows.
>>> and I can control the speed with the switch.
>>>
>>> Good Q - how did that happen?
>>> The wiring diagram shows no relay in the circuit at all. Are you shure
>>> that you have a relay ? Were is this relay located ?
>>>
>>>
>> Whoops.
>> Good Q - how did that happen?
>>
>>
>> Bat+ -- 40A fuse -- blower motor -- resistor pack == switch --x- relay
>> switch -y-- PCM? -- Ground.
>>
>> The relay coil side is driven by the ignition switch and the air flow
>> control switch (off and 7 on's: max, norm, bi, vent, heat, heat/def, def)
>>
>> If I ground X, the blower blows and I can adjust the speed with the speed
>> switch: low to high (no off).
>>
>> If I ground Y, the blower only blows when the relay is engaged: ignition
>> and air flow control switch on.
>>
>> If the far side of the relay was just going to ground, where would the
>> wire terminate?
>>
>> The relay is mounted inside the box that the 3 controls are in: fan speed,
>> air flow and hot/cold. if you look at the back of the box, you can see
>> the 4 connectors, you have to disassemble the box to pull the relay out.
>>
>> I am hung up on it going to the PCM just because of the XJ wiring diagram
>> I have. but it is significantly different (like the relay is between the
>> 40A fuse and the motor) , so it won't surprise me if it just goes to
>> ground.
>>
>> Carl K
>>
>
> Carl
>
> I have a wiring diagram and it is not showing a relay in the blower motor
> circuit. It also is not connected to the PCM. Are you sure what you are
> calling a relay is not part of the A/C switch ?
well, it is a relay that is part of the AC/air control assembly
picture of the relay, in it's socket (or whatever you call the place it plugs into)
http://pictures.personnelware.com/ga...g2_itemId=2003
do prev/next to see a bunch of pictures of that assembly.
> I believe that is what you
> are grounding.
I did ground everything on the ground side of the blower :)
> From what you are saying it soumds like you have a bad blower
> motor switch.
except that when I ground 'something' the blower switch functions correctly. I
am not sure a faulty switch would 'work' under some other configuration. Maybe
if the thing was so broken that 2 contacts had a bridge between them it would
get the blower to go, but the low, m1, m2, high wouldn't all work as expected.
> It appears that the ground for the blower switch is opened
> inside the switch. I can send you a copy of the wiring diagram if you have a
> valid email address.
>
>
carl@personnelware.com
Thanks.
Guest
Posts: n/a
Re: PCM not letting heat/AC blower blow?
Mike wrote:
> "Carl K" <carl@personnelware.com> wrote in message
> news:LqWdne-5K4JAdiPZnZ2dnUVZ_qmdnZ2d@comcast.com...
>> Mike wrote:
>>> "Carl K" <carl@personnelware.com> wrote in message
>>> news:Ad-dnScCL541OCPZnZ2dnUVZ_qWdnZ2d@comcast.com...
>>>> Mike wrote:
>>>>> "Carl K" <carl@personnelware.com> wrote in message
>>>>> news:pOydnfaDzraa6iPZnZ2dnUVZ_radnZ2d@comcast.com. ..
>>>>>> Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>>>>> to the library to confirm - Haynes wiring didn't have it.)
>>>>>>
>>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>>> Powertrain Control Module -- Battery(-)
>>>>>>
>>>>>> the == is 4 wires, 1 for each speed
>>>>>>
>>>>>> If I hook the far side of the relay to ground, the blower blows. The
>>>>>> relay is controlled by both ignition and vent selector, so just making
>>>>>> a permanent connection to ground would leave me with a fully
>>>>>> functional system.
>>>>>>
>>>>>> But before I go with that hack, wondering if I am missing something?
>>>>>>
>>>>>> The PCM is $480+installation required to program it.
>>>>>>
>>>>>> Will a "diagnostic code reader" ($99 from local auto store) tell me if
>>>>>> the PCM is not letting the blower blow?
>>>>>>
>>>>>> Also, $99 gets me "just numeric codes for '96 and up" but $250 get a
>>>>>> 'delux' that works on "all cars" and gives descriptions. the 97 is
>>>>>> the only car I have that has any sort of diag system (like it will do
>>>>>> my 68 pickup any good) - and I somehow doubt the delux will really
>>>>>> tell me everything I need to know anyway. any comments?
>>>>>>
>>>>>>
>>>>>> Carl K
>>>>> The PCM has nothing to do with your blower motor. What type of heat/
>>>>> A/C controls do you have ? There are two choices, ATM ( Automatic temp
>>>>> control ) or manual control. The wiring is totally different depending
>>>>> on which one you have.
>>>> Manual switches.
>>>>
>>>> I have a 97, this is for a 98:
>>>>
>>>> "The PCM manages air-conditioning compressor and coolant-fan operation,
>>>> but it has to see the correct incoming signals before sending outgoing
>>>> commands. When the climate-control head is switched to A/C-on mode, a
>>>> signal is sent to the PCM. The PCM must also receive a signal from the
>>>> A/C low- and high-prcoolant-fan operationessure switches before it turns
>>>> on the compressor and/or coolant fan. These switches prevent damage to
>>>> the system. I'm not sure what method you used to check for a sufficient
>>>> charge of R-134a refrigerant, but a low charge will kill the signal from
>>>> the low-pressure switch and therefore prevent the system from working.
>>>> It could be a low refrigerant charge, defective PCM, faulty
>>>> climate-control head, one of the pressure switches on the blink, a break
>>>> in related power, or an issue with the ground circuit wiring."
>>>
>>> The above info is in reference to an ATC system not a manual system.
>>> The wiring is completely different from one to the other. Also, it talks
>>> about the PCM controlling the A/C compressor and the coolant fan. That is
>>> all the PCM controls and it is the same with either system.
>>>
>>>
>>>> http://trucktrend.com/features/advic...rd_ranger.html
>>>>
>>>> Isn't the "coolant-fan operation" the "blower motor" ?
>>>
>>> No. The coolant fan motor is the radiator fan.
>> ah - I was wondering why it was called something other than "blower
>> motor."
>>
>>>> I am hoping for something else besides the PCM between the relay and the
>>>> Battery(-), like an relay or some other $20 part.
>>>> C
>>> The PCM does not have anything to do with the blower motor.
>>>
>>> From what you stated above:
>>>
>>> "Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>> to
>>>>>> the library to confirm - Haynes wiring didn't have it.)
>>>>>>
>>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>>> Powertrain Control Module -- Battery(-)
>>>>>>
>>> That's fairly close. It is actually alot simpler. Bat + -- 40A
>>> fuse -- blower motor -- resistor pack -- switch -- Ground.
>>>
>>> The blower motor switch uses the resistor pack to vary the resistance
>>> on the ground side of the blower motor to change speeds. For high speed
>>> the resistor is bypassed comepletely.
>>>
>>>
>>> From your other post, so this is easier to follow. You stated :
>>>
>>>>> If I hook the far side of the relay to ground, the blower blows.
>>> and I can control the speed with the switch.
>>>
>>> Good Q - how did that happen?
>>> The wiring diagram shows no relay in the circuit at all. Are you shure
>>> that you have a relay ? Were is this relay located ?
>>>
>>>
>> Whoops.
>> Good Q - how did that happen?
>>
>>
>> Bat+ -- 40A fuse -- blower motor -- resistor pack == switch --x- relay
>> switch -y-- PCM? -- Ground.
>>
>> The relay coil side is driven by the ignition switch and the air flow
>> control switch (off and 7 on's: max, norm, bi, vent, heat, heat/def, def)
>>
>> If I ground X, the blower blows and I can adjust the speed with the speed
>> switch: low to high (no off).
>>
>> If I ground Y, the blower only blows when the relay is engaged: ignition
>> and air flow control switch on.
>>
>> If the far side of the relay was just going to ground, where would the
>> wire terminate?
>>
>> The relay is mounted inside the box that the 3 controls are in: fan speed,
>> air flow and hot/cold. if you look at the back of the box, you can see
>> the 4 connectors, you have to disassemble the box to pull the relay out.
>>
>> I am hung up on it going to the PCM just because of the XJ wiring diagram
>> I have. but it is significantly different (like the relay is between the
>> 40A fuse and the motor) , so it won't surprise me if it just goes to
>> ground.
>>
>> Carl K
>>
>
> Carl
>
> I have a wiring diagram and it is not showing a relay in the blower motor
> circuit. It also is not connected to the PCM. Are you sure what you are
> calling a relay is not part of the A/C switch ?
well, it is a relay that is part of the AC/air control assembly
picture of the relay, in it's socket (or whatever you call the place it plugs into)
http://pictures.personnelware.com/ga...g2_itemId=2003
do prev/next to see a bunch of pictures of that assembly.
> I believe that is what you
> are grounding.
I did ground everything on the ground side of the blower :)
> From what you are saying it soumds like you have a bad blower
> motor switch.
except that when I ground 'something' the blower switch functions correctly. I
am not sure a faulty switch would 'work' under some other configuration. Maybe
if the thing was so broken that 2 contacts had a bridge between them it would
get the blower to go, but the low, m1, m2, high wouldn't all work as expected.
> It appears that the ground for the blower switch is opened
> inside the switch. I can send you a copy of the wiring diagram if you have a
> valid email address.
>
>
carl@personnelware.com
Thanks.
> "Carl K" <carl@personnelware.com> wrote in message
> news:LqWdne-5K4JAdiPZnZ2dnUVZ_qmdnZ2d@comcast.com...
>> Mike wrote:
>>> "Carl K" <carl@personnelware.com> wrote in message
>>> news:Ad-dnScCL541OCPZnZ2dnUVZ_qWdnZ2d@comcast.com...
>>>> Mike wrote:
>>>>> "Carl K" <carl@personnelware.com> wrote in message
>>>>> news:pOydnfaDzraa6iPZnZ2dnUVZ_radnZ2d@comcast.com. ..
>>>>>> Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>>>>> to the library to confirm - Haynes wiring didn't have it.)
>>>>>>
>>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>>> Powertrain Control Module -- Battery(-)
>>>>>>
>>>>>> the == is 4 wires, 1 for each speed
>>>>>>
>>>>>> If I hook the far side of the relay to ground, the blower blows. The
>>>>>> relay is controlled by both ignition and vent selector, so just making
>>>>>> a permanent connection to ground would leave me with a fully
>>>>>> functional system.
>>>>>>
>>>>>> But before I go with that hack, wondering if I am missing something?
>>>>>>
>>>>>> The PCM is $480+installation required to program it.
>>>>>>
>>>>>> Will a "diagnostic code reader" ($99 from local auto store) tell me if
>>>>>> the PCM is not letting the blower blow?
>>>>>>
>>>>>> Also, $99 gets me "just numeric codes for '96 and up" but $250 get a
>>>>>> 'delux' that works on "all cars" and gives descriptions. the 97 is
>>>>>> the only car I have that has any sort of diag system (like it will do
>>>>>> my 68 pickup any good) - and I somehow doubt the delux will really
>>>>>> tell me everything I need to know anyway. any comments?
>>>>>>
>>>>>>
>>>>>> Carl K
>>>>> The PCM has nothing to do with your blower motor. What type of heat/
>>>>> A/C controls do you have ? There are two choices, ATM ( Automatic temp
>>>>> control ) or manual control. The wiring is totally different depending
>>>>> on which one you have.
>>>> Manual switches.
>>>>
>>>> I have a 97, this is for a 98:
>>>>
>>>> "The PCM manages air-conditioning compressor and coolant-fan operation,
>>>> but it has to see the correct incoming signals before sending outgoing
>>>> commands. When the climate-control head is switched to A/C-on mode, a
>>>> signal is sent to the PCM. The PCM must also receive a signal from the
>>>> A/C low- and high-prcoolant-fan operationessure switches before it turns
>>>> on the compressor and/or coolant fan. These switches prevent damage to
>>>> the system. I'm not sure what method you used to check for a sufficient
>>>> charge of R-134a refrigerant, but a low charge will kill the signal from
>>>> the low-pressure switch and therefore prevent the system from working.
>>>> It could be a low refrigerant charge, defective PCM, faulty
>>>> climate-control head, one of the pressure switches on the blink, a break
>>>> in related power, or an issue with the ground circuit wiring."
>>>
>>> The above info is in reference to an ATC system not a manual system.
>>> The wiring is completely different from one to the other. Also, it talks
>>> about the PCM controlling the A/C compressor and the coolant fan. That is
>>> all the PCM controls and it is the same with either system.
>>>
>>>
>>>> http://trucktrend.com/features/advic...rd_ranger.html
>>>>
>>>> Isn't the "coolant-fan operation" the "blower motor" ?
>>>
>>> No. The coolant fan motor is the radiator fan.
>> ah - I was wondering why it was called something other than "blower
>> motor."
>>
>>>> I am hoping for something else besides the PCM between the relay and the
>>>> Battery(-), like an relay or some other $20 part.
>>>> C
>>> The PCM does not have anything to do with the blower motor.
>>>
>>> From what you stated above:
>>>
>>> "Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>> to
>>>>>> the library to confirm - Haynes wiring didn't have it.)
>>>>>>
>>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>>> Powertrain Control Module -- Battery(-)
>>>>>>
>>> That's fairly close. It is actually alot simpler. Bat + -- 40A
>>> fuse -- blower motor -- resistor pack -- switch -- Ground.
>>>
>>> The blower motor switch uses the resistor pack to vary the resistance
>>> on the ground side of the blower motor to change speeds. For high speed
>>> the resistor is bypassed comepletely.
>>>
>>>
>>> From your other post, so this is easier to follow. You stated :
>>>
>>>>> If I hook the far side of the relay to ground, the blower blows.
>>> and I can control the speed with the switch.
>>>
>>> Good Q - how did that happen?
>>> The wiring diagram shows no relay in the circuit at all. Are you shure
>>> that you have a relay ? Were is this relay located ?
>>>
>>>
>> Whoops.
>> Good Q - how did that happen?
>>
>>
>> Bat+ -- 40A fuse -- blower motor -- resistor pack == switch --x- relay
>> switch -y-- PCM? -- Ground.
>>
>> The relay coil side is driven by the ignition switch and the air flow
>> control switch (off and 7 on's: max, norm, bi, vent, heat, heat/def, def)
>>
>> If I ground X, the blower blows and I can adjust the speed with the speed
>> switch: low to high (no off).
>>
>> If I ground Y, the blower only blows when the relay is engaged: ignition
>> and air flow control switch on.
>>
>> If the far side of the relay was just going to ground, where would the
>> wire terminate?
>>
>> The relay is mounted inside the box that the 3 controls are in: fan speed,
>> air flow and hot/cold. if you look at the back of the box, you can see
>> the 4 connectors, you have to disassemble the box to pull the relay out.
>>
>> I am hung up on it going to the PCM just because of the XJ wiring diagram
>> I have. but it is significantly different (like the relay is between the
>> 40A fuse and the motor) , so it won't surprise me if it just goes to
>> ground.
>>
>> Carl K
>>
>
> Carl
>
> I have a wiring diagram and it is not showing a relay in the blower motor
> circuit. It also is not connected to the PCM. Are you sure what you are
> calling a relay is not part of the A/C switch ?
well, it is a relay that is part of the AC/air control assembly
picture of the relay, in it's socket (or whatever you call the place it plugs into)
http://pictures.personnelware.com/ga...g2_itemId=2003
do prev/next to see a bunch of pictures of that assembly.
> I believe that is what you
> are grounding.
I did ground everything on the ground side of the blower :)
> From what you are saying it soumds like you have a bad blower
> motor switch.
except that when I ground 'something' the blower switch functions correctly. I
am not sure a faulty switch would 'work' under some other configuration. Maybe
if the thing was so broken that 2 contacts had a bridge between them it would
get the blower to go, but the low, m1, m2, high wouldn't all work as expected.
> It appears that the ground for the blower switch is opened
> inside the switch. I can send you a copy of the wiring diagram if you have a
> valid email address.
>
>
carl@personnelware.com
Thanks.
Guest
Posts: n/a
Re: PCM not letting heat/AC blower blow?
Mike wrote:
> "Carl K" <carl@personnelware.com> wrote in message
> news:LqWdne-5K4JAdiPZnZ2dnUVZ_qmdnZ2d@comcast.com...
>> Mike wrote:
>>> "Carl K" <carl@personnelware.com> wrote in message
>>> news:Ad-dnScCL541OCPZnZ2dnUVZ_qWdnZ2d@comcast.com...
>>>> Mike wrote:
>>>>> "Carl K" <carl@personnelware.com> wrote in message
>>>>> news:pOydnfaDzraa6iPZnZ2dnUVZ_radnZ2d@comcast.com. ..
>>>>>> Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>>>>> to the library to confirm - Haynes wiring didn't have it.)
>>>>>>
>>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>>> Powertrain Control Module -- Battery(-)
>>>>>>
>>>>>> the == is 4 wires, 1 for each speed
>>>>>>
>>>>>> If I hook the far side of the relay to ground, the blower blows. The
>>>>>> relay is controlled by both ignition and vent selector, so just making
>>>>>> a permanent connection to ground would leave me with a fully
>>>>>> functional system.
>>>>>>
>>>>>> But before I go with that hack, wondering if I am missing something?
>>>>>>
>>>>>> The PCM is $480+installation required to program it.
>>>>>>
>>>>>> Will a "diagnostic code reader" ($99 from local auto store) tell me if
>>>>>> the PCM is not letting the blower blow?
>>>>>>
>>>>>> Also, $99 gets me "just numeric codes for '96 and up" but $250 get a
>>>>>> 'delux' that works on "all cars" and gives descriptions. the 97 is
>>>>>> the only car I have that has any sort of diag system (like it will do
>>>>>> my 68 pickup any good) - and I somehow doubt the delux will really
>>>>>> tell me everything I need to know anyway. any comments?
>>>>>>
>>>>>>
>>>>>> Carl K
>>>>> The PCM has nothing to do with your blower motor. What type of heat/
>>>>> A/C controls do you have ? There are two choices, ATM ( Automatic temp
>>>>> control ) or manual control. The wiring is totally different depending
>>>>> on which one you have.
>>>> Manual switches.
>>>>
>>>> I have a 97, this is for a 98:
>>>>
>>>> "The PCM manages air-conditioning compressor and coolant-fan operation,
>>>> but it has to see the correct incoming signals before sending outgoing
>>>> commands. When the climate-control head is switched to A/C-on mode, a
>>>> signal is sent to the PCM. The PCM must also receive a signal from the
>>>> A/C low- and high-prcoolant-fan operationessure switches before it turns
>>>> on the compressor and/or coolant fan. These switches prevent damage to
>>>> the system. I'm not sure what method you used to check for a sufficient
>>>> charge of R-134a refrigerant, but a low charge will kill the signal from
>>>> the low-pressure switch and therefore prevent the system from working.
>>>> It could be a low refrigerant charge, defective PCM, faulty
>>>> climate-control head, one of the pressure switches on the blink, a break
>>>> in related power, or an issue with the ground circuit wiring."
>>>
>>> The above info is in reference to an ATC system not a manual system.
>>> The wiring is completely different from one to the other. Also, it talks
>>> about the PCM controlling the A/C compressor and the coolant fan. That is
>>> all the PCM controls and it is the same with either system.
>>>
>>>
>>>> http://trucktrend.com/features/advic...rd_ranger.html
>>>>
>>>> Isn't the "coolant-fan operation" the "blower motor" ?
>>>
>>> No. The coolant fan motor is the radiator fan.
>> ah - I was wondering why it was called something other than "blower
>> motor."
>>
>>>> I am hoping for something else besides the PCM between the relay and the
>>>> Battery(-), like an relay or some other $20 part.
>>>> C
>>> The PCM does not have anything to do with the blower motor.
>>>
>>> From what you stated above:
>>>
>>> "Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>> to
>>>>>> the library to confirm - Haynes wiring didn't have it.)
>>>>>>
>>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>>> Powertrain Control Module -- Battery(-)
>>>>>>
>>> That's fairly close. It is actually alot simpler. Bat + -- 40A
>>> fuse -- blower motor -- resistor pack -- switch -- Ground.
>>>
>>> The blower motor switch uses the resistor pack to vary the resistance
>>> on the ground side of the blower motor to change speeds. For high speed
>>> the resistor is bypassed comepletely.
>>>
>>>
>>> From your other post, so this is easier to follow. You stated :
>>>
>>>>> If I hook the far side of the relay to ground, the blower blows.
>>> and I can control the speed with the switch.
>>>
>>> Good Q - how did that happen?
>>> The wiring diagram shows no relay in the circuit at all. Are you shure
>>> that you have a relay ? Were is this relay located ?
>>>
>>>
>> Whoops.
>> Good Q - how did that happen?
>>
>>
>> Bat+ -- 40A fuse -- blower motor -- resistor pack == switch --x- relay
>> switch -y-- PCM? -- Ground.
>>
>> The relay coil side is driven by the ignition switch and the air flow
>> control switch (off and 7 on's: max, norm, bi, vent, heat, heat/def, def)
>>
>> If I ground X, the blower blows and I can adjust the speed with the speed
>> switch: low to high (no off).
>>
>> If I ground Y, the blower only blows when the relay is engaged: ignition
>> and air flow control switch on.
>>
>> If the far side of the relay was just going to ground, where would the
>> wire terminate?
>>
>> The relay is mounted inside the box that the 3 controls are in: fan speed,
>> air flow and hot/cold. if you look at the back of the box, you can see
>> the 4 connectors, you have to disassemble the box to pull the relay out.
>>
>> I am hung up on it going to the PCM just because of the XJ wiring diagram
>> I have. but it is significantly different (like the relay is between the
>> 40A fuse and the motor) , so it won't surprise me if it just goes to
>> ground.
>>
>> Carl K
>>
>
> Carl
>
> I have a wiring diagram and it is not showing a relay in the blower motor
> circuit. It also is not connected to the PCM. Are you sure what you are
> calling a relay is not part of the A/C switch ?
well, it is a relay that is part of the AC/air control assembly
picture of the relay, in it's socket (or whatever you call the place it plugs into)
http://pictures.personnelware.com/ga...g2_itemId=2003
do prev/next to see a bunch of pictures of that assembly.
> I believe that is what you
> are grounding.
I did ground everything on the ground side of the blower :)
> From what you are saying it soumds like you have a bad blower
> motor switch.
except that when I ground 'something' the blower switch functions correctly. I
am not sure a faulty switch would 'work' under some other configuration. Maybe
if the thing was so broken that 2 contacts had a bridge between them it would
get the blower to go, but the low, m1, m2, high wouldn't all work as expected.
> It appears that the ground for the blower switch is opened
> inside the switch. I can send you a copy of the wiring diagram if you have a
> valid email address.
>
>
carl@personnelware.com
Thanks.
> "Carl K" <carl@personnelware.com> wrote in message
> news:LqWdne-5K4JAdiPZnZ2dnUVZ_qmdnZ2d@comcast.com...
>> Mike wrote:
>>> "Carl K" <carl@personnelware.com> wrote in message
>>> news:Ad-dnScCL541OCPZnZ2dnUVZ_qWdnZ2d@comcast.com...
>>>> Mike wrote:
>>>>> "Carl K" <carl@personnelware.com> wrote in message
>>>>> news:pOydnfaDzraa6iPZnZ2dnUVZ_radnZ2d@comcast.com. ..
>>>>>> Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>>>>> to the library to confirm - Haynes wiring didn't have it.)
>>>>>>
>>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>>> Powertrain Control Module -- Battery(-)
>>>>>>
>>>>>> the == is 4 wires, 1 for each speed
>>>>>>
>>>>>> If I hook the far side of the relay to ground, the blower blows. The
>>>>>> relay is controlled by both ignition and vent selector, so just making
>>>>>> a permanent connection to ground would leave me with a fully
>>>>>> functional system.
>>>>>>
>>>>>> But before I go with that hack, wondering if I am missing something?
>>>>>>
>>>>>> The PCM is $480+installation required to program it.
>>>>>>
>>>>>> Will a "diagnostic code reader" ($99 from local auto store) tell me if
>>>>>> the PCM is not letting the blower blow?
>>>>>>
>>>>>> Also, $99 gets me "just numeric codes for '96 and up" but $250 get a
>>>>>> 'delux' that works on "all cars" and gives descriptions. the 97 is
>>>>>> the only car I have that has any sort of diag system (like it will do
>>>>>> my 68 pickup any good) - and I somehow doubt the delux will really
>>>>>> tell me everything I need to know anyway. any comments?
>>>>>>
>>>>>>
>>>>>> Carl K
>>>>> The PCM has nothing to do with your blower motor. What type of heat/
>>>>> A/C controls do you have ? There are two choices, ATM ( Automatic temp
>>>>> control ) or manual control. The wiring is totally different depending
>>>>> on which one you have.
>>>> Manual switches.
>>>>
>>>> I have a 97, this is for a 98:
>>>>
>>>> "The PCM manages air-conditioning compressor and coolant-fan operation,
>>>> but it has to see the correct incoming signals before sending outgoing
>>>> commands. When the climate-control head is switched to A/C-on mode, a
>>>> signal is sent to the PCM. The PCM must also receive a signal from the
>>>> A/C low- and high-prcoolant-fan operationessure switches before it turns
>>>> on the compressor and/or coolant fan. These switches prevent damage to
>>>> the system. I'm not sure what method you used to check for a sufficient
>>>> charge of R-134a refrigerant, but a low charge will kill the signal from
>>>> the low-pressure switch and therefore prevent the system from working.
>>>> It could be a low refrigerant charge, defective PCM, faulty
>>>> climate-control head, one of the pressure switches on the blink, a break
>>>> in related power, or an issue with the ground circuit wiring."
>>>
>>> The above info is in reference to an ATC system not a manual system.
>>> The wiring is completely different from one to the other. Also, it talks
>>> about the PCM controlling the A/C compressor and the coolant fan. That is
>>> all the PCM controls and it is the same with either system.
>>>
>>>
>>>> http://trucktrend.com/features/advic...rd_ranger.html
>>>>
>>>> Isn't the "coolant-fan operation" the "blower motor" ?
>>>
>>> No. The coolant fan motor is the radiator fan.
>> ah - I was wondering why it was called something other than "blower
>> motor."
>>
>>>> I am hoping for something else besides the PCM between the relay and the
>>>> Battery(-), like an relay or some other $20 part.
>>>> C
>>> The PCM does not have anything to do with the blower motor.
>>>
>>> From what you stated above:
>>>
>>> "Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>> to
>>>>>> the library to confirm - Haynes wiring didn't have it.)
>>>>>>
>>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>>> Powertrain Control Module -- Battery(-)
>>>>>>
>>> That's fairly close. It is actually alot simpler. Bat + -- 40A
>>> fuse -- blower motor -- resistor pack -- switch -- Ground.
>>>
>>> The blower motor switch uses the resistor pack to vary the resistance
>>> on the ground side of the blower motor to change speeds. For high speed
>>> the resistor is bypassed comepletely.
>>>
>>>
>>> From your other post, so this is easier to follow. You stated :
>>>
>>>>> If I hook the far side of the relay to ground, the blower blows.
>>> and I can control the speed with the switch.
>>>
>>> Good Q - how did that happen?
>>> The wiring diagram shows no relay in the circuit at all. Are you shure
>>> that you have a relay ? Were is this relay located ?
>>>
>>>
>> Whoops.
>> Good Q - how did that happen?
>>
>>
>> Bat+ -- 40A fuse -- blower motor -- resistor pack == switch --x- relay
>> switch -y-- PCM? -- Ground.
>>
>> The relay coil side is driven by the ignition switch and the air flow
>> control switch (off and 7 on's: max, norm, bi, vent, heat, heat/def, def)
>>
>> If I ground X, the blower blows and I can adjust the speed with the speed
>> switch: low to high (no off).
>>
>> If I ground Y, the blower only blows when the relay is engaged: ignition
>> and air flow control switch on.
>>
>> If the far side of the relay was just going to ground, where would the
>> wire terminate?
>>
>> The relay is mounted inside the box that the 3 controls are in: fan speed,
>> air flow and hot/cold. if you look at the back of the box, you can see
>> the 4 connectors, you have to disassemble the box to pull the relay out.
>>
>> I am hung up on it going to the PCM just because of the XJ wiring diagram
>> I have. but it is significantly different (like the relay is between the
>> 40A fuse and the motor) , so it won't surprise me if it just goes to
>> ground.
>>
>> Carl K
>>
>
> Carl
>
> I have a wiring diagram and it is not showing a relay in the blower motor
> circuit. It also is not connected to the PCM. Are you sure what you are
> calling a relay is not part of the A/C switch ?
well, it is a relay that is part of the AC/air control assembly
picture of the relay, in it's socket (or whatever you call the place it plugs into)
http://pictures.personnelware.com/ga...g2_itemId=2003
do prev/next to see a bunch of pictures of that assembly.
> I believe that is what you
> are grounding.
I did ground everything on the ground side of the blower :)
> From what you are saying it soumds like you have a bad blower
> motor switch.
except that when I ground 'something' the blower switch functions correctly. I
am not sure a faulty switch would 'work' under some other configuration. Maybe
if the thing was so broken that 2 contacts had a bridge between them it would
get the blower to go, but the low, m1, m2, high wouldn't all work as expected.
> It appears that the ground for the blower switch is opened
> inside the switch. I can send you a copy of the wiring diagram if you have a
> valid email address.
>
>
carl@personnelware.com
Thanks.
Guest
Posts: n/a
Re: PCM not letting heat/AC blower blow?
Mike wrote:
> "Carl K" <carl@personnelware.com> wrote in message
> news:LqWdne-5K4JAdiPZnZ2dnUVZ_qmdnZ2d@comcast.com...
>> Mike wrote:
>>> "Carl K" <carl@personnelware.com> wrote in message
>>> news:Ad-dnScCL541OCPZnZ2dnUVZ_qWdnZ2d@comcast.com...
>>>> Mike wrote:
>>>>> "Carl K" <carl@personnelware.com> wrote in message
>>>>> news:pOydnfaDzraa6iPZnZ2dnUVZ_radnZ2d@comcast.com. ..
>>>>>> Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>>>>> to the library to confirm - Haynes wiring didn't have it.)
>>>>>>
>>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>>> Powertrain Control Module -- Battery(-)
>>>>>>
>>>>>> the == is 4 wires, 1 for each speed
>>>>>>
>>>>>> If I hook the far side of the relay to ground, the blower blows. The
>>>>>> relay is controlled by both ignition and vent selector, so just making
>>>>>> a permanent connection to ground would leave me with a fully
>>>>>> functional system.
>>>>>>
>>>>>> But before I go with that hack, wondering if I am missing something?
>>>>>>
>>>>>> The PCM is $480+installation required to program it.
>>>>>>
>>>>>> Will a "diagnostic code reader" ($99 from local auto store) tell me if
>>>>>> the PCM is not letting the blower blow?
>>>>>>
>>>>>> Also, $99 gets me "just numeric codes for '96 and up" but $250 get a
>>>>>> 'delux' that works on "all cars" and gives descriptions. the 97 is
>>>>>> the only car I have that has any sort of diag system (like it will do
>>>>>> my 68 pickup any good) - and I somehow doubt the delux will really
>>>>>> tell me everything I need to know anyway. any comments?
>>>>>>
>>>>>>
>>>>>> Carl K
>>>>> The PCM has nothing to do with your blower motor. What type of heat/
>>>>> A/C controls do you have ? There are two choices, ATM ( Automatic temp
>>>>> control ) or manual control. The wiring is totally different depending
>>>>> on which one you have.
>>>> Manual switches.
>>>>
>>>> I have a 97, this is for a 98:
>>>>
>>>> "The PCM manages air-conditioning compressor and coolant-fan operation,
>>>> but it has to see the correct incoming signals before sending outgoing
>>>> commands. When the climate-control head is switched to A/C-on mode, a
>>>> signal is sent to the PCM. The PCM must also receive a signal from the
>>>> A/C low- and high-prcoolant-fan operationessure switches before it turns
>>>> on the compressor and/or coolant fan. These switches prevent damage to
>>>> the system. I'm not sure what method you used to check for a sufficient
>>>> charge of R-134a refrigerant, but a low charge will kill the signal from
>>>> the low-pressure switch and therefore prevent the system from working.
>>>> It could be a low refrigerant charge, defective PCM, faulty
>>>> climate-control head, one of the pressure switches on the blink, a break
>>>> in related power, or an issue with the ground circuit wiring."
>>>
>>> The above info is in reference to an ATC system not a manual system.
>>> The wiring is completely different from one to the other. Also, it talks
>>> about the PCM controlling the A/C compressor and the coolant fan. That is
>>> all the PCM controls and it is the same with either system.
>>>
>>>
>>>> http://trucktrend.com/features/advic...rd_ranger.html
>>>>
>>>> Isn't the "coolant-fan operation" the "blower motor" ?
>>>
>>> No. The coolant fan motor is the radiator fan.
>> ah - I was wondering why it was called something other than "blower
>> motor."
>>
>>>> I am hoping for something else besides the PCM between the relay and the
>>>> Battery(-), like an relay or some other $20 part.
>>>> C
>>> The PCM does not have anything to do with the blower motor.
>>>
>>> From what you stated above:
>>>
>>> "Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>> to
>>>>>> the library to confirm - Haynes wiring didn't have it.)
>>>>>>
>>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>>> Powertrain Control Module -- Battery(-)
>>>>>>
>>> That's fairly close. It is actually alot simpler. Bat + -- 40A
>>> fuse -- blower motor -- resistor pack -- switch -- Ground.
>>>
>>> The blower motor switch uses the resistor pack to vary the resistance
>>> on the ground side of the blower motor to change speeds. For high speed
>>> the resistor is bypassed comepletely.
>>>
>>>
>>> From your other post, so this is easier to follow. You stated :
>>>
>>>>> If I hook the far side of the relay to ground, the blower blows.
>>> and I can control the speed with the switch.
>>>
>>> Good Q - how did that happen?
>>> The wiring diagram shows no relay in the circuit at all. Are you shure
>>> that you have a relay ? Were is this relay located ?
>>>
>>>
>> Whoops.
>> Good Q - how did that happen?
>>
>>
>> Bat+ -- 40A fuse -- blower motor -- resistor pack == switch --x- relay
>> switch -y-- PCM? -- Ground.
>>
>> The relay coil side is driven by the ignition switch and the air flow
>> control switch (off and 7 on's: max, norm, bi, vent, heat, heat/def, def)
>>
>> If I ground X, the blower blows and I can adjust the speed with the speed
>> switch: low to high (no off).
>>
>> If I ground Y, the blower only blows when the relay is engaged: ignition
>> and air flow control switch on.
>>
>> If the far side of the relay was just going to ground, where would the
>> wire terminate?
>>
>> The relay is mounted inside the box that the 3 controls are in: fan speed,
>> air flow and hot/cold. if you look at the back of the box, you can see
>> the 4 connectors, you have to disassemble the box to pull the relay out.
>>
>> I am hung up on it going to the PCM just because of the XJ wiring diagram
>> I have. but it is significantly different (like the relay is between the
>> 40A fuse and the motor) , so it won't surprise me if it just goes to
>> ground.
>>
>> Carl K
>>
>
> Carl
>
> I have a wiring diagram and it is not showing a relay in the blower motor
> circuit. It also is not connected to the PCM. Are you sure what you are
> calling a relay is not part of the A/C switch ?
well, it is a relay that is part of the AC/air control assembly
picture of the relay, in it's socket (or whatever you call the place it plugs into)
http://pictures.personnelware.com/ga...g2_itemId=2003
do prev/next to see a bunch of pictures of that assembly.
> I believe that is what you
> are grounding.
I did ground everything on the ground side of the blower :)
> From what you are saying it soumds like you have a bad blower
> motor switch.
except that when I ground 'something' the blower switch functions correctly. I
am not sure a faulty switch would 'work' under some other configuration. Maybe
if the thing was so broken that 2 contacts had a bridge between them it would
get the blower to go, but the low, m1, m2, high wouldn't all work as expected.
> It appears that the ground for the blower switch is opened
> inside the switch. I can send you a copy of the wiring diagram if you have a
> valid email address.
>
>
carl@personnelware.com
Thanks.
> "Carl K" <carl@personnelware.com> wrote in message
> news:LqWdne-5K4JAdiPZnZ2dnUVZ_qmdnZ2d@comcast.com...
>> Mike wrote:
>>> "Carl K" <carl@personnelware.com> wrote in message
>>> news:Ad-dnScCL541OCPZnZ2dnUVZ_qWdnZ2d@comcast.com...
>>>> Mike wrote:
>>>>> "Carl K" <carl@personnelware.com> wrote in message
>>>>> news:pOydnfaDzraa6iPZnZ2dnUVZ_radnZ2d@comcast.com. ..
>>>>>> Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>>>>> to the library to confirm - Haynes wiring didn't have it.)
>>>>>>
>>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>>> Powertrain Control Module -- Battery(-)
>>>>>>
>>>>>> the == is 4 wires, 1 for each speed
>>>>>>
>>>>>> If I hook the far side of the relay to ground, the blower blows. The
>>>>>> relay is controlled by both ignition and vent selector, so just making
>>>>>> a permanent connection to ground would leave me with a fully
>>>>>> functional system.
>>>>>>
>>>>>> But before I go with that hack, wondering if I am missing something?
>>>>>>
>>>>>> The PCM is $480+installation required to program it.
>>>>>>
>>>>>> Will a "diagnostic code reader" ($99 from local auto store) tell me if
>>>>>> the PCM is not letting the blower blow?
>>>>>>
>>>>>> Also, $99 gets me "just numeric codes for '96 and up" but $250 get a
>>>>>> 'delux' that works on "all cars" and gives descriptions. the 97 is
>>>>>> the only car I have that has any sort of diag system (like it will do
>>>>>> my 68 pickup any good) - and I somehow doubt the delux will really
>>>>>> tell me everything I need to know anyway. any comments?
>>>>>>
>>>>>>
>>>>>> Carl K
>>>>> The PCM has nothing to do with your blower motor. What type of heat/
>>>>> A/C controls do you have ? There are two choices, ATM ( Automatic temp
>>>>> control ) or manual control. The wiring is totally different depending
>>>>> on which one you have.
>>>> Manual switches.
>>>>
>>>> I have a 97, this is for a 98:
>>>>
>>>> "The PCM manages air-conditioning compressor and coolant-fan operation,
>>>> but it has to see the correct incoming signals before sending outgoing
>>>> commands. When the climate-control head is switched to A/C-on mode, a
>>>> signal is sent to the PCM. The PCM must also receive a signal from the
>>>> A/C low- and high-prcoolant-fan operationessure switches before it turns
>>>> on the compressor and/or coolant fan. These switches prevent damage to
>>>> the system. I'm not sure what method you used to check for a sufficient
>>>> charge of R-134a refrigerant, but a low charge will kill the signal from
>>>> the low-pressure switch and therefore prevent the system from working.
>>>> It could be a low refrigerant charge, defective PCM, faulty
>>>> climate-control head, one of the pressure switches on the blink, a break
>>>> in related power, or an issue with the ground circuit wiring."
>>>
>>> The above info is in reference to an ATC system not a manual system.
>>> The wiring is completely different from one to the other. Also, it talks
>>> about the PCM controlling the A/C compressor and the coolant fan. That is
>>> all the PCM controls and it is the same with either system.
>>>
>>>
>>>> http://trucktrend.com/features/advic...rd_ranger.html
>>>>
>>>> Isn't the "coolant-fan operation" the "blower motor" ?
>>>
>>> No. The coolant fan motor is the radiator fan.
>> ah - I was wondering why it was called something other than "blower
>> motor."
>>
>>>> I am hoping for something else besides the PCM between the relay and the
>>>> Battery(-), like an relay or some other $20 part.
>>>> C
>>> The PCM does not have anything to do with the blower motor.
>>>
>>> From what you stated above:
>>>
>>> "Pretty sure this is how my 97 Grand Cherokee is wired: (I may make it
>>> to
>>>>>> the library to confirm - Haynes wiring didn't have it.)
>>>>>>
>>>>>> Battery(+) -- 40A fuse -- motor -- resistor pack == switch -- relay --
>>>>>> Powertrain Control Module -- Battery(-)
>>>>>>
>>> That's fairly close. It is actually alot simpler. Bat + -- 40A
>>> fuse -- blower motor -- resistor pack -- switch -- Ground.
>>>
>>> The blower motor switch uses the resistor pack to vary the resistance
>>> on the ground side of the blower motor to change speeds. For high speed
>>> the resistor is bypassed comepletely.
>>>
>>>
>>> From your other post, so this is easier to follow. You stated :
>>>
>>>>> If I hook the far side of the relay to ground, the blower blows.
>>> and I can control the speed with the switch.
>>>
>>> Good Q - how did that happen?
>>> The wiring diagram shows no relay in the circuit at all. Are you shure
>>> that you have a relay ? Were is this relay located ?
>>>
>>>
>> Whoops.
>> Good Q - how did that happen?
>>
>>
>> Bat+ -- 40A fuse -- blower motor -- resistor pack == switch --x- relay
>> switch -y-- PCM? -- Ground.
>>
>> The relay coil side is driven by the ignition switch and the air flow
>> control switch (off and 7 on's: max, norm, bi, vent, heat, heat/def, def)
>>
>> If I ground X, the blower blows and I can adjust the speed with the speed
>> switch: low to high (no off).
>>
>> If I ground Y, the blower only blows when the relay is engaged: ignition
>> and air flow control switch on.
>>
>> If the far side of the relay was just going to ground, where would the
>> wire terminate?
>>
>> The relay is mounted inside the box that the 3 controls are in: fan speed,
>> air flow and hot/cold. if you look at the back of the box, you can see
>> the 4 connectors, you have to disassemble the box to pull the relay out.
>>
>> I am hung up on it going to the PCM just because of the XJ wiring diagram
>> I have. but it is significantly different (like the relay is between the
>> 40A fuse and the motor) , so it won't surprise me if it just goes to
>> ground.
>>
>> Carl K
>>
>
> Carl
>
> I have a wiring diagram and it is not showing a relay in the blower motor
> circuit. It also is not connected to the PCM. Are you sure what you are
> calling a relay is not part of the A/C switch ?
well, it is a relay that is part of the AC/air control assembly
picture of the relay, in it's socket (or whatever you call the place it plugs into)
http://pictures.personnelware.com/ga...g2_itemId=2003
do prev/next to see a bunch of pictures of that assembly.
> I believe that is what you
> are grounding.
I did ground everything on the ground side of the blower :)
> From what you are saying it soumds like you have a bad blower
> motor switch.
except that when I ground 'something' the blower switch functions correctly. I
am not sure a faulty switch would 'work' under some other configuration. Maybe
if the thing was so broken that 2 contacts had a bridge between them it would
get the blower to go, but the low, m1, m2, high wouldn't all work as expected.
> It appears that the ground for the blower switch is opened
> inside the switch. I can send you a copy of the wiring diagram if you have a
> valid email address.
>
>
carl@personnelware.com
Thanks.
Guest
Posts: n/a
Re: PCM not letting heat/AC blower blow?
This looks like a subset of what I have been working from
"The blower motor relay is installed in a wire har-
ness connector that is secured to the passenger side
outboard end of the HVAC housing in the passenger
compartment, next to the HVAC wire harness con-
nector."
No, it isn't. I even pulled the glove box apart just to be sure.
But thanks anyway.
Carl K
L.W.(Bill) ------ III wrote:
> http://www.----------.com/blower.pdf
> God Bless America, Bill O|||||||O
> mailto:--------------------
>
> Carl K wrote:
>> Whoops.
>> Good Q - how did that happen?
>>
>> Bat+ -- 40A fuse -- blower motor -- resistor pack == switch --x- relay switch
>> -y-- PCM? -- Ground.
>>
>> The relay coil side is driven by the ignition switch and the air flow control
>> switch (off and 7 on's: max, norm, bi, vent, heat, heat/def, def)
>>
>> If I ground X, the blower blows and I can adjust the speed with the speed
>> switch: low to high (no off).
>>
>> If I ground Y, the blower only blows when the relay is engaged: ignition and air
>> flow control switch on.
>>
>> If the far side of the relay was just going to ground, where would the wire
>> terminate?
>>
>> The relay is mounted inside the box that the 3 controls are in: fan speed, air
>> flow and hot/cold. if you look at the back of the box, you can see the 4
>> connectors, you have to disassemble the box to pull the relay out.
>>
>> I am hung up on it going to the PCM just because of the XJ wiring diagram I
>> have. but it is significantly different (like the relay is between the 40A
>> fuse and the motor) , so it won't surprise me if it just goes to ground.
>>
>> Carl K
"The blower motor relay is installed in a wire har-
ness connector that is secured to the passenger side
outboard end of the HVAC housing in the passenger
compartment, next to the HVAC wire harness con-
nector."
No, it isn't. I even pulled the glove box apart just to be sure.
But thanks anyway.
Carl K
L.W.(Bill) ------ III wrote:
> http://www.----------.com/blower.pdf
> God Bless America, Bill O|||||||O
> mailto:--------------------
>
> Carl K wrote:
>> Whoops.
>> Good Q - how did that happen?
>>
>> Bat+ -- 40A fuse -- blower motor -- resistor pack == switch --x- relay switch
>> -y-- PCM? -- Ground.
>>
>> The relay coil side is driven by the ignition switch and the air flow control
>> switch (off and 7 on's: max, norm, bi, vent, heat, heat/def, def)
>>
>> If I ground X, the blower blows and I can adjust the speed with the speed
>> switch: low to high (no off).
>>
>> If I ground Y, the blower only blows when the relay is engaged: ignition and air
>> flow control switch on.
>>
>> If the far side of the relay was just going to ground, where would the wire
>> terminate?
>>
>> The relay is mounted inside the box that the 3 controls are in: fan speed, air
>> flow and hot/cold. if you look at the back of the box, you can see the 4
>> connectors, you have to disassemble the box to pull the relay out.
>>
>> I am hung up on it going to the PCM just because of the XJ wiring diagram I
>> have. but it is significantly different (like the relay is between the 40A
>> fuse and the motor) , so it won't surprise me if it just goes to ground.
>>
>> Carl K
Guest
Posts: n/a
Re: PCM not letting heat/AC blower blow?
This looks like a subset of what I have been working from
"The blower motor relay is installed in a wire har-
ness connector that is secured to the passenger side
outboard end of the HVAC housing in the passenger
compartment, next to the HVAC wire harness con-
nector."
No, it isn't. I even pulled the glove box apart just to be sure.
But thanks anyway.
Carl K
L.W.(Bill) ------ III wrote:
> http://www.----------.com/blower.pdf
> God Bless America, Bill O|||||||O
> mailto:--------------------
>
> Carl K wrote:
>> Whoops.
>> Good Q - how did that happen?
>>
>> Bat+ -- 40A fuse -- blower motor -- resistor pack == switch --x- relay switch
>> -y-- PCM? -- Ground.
>>
>> The relay coil side is driven by the ignition switch and the air flow control
>> switch (off and 7 on's: max, norm, bi, vent, heat, heat/def, def)
>>
>> If I ground X, the blower blows and I can adjust the speed with the speed
>> switch: low to high (no off).
>>
>> If I ground Y, the blower only blows when the relay is engaged: ignition and air
>> flow control switch on.
>>
>> If the far side of the relay was just going to ground, where would the wire
>> terminate?
>>
>> The relay is mounted inside the box that the 3 controls are in: fan speed, air
>> flow and hot/cold. if you look at the back of the box, you can see the 4
>> connectors, you have to disassemble the box to pull the relay out.
>>
>> I am hung up on it going to the PCM just because of the XJ wiring diagram I
>> have. but it is significantly different (like the relay is between the 40A
>> fuse and the motor) , so it won't surprise me if it just goes to ground.
>>
>> Carl K
"The blower motor relay is installed in a wire har-
ness connector that is secured to the passenger side
outboard end of the HVAC housing in the passenger
compartment, next to the HVAC wire harness con-
nector."
No, it isn't. I even pulled the glove box apart just to be sure.
But thanks anyway.
Carl K
L.W.(Bill) ------ III wrote:
> http://www.----------.com/blower.pdf
> God Bless America, Bill O|||||||O
> mailto:--------------------
>
> Carl K wrote:
>> Whoops.
>> Good Q - how did that happen?
>>
>> Bat+ -- 40A fuse -- blower motor -- resistor pack == switch --x- relay switch
>> -y-- PCM? -- Ground.
>>
>> The relay coil side is driven by the ignition switch and the air flow control
>> switch (off and 7 on's: max, norm, bi, vent, heat, heat/def, def)
>>
>> If I ground X, the blower blows and I can adjust the speed with the speed
>> switch: low to high (no off).
>>
>> If I ground Y, the blower only blows when the relay is engaged: ignition and air
>> flow control switch on.
>>
>> If the far side of the relay was just going to ground, where would the wire
>> terminate?
>>
>> The relay is mounted inside the box that the 3 controls are in: fan speed, air
>> flow and hot/cold. if you look at the back of the box, you can see the 4
>> connectors, you have to disassemble the box to pull the relay out.
>>
>> I am hung up on it going to the PCM just because of the XJ wiring diagram I
>> have. but it is significantly different (like the relay is between the 40A
>> fuse and the motor) , so it won't surprise me if it just goes to ground.
>>
>> Carl K
Guest
Posts: n/a
Re: PCM not letting heat/AC blower blow?
This looks like a subset of what I have been working from
"The blower motor relay is installed in a wire har-
ness connector that is secured to the passenger side
outboard end of the HVAC housing in the passenger
compartment, next to the HVAC wire harness con-
nector."
No, it isn't. I even pulled the glove box apart just to be sure.
But thanks anyway.
Carl K
L.W.(Bill) ------ III wrote:
> http://www.----------.com/blower.pdf
> God Bless America, Bill O|||||||O
> mailto:--------------------
>
> Carl K wrote:
>> Whoops.
>> Good Q - how did that happen?
>>
>> Bat+ -- 40A fuse -- blower motor -- resistor pack == switch --x- relay switch
>> -y-- PCM? -- Ground.
>>
>> The relay coil side is driven by the ignition switch and the air flow control
>> switch (off and 7 on's: max, norm, bi, vent, heat, heat/def, def)
>>
>> If I ground X, the blower blows and I can adjust the speed with the speed
>> switch: low to high (no off).
>>
>> If I ground Y, the blower only blows when the relay is engaged: ignition and air
>> flow control switch on.
>>
>> If the far side of the relay was just going to ground, where would the wire
>> terminate?
>>
>> The relay is mounted inside the box that the 3 controls are in: fan speed, air
>> flow and hot/cold. if you look at the back of the box, you can see the 4
>> connectors, you have to disassemble the box to pull the relay out.
>>
>> I am hung up on it going to the PCM just because of the XJ wiring diagram I
>> have. but it is significantly different (like the relay is between the 40A
>> fuse and the motor) , so it won't surprise me if it just goes to ground.
>>
>> Carl K
"The blower motor relay is installed in a wire har-
ness connector that is secured to the passenger side
outboard end of the HVAC housing in the passenger
compartment, next to the HVAC wire harness con-
nector."
No, it isn't. I even pulled the glove box apart just to be sure.
But thanks anyway.
Carl K
L.W.(Bill) ------ III wrote:
> http://www.----------.com/blower.pdf
> God Bless America, Bill O|||||||O
> mailto:--------------------
>
> Carl K wrote:
>> Whoops.
>> Good Q - how did that happen?
>>
>> Bat+ -- 40A fuse -- blower motor -- resistor pack == switch --x- relay switch
>> -y-- PCM? -- Ground.
>>
>> The relay coil side is driven by the ignition switch and the air flow control
>> switch (off and 7 on's: max, norm, bi, vent, heat, heat/def, def)
>>
>> If I ground X, the blower blows and I can adjust the speed with the speed
>> switch: low to high (no off).
>>
>> If I ground Y, the blower only blows when the relay is engaged: ignition and air
>> flow control switch on.
>>
>> If the far side of the relay was just going to ground, where would the wire
>> terminate?
>>
>> The relay is mounted inside the box that the 3 controls are in: fan speed, air
>> flow and hot/cold. if you look at the back of the box, you can see the 4
>> connectors, you have to disassemble the box to pull the relay out.
>>
>> I am hung up on it going to the PCM just because of the XJ wiring diagram I
>> have. but it is significantly different (like the relay is between the 40A
>> fuse and the motor) , so it won't surprise me if it just goes to ground.
>>
>> Carl K
