Cherokee Heating problem
 

Hi -

My son has a 1994 Jeep Cherokee and the heater has stopped blowing
warm air. The A/C works fine; however, when he switches it to "heat" -
only cool air comes out.

There doesn't appear to be any leak in the Heater Core - Since I'm
not sure if any fuses control the heater - I checked all of them since
I couldn't find a schematic or diagram listing what each fuse is for -
but all the fuses are fine.

He took it to a dealer for an estimate - they quickly said it was
probably the water pump, hoses, T-Stat and would cost about $700.

I know next to nothing about auto repairs except what i have
experienced in the cars I have owned over the years - but it strikes
me as odd that we never saw any water or any other liquid leaking
which perplexes me a bit if they said the water pump was leaking - and
I also don't understand the connection between the water pump and
heater. Since the A/C works fine - and the heater blows air - just
cool and not warm/hot - It's a bit confusing for me.

Does it sound reasonable what the dealership claims is the problem -
if so, does their quote seem reasonable? - and if it isn't a "leaky"
water pump - any ideas on that the problem could be?

Thanks so much in advance and will rely on your input to determine
if he should take it back to the dealer for the new water pump -
or ????

Rick

Re: Cherokee Heating problem
 

Nightcheck wrote:
> Hi -
>
> My son has a 1994 Jeep Cherokee and the heater has stopped blowing
> warm air. The A/C works fine; however, when he switches it to "heat" -
> only cool air comes out.
>
> There doesn't appear to be any leak in the Heater Core - Since I'm
> not sure if any fuses control the heater - I checked all of them since
> I couldn't find a schematic or diagram listing what each fuse is for -
> but all the fuses are fine.
>
> He took it to a dealer for an estimate - they quickly said it was
> probably the water pump, hoses, T-Stat and would cost about $700.

Run away, your dealer is quite possibly a moron.

After you run the engine for a while, pop the hood and feel the
heater lines that run from the water pump back to the firewall.
If they are hot then you have circulation. I'd check after a run
to the mall or something. It is very rare for a heater core to plug
and not have other problems (like overheating from a plugged radiator)

The temperature blend door is likely your problem. I'm not exactly
sure about your XJ, but in the 93 ZJ the blend door is controlled
by a stepper motor. Usually you can hear the motor move as you
turn the heater knob from cool to hot.

The blend door motor to arm connector is known to pop off and the
arm can also break. That requires getting under the airbox and
looking. I don't have a picture, hopefully someone else here has
a photo or can tell you were to look. In the ZJ it's a pain in
the ass to get at.


--
DougW

Re: Cherokee Heating problem
 

Nightcheck wrote:
> Hi -
>
> My son has a 1994 Jeep Cherokee and the heater has stopped blowing
> warm air. The A/C works fine; however, when he switches it to "heat" -
> only cool air comes out.
>
> There doesn't appear to be any leak in the Heater Core - Since I'm
> not sure if any fuses control the heater - I checked all of them since
> I couldn't find a schematic or diagram listing what each fuse is for -
> but all the fuses are fine.
>
> He took it to a dealer for an estimate - they quickly said it was
> probably the water pump, hoses, T-Stat and would cost about $700.

Run away, your dealer is quite possibly a moron.

After you run the engine for a while, pop the hood and feel the
heater lines that run from the water pump back to the firewall.
If they are hot then you have circulation. I'd check after a run
to the mall or something. It is very rare for a heater core to plug
and not have other problems (like overheating from a plugged radiator)

The temperature blend door is likely your problem. I'm not exactly
sure about your XJ, but in the 93 ZJ the blend door is controlled
by a stepper motor. Usually you can hear the motor move as you
turn the heater knob from cool to hot.

The blend door motor to arm connector is known to pop off and the
arm can also break. That requires getting under the airbox and
looking. I don't have a picture, hopefully someone else here has
a photo or can tell you were to look. In the ZJ it's a pain in
the ass to get at.


--
DougW

Re: Cherokee Heating problem
 

Nightcheck wrote:
> Hi -
>
> My son has a 1994 Jeep Cherokee and the heater has stopped blowing
> warm air. The A/C works fine; however, when he switches it to "heat" -
> only cool air comes out.
>
> There doesn't appear to be any leak in the Heater Core - Since I'm
> not sure if any fuses control the heater - I checked all of them since
> I couldn't find a schematic or diagram listing what each fuse is for -
> but all the fuses are fine.
>
> He took it to a dealer for an estimate - they quickly said it was
> probably the water pump, hoses, T-Stat and would cost about $700.

Run away, your dealer is quite possibly a moron.

After you run the engine for a while, pop the hood and feel the
heater lines that run from the water pump back to the firewall.
If they are hot then you have circulation. I'd check after a run
to the mall or something. It is very rare for a heater core to plug
and not have other problems (like overheating from a plugged radiator)

The temperature blend door is likely your problem. I'm not exactly
sure about your XJ, but in the 93 ZJ the blend door is controlled
by a stepper motor. Usually you can hear the motor move as you
turn the heater knob from cool to hot.

The blend door motor to arm connector is known to pop off and the
arm can also break. That requires getting under the airbox and
looking. I don't have a picture, hopefully someone else here has
a photo or can tell you were to look. In the ZJ it's a pain in
the ass to get at.


--
DougW

Re: Cherokee Heating problem
 

Nightcheck wrote:
> Hi -
>
> My son has a 1994 Jeep Cherokee and the heater has stopped blowing
> warm air. The A/C works fine; however, when he switches it to "heat" -
> only cool air comes out.
>
> There doesn't appear to be any leak in the Heater Core - Since I'm
> not sure if any fuses control the heater - I checked all of them since
> I couldn't find a schematic or diagram listing what each fuse is for -
> but all the fuses are fine.
>
> He took it to a dealer for an estimate - they quickly said it was
> probably the water pump, hoses, T-Stat and would cost about $700.

Run away, your dealer is quite possibly a moron.

After you run the engine for a while, pop the hood and feel the
heater lines that run from the water pump back to the firewall.
If they are hot then you have circulation. I'd check after a run
to the mall or something. It is very rare for a heater core to plug
and not have other problems (like overheating from a plugged radiator)

The temperature blend door is likely your problem. I'm not exactly
sure about your XJ, but in the 93 ZJ the blend door is controlled
by a stepper motor. Usually you can hear the motor move as you
turn the heater knob from cool to hot.

The blend door motor to arm connector is known to pop off and the
arm can also break. That requires getting under the airbox and
looking. I don't have a picture, hopefully someone else here has
a photo or can tell you were to look. In the ZJ it's a pain in
the ass to get at.


--
DougW

Re: Cherokee Heating problem
 

You can eliminate the thermostat as a source of the problem if the engine
reaches normal operating temperature. You can eliminate the water pump if
the radiator does not boil over. The hoses may or may not need to be
replaced because of age, but that would have nothing to do with the heater.
These guys are shooting in the dark, hoping that if they replace everything
your problem will just go away.

It is more likely that your heater temperature control has stopped working.
I am not familiar with the Cherokee, but there are basically four types,
vacuum operated air door and coolant valve, and cable operated air door and
coolant valve. If this is the problem you have, a cable is bent or broken
or a vacuum servo has given up the ghost. A quick test is to warm up the
engine and check whether the heater hoses are hot or not. If they are hot
then there is an air blockage. I am sure that someone who owns one of these
critters will chip in here.

Another possibility is heater core clogged with dirt, so either air or
coolant can't get through it.

It is likely that you can have your water pump, hoses and thermostat all
replaced, and the heater still won't work.

Earle

"Nightcheck" <Nightcheck@cox.net> wrote in message
news:1170203137.781487.307450@h3g2000cwc.googlegro ups.com...
> Hi -
>
> My son has a 1994 Jeep Cherokee and the heater has stopped blowing
> warm air. The A/C works fine; however, when he switches it to "heat" -
> only cool air comes out.
>
> There doesn't appear to be any leak in the Heater Core - Since I'm
> not sure if any fuses control the heater - I checked all of them since
> I couldn't find a schematic or diagram listing what each fuse is for -
> but all the fuses are fine.
>
> He took it to a dealer for an estimate - they quickly said it was
> probably the water pump, hoses, T-Stat and would cost about $700.
>
> I know next to nothing about auto repairs except what i have
> experienced in the cars I have owned over the years - but it strikes
> me as odd that we never saw any water or any other liquid leaking
> which perplexes me a bit if they said the water pump was leaking - and
> I also don't understand the connection between the water pump and
> heater. Since the A/C works fine - and the heater blows air - just
> cool and not warm/hot - It's a bit confusing for me.
>
> Does it sound reasonable what the dealership claims is the problem -
> if so, does their quote seem reasonable? - and if it isn't a "leaky"
> water pump - any ideas on that the problem could be?
>
> Thanks so much in advance and will rely on your input to determine
> if he should take it back to the dealer for the new water pump -
> or ????
>
> Rick
>

Re: Cherokee Heating problem
 

You can eliminate the thermostat as a source of the problem if the engine
reaches normal operating temperature. You can eliminate the water pump if
the radiator does not boil over. The hoses may or may not need to be
replaced because of age, but that would have nothing to do with the heater.
These guys are shooting in the dark, hoping that if they replace everything
your problem will just go away.

It is more likely that your heater temperature control has stopped working.
I am not familiar with the Cherokee, but there are basically four types,
vacuum operated air door and coolant valve, and cable operated air door and
coolant valve. If this is the problem you have, a cable is bent or broken
or a vacuum servo has given up the ghost. A quick test is to warm up the
engine and check whether the heater hoses are hot or not. If they are hot
then there is an air blockage. I am sure that someone who owns one of these
critters will chip in here.

Another possibility is heater core clogged with dirt, so either air or
coolant can't get through it.

It is likely that you can have your water pump, hoses and thermostat all
replaced, and the heater still won't work.

Earle

"Nightcheck" <Nightcheck@cox.net> wrote in message
news:1170203137.781487.307450@h3g2000cwc.googlegro ups.com...
> Hi -
>
> My son has a 1994 Jeep Cherokee and the heater has stopped blowing
> warm air. The A/C works fine; however, when he switches it to "heat" -
> only cool air comes out.
>
> There doesn't appear to be any leak in the Heater Core - Since I'm
> not sure if any fuses control the heater - I checked all of them since
> I couldn't find a schematic or diagram listing what each fuse is for -
> but all the fuses are fine.
>
> He took it to a dealer for an estimate - they quickly said it was
> probably the water pump, hoses, T-Stat and would cost about $700.
>
> I know next to nothing about auto repairs except what i have
> experienced in the cars I have owned over the years - but it strikes
> me as odd that we never saw any water or any other liquid leaking
> which perplexes me a bit if they said the water pump was leaking - and
> I also don't understand the connection between the water pump and
> heater. Since the A/C works fine - and the heater blows air - just
> cool and not warm/hot - It's a bit confusing for me.
>
> Does it sound reasonable what the dealership claims is the problem -
> if so, does their quote seem reasonable? - and if it isn't a "leaky"
> water pump - any ideas on that the problem could be?
>
> Thanks so much in advance and will rely on your input to determine
> if he should take it back to the dealer for the new water pump -
> or ????
>
> Rick
>

Re: Cherokee Heating problem
 

You can eliminate the thermostat as a source of the problem if the engine
reaches normal operating temperature. You can eliminate the water pump if
the radiator does not boil over. The hoses may or may not need to be
replaced because of age, but that would have nothing to do with the heater.
These guys are shooting in the dark, hoping that if they replace everything
your problem will just go away.

It is more likely that your heater temperature control has stopped working.
I am not familiar with the Cherokee, but there are basically four types,
vacuum operated air door and coolant valve, and cable operated air door and
coolant valve. If this is the problem you have, a cable is bent or broken
or a vacuum servo has given up the ghost. A quick test is to warm up the
engine and check whether the heater hoses are hot or not. If they are hot
then there is an air blockage. I am sure that someone who owns one of these
critters will chip in here.

Another possibility is heater core clogged with dirt, so either air or
coolant can't get through it.

It is likely that you can have your water pump, hoses and thermostat all
replaced, and the heater still won't work.

Earle

"Nightcheck" <Nightcheck@cox.net> wrote in message
news:1170203137.781487.307450@h3g2000cwc.googlegro ups.com...
> Hi -
>
> My son has a 1994 Jeep Cherokee and the heater has stopped blowing
> warm air. The A/C works fine; however, when he switches it to "heat" -
> only cool air comes out.
>
> There doesn't appear to be any leak in the Heater Core - Since I'm
> not sure if any fuses control the heater - I checked all of them since
> I couldn't find a schematic or diagram listing what each fuse is for -
> but all the fuses are fine.
>
> He took it to a dealer for an estimate - they quickly said it was
> probably the water pump, hoses, T-Stat and would cost about $700.
>
> I know next to nothing about auto repairs except what i have
> experienced in the cars I have owned over the years - but it strikes
> me as odd that we never saw any water or any other liquid leaking
> which perplexes me a bit if they said the water pump was leaking - and
> I also don't understand the connection between the water pump and
> heater. Since the A/C works fine - and the heater blows air - just
> cool and not warm/hot - It's a bit confusing for me.
>
> Does it sound reasonable what the dealership claims is the problem -
> if so, does their quote seem reasonable? - and if it isn't a "leaky"
> water pump - any ideas on that the problem could be?
>
> Thanks so much in advance and will rely on your input to determine
> if he should take it back to the dealer for the new water pump -
> or ????
>
> Rick
>

Re: Cherokee Heating problem
 

You can eliminate the thermostat as a source of the problem if the engine
reaches normal operating temperature. You can eliminate the water pump if
the radiator does not boil over. The hoses may or may not need to be
replaced because of age, but that would have nothing to do with the heater.
These guys are shooting in the dark, hoping that if they replace everything
your problem will just go away.

It is more likely that your heater temperature control has stopped working.
I am not familiar with the Cherokee, but there are basically four types,
vacuum operated air door and coolant valve, and cable operated air door and
coolant valve. If this is the problem you have, a cable is bent or broken
or a vacuum servo has given up the ghost. A quick test is to warm up the
engine and check whether the heater hoses are hot or not. If they are hot
then there is an air blockage. I am sure that someone who owns one of these
critters will chip in here.

Another possibility is heater core clogged with dirt, so either air or
coolant can't get through it.

It is likely that you can have your water pump, hoses and thermostat all
replaced, and the heater still won't work.

Earle

"Nightcheck" <Nightcheck@cox.net> wrote in message
news:1170203137.781487.307450@h3g2000cwc.googlegro ups.com...
> Hi -
>
> My son has a 1994 Jeep Cherokee and the heater has stopped blowing
> warm air. The A/C works fine; however, when he switches it to "heat" -
> only cool air comes out.
>
> There doesn't appear to be any leak in the Heater Core - Since I'm
> not sure if any fuses control the heater - I checked all of them since
> I couldn't find a schematic or diagram listing what each fuse is for -
> but all the fuses are fine.
>
> He took it to a dealer for an estimate - they quickly said it was
> probably the water pump, hoses, T-Stat and would cost about $700.
>
> I know next to nothing about auto repairs except what i have
> experienced in the cars I have owned over the years - but it strikes
> me as odd that we never saw any water or any other liquid leaking
> which perplexes me a bit if they said the water pump was leaking - and
> I also don't understand the connection between the water pump and
> heater. Since the A/C works fine - and the heater blows air - just
> cool and not warm/hot - It's a bit confusing for me.
>
> Does it sound reasonable what the dealership claims is the problem -
> if so, does their quote seem reasonable? - and if it isn't a "leaky"
> water pump - any ideas on that the problem could be?
>
> Thanks so much in advance and will rely on your input to determine
> if he should take it back to the dealer for the new water pump -
> or ????
>
> Rick
>

Re: Cherokee Heating problem
 

Nightcheck proclaimed:

> Hi -
>
> My son has a 1994 Jeep Cherokee and the heater has stopped blowing
> warm air. The A/C works fine; however, when he switches it to "heat" -
> only cool air comes out.
>
> There doesn't appear to be any leak in the Heater Core - Since I'm
> not sure if any fuses control the heater - I checked all of them since
> I couldn't find a schematic or diagram listing what each fuse is for -
> but all the fuses are fine.
>
> He took it to a dealer for an estimate - they quickly said it was
> probably the water pump, hoses, T-Stat and would cost about $700.
>
> I know next to nothing about auto repairs except what i have
> experienced in the cars I have owned over the years - but it strikes
> me as odd that we never saw any water or any other liquid leaking
> which perplexes me a bit if they said the water pump was leaking - and
> I also don't understand the connection between the water pump and
> heater. Since the A/C works fine - and the heater blows air - just
> cool and not warm/hot - It's a bit confusing for me.
>
> Does it sound reasonable what the dealership claims is the problem -
> if so, does their quote seem reasonable? - and if it isn't a "leaky"
> water pump - any ideas on that the problem could be?
>
> Thanks so much in advance and will rely on your input to determine
> if he should take it back to the dealer for the new water pump -
> or ????

Does the temperature guage show the engine is getting hot?

Coolant nice and fresh or all crudded up?

If you check the hoses going to the heater core, do they get hot?
Suspect your thermostat has a bypass, so even a closed thermostat
shouldn't cause loss of heat. I would think a bad water pump would
cause engine overheat unless it is extremely cold.

Got any fluid flow in the radiator?

You could temporarily pull the hose at the heater inlet and see if you
get flow [into a big container].