1996 XJ 4.0 Cherokee Heater Controls, Heater Lukewarm
 

I'm troubleshooting a lukewarm heater problem and a couple questions
have arisen which I haven't found answers to.

First - the vacuum valves and heater slider flap (thing) under the dash
all seem to be working correctly, just to make sure I also verified
there are no climate control/vacuum leaks - connected a vacuum pump to
the vacuum source line going into the Heater/AC unit from the line to
the intake manifold & tank. I moved the climate control switch to each
position and pumped up vacuum - the valve works for each and vacuum
holds, good.
I did notice that the heater valve is "off" (bypass) when the climate
control switch is off, "on" (no heater core bypass) for all other
positions (AC, Vent, Heat, Defrost, etc.), not sure if this is normal.

Questions, any insight would be most appreciated:

I have read where the heater can blow only lukewarm air in the cab if
air is trapped in the core or hoses. Does anyone have suggestions on a
good way to purge air from the heater lines/core?

Can someone verify how the heater hoses are supposed to connect to the
heater control valve under the hood? I bought the XJ used and it had a
wrong valve installed, so I couldn't hook the (hopefully) new/correct
one (from my local dealer) same as the old one. Mine is currently:
With valve on side facing you, two parallel in vertical plane fittings
on right side going to engine - upper to thermostat housing, lower to
water pump, two fittings on left side at odd angles and down lower than
the ones on the right - lower of these going to upper heater core tube,
upper of these going to lower heater core tube. The main reason for
this is - I bought all new factory hoses and valve, and with various
fitting sizes (some 5/8, some 11/16) and hose angles, this
configuration seemed to match up, but I haven't found a picture to see
if I have them right.

Can someone see if this is normal for the heater valve control from the
climate control vacuum switch:
Climate control switch in any other than in the Off position, vacuum
applied to heater valve and sending hot water thru heater core.
Climate control switch in Off position, vacuum removed from heater
valve and bypassing the heater core.

Thanks - KR

Re: 1996 XJ 4.0 Cherokee Heater Controls, Heater Lukewarm
 

A thought ... does your temp gauge indicate heat (mine reads around 100C ...
cdn, eh)? The previous owner could even have removed the thermostat.

Re: 1996 XJ 4.0 Cherokee Heater Controls, Heater Lukewarm
 

A thought ... does your temp gauge indicate heat (mine reads around 100C ...
cdn, eh)? The previous owner could even have removed the thermostat.

Re: 1996 XJ 4.0 Cherokee Heater Controls, Heater Lukewarm
 

A thought ... does your temp gauge indicate heat (mine reads around 100C ...
cdn, eh)? The previous owner could even have removed the thermostat.

Re: 1996 XJ 4.0 Cherokee Heater Controls, Heater Lukewarm
 

Thanks for the reply. I've replaced the thermostat and cover (due to a
leak) and the engine warms up to normal temp - around 200F - so the
thermostat appears to be working normally.

Re: 1996 XJ 4.0 Cherokee Heater Controls, Heater Lukewarm
 

Thanks for the reply. I've replaced the thermostat and cover (due to a
leak) and the engine warms up to normal temp - around 200F - so the
thermostat appears to be working normally.

Re: 1996 XJ 4.0 Cherokee Heater Controls, Heater Lukewarm
 

Thanks for the reply. I've replaced the thermostat and cover (due to a
leak) and the engine warms up to normal temp - around 200F - so the
thermostat appears to be working normally.

Re: 1996 XJ 4.0 Cherokee Heater Controls, Heater Lukewarm
 

Might be as simple as a plugged up heater core. I flushed mine out
last summer and got an amazing amount of crap out of it - plus a lot
more heat when I was done. I took both hoses off the core then ran a
garden hose to force water through in both directions. Took a few
minutes to run clear and I had to switch directions 3-4 times to get
it to run clear from the start.

On Mon, 28 Nov 2005 20:22:27 UTC "WildWestAZ" <kmreid@yahoo.com>
wrote:

> I'm troubleshooting a lukewarm heater problem and a couple questions
> have arisen which I haven't found answers to.
>
> First - the vacuum valves and heater slider flap (thing) under the dash
> all seem to be working correctly, just to make sure I also verified
> there are no climate control/vacuum leaks - connected a vacuum pump to
> the vacuum source line going into the Heater/AC unit from the line to
> the intake manifold & tank. I moved the climate control switch to each
> position and pumped up vacuum - the valve works for each and vacuum
> holds, good.
> I did notice that the heater valve is "off" (bypass) when the climate
> control switch is off, "on" (no heater core bypass) for all other
> positions (AC, Vent, Heat, Defrost, etc.), not sure if this is normal.
>
> Questions, any insight would be most appreciated:
>
> I have read where the heater can blow only lukewarm air in the cab if
> air is trapped in the core or hoses. Does anyone have suggestions on a
> good way to purge air from the heater lines/core?
>
> Can someone verify how the heater hoses are supposed to connect to the
> heater control valve under the hood? I bought the XJ used and it had a
> wrong valve installed, so I couldn't hook the (hopefully) new/correct
> one (from my local dealer) same as the old one. Mine is currently:
> With valve on side facing you, two parallel in vertical plane fittings
> on right side going to engine - upper to thermostat housing, lower to
> water pump, two fittings on left side at odd angles and down lower than
> the ones on the right - lower of these going to upper heater core tube,
> upper of these going to lower heater core tube. The main reason for
> this is - I bought all new factory hoses and valve, and with various
> fitting sizes (some 5/8, some 11/16) and hose angles, this
> configuration seemed to match up, but I haven't found a picture to see
> if I have them right.
>
> Can someone see if this is normal for the heater valve control from the
> climate control vacuum switch:
> Climate control switch in any other than in the Off position, vacuum
> applied to heater valve and sending hot water thru heater core.
> Climate control switch in Off position, vacuum removed from heater
> valve and bypassing the heater core.
>
> Thanks - KR
>


--
Will Honea

Re: 1996 XJ 4.0 Cherokee Heater Controls, Heater Lukewarm
 

Might be as simple as a plugged up heater core. I flushed mine out
last summer and got an amazing amount of crap out of it - plus a lot
more heat when I was done. I took both hoses off the core then ran a
garden hose to force water through in both directions. Took a few
minutes to run clear and I had to switch directions 3-4 times to get
it to run clear from the start.

On Mon, 28 Nov 2005 20:22:27 UTC "WildWestAZ" <kmreid@yahoo.com>
wrote:

> I'm troubleshooting a lukewarm heater problem and a couple questions
> have arisen which I haven't found answers to.
>
> First - the vacuum valves and heater slider flap (thing) under the dash
> all seem to be working correctly, just to make sure I also verified
> there are no climate control/vacuum leaks - connected a vacuum pump to
> the vacuum source line going into the Heater/AC unit from the line to
> the intake manifold & tank. I moved the climate control switch to each
> position and pumped up vacuum - the valve works for each and vacuum
> holds, good.
> I did notice that the heater valve is "off" (bypass) when the climate
> control switch is off, "on" (no heater core bypass) for all other
> positions (AC, Vent, Heat, Defrost, etc.), not sure if this is normal.
>
> Questions, any insight would be most appreciated:
>
> I have read where the heater can blow only lukewarm air in the cab if
> air is trapped in the core or hoses. Does anyone have suggestions on a
> good way to purge air from the heater lines/core?
>
> Can someone verify how the heater hoses are supposed to connect to the
> heater control valve under the hood? I bought the XJ used and it had a
> wrong valve installed, so I couldn't hook the (hopefully) new/correct
> one (from my local dealer) same as the old one. Mine is currently:
> With valve on side facing you, two parallel in vertical plane fittings
> on right side going to engine - upper to thermostat housing, lower to
> water pump, two fittings on left side at odd angles and down lower than
> the ones on the right - lower of these going to upper heater core tube,
> upper of these going to lower heater core tube. The main reason for
> this is - I bought all new factory hoses and valve, and with various
> fitting sizes (some 5/8, some 11/16) and hose angles, this
> configuration seemed to match up, but I haven't found a picture to see
> if I have them right.
>
> Can someone see if this is normal for the heater valve control from the
> climate control vacuum switch:
> Climate control switch in any other than in the Off position, vacuum
> applied to heater valve and sending hot water thru heater core.
> Climate control switch in Off position, vacuum removed from heater
> valve and bypassing the heater core.
>
> Thanks - KR
>


--
Will Honea

Re: 1996 XJ 4.0 Cherokee Heater Controls, Heater Lukewarm
 

Might be as simple as a plugged up heater core. I flushed mine out
last summer and got an amazing amount of crap out of it - plus a lot
more heat when I was done. I took both hoses off the core then ran a
garden hose to force water through in both directions. Took a few
minutes to run clear and I had to switch directions 3-4 times to get
it to run clear from the start.

On Mon, 28 Nov 2005 20:22:27 UTC "WildWestAZ" <kmreid@yahoo.com>
wrote:

> I'm troubleshooting a lukewarm heater problem and a couple questions
> have arisen which I haven't found answers to.
>
> First - the vacuum valves and heater slider flap (thing) under the dash
> all seem to be working correctly, just to make sure I also verified
> there are no climate control/vacuum leaks - connected a vacuum pump to
> the vacuum source line going into the Heater/AC unit from the line to
> the intake manifold & tank. I moved the climate control switch to each
> position and pumped up vacuum - the valve works for each and vacuum
> holds, good.
> I did notice that the heater valve is "off" (bypass) when the climate
> control switch is off, "on" (no heater core bypass) for all other
> positions (AC, Vent, Heat, Defrost, etc.), not sure if this is normal.
>
> Questions, any insight would be most appreciated:
>
> I have read where the heater can blow only lukewarm air in the cab if
> air is trapped in the core or hoses. Does anyone have suggestions on a
> good way to purge air from the heater lines/core?
>
> Can someone verify how the heater hoses are supposed to connect to the
> heater control valve under the hood? I bought the XJ used and it had a
> wrong valve installed, so I couldn't hook the (hopefully) new/correct
> one (from my local dealer) same as the old one. Mine is currently:
> With valve on side facing you, two parallel in vertical plane fittings
> on right side going to engine - upper to thermostat housing, lower to
> water pump, two fittings on left side at odd angles and down lower than
> the ones on the right - lower of these going to upper heater core tube,
> upper of these going to lower heater core tube. The main reason for
> this is - I bought all new factory hoses and valve, and with various
> fitting sizes (some 5/8, some 11/16) and hose angles, this
> configuration seemed to match up, but I haven't found a picture to see
> if I have them right.
>
> Can someone see if this is normal for the heater valve control from the
> climate control vacuum switch:
> Climate control switch in any other than in the Off position, vacuum
> applied to heater valve and sending hot water thru heater core.
> Climate control switch in Off position, vacuum removed from heater
> valve and bypassing the heater core.
>
> Thanks - KR
>


--
Will Honea