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

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

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" > wrote in message
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
>

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].

On Jan 30, 6:25 pm, "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.
>
> 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

First) The heater hoses WILL be hot all the way to the "Heater Control
Valve" located toward the rear of the engine compartment whether or
not the valve is working because it has a "Circulate" feature.

Second) The easiest and least expensive part to change is the "Heater
Control Valve", and it should be changed periodically anyway.

Third) There is a vacuum actuator hose that operates the "HCV", check
to see if the valve's control arm moves when you change the setting on
the dash from OFF to HEAT and move the slider from HOT to COLD. Do
this several times with the ENGINE RUNNING to provide a source of
vacuum. If the valve does not move, pull off the tiny hose and perform
the same test again while feeling for vacuum at the hose end. If you
can not detect any vacuum, the "Control Head" on the dash could be the
problem or you may not be getting any vacuum from the engine to that
"Control Head". If the that is the case, make sure you are getting a
vacuum supply to the "CH" before spending money.

Fourth) Sadly, your local "Dealer" appears to be CROOKED. Avoid them
in the future, they will eventually go away.

Best bet is to find Two (2) VERY reputable independant shops and get a
second opinion. You didn't say where you were located, but looking
online for a site the rates shops is sometimes a good thing.

Diagnosing this problem would take about 5 minutes for someone
familiar with the Cherokee, I have had my 1995 since new and took the
time to learn all of its systems and have done all of the repair work
myself.

Good luck!

If the core is clogged with sediment, an easy way to blow it out is with
your 5/8" garden hose clamped to the back flush side, letting it exit
through the disconnected hose at thermostat. I've seen that work a couple of
times on what I thought was a well maintained cooling system.
God Bless America, Bill 0|||||||0
http://www.billhughes.com/

"Nightcheck" > wrote in message
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
>

That is a part of good cooling system maintenance too. Verify that if you
pour water into one connection on the heater core, that it comes out the
other one.

Earle

"L.W. (Bill) Hughes III" > wrote in message
...
> If the core is clogged with sediment, an easy way to blow it out is
with
> your 5/8" garden hose clamped to the back flush side, letting it exit
> through the disconnected hose at thermostat. I've seen that work a couple
of
> times on what I thought was a well maintained cooling system.
> God Bless America, Bill 0|||||||0
> http://www.billhughes.com/
>
> "Nightcheck" > wrote in message
> 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
> >
>
>

Hi Rick

These guys are right and the dealer is wrong!

I suspect those dealership greaseballs are on commission and they will
replace the radio before they fix the problem.

Can I assume that your rad is full and the temperature guage shows
normal reading? I suspect the heater blend flap, but it could be a
clogged heater core. Does the defroster blow warm air on the
windshield. If yes, probable problem is the heater blend flap (door).
If not, you may have a clogged heater core.

The heater, defroster and AC use a combination of blend door settings.

Merrill


On Jan 30, 7:25 pm, "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.
>
> 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

I will agree that the place you went are thieves! They should be
exposed to the local news media.

None of the things mentioned have much bearing on 'no heat' only. If
any were bad, you would have a 'no engine running' situation with
coolant blowing all over the place.

I also would start with the fluid shut off valve to verify it is
working. It is just before the firewall on one heater hose and defaults
to off if it has no vacuum to the switch. Or the lever just rots away
sometimes....

Also note that if the coolant is low in the radiator itself, the heater
lines will airlock really easily so you get no inside heat.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

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.
>
> 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
>