Cherokee Heating problem

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.

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 proclaimed:

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].

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!

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

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

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