What now???

[aceofphoenix]

Hello everyone,

Sorry I haven't been on in a while. Well I really appreciate the help the last couple of times. The tranny filter was replaced and new fluid added, she shifts a little better but I still am in fourth gear @ 40-45mph. I don't think this is right, but I am use to a 5 speed automatic not a 4 speed automatic. But the filter was long overdue for a change.

So one day the heater was working fine and I was doing something under the hood(I don't remember what I was working on). Well I jumped in the jeep to go somewhere and no heater. I don't even get heat on the vent position. The blower is blowing good but no heat at all. The A/C blows really cold when it wants to. I am not sure if it has R12 or R134a in the system and not sure how to tell. All I know is that my jeep is really cold when driving anywhere no matter what the engine temp is. So I called the parts house and checked on the price of a heater core and it is $36. I am not sure if that would be the problem or not just trying to get my ducks lined up. I also have never changed a heater core before. So where should I begin and is this a common problem for the cherokees?

Thank you for your time.
Happy holidays to everyone.

Mark

[4.3LXJ]

Check your coolant fluid level lately? If it is down it will starve the heater core.

[firehawk]

Hello everyone,

Sorry I haven't been on in a while. Well I really appreciate the help the last couple of times. The tranny filter was replaced and new fluid added, she shifts a little better but I still am in fourth gear @ 40-45mph. I don't think this is right, but I am use to a 5 speed automatic not a 4 speed automatic. But the filter was long overdue for a change.

So one day the heater was working fine and I was doing something under the hood(I don't remember what I was working on). Well I jumped in the jeep to go somewhere and no heater. I don't even get heat on the vent position. The blower is blowing good but no heat at all. The A/C blows really cold when it wants to. I am not sure if it has R12 or R134a in the system and not sure how to tell. All I know is that my jeep is really cold when driving anywhere no matter what the engine temp is. So I called the parts house and checked on the price of a heater core and it is $36. I am not sure if that would be the problem or not just trying to get my ducks lined up. I also have never changed a heater core before. So where should I begin and is this a common problem for the cherokees?

Thank you for your time.
Happy holidays to everyone.

Mark

My 2000 with the AW4 transmission shifts into 4th at around 43 mph. So yours "sounds" normal.

As far as the heater is concerned....do XJ's have a heater control valve? I don't know but I think I read somewhere that coolant flows thru the heater core all the time. I can't see how, and not radiate heat into the interior all the time.:smiley-gen165: If there is a heater control valve, make sure you didn't bump it and disconnect the wiring harness somehow.

You might also check the two heater hoses that run along the valve cover and see if BOTH are hot. If so, then there is coolant running thru the heater core. Maybe the "blend door" in the heater ducting is stuck closed.

Just some ideas.:thumbsup:

[Mudderoy]

My 2000 with the AW4 transmission shifts into 4th at around 43 mph. So yours "sounds" normal.

As far as the heater is concerned....do XJ's have a heater control valve? I don't know but I think I read somewhere that coolant flows thru the heater core all the time. I can't see how, and not radiate heat into the interior all the time.:smiley-gen165: If there is a heater control valve, make sure you didn't bump it and disconnect the wiring harness somehow.

You might also check the two heater hoses that run along the valve cover and see if BOTH are hot. If so, then there is coolant running thru the heater core. Maybe the "blend door" in the heater ducting is stuck closed.

Just some ideas.:thumbsup:

I think the coolant flows through the heater core all the time, well at least flows through after the thermostat opens up. I guess there could be a valve behind the firewall, but I don't think so. I suspect you don't feel the heat unless air is flowing over the core.

[4.3LXJ]

On XJs, coolant is supposed to flow through all the time unless in MAX AC. Then the inline valve is closed.

[BlueXJ]

If yopu still have the closed system there is a heater control valve and it is on the passenger side of the engine and has several hoses running from it and the pressure tank. They are plastic and can be fragile after twenty years of use.
Thius is it.............http://www.oreillyauto.com/site/c/detail/MUR0/74774.oap?year=1990&make=Jeep&model=Cherokee&vi=1180011&keyword=heater+control+valve&partType=02708&parentPartType=C0331

[aceofphoenix]

Ok well I have already replaced the Heater control valve before making this post. Maybe the vacuum line broke after 20 years of service. I am not sure how to test this or should I just replace this. The coolant level is good just did a flush on the radiator about 2 weeks ago. I had a small leak from the thermostat gasket, so I took that off and removed the thermostat and replaced the seal with a new one. The jeep has not overheated but was just an idea I thought I would try so far still no heat. :stars:

[xj4life2]

Check the plastic lines (vac) comming out of the firewall on the pass side firewall. they are the controll lines for your heater chances are they are rotted and leaking. One should go to the heater ctl valve.

[96xj]

im having the same problem too my coolent level is good, hoses are NOT cracked or leaking so what would be my next step ?

[aceofphoenix]

I would double check the vacum lines again. I found that one of mine was melted and dry cracked. If all of your vac lines are good, then I would start looking at pulling out the heater core and seeing if it is plugged. If it is they are about $30-$40 at the parts house.

[aceofphoenix]

Just thought about this....before you take out your heater core have you looked at the heater control valve? I think this is only like $30 as well I could be wrong.