2000gdc

First post here...
I have a 2000 xj, 6 cyl. I had the radiator changed by a jeep dealership about a year ago. Recently my heater stopped working and the temperature gauge would shoot up all the way and the check engine light would go on. I changed the heater core and nothing changed. I changed the coolant temperature sensor and the check engine light issue went away but I still have no hot air from my heater.

The next day I started the jeep and the check engine light stayed on, there is no hot air from the heater, and the thing seems to be idling at 215 (the second tick-mark after 210). I've flushed the coolant/anti-freeze 3 times now and that doesn't seem to make a difference. I am at loss for what to do next. Any suggestions? Thanks.

93gc40

Have the code read to see what the computer is telling you. Replace the radiator cap and T-stat. Is your E-fan turning on when it gets HOT and when you turn the AC or Defroster on?
Also sounds like you have a vacum motor issue in the HVAC system. Sounds like you have 2 seperate problems something in the AC/heater system and something in the engine cooling system.

2000gdc

Started it up today and the check engine light did not stay on- strange but good. Still no heat from the heater.

I changed the t-stat about 6 months ago and the radiator cap seems fine. So, I think the engine cooling system issue might be over.

Any other ideas on the AC/heater system? Why no heat?

93gc40

temp control is done by a vacum motor. So there is a leak somewhere or the vac motor is bad. Can you get air from all the vents, lower, dash and defrost. Not real familar with the 2000 system I know it is a little different than mine, but basic operation is the same just some different parts. Do your heater hoses go straight into the firewall or connect to one of these, Heater Control Valve:

2000gdc

I took off the pressure/heater control valve after I noticed it was making a clicking noise-could be going bad? I disconnected the two hoses connected to it and now I'm getting hot air from the heater. Victory.

Check engine light is off and the car is not overheating. Only issue is its running at 215 and electric fan comes on all the time. The temp basically stays at the 215 mark and electric fan always stays on. So, that is the last issue-215 and temp never drops down from there. Any suggestions on this? Thank you.

TheJerm

Test you mechanical clutch fan. After its hot it should be much harder to spin with your hand than when its cold. Just looking at the rad cap wont tell you if its good or not. They wear out from lots of thermal cycles but its probably your fan clutch.

SeriousOffroad

No it is not. The OP has a 00' XJ.

Heat is controled by the door in the HVAC housing behind the dash. The door position is controlled by engine vacuum. Check your connections at the vaccum canister behind the bumper on the passenger side and then work your way back. If no leaks are found then it's a safe bet that the dash control is bad or possibly just not connected..

djb383

For what it's worth, the second mark after 210 would be approx. 235F.

2000gdc

My mistake, djb383. I guess I meant the first tick-mark=222.5. Still too dang hot, though.

I'll check the the vaccum canister behind the bumper and work my way back FrankZ.

Fan clutch! I should have checked that already. Thanks for pointing me in that direction, thejerm.

2000gdc

Update- I now have hot air blowing from the heater. The check engine light is not coming on anymore. The temp gauge is not shooting up anymore either.

I have changed the t-stat, coolant temp sensor, heater core, fan clutch, radiator cap, the coolant/anti-freeze, and had the radiator changed about a year ago.-the temp is still at almost 222 at idle and drops just 2 or 3 degrees on the freeway.

I am at a loss as to what to do next. compression issue?

TTMK5

try burping the system. park on steep slope with rad cap off. start and keep squeezing hoses for a while. til air works through. could be a simple fix. good luck to you