'97+: Temperature knob on climate control is stuck!

[iroc86]

I have been fighting with the climate control on my '98 since I bought my Jeep last year. The knob to select the interior temperature gets stuck after being turned to "full hot" (clockwise). I took the linkage apart and found that the cable was bent and wouldn't allow the knob to turn. I bent it back and the dial worked for about twenty minutes -- after it remained on full hot for a while it refused to turn counterclockwise.

I took it apart again last night, finding that the cable was bent like before. I rotated it to have the force pushing against the bend, which should make the cable more resistant to bending in the opposite direction. Same deal... worked last night but on my morning drive I couldn't select the temperature. If I reach under the dash and push the lever on the heater box I can change the temperature without a problem. After the interior warmed up and the heater box got hot (about twenty minutes later), the knob would turn.

It almost seems like something is jamming up the flap inside the heater box when everything is cold, but that's silly justification for a problem like this, IMHO. Has anyone experienced something similar on their '97+ and maybe found a fix?

 

[JEEPZZ]

I've never encountered the problem on my 97 but my 87 had a very similiar bent cable problem like you described only with the slide heat selector (rather than the newer dial control). I purchased a new cable from the dealer and it solved the problem. I never check for an obstuction that could have caused the damaged cable to begin with but the new cable hasn't had a problem since the install 7 years back (knock on wood).

 

[gmars]

same prob on my 97 couple years ago. pita cuz its a terminal issue w/all cold weather jeeps - where the temp is moved alot. its the "mixer door" or somethign like that. spendy thru the dealer, only place to get the part. ask a delaer, they'll know right away. got no chocie but o replace the whole show. if you do get it fixed, hang on ot the receipt,a s mine has need to be replaced TWICE since, at no cost to me. i wanna say about $250 or so. but i've had it done 3 tiems now! PS - have them look at the defrost mix door as well, cuz its next to go and similar $ alone.

 

[iroc86]

I think my next step is the cable if this thing gets jammed again... the braided wire can only bend so many times before it won't go back to its original position.

The mixer door theory sounds like the main cause of my problem, though. I have noticed some other HVAC-related problems with the temperature selector; things that normally wouldn't be affected by it (e.g. airflow gets redirected to other vents when choosing a temperature, but only sometimes -- maybe something is jammed up between mixer doors inside the ducting). I've had the whole heater assembly out once before, and it was a PITA between the heater core, AC evaporator, dashboard, etc. Does everything need to come out to replace the mixer door?

For the time being, I've found a temporary fix: If I don't turn the knob past the second-to-last notch, it doesn't jam. I looked at the cable under the dash when I pulled it the whole way and it appears to be overextending the lever (by maybe 1/16"), which is enough to get stuck when everything is cold and the plastic has contracted.

 

[gmars]

If you can get by it might be worth finding a "spot' that works and leaving it. Thats what I do if I have to (saving for the defrost door fix) since my temp mixer works pretty well, I'm waiting til it busts again and then I'll bring it back and have them do it right at the dealership. Get the door fixed as well when the dash is ripped apart. also noticed that the defrost "door" moves when there's pressure changes inside - opening a window, door, etc. Good luck.

 

[Red97XJ]

My temp control is getting stuck also, where do I look to find this possibly bent cable??

 

[iroc86]

It's actually right under the dash, on the passenger's side. You don't even have to take anything apart to see the end of the cable that goes into the heater box.

Incidentally, I think I figured out why my cable was bent to begin with. Trying to change the climate temperature when the fan is on anything higher than "1" makes it darn near impossible to turn the knob, almost as if the airflow through the box is causing resistance. These days, I make sure the fan is on low before I make any adjustments to the mixer. I've had absolutely no problems since, and I'm even reusing the old cable. I did have to straighten out the original cable with a pair of pliers, but that's all.

Oh, and you don't need to rip the entire dash apart to get to it... I was repairing a water leak in the heater box when the picture below was taken .

 

[scoobyxj]

FYI the 2000-01 uses an electronic door and nob. I don't see why they couldn't replace the older style cable operated unit. Also the vent selector is completely vacuum operated. Is the 97-99 the same set up on that?

 

[iroc86]

FYI the 2000-01 uses an electronic door and nob. I don't see why they couldn't replace the older style cable operated unit. Also the vent selector is completely vacuum operated. Is the 97-99 the same set up on that?

Hmm, I didn't know that. Might be a good upgrade...

The vent selector on my '98 is vacuum-operated, but there is an electrical switch in there for the A/C signal.