I have a 2000 Grand Cherokee Limited (4.7L). I've noticed over the past couple years that in the winter time (I live in the great white North) after a couple minutes my climate control will attempt to heat the vehicle to the desired temperature and then just start blowing cold air. Here are the symptoms after driving for an extended period of time after realizing I'm freezing:

The middle aspect of the dash gets VERY hot. The area from the radio down to the climate control temperature sensor. The temperature sensor gets too hot to touch.

I have to turn the dual climate control to "hi" in order to get heat out of it (I'm assuming because the sensor gets so hot that it "tricks" the computer into thinking its already 29 in the jeep when in actuality its like 20).

I get air blowing out of the "face vents" no matter the desired selection (feet or defrost).

The dual climate control works because I can the driver side to "hi" and get heat and get cold out of the passenger side (when it is set to anything BUT "hi") and vice versa.

Any suggestions? The guys at the auto parts store suggested the "air box assembly" sold by the dealership. It consists of the motors and doors. I called the dealership and they said there is no such thing and you have to buy the 2 motors and "air inlet door" separately. I thought it was the sensor aspect as it gets so hot that it would make sense that the computer would think it was 29 degrees inside and want to blow cold air. I'm not willing to take it to a dealership and let them nickel and dime me until they figure it out. I'd rather attempt it myself and then if unsuccessful let them deal with it.

Thanks!

 

it sounds like you may have a disconnected vacuum line

 

Its auto temp control, there will be codes in it. Take it to a dealer and know what's broke. I.E. a door, actuator, control head or what. Broken doors are real common on grand Cherokees. Or just tear it apart and open heater box.

 

Its all electronic no vacuum involved

 

bsmith97xj, do you think you could elaborate on this a bit? If I was to do this myself wouldn't I just be better off replacing everything (blend doors, actuator)? What's a control head?

Is it fairly easy to take the dash off in order to get to this "assembly" if you will? I bought those Haynes manuals but a little ridiculous to follow when your covering two different models.

thanks.