Dang. Swartlkk above talks of a sensor on the plenum. I guess that would be next Maybe send him a note. Or the donor control or the ambient replacements are defective. Keep trying !

 

So far I"ve replaced, with new items, the above drivers head sensor, the sensor down on tunnel by drivers right foot, the heater box control motor, and a donor control panel. It does have the Climate Control and sort of wish it was the manual style about now. One local guy said he thought it was the blower motor relay. Hadn't heard that. Fortunately the right foot located sensor was only 10 bucks, the over head was 60, so not totally in the hole. The blower relay around 20 so I guess its next! Does AllData have a test program for this issue? Someone?? Thanks in Ca.

 

I have a 2000 jimmy that has the same but opposite problem. I have replaced the control panel and have removed the blending door actuator. With the actuator removed but plugged in it will rotate to hot and back to full cold. It does the same thing when put to cold. I understand this may be because there is no physical resistance but I don't know. The local pull a part has some really good donors that I have cannibalized for other parts. Can anyone tell me if that actuator should stop in the proper position even if it is not installed. Right now I am simply moving the blending door by hand but I would really like to get this fixed.

 

My issue was no heat until you went all the way to the right with the dial and the final clik, then big heat. Nothing in between. I changed a lot of stuff, no result. Every time you start the vehicle, the blend door goes thru a cycle, then back to low. I changed the sensor above your head on the headliner, the sensor under the dash unit, the blend door, a used control, geeez, sorry for the news but I sold mine and haven't thought about it till this post. I did get temporary help when I backflushed the core, which is super easy. If you want the headliner sensor, I'll sell it for cost, its brand new in the Chevy wrapper, think it was around 60? David in Ca.

 

This same thing happened to my Durango. What I finally found is a plug with a pigtail that was up under the glove compartment/kick panel that had some melting going on and the wire ends had shorted or something. It was quite awhile ago, but all I remember was the plug was ugly melted and blackened. I went to the dealership and they wanted $75.00 for it. I think I told them that smoking crack was illegal or something like that. I ended just splicing new wires in place with no plugs and it fixed the problem. It was a contortionist job though working upside down.