I have been having issues with my 2005 Cadillac Escalade rear climate control. I could not get warm air to blow so first thing I checked and replaced was the rear blend door actuator. This didnt help and after re-calibrating i noticed it would turn to the full cold position after starting the truck, no matter what the setting. So, I replaced the rear control module (ACDelco 15-73506 Control Module Kit), re-calibrated and started the truck. I turned it to hot and it worked! I thought I solved my problem but no. I tried to turn it back cold but it wouldn't budge. I turned the car off and back on, and it went right back to full cold again. I tried re-calibrating multiple times to no avail. I have read and read and read about this subject and thought I had it nailed. What else could be causing this problem, bad air temperature sensor? Any input would be great please let me know if you have any questions.