Rear AC/Heater

03GMCYukon · September 24, 2012

I have a 03 Yukon with the rear AC/Heater. Fortunately I live in Phoenix because the temp door is stuck in the position where it will provide cool air but not heater air. I replaced the door actuator and it didn't have any effect. I popped open the actuator and put it in the center position, aligned the door. It will go to the cold air position and stay there.

The only other part I could think of replacing is the module. The parts are expensive so I was wondering if there is a test I could do to determine which part is at fault. Or is this an issue to take to the dealer?

03GMCYukon · October 18, 2012

I took my Yukon to the dealer and paid the $125 for a diagnostic. The dealer said it is the HVAC Control Module - Auxiliary. Part is only ~$100 but they want to charge 3.5 hrs tech time to calibrate the system for a total of $550. According to the service manual, the recalibration is very simple: ign off, install new module, start vehicle, wait 40 seconds for the module to recalibrate.

Does anyone know if there is more to it to replace then recalibrate the module/actuators? I can't imagine the dealer would just make up 3.5 hrs of tech time if there wasn't anything to do.

Duelin · October 18, 2012

Out of curiosity have you tried to disconnect the battery for about 10 minutes to see what would happen? Make sure the A/C controls are in the off position. After connecting the battery turn the key to the on position for 40 seconds. Then check it. Also if you do have to buy a new module I think that they have been revised. The original module let the doors travel too far and get out of sync.