The problem started with rear ac blowing hot so I removed cowling to find that on 2012 GMC Yukon Denali has blend door actuators behind heater unit. I removed the ducking so I could see position of doors. After recal the floor control moved from top to bottom but then wouldn’t switch back to overhead and ac-heat door stayed on heat.
What should I do next? I put front and rear controls on auto but when I put fuse back in temp stayed at 74 but auto wasn’t lit and I hear or feel any action on blend door motors.
Okay, I have been looking for the best way to recalibrate your rear system without a scan tool. The following is what is stated in GM service information. However, I believe that will only work for the front system. I have done some research and I think if you pull the radio RDO fuse #42 in the underhood fuse box instead of the HVAC/ECAS fuse it may work. You may have to disconnect the battery instead but I prefer not to do that as so many things will need to be relearned by the computer systems.
Alternate Method (w/o Scan Tool)
Clear all DTCs.
Place the ignition switch to the OFF position.
Install the HVAC control module or HVAC actuator.
Connect all previously disconnected components.
Remove the HVAC/ECAS fuse for a minimum of 10 seconds.
Install the HVAC/ECAS fuse.
Start the vehicle.
Wait 40 seconds for the HVAC control module to self-calibrate.