TOPIC: '03-'07 GM Truck/SUV HVAC Actuator Resync Procedure

Sometimes, when clearing the ECU, the electronic portion of the HVAC Actuators go out of sync in these vehicles.

Here is the procedure to restore their operations.

Recalibration Procedure for HVAC Blender Control, 03-07 GM Trucks/SUV’s

1) MANUAL CONTROL- Move temp sliders to between 0.5” and 0.75” up from full cold, Fan to speed 3.
2) Ignition ON. (NOT RUNNING)
3) DIGITAL SYSTEMS-Set to “AUTO”
4) Ignition OFF
5) Electrical Panel under hood, remove HVAC fuse (10A, position varies, so CHECK DIAGRAM UNDER COVER!) for about ONE MINUTE.

6) Reinstall the fuse.
7) Start the vehicle and let run for 2 minutes. DO NOT TOUCH THE CONTROLS.
8 ) Turn OFF engine and wait 10-20 seconds and NO LONGER THAN 30 SECONDS!
9) Restart engine.

Calibration should be complete.

Another catastrophe averted by yours truly (who discovered this when HE screwed one up!)

Ron Hatton
Gadgetman

That sounds like a GM Service bulletin procedure to me...
It reminds me of the story of the Apollo 12 mission, when right after launch, the Saturn V was thundering aloft, and lightning struck the rocket. The crew and ground controllers had to immediately analyze and find a solution, as critical electrical systems had gone offline, even as seconds ticked away before staging of the first stage. They figured it out in time to avoid having to abort the mission. They Squeeked it!

Thanks for this Ron, I'll remember it if I have to reset a GM truck/SUV from those years. That kind of thing makes one nostalgic for manual heater/A/C controls and wing vent windows...

Tracy G