2004 Yukon rear HVAC

[Gnarley]

This has likely been asked in many other posts, There should be a reasonable way to isolate and fix the real blend door, I'm looking for suggestions.

The factory actuators seem fine I swapped the blend actuator with the zone actuator, the zone worked fine where it was but when swapped into the blend position there was no change and it go right to stuck on full cold. I can swap them and no matter what I do the blend goes to full cold. I bought a new actuator and installed it on the bend door and then it went to full hot.

I've tried to recalibrate by disconnecting the battery for about 5 minutes and shorted +- together then hooked back up and started the engine and let it warm up and there was no change in operation to the blend door. I disconnected the rear controller and plugged it back in and the blend door stays pegged cold with the OEM actuator or hot with the new actuator. I even bought a spare rear controller and there was no change.

What am I doing wrong or what is wrong, any ideas? I'm pretty clear that I'm missing something

 

[Joseph Garcia]

I believe that @swathdiver has a good handle on blend door operations and may be able to offer you some insight.

 

[swathdiver]

This has likely been asked in many other posts, There should be a reasonable way to isolate and fix the real blend door, I'm looking for suggestions.

The factory actuators seem fine I swapped the blend actuator with the zone actuator, the zone worked fine where it was but when swapped into the blend position there was no change and it go right to stuck on full cold. I can swap them and no matter what I do the blend goes to full cold. I bought a new actuator and installed it on the bend door and then it went to full hot.

I've tried to recalibrate by disconnecting the battery for about 5 minutes and shorted +- together then hooked back up and started the engine and let it warm up and there was no change in operation to the blend door. I disconnected the rear controller and plugged it back in and the blend door stays pegged cold with the OEM actuator or hot with the new actuator. I even bought a spare rear controller and there was no change.

What am I doing wrong or what is wrong, any ideas? I'm pretty clear that I'm missing something

Hi Gnarley,

Are you talking about the actuators for the rear AC? First off, aftermarket actuators usually don't play nice with the computer system and many are of such low quality that they fail soon after installing them. I have never been successful in doing a manual relearn or calibration, I've always had to use my Tech-2 to calibrate the door positions.

As our trucks age, the foam around the doors starts to fall away and can cause air leaks and jams. Some folks have created stops to limit or change how far they move, others take everything apart and put in new doors. Quite a few videos on youtube on this.

Well, if yours were mine I would get hold of someone with a bi-directional scan tool that can talk to the actuators, see what they're doing internally and calibrate them.