Disconnect Battery = Defrost Vents Only For The Ac

[TravisAZ]

Hey guys - Starting new thread for this since I hi-jacked someone else's.

 

Problem: Truck has always had a noise of a HVAC door flapping behind the dash somewhere. When the AC is not on, the door clucks consistantly every 3-4 seconds. Cold air would blow through all vents. Everything worked, there was just a super annoying noise.

 

I disconnected the battery, waited 10 mins. REconnected it. Got in the truck. Turn the key to ON, wait a minute. Start the truck, ran for 5 mins. Turned off the truck, open and closed the door. Waited a min, start the truck, drive 45 mph.

 

During this process I could hear the HVAC doors going through their calibration.

 

AT THE END OF THIS, NOW I ONLY HAVE fLOW THROUGH THE DEFROST VENTS. FML!!!!

 

I have driven the truck for 3 days like this, hoping enough duty cycles would straighten it out.

 

I also did the pull both HVAC fuses thing.

 

Whats my play? Truck is a 2003 SS with manual controls.

[bill190]

There are electric actuator motors which make the little doors move back and forth.

 

And there is a specific procedure for replacing these in the GM Factory Service Manual set for your year/model vehicle. (Order from helminc.com or a GM dealer.)

 

It is possible that someone replaced one or more of these actuators wrong and it stripped the gears. Basically each little door can move all the way this way or that way, but if you install a new actuator and the electronic controller thinks the door is "open" (but it is actually closed), then tries to open it, it would could try moving the door even though the door can't move any further that direction! And then something breaks.

 

So best to follow the factory directions for replacing these. The factory book would show which actuator was for defrost. Hopefully it would just be a problem with the actuator and not the little door.

[don0442]

I had the same problem after I repaced the battery in my 05 Sierra 1500, with manual controls. For the first two days, my A/C came out of the defrost only, and my eng temp guage refused to work. The second day, I was playing around with the controls and hit the recurculated air button, and the A/C came out the vents it is suppost to. Temp guage started working today. Must be a learn cycle or something.