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HVAC More Questions!!!!! HELP!!!!

super_probie

Full Member
Joined
Jan 8, 2009
Messages
20
I have seen several topics that cover HVAC problems with the Avalanche. This is no news at all. I have also seen several topics that cover different characteristics. So I figured that I would post what I have going on in an attempt to utilize all the Avy Knowledge out there and come to a possible primary conclusion to fix it. So here goes.

I have a 2004 Avalanche Z71 1500. It has the digital dual climate controls. I have checked my coolant levels, a/c compressor and Freon levels. All seem to be okay. For starters, similar to several folks, my HVAC problem presented itself during one of the hottest days of the summer. We had the a/c cranked down blowing full speed. All of a sudden, it felt like the sun had landed in the drivers seat with me, meanwhile, the passenger side was maintaining cold air. My simple solution was to turn off the HVAC unit and roll me down some windows. After a while I would turn it back on and all was good. Then repeat. Wash, rinse, repeat.

The next presentation would be that is switched sides. Now the passenger get to hold the Sun, while I get to relax in the cold environment. Yay me!!!!  Same solution. Wash, rinse, repeat.

Next would be that the control unit will turn itself off. I can adjust the settings, and a couple minutes later, the unit shuts off. Nothing works. So to fix that problem, temporarily, I press the button to turn it back on and readjust the settings. Another classic instance of wash, rinse, repeat.

The latest presentation would be that with the heat on (floor, defrost, vent), it blows cold air. No heat (again coolant levels good, no overheating, blower motor working fine, just blows cold air. I have not determined a solid temp fix for this one yet. Sometimes turning the truck off and restarting fixes it other times I can just wait it out and all of a sudden it starts blowing cold air.

Can anybody give me some advice here. I would assume that I have a bad actuator, possible on the blend door. I have not tried changing control units yet, primarily because some of the issues presented a couple years before the control unit would turn itself off (which in itself is intermittent). Could someone give me some direction here. Vent door/blend door actuator?? Please and thank you in advance. Feel free to ask additional questions.
 
Same issue here Super-Probie. Been dealing with this for a long time. Now needing to change the battery again, which will start the issues all over again. Is there a way to keep power to the computer controlling the blend door actuator during battery replacement? Or what should I do when changing the battery?? Thanks, Scott
 
Try this
https://www.amazon.com/12V-Automotive-Settings-Keeper-Battery/dp/B002C0NP5I/?tag=leosm1-20
 
If I remember correctly you need to shut off all a/c heater settings before replacing battery. Then once battery is replaced you can turn on air or heat as needed. From what I have read the control units need to go through a relearning and calibration process on it's own when a battery is changed.
 
ronthehandymanga said:
Try this
https://www.amazon.com/12V-Automotive-Settings-Keeper-Battery/dp/B002C0NP5I/?tag=leosm1-20

According to your link 67% of reviewers gave that product a one star rating??
 
I use one with no problems and is why I posted it.
 
Search for the HVAC 101 thread on here. It goes over the different actuators. I believe there's one for driver temp control, passenger temp control, vent selection, and air inlet door. I could be wrong on that. With multiple actuators acting weird and the control panel acting up, I would guess the control panel may be on the fritz. I used car gauge pro on my phone with a Bluetooth elm adapter to read my body codes and they pointed straight to the air inlet door actuator. The app was $9 and the adapter $20. It could save you money over replacing parts willy-nilly.
 
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