A/c Blows Cold And Hot

[RickN]

Last time I changed batteries on my 04 Duramax, I had a problem with the drivers side ducts blowing cold air and the passenger side blowing hot.

 

Had to replace the auxillary battery last week, and now I have the same problem again. I can't remember the fix, but someone on here knew about it last time.

 

Little help here please.

 

RickN

[TexasEdition]

Last time I changed batteries on my 04 Duramax, I had a problem with the drivers side ducts blowing cold air and the passenger side blowing hot.

 

Had to replace the auxillary battery last week, and now I have the same problem again. I can't remember the fix, but someone on here knew about it last time.

 

Little help here please.

 

RickN

 

 

Rick,

I have the same problem. I just posted this today. Mine is just the opposite. Driver side is hot and passenger is cold. Let me know what you find out. Good luck!!

 

Bob

[gave20]

You can try pulling the HVAC fuse under the hood, turn the key to run then shut back off. then replace the fuse and start the truck don't touch the HVAC, give it a few minutes to cycle then shut it off. That should work , if not it should return to normal after 6-7 start ups. These auto HVAC systems are a piece of shit.

[TexasEdition]

This does not happen all the time. Will this be a permanent fix? This happens to me about once a week.

[norsemanberg]

It's worth a try, might just reset the system.

[gave20]

This does not happen all the time. Will this be a permanent fix? This happens to me about once a week.

 

It sounds like one of your actuators is out of calibration. If you've never replaced them there was a TSB out on overtravel of the actuator causing it to stick. If the method I described previously doesn't work you'll have to take it to a dealer for them to recalibrate the system. For me it was $30 for a1/2hr labor charge. It took 5 minutes to reflash the BCM.

[RickN]

Talked to an ex GM tech today. He said that there was a recalibration technique of some sort.

 

Seems like the last time I had this problem, I had to disconnect the batteries, so that the system would reboot or something.

 

Will try what you suggested.

 

RickN

[RickN]

Okay, I tried something, and it worked!

 

Turned a/c off, and everything else, turned truck off, disconnected the ground from both batteries.

 

Reconnected ground, started truck, turned a/c back on.....presto, everything is functioning per normal.

 

Might have been able to do the same thing with the fuse removal, but I remembered last time I had to disconnect the batteries.

 

And I only changed one battery to make this all start screwing up.

 

Truck is very particular. By the way, it's an 04 Duramax 2500HD.

 

Hope this saves someone else a trip to the dealership.

 

Rick