Good morning to all,

Just replaced both batteries on my 2004 2500HD Duramax (yesterday). Everything was turned off prior to this R&R (a/c, radio and all). Truck starts and runs great, with the exception that my A/C only blows thru the defroster on the window. Not the vents nor the floor, I have turned the knob both directions with no change.

I've already removed and replaced the HVAC/ECAS fuse, for at least 10 seconds (as recommended) and then restarted the truck allowing the a/c to reset itself? No good.

If it was an older truck I would assume a vacuum line/hose, but I have not found such. I have also (since battery change-out and start/run) cleaned the compartment with mild pressure of straight water.

Please advise for I am lost.

Thanks in advance for your time and knowledge.

Local delear stated to remove ONLY negative cables and computer would re-learn itself. Cool huh. Thanks anyhow.

Dealer suggestion did not work, left all cable off all night, even R&R the HVAC/ECAS fuse and replaced after a few minutes. To no avail. Going to look online for Chevrolet a/c problems, but please post if you have any suggestions, for I would really aappreciate any/all assistance, it is HOT in the Houston area. Thanks in advance.

try running a search for terms like hvac and batteries on the forum. this is pretty common and there is tons of info here on it

Changed both of my battery's a few days ago. The only thing I noticed was that the A/C took a few seconds longer to figure out what to do. IIRC somewhere I read the door actuation motors are electric on our trucks. Maybe it coincidently burned up a door position motor when it powered up. I don't think you could have hit or bumped anything during the battery change.

Moved to Interior from the forum ops section!

I'm having the same problem (A/C stuck on defrost after battery change), and have searched this forum for "hvac batteries" to no avail. Is there a solution to this, or do I have to take it into the stealer to fix this?

try running a search for terms like hvac and batteries on the forum. this is pretty common and there is tons of info here on it

Fixed: http://www.dieselplace.com/forum/showthread.php?p=2824497#post2824497