Battery Died..now Hvac Afu...help

MB2008LTZ · July 17, 2011

OK, so I was detailing my truck Friday and was playing the radio and I drained my battery. I get the jump pack out and hook it to my battery and wait a few minutes, my truck fires right up. Now it is blowing cold air on the driver side and hot air on the passenger side. It did this once before when I had the battery unhooked to install my amps, but it went away almost as soon as it happened. My truck is 2008 LTZ with duel zone climate control. I searched for a bit but all the info I found was for older body styles. Please help, its about 100 degrees here. Thanks

txab · July 17, 2011

Try this reset procedure.

Info from a recent post:

Just got done fixing the similar problem couple days ago on my wife's 04 yukon xl. Posting this in case somebody else runs into the same problem. Had an error code for 02 sensor, fixed the problem, disconnected the battery to clear the CEL/MIL, had it off 15 min, came back out started it up, o2 sensor code cleared, took it for a drive, and only had air coming out the defrost vents, no matter which HVAC function chosen, all air come out defrost vents. Friend of a friend has a friend who works for GM, and indicated this was a common problem for both sierras/yukons, etc after disconnecting the battery and it loses the memory/setting, whether hot air comes through the dash or the defrost, or only through the defrost. It has to reprogram itself, and if the problem isn't fixed soon, the actuator, over time, will go bad.

Fix: Turn the ignition to run (without starting the vehicle), then cycle from on to off 3x, then pull the HVAC fuse. Mine was listed as "HVAC 1", located at driver's side dash, by the door, though the guy originally indicated it was HVAC 2 or HVAC B. After pulling the fuse, wait at least 60 sec, cycle from on to off 3 more times, then reinsert the fuse. Leave the ignition in on, and wait about 5 min. After about 3 min, the air switched from defrost to the dash, then turn the key to off (Do not start it). I did not turn the key off (as that wasn't part of the fix originally), but rather started it up, and air switched from the dash to defrost again. Drove it around thinking that it was still recalibrating/programming itself. Later in the evening, turned it to run, air came out dash, and all functions/selections worked, floor, dash, defrost, started it up, and again air switched from dash to defrost, then to dash, then to defrost over ~45 sec. Shut it down, waited a minute, turned to run, confirmed all modes worked, turned ignition off, waited a minute, started back up, everything works as it should now. Been running fine for the last two days. Only thing i can think of for the delay, is that i didn't turn the car off before starting it up the first two times.

hope the info helps someone down the road.

Think i'll buy something to hold the memory while taking the battery off, to avoid this crap in the future...don't mind reprogramming radio stations, but this kind of stuff is irritating.

desrtrat · July 17, 2011

i had a issue with my 03 SS. changed the battery out due to a bad cell, when i restarted it the defroster was the only thing that would work. the fix was to disconnect the negative cable for about 1 min. and re hooked the neg. and all was fine. try that and see if it corrects it self..

good luck