AC/Heater Issue. Please Help
 

Hello guys. It finally started getting cold enough in South Texas to were the heater is needed. I tried moving the Temp adjustment knob only to find out that my Hummer goes from really cold to really hot with the slightest movement of the knob. Has anyone experienced this before? Is it a knob issue? AC/Heater issue? Please help

BTW the Hummer is a 2007 Adv pkg with 43,xxx miles if it helps

Thanks in advanced for your replies

There are others including myself who have experienced this issue as well. Here is one thread about this problem, i know there are others you might want to search for. https://www.hummerforums.com/forum/h...t=hvac+control
In my case the temperature problem didnt appear until i ran the "temp control calibration" sequence with hopes of fixing a different a/c problem. The calibration process seemed to cycle through some modes with knobs flashing like it actually calibrated something. all it did was give me boiling heat when the knob was only 1 click to the right. I refused to believe i broke anything though just by pressing a few buttons and i wasn't going to take it to a dealership for them to rip me off so i let it be since it was the summer anyway. Well to make a long story short after a few months of maybe turning the knobs here and there it works perfectly again. Good luck with yours.

Same problem with mine. Took it to the dealership they replaced the control module under warranty...

I had the same problem, then when i put the Temp knob all the way over I hear 3 thumping noises and the hot is still cold. I have no heat now. Is the control module the actual knob or is it a vaccum line or something like that?

I got the same problem, i got rid of the noise by disconnecting a wire that i believe the power for the fan, but my temperature is stuck in cold, no hot air anymore. Did you fix your problem?

you might want to spend some time reading past posts on the forum.
the last entry here was 2 yrs ago, go back some more and read away!