I am new to this and have looked and already found performance questions I had, but now have a ? I have a 2005 gmc 1500 HD sierra 500 miles out of warranty I turned on the defrost and now the ac blows only very hot air is there a reset or something easy to test or do I have to take it to a shop. thanks

 

My 05 does this also sometimes. If it is doing the same as mine were it blows hot air out the driver side and blows cold air out the passenger side then just unplug your battery and wait a few secs and then plug it back in. This should fix it. Thats is if that is what its doing.

 

thanks I will try that if it happens again , it just started working again.