Good Evening everyone,
I have a question concerning my 2004 Silverado 1500 4x4 ext. cab 5.3. My a/c will blow cold air most of the time but every so often it goes to hot air. I didn't change any settings. I just noticed the heater is doing the same thing now. For no reason it will blow hot air and suddenly change on its own to cold. I'm not sure if the actuators are the cause because when I change the modes, each door seems to open and close as normal. This is a dual comfort system, each side has it's own temp control. When I set the temp, they stay set, the air will just seem to change from hot to cold for the heat and cold to hot when the air is on. Can anyone provide a starting point for to diagnose? Thanks in advance for your help.

 

for the heat issue...does it go cold at idle conditions but then back to hot when the engine is revved up and held at 2000rpm?

 

I disconnected the negative battery terminal and waited 10/15 seconds and reconnected. Seems to have fixed the problem. Thanks for the reply