HVAC Controls have a mind of their own

[WNCFirefighter]

Ok I searched for 30 minutes and found nothing on here resembling my problem. I just bought an 03 Tahoe Z71. The day before I went to pick it up, the dealer called and said the A/C wasn't blowing cold for about 10 minutes and then got cold all of a sudden. They took some money off the price for the issue so I brought it on home. Now no matter what temperature or position it is set on, the compressor will not engage. I also noticed the HVAC controls will completely turn off and have a blank screen while driving, and the fan will change speeds on it's own. The refrigerant pressure has been checked and it has a good charge. I'm thinking it has to be the HVAC control going bad. The rear AC also does not work. Does the front AC have to be turned on for the rear to work?

 

[1fatho]

Your z came with ventilation? =) Things are known for it, I got the same rig to the year and my heater wont blow in the back vents. It can be blowing 90 in the front and freezing in the back

 

[chip]

Try disconnecting your battery for about ten minutes. See if that helps.