Intermittent Ac Blowing Hot

[chevrolet1616]

I have dual zone climate control on an 04 Silverado. My AC has been blowing hot at random times. The only way to fix this is to stop the car, turn it off and turn it back on. Also, the AC used to blow ice cold, now the temp varies between ice cold and moderate (I checked the compressor already). This happens whether the air is set on recirculate or not. Also during the winter it started blowing cold air randomly

 

I suspect there is an issue with the blend door because I hear a "thumping" noise almost like a vane is opening and closing at random times. From what i understand the actuator gets grease on it causing shorts. I have also heard of temperature sensors. Any suggestions would be welcome! Thanks!

[bill190]

Complete troubleshooting instructions for this problem would be in a GM Factory Service Manual set for your year/model vehicle.

 

And for replacing an actuator, I would advise following the procedures in these books. You can order these books from helminc.com or a GM dealer.

 

You would also need to know how to use a multimeter (for testing). How to use a multimeter...

http://www.google.com/search?hl=en&saf...ter&aqi=g10