swathdiver
Full Access Member
You are probably low on refrigerant. My two cents is not to throw parts at it as such can open other cans of worms.08 Tahoe.
Weird it started the other day while driving on the first really hot day out. I noticed the snowflake icon on my a/c flashing and my ac got warm. I got out the truck at my next destination with it running and the fans were on wide open. I checked coolant, good. A/C belt, good. Got out my scan tool. No codes. Coolant temp showing 190. So I shut it down. Next morning did a cold start. Same thing fans wide open when cold and A/c wont work. I replaced the coolant temp sensor like some suggest but its still present. I thought maybe a bad relay but they stick on even when truck is off. I see thread but none solved. My thoughts are in the direction of a high pressure switch or maybe and issue causing a high pressure backup in the system.
Any direction is appreciated.
Put a manifold on the high and low side of your AC system and compare the pressure with the outside temp to see if she's or low or not. If so, my advise it to empty the system, make sure it holds a vacuum for 30 minutes or so and then introduce the proper amount of refrigerant by weight, using a scale if necessary. Tahoes with rear AC hold 2.6 pounds of R134 if memory serves.