2021 sierra At4 1500 AC intermittently not cooling

[EBTulsa]

Mostly when it’s really hot, about half the time my ac blows VERY hot air when sitting still.  It will cool once I’m driving, but not quickly and not well. 

other times, I start it up and it will cool just fine parked, and if it does that it works normally while driving. Maybe not quite as cool as it once was, but still okay. 
 

Refrigerant level reads perfect.  Dealer has been zero help. They got it to fail once, but had no ideas why.  Said they would research it. I’m doubtful.  Any thoughts?

[Kevin lambright]

Have a 22 high country that will just quit blowing anywhere, left at dealer 4 plus times and the last two times I had them call up Chevrolet. The supposed smart people changed a temp sensor and the last time changed the evaporator core. Waiting for it to mess up again. Go above the dealer, have them make a ticked and call the engineers at Chevrolet 

[Mshawn]

That would have t

On 9/14/2023 at 8:35 PM, EBTulsa said:

Mostly when it’s really hot, about half the time my ac blows VERY hot air when sitting still.  It will cool once I’m driving, but not quickly and not well. 

other times, I start it up and it will cool just fine parked, and if it does that it works normally while driving. Maybe not quite as cool as it once was, but still okay. 
 

Refrigerant level reads perfect.  Dealer has been zero help. They got it to fail once, but had no ideas why.  Said they would research it. I’m doubtful.  Any thoughts?

That would have to do with your evap temp sensor or expansion valve. It gets its reading from the evaporator core and the bcm compares it to the ambient air temp in the cab and cycles the compressor accordingly. Take it to the dealer and tell the tech to watch the temp readings, which are usually read in volts or millivolts, and watch for quick changes in one or the other sensors . Problem is it will take some time to find it as it is intermittent. It could be a sticking expansion valve. I hope this helps

[EBTulsa]

On 9/15/2023 at 4:28 PM, Kevin lambright said:

Have a 22 high country that will just quit blowing anywhere, left at dealer 4 plus times and the last two times I had them call up Chevrolet. The supposed smart people changed a temp sensor and the last time changed the evaporator core. Waiting for it to mess up again. Go above the dealer, have them make a ticked and call the engineers at Chevrolet 

Thanks Kevin. That's good advice. 

[EBTulsa]

Mshawn, thanks. I'll talk to them about those things when I take it in. Question, if it's the temp sensor or expansion valve, is it harming anything else when it's not working? Worried about how quickly they'll find the issue given our daily high temps are coming down quickly.