DUG DUG

Hello all. New here. I've got a 2023 Sierra 2500 AT4 gasser. I've been having a slight issue with the AC over the last few months. Quite often here lately when I start the truck the AC will blow ambient temperature air for a bizarrely long time. Several minutes sometimes, then all of the sudden the air will get cold. It's like the compressor is just not being told to turn on or something. Sometimes I can manually shut off the climate control and turn it back on and the air will immediately get cool. Or I'll restart the truck and the air will quickly get cool. It seems to do this more often when the truck has sat for awhile. It never fails to eventually work but I believe something must be wrong when it's 90 degrees outside and I've driven a couple miles and I've still got hot air blowing at me. Dealer says I may have to leaved the truck with them for up to three days for diagnostics. Figured I'd see if anyone has any ideas before I do that.