Good morning all I have a 2021 2500 HD with 27,000 miles on it over the past 4 months I have been experiencing issues with the A/C . In my company truck on a normal day it sits running at an idle for 12 to 13 hours . The A/C works as it should for 6-8 hours and then all of a sudden it will start blowing extremely hot air out of the vents and will keep doing so until I take it for a drive (5 miles or more )and then it blows cold air again. I have had it to the local chevy dealership and they are saying the system is fully charged and the compressor is working as it should. They said they are unable to diagnose the issue. I have shown a picture of the A/C line when the air gets hot it is hot to touch and when the air is cold it’s cold to touch . If anyone has suggestions I would greatly appreciate it Thank You Steve

 

This is the welcome section so welcome. post future help threads is the help section for your build.

does the air flow reduce when the problem occurs...if yes, maybe the evaporator is icing up.

the pic is the low side service port. it should be cold...when it gets hot....check if the compressor clutch is engaged.

 

Welcome to the forum. Moving your post to the correct section of the forum where it will get more views.