I have a 2020 3500 SWB Z71 LTZ. I've been having A/C problems for a while now but up until today it's been pretty intermittent. Most of the time it would work exactly right, but occasionally it would cut out for a few minutes and then get cold again. At the start of a drive after a day or so of sitting it would take about 10 to 15 minutes to work but once it did it was fine. Today it decided to just not work at all. It's a 100 degrees outside and I'm dying over here. We've checked the evaporator and the compressor both seem to be working nominally. We've hooked it up to a mid grade diagnosing tool and there's no codes, except here and there a mention of going into safe mode and shutting down because of either low battery voltage or low RPM. I've checked my batteries they're working fine. Besides I just replaced one this past winter. At idle my engine usually runs about 600Rpm and doesn't dip. Driving speed it hovers between 1500 to 1800Rpm.

Is there any known issue with some of the A/C components I'm not aware of like bad control modules for that year or bad dampers or step motors? Where should i be looking because the things I know to check are all fine.

 

Have you checked the refrigerant high side and low side pressures to make sure there is sufficient refrigerant in the system?

Please remember that these AC systems are charged by the weight of refrigerant put into them, hence if the pressures are not within their normal ranges, then the system must be evacuated, leak tested, repaired, and then recharged by weight, not pressure.

If you do not have the proper tools, then it's time to take it to a shop that does AC work.

Good Luck!

 

Yeah, we've actually done both. Hooked up mechanical highside lowside gauges to the system, as well checking with a decent electronic diagnosis tool. In both instances the gauges and the app gave good readings. It might have been a little low on the highside, but not enough to justify adding anything. Highside pressures ranged from 188 to 210 depending on the state of the compressor. I believe that pressure is supposed to be between 200 to 220. Low side was hanging around 150 in both cases

 

Well the pressures seem to be in line. Is your Engine Coolant Temperature (ECT) sensor working properly?

You might need to take in to a shop that specializes in AC in order to see if thee is a bad sensor somewhere that is not providing the correct data to the ECM, BCM, or HVAC control module. It seems like there are a whole lot of sensors involved in today's HVAC systems that can keep the AC from operating properly. Everything from engine speed to ambient temperature and engine coolant temperature. Diagnosis requires the use of a high end code reader/live data scanner in the hands of a qualified technician.

Good Luck!