HVAC Issue

[AmmoVan]

Long time lurker here. 2017 1500 limited, I am having an intermittent problem with my AC. freon pressures are good, E fan works, and I have replaced the low pressure sensor. It works great at all speeds on the road and sitting in traffic. And, then for some reason , the fan slows down and it blows warm air and then cold, then warm then cold etc. at all speeds and idle. Idle is when its the worst. I am thinking it may be the HVAC module. What is your opinion? Went to the dealer to let them look at it, had an appointment today at 0800, then they tell me it will be a week before they can get to it because it has to go into the main line for diag. I was more than a little irritated.

Thanks

 

[Jeepwalker]

It might be the module. Hard to say. It's one of those things you don't know till ya swap it out. A lot of times the electrical was bad but gets corrected in the swapping process. Sometimes they swap in a new module and the problem comes back (didn't get it resolved). Modern vehicles with all the electrical, good electrical paths are more important than ever. There are more grounds on a vehicle these days than most guys realize.

If you wanted to do a little DIY, double-check all battery and ground connections, and battery to body connection. Wiggle each fuse. Wiggle the main connector on the module. You could try to see if Autozone or OReilly's can read the HVAC module codes, with their scan tool. Or maybe you just want to let the dealer mess with it (??).

 

[EdGs]

Was going to suggest intermittent e fan, but that should be easily seen, and you said that it works.

Also, a bad fan will present as low/no cooling at idle due to lack of airflow over the condenser coil.