Any suggestions/ or ideas on what the problem is with my a/c with my Peterbilt 379.
In 3 years, I have been through 5 a/c compressors. This last time, I had the a/c compressor replaced, all pressure switches replaced, new belts, hoses, and recharged.
Like the last 3 years, it works great for a month after repair, and then it starts to blow warm. In the past, there used to be a ticking noise when it would start to go out and then the a/c compressor would blow. However since I had the pressure switches replaced, it isn't doing that, but once again its blowing warm air.
Not sure what else to do, but I drive South so having a/c is a must.
I've been to Kenworth dealerships, Peterbilt dealerships and other service stations and nobody can figure it out!

Time to put some dye in the system and find the leak.

Most places add dye as standard operating procedure. At least I know the TA's, my local Cummins shop and the Peterbilt dealers I've used over the years have.

Just need to find the leak, it can be frustrating, I would uspect the condensor, it is in front of the radiator, and easy to get hit by something, a tiny pin hole is all it takes, and sometimes it inside the fins.

Either that or one of the lines, you didn't say how old the truck is, my 99 KW has had almost all the lines changed at one time or another.