Air Conditioner Problem 3 shops can't find problem so far

@Heavyd will be along shortly to guide you down the best path....listen to what he tells you, the man knows his stuff!

 

I have the same problem with one of my 2012 Prostars. It will blow cold for 2 - 3 hours, then start blowing warm. If you stop the truck, turn it off, then cycle the key 5 times quickly, it will work again for a couple hours again. Dealer couldn't find the problem.

 

Ok obviously you'll have to expand that second quote to read what I wrote.
I'm not retyping it, lol.

 

Check the wiring at the high pressure switch. Start at the switch and work back, odds are there is a broken wire. I had the same issue a few weeks ago on my ProStar with Cummins, the wire was broken say two inches from the switch. That is located on the high pressure line, right up near the CAC/Condensor.

And that switch, you do not need to evacuate the system to work on it if say it is bad, just plug and play. They run around $90 if it is bad, and they do at times fail. I think I have to install a new one every say year and a half two years.

 

Hard to really tell what’s going on with the rest of the system using that cheap gauge that comes with the bottle of 134. Would like to have seen the video with dual gauges hooked up to see if there is a potential issue in the system that maybe be causing the system to not come on. Could be a blockage or a sensor. Who knows

 

Been through this too... Find the Ambient Air Temperature sensor. It is usually buried in the harness at the driver side found under or very near the radiator, forward of the steering box. Dig that out, and get it into the open air. I rewired mine and placed it up at the drivers door and clipped to the windshield wiper cowl. The issues you described went away, I have had AC ever since moving that sensor.

Here is a photo of what you are looking for... Get it into the fresh air away from as much heat as possible. Your dash board outdoor temp reading will also be a bit more accurate.

And to you naysayers, look up Navistar Bodybuilder, the electrical schematics, trace that sensor, it is tied directly into the AC system. That is how I discovered this, chasing down an electrical issue with my AC. The same AC that has not worked in the first four years of owning this truck. Thousands upon thousands of dollars spent on this AC system. This is the first time it has worked, going on second year with ice cold AC. I now do all of my own AC work.

 

Is your defroster working proper? Not just blowing air, but is the compressor cycling proper?

 

First, take that jumper wire off before you blow your system. You are forcing the compressor to say on full time. You have no protection from over pressure at all and it's a ticking time bomb. After that, the computer is the first tool I grab to see why it isn't engaging. When ac doesn't work in these you need someone properly qualified. You need a guy that knows how ac works, knows Internationals, knows electrical and electronics and knows how to use Diamond logic builder software. You have had a lot of work done there, I suggest you disconnect your batteries for a minute to allow everything to cold boot and retest.