I have a 2015 f550. The A/c works fine until you put any load on it. Then it blows hot. If you pull just a little rise in the road it blows hot. Going down the other side it gets cold again. If you hook up a goosneck, just the load of the trailer will cause it to happen.

It appears the computer is telling the a/c to shut off because the engine needs the power, but the engine is not really stressed when it happens.I could understand it if I was pulling a big load up a hill, but it does it just driving around town. There has to be a sensor that is telling the computer to do this, but I have no idea where to start.

 

You are correct that the computer is doing this. You need to go to the dealer and let them upload a fix for this.

 

Thanks for the feedback. I'll get it in for the update.