A/C won't shut off

Stay South so you always need your AC.
Real answer is I'm sorry IDK. I know my way around car AC and plenty of car wrenching experience, but haven't worked on any rigs before, except for assorted service tasks I did when I was a kid working a gas station that was the closest thing to a truck stop my little town had. Found out where the term grease monkey comes from, ya gotta be a monkey to get at all the grease fittings on a rig. This was the early to mid 70's so unsure if they are still the same. Back then all the tires except the steers had split rims and I fixed lots of fixed rim flats.

 

If your air control is set on defrost your A/C is on to reduce moisture on the windshield.
Or check that the bunk control is not set to A/C and over-riding the drivers controls.

 

Turn your cab and bunk blowers off. If the ac is still running, then the compressor is getting 12 volts all the time from either a faulty body controller or someone has done some rewiring. Since the ac is controlled ultimately by the body controller, the only way to really see what is going on is to use Diamond logic software to diagnose this.

 

My uncle rewired a car once. Couldn't get it to start. Tore apart the dash several times. Nothing wrong. Mom got in and started the car.

He wasn't pushing in the clutch.

Sometimes as a mechanic, you can't see the forest for the trees.