2015 389 Peterbilt

Lose the belt?

 

Clutch fan is air and operated by solenoid. If there is a fault or blown fuse, it should come on by default so truck does not overheat. Uses air psi to disengage so if you have a blown air line going to fan, the fan will engage and stay engage so truck does not overheat.So you are saying the clutch fan is not engaged? Times may have changed and things may be different with new trucks but you have a glider truck with old detroit.
If fan comes on and wont shut off with a/c running, i would blame that on a bad switch on one of the a/c lines.

 

Is the truck parked and the A/C doesn't work? Or is it not working when driving down the highway?

The A/C system will not produce cold air in the cab if the heat can't be removed from the condensor up front. So if A/C works just fine while travelling at highway speeds but blows warm when parked, I'd lean towards a switch in the A/C system that has failed open.

 

Ok. thanks for the update on the info and wish i could be more help