2015 389 Peterbilt

Does the truck have a manual fan switch? Does the fan come on at all when the engine gets hot?

 

I know you say AC quit, not sure about the other? The AC clutch is fine, or is that something else?

 

Realized after i posted..thanks.

 

All i can add is. In the ac lines on my 01, think 3 plug connections. One controls the fan for the ac when ac is on. Think others are low freon pressure. Not a expert on this. But if i unplugged the one up on right side of radiator and jumper connected it, i could make the fan go off and on.

 

Thanks for update. You have a driver that seems to know their stuff.

 

The low pressure switch kicks the compressor on at 50 psi. Shuts off at 20 psi.

The hi pressure switch shuts the compressor off if it gets overcharged and hi pressure gets too hi. I"m not sure on that number as those big fans on semis pull a lot of air. Therefore, hi pressure on semis don't read as hi as cars. It's somewhere between 350 and 400 psi.

The other hi pressure switch switch kicks the fan on when hi pressure gets hi enough. As in idle and parked. Driving down the freeway there's enough air going through the condensor so fan isn't needed.

I'm not sure on gliders, and it might be different on semis entirely. But the ac electrical system is controlled through the body control module. BCM.

No clue on the fan though when ac is not needed. Other then what was already mentioned.