06 western star a/c help

There is no separate high/ low pressure sensors.

That big switch on top of dryer is the trinary switch. The power to the compressor runs through it. If refrigerant is to high or to low it cuts power to compressor. It's easy enough to replace. It's just a shrader valve.

 

It can get a little convaluted with different fan clutches. Most of them here have two hot wires on that plug. One of them is a low pressure switch and it goes to the wire next to it and powers the A/C clutch.
The other one is for the fan ( engine ) and when the high side pressure gets up around 275-325 it connects and sends power to the fan solinoid. When the engine fan cuts in the head pressure comes down and the cycle continues. Some fan clutches are air engauged and there is a different trinary switch for them. I like manual fan switches as a adition.
The wiring diagram is very complicated as the diagram is on the side of the new trinary switch. May be they installed the wrong one. There are not to many different ways to get that to operate the fan regardless of the engine or truck manufacture.
This was one of the best working most simplistic systems ever made.
Past that need to know some pressures.

 

there will also be a thermal switch in the evaporator core. this cuts A/C compressor clutch power also when the core is too cold. this allows the core to warm back up and prevent the core freezing into one big ice block as would happen if the A/C compressor kept pumping gas.

the low pressure liquid boils into a gas cooling the evaporator as it does. without regulation of this the core ices up and no air can flow over it.....

provided the A/C clutch fuse isn't blown or power wires broken/shorted the only other signals that will cut A/C fan clutch power

ECM overrides ie for over heats etc
thermal switch in evaporator
high pressure switch
low pressure switch

 

I'm having problems with my air conditioning and I replaced everything and the fuse keeps blowing everything is new someone who can give me a hand????

 

Probably got a wire rubbed through somewhere.

 

Having problems with my ac as well. Ac clutch stays engaged all the time. I believe this problem is also making my fan clutch stay on as well. I can disable the engine fan by jumping the power to the fan clutch selinoid and the selinoid will operate. New compressor , drier, trinary switch. Unplugging the trinary switch does nothing. Plugging the old trinary switch, but not screwed on the drier, does nothing.I have no positive power source at the dash switch or trinary switch. 2 wires at the dash switch show a ground with my test light probe, but the clip on a positive source. Trinary shows 2 strong ground terminals and on very weak ( dim light ) on my test light, 4th terminal does nothing. I don't see an ac fuse or relay in the fuse box. Beginning to think the ac might be controled by a pcm or something. Does anyone have a wiring diagram or expertise on this system?

 

Do you still have power to the clutch when the trinary is unpluged? If not is the clutch not locked engaged?

 

Yes the clutch stays engaged all the time. Only thing that shuts it off is unplugging the compressor. Even with the trinary unplugged or the old trinary plugged in, buy not screwed onto the port. I have not had any positive source at the trinary or at the dash switch. With no ac fuse or relay in the fuse box, does the pcm or ecm control these functions