I have no power to my a/c clutch. I have power to the low pressure switch and even when I jump it, I have no power to the clutch. Bad wire? Or is there some other thing between the low pressure switch and clutch

 

Is there a high pressure switch in back of the compressor??? Some systems do, some don't......

 

Does your clutch engage manually by jumping it? The low pressure switch would interrupt to shut off the compressor.. But I cannot tell you for sure if it is supposed to have power or not, or if jumping it would turn on your compressor clutch.

There should be a fuse for the compressor clutch, if not a relay somewhere. Again, I can not tell you for sure without a schematic.

I had a friend who kept blowing a fuse every time he turned on his a/c. Come to find out there was a bad clutch. Replaced it and fine.

 

Is that compressor a replacement? I've heard some have a rather short cable that's weak to boot. Try what Volvo said.

 

Everything is OEM Stock. There is no high pressure switch on the compressor.
I am getting ZERO power to the plug for the compressor. 15amp fuse is good

 

If that is the case and you are positive you have ZERO power to the plug for the compressor and your fuse is intact, it is most likely a broken wire somewhere. Simple circuit.

I believe I read that these trucks have the compressor tied to the ECM (for idle up purposes) so that makes it a little easier or more difficult, depending on your views of half empty or half full.

 

Is there a relay?

 

There should be a relay considering the power activating the electromagnet.. Unless of course it is tied to the ECM in which that would be done internal.

 

Brb with the relay info...

On Edit: no relay for the A/C clutch, only a 15 Amp fuse.

 

Which truck of yours are we talking here? And what engine?
Assuming its your '94-'96 or '97 im quite sure they ALL have high pressure cut out switches.
And only the 4.9 has a relay.
The PCM is notified when the A/C clutch sees power but does not controll it.
Power goes from the fuse to the selector on the dash panel then to the cycling (low) pressure switch then to the high pressure switch then to the A/C clutch/resistor diode in paralell with the clutch.

 

I think I just blew a relay by reading this!! lol

 

Your truck is using R-134 for the A/C system. It uses a High Pressure Cut-out switch. It is electrically in series with the power and the low pressure/clutch cycling switch. My EVTM shows it located near the compressor. It should be attached to the high pressure line coming out of the compressor. My EVTM CD has a crappy line drawing otherwise I would pose a photo.

Follow the Dark Green/Orange wire back to the High Pressure switch. That switch is fed from a Black/Yellow wire from the low pressure/clutch cycling switch.

 

Well the problem was the high pressure switch(on line behind compressor). It was unplugged and turned 90*. The ONLY one who touches my truck are the inspection guys.(just got inspected last week) they must have knocked the plug off the switch and just shoved it back on

 

Glad to hear you found it Brad!