No power to A/C compressor

[rotorjockey]

1994 full size blazer and there is no power to the compressor. There is power at the fusebox and at the control box in the cab. All switches work, just nothing going to the compressor. The wiring color codes do not match the book so I'm pretty lost as to where to look now.
Are there any relays or hidden fuses that could be causing this?

 

[sweetk30]

comp clutch will not activate is low psi or high psi switch is activated .

so if you are empty or under charged or over charged it will help save the system from burning up a compressor .

this is the first thing that comes to mind.

 

[paratrooper307]

That'd be the first thing to check. Bypass the pressure switch and see if that fixes the problem.

 

[rotorjockey]

The system is empty. How do I bypass the switch and which one? High or low or both?

 

[sweetk30]

if system is empty you need to know why .

if replaced parts it need a vac down then if holds vac fill with oil/Freon to spec .

if you don't know why empty . then need to find out why .

you cant just run a empty system or you can trash the compressor .

 

[rotorjockey]

There is a leak in the compressor so I don't want to dump refrigerant in there knowing that or replace it yet because there is no voltage to the pressure switch on the back of it or the connection in the front. The book shows those wires going to a compressor relay but I have no idea where that is. The pressure switch on the accumulator has 12v. Once I fix the voltage problem, I will fix the leak issue.

 

[Fordum]

The pressure switch on the accumulator should be the one stopping the compressor. If you want to do a quick test, turn on the ignition, turn on the AC and bypass the switch.
You should get power to the clutch, and usually will hear a click.

Like they say, running the compressor without freon is not advised.