Help A/C Compressor no power

[Cube911]

I have a 91 Man 4.0l, The problem I am having is that at the accumulator switch I am getting voltages through the accumulator switch but it is not making it to the compressor. I have ohmed from the hot side of the compressor to the fuse and its closed as I imagine it should be, but only with the ignition off. Once the ignition is on then it is "open" and doesn't start the compressor. I can jump the compressor on, and it cools properly, freon is "close enough for govt work". With the a/c switch inside on, the truck seems to act as if the a/c was working properly, idling differently compensating for the a/c, but no clutch spinning. I have checked the wiring through the engine compartment and it is all properly intact.

My only solution is going to be to run the power from the accumulator switch to the compressor, if nobody can lead me in the right direction. I will leave the accumulator switch of course inline. But in Ga A/C is a MUST!!!

Thanks

Jason

 

[shadetree]

The compressor is controlled by a relay. If you are getting voltage thru the low pressure switch, but it is not getting to the compressor coil, check the relay. It could be bad, missing operating voltages, or getting a reading from the high pressure side.

The high pressure switch will cause the relay to open cutting voltage from the compressor coil.

The relay is also controlled by the ECU as it opens the relay during wide open throttle conditions.:shady

 

[Cube911]

Mr. Shadey, Call me crazy, but I don't believe I have a high pressure switch, just the accumulator switch which is off the low pressure side on the accumulator. And as far as relays I only know of 3 the EEC, Fuel Pump and Starter. I know all a/c's work the same GENERALLY, but is it possible I have only the accumulator switch which acts as the relay sending the voltage to ????? and then to the compressor. I have to figure out what the ???? or where it is.

Thanks
Jason

Ok So any clue as to where the Relay could possibly be?
High pressure switch is where? I'll bypass it lol...

 

[Cube911]

ok it was the ecu relay, under the fenderwell fuse box. Thanks for the help!