cant get my A/C to work I have 12volts going in and coming out of the pressure switch when the a/c is on,however there is no voltage at the compressor.
Possible WOT relay failure The WOT relay turns the A/C off when you got Wide Open Throttle. Check the relay, socket and wiring, The heat from the exhaust system tends to cook the relay and wiring.
Diagram courtesy of Tmoss & Stang&2birds
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Jrichker is right-on. Sometimes just grabbing the relay and socket will make the clutch engage for a second (till it moves an iota and kicks off because of vulcanized wiring).
If the relay has power leaving the normally closed terminal, disconnect the clutch connector and relay socket and check continuity between both ends of the blk/yellow wire. If ok, ohm out the clutch's ground.