Don't short the wires to a three-wire unit. That is a sensor with a voltage feed wire that will get shorted to the ground wire and potentially cause more problems. It's only the two-wire units that are on / off switches that can be bypassed.
If you jumpered terminals 30 and 87 in the relay socket, and the compressor ran, that proves the high-current wiring to the compressor clutch, and the clutch are okay. Now we have to figure out why the Engine Computer is not turning the relay on.
The only thing you're going to be able to do yourself is check terminal 86. That should have 12 volts anytime the ignition switch is on. If you don't, try terminal 85. Wiring diagrams have been known to have mistakes.
If you do have 12 volts on terminal 86, you can raise the relay slightly, or insert a thin piece of wire into terminal 85, then insert the relay. Don't use such a fat wire that it stretches the terminal. That can result in more intermittent operation later. This is the terminal that did not have voltage with the relay removed. You will find voltage there now, once the relay is reinstalled. Use a small jumper wire to ground the wire in terminal 85. That will activate the relay and you'll hear the click of the compressor clutch.
At this point a number of computers get involved, and you're going to need a scanner to talk to them and command them to do things. There may be diagnostic fault codes too that will direct the mechanic to the circuit that needs further diagnosis.
Saturday, July 25th, 2015 AT 10:45 PM