96 Bravada A/C Problems

[miguel120]

A/C does not cool, readings and observations:
1. Compressor does not engage
2. 45 psi Low side / 40 psi High side
3. The accumulator and the evaporator inlets are warm to hot.

Done the following:
a. A/C relay plug have power (12v)
b. Jump wired the low pressure switch, compressor does not engage.
c. Check for power at the above switch, (none)
d. Check for power at the compressor, (none)
e. Ran A/C and apply direct battery power to compressor switch,( compressor engaged)
f. Check all fuses and they are OK.

Need Help from here.....

Thanks!!

[Chris Stewart]

Sorry for my lateness....
It seems the AC relay should have 12v on the "signal" wire from the AC switch inside the car, 12v on a bigger "work" wire going to the high pressure switch, low pressure switch and ending up at the compressor clutch and a ground or 2. My '97 manual doesn't have an AC wiring diagram for AC...probably in an optional or speciality book.
After turning the keyswitch on (don't start the engine), put your finger on the AC relay, have somebody push the AC button off and on and you feel for a "click" , confirming the AC relay coil is not shorted or the coil circuit is open.
If you do feel a click, the contacts inside the relay may not be conducting the voltage to the "work" wire, still making the relay replacement necessary.
Have you replaced the compressor lately?
Some replacement compressors don't have the high pressure switch to plug into, just a "blow out" plug. Without closing the electrical circuit through the high pressure switch, the compressor clutch won't engage. I replaced my compressor with rebuilt compressor without the high pressure switch, but still engaged the compressor by putting a small piece of wire into the high pressure switch wiring connector holes thereby closing the circuit and engaging the compressor.