Isuzu Repair: A/C, voltage drop test, ebay

Question
I bought a 94 trooper about 2 months ago and the air worked in it.  Now its not working.  The compressor or clutch does not seem to be coming on.  I had it checked out & the mechanic said it all looks good but not turning on. It may be a wiring issue.  I thought it may be the switch on the control head module so i bought a used one on ebay and took out my switch and replaced it with that one but no luck.  The relays all look good and i cant see any breaks in the wiring from what i can tell.  Any suggestions 94 trooper 6 cyl

Answer
Well is the switch on the actual compressor good? There should be a black wire running off of the compressor that activates the clutch and if that is loose, corroded or bad it won't work Curt. So if everyhing is hooked up right but it won't turn on then we know that either you are not getting voltage, or worse, your compressor could be locked up, which I doubt in this case. Have you done a voltage drop test on the A/C system yet? I recommend doing one as this will tell you a great deal about that system okay? Any other questions please let me know.