Chasing a lack of cold air in the cabin, I have found myself at the compressor itself... I've got voltage at the 2-pin compressor connector when the A/C is switched on, which tells me the panel **** is functioning and the relay and low pressure switch are OK. I guess now I'm not sure what to check for? The clutch simply isn't grabbing, and thus not cycling the compressor?

 

Doesn't the low pressure cycle switch on the drier control the ground ?

 

Did you measure the resistance of the clutch coil to see that it has continuity? Also, you should use a test lamp ( 12 volt Automotive tail lamp in a socket with pigtail wire leads) to make sure there is adequate current in addition to voltage to engage the coil. Measureing with a voltmeter requires very little current and often a bad connection can limit the current below that required to engage the clutch. The lamp will simulate the clutch coil (load) and give a visual confirm that the voltage you are reading is 'real'.

 

I should have been more specific on that: yes I did use a test light and not a DVM when checking... I've been through that fiasco before, so I always use a test light when looking for power. At any rate, no I have not checked the resistance across the clutch pins, so whats the target number I should find if it's OK? I assume all I need to do is put the DVM across the two pins when uplugged from the harness and take the reading, right?

 

BTT - what am I looking for at the clutch pins?

 

Look for anything at all that is not either a direct short or open circuit.

 

OK, I took my DVM out there and here's what I found:

1.) No continuity between the two pins on the compressor itself...

2.) No continuity between either pin and ground...

3.) 3.7ohms resistance between the two pins on the compressor itself...

Does this information offer any clues? Should I be looking for any information on the pigtail connector from the wiring harness other than switched power, which I have already verified with a test light?

 

If you had the connector unplugged..as you should have..not back probing the connector...test #1 in your above post dictates an open clutch coil..test #2 indicates thats the way it should be....test #3 dictates that you either didn't have a good connection of your test leads on test#1...or..you just uncovered an intermittent open of your clutch coil.

 

Yes, completely unplugged... Each "test" was repeated several times and the results were always exactly as described?

 

I just remebered somethin'.............there may be a diode in the clutch coil to prevent voltage spike while the clutch is cycling. If there is a diode...and its good...you would have continuity with leads placed one way and none with leads reversed....

 

Sounds to me like I need a new compressor clutch??