The A/C on my '92 has been a bit intermittent for years -- if it didn't come on when I turned on the switch I could get it working by turning it off and on again. Now it won't come on at all. To test the switch, relay, fuse(s) and wiring all at once I used mode 2 on the diagnostic black box. I got the code for the A/C control turning off and on (1-1-4), but not for the compressor starting (1-3-4). I'd like to test the compressor clutch -- but there's no easily accessible wiring connector on the Seiko-Seiki compressor. It has a screw-in connector, but the screw is hard to access under the PS pump. One wire at the compressor seems to be the ground, as it goes straight back to the metal body of the compressor. The other goes to a (aftermarket?) fuse box near the battery. If I connect this wire to the battery positive, and from the battery negative to the compressor body can I look for clutch function without damaging anything? Similarly, can I test the resistance of the compressor coil using the compressor body as the ground and the wire that goes to the little fuse box and be likely to get a genuine resistance reading? The car has a modern-looking drier (big tin cylinder) -- alternatively can I test the compressor from the wiring connector to the drier instead? I have a little knowledge of electrics, but clearly not enough...