Did a bit of a search prior to posting. Not clear on a few things.

1993 240 Compressor is a Seiko # SS121DS5

Went to turn on the ac and the clutch did not engage. There is a single wire that runs out of the top of the compressor and connects into a green wire under the intake manifold. It is my understanding that I can test for clutch engagement by disconnecting that wire and connecting the wire leading to the clutch to +12v at the battery and it should engage. It did not.

- Did I presume the clutch test correctly?
- Is there a resistance check I can do?
- Is there something else I should look for before I start figuring out how to replace the clutch...or is it wiser to replace the clutch and compressor?
- Is there dedicated ground wire or does it get its ground from the casing?
- Can the clutch be replaced on the car or do I have to remove the compressor?
- What is the small sealed box on top of the compressor that the wire runs into and out of as it heads for the clutch?
- Is it easier to R&R the compressor or clutch from underneath the car?

THANKS!!!