All, I'm fairly sure that my AC Compressor is dead. It lost its clutch, spacers, and felt ring some time ago. Replacement of the lost components with identical parts hasn't helped. I checked grounds and applied 12V directly to it. Clutch does nothing - it just sits there DOA... Got some good advice in a previous thread. I think this unit is beyond resurrection.

I just picked up a replacement compressor from the pick-n-pull. It is identical, spins freely, and the clutch engages perfectly with 12v applied. The compressor-donor car is a 1996 940 with low miles.

The used compressor cost me 10% of the cost of a rebuilt unit. Cost/Benefit-wise, I think it's well-worth my time and effort to install the used unit.

I know this is more complicated than a simple bolt-on fix, so I am asking for advice on relieving the R134a pressure, disconnecting the old compressor and getting the new compressor sealed up. This does not seem to be covered in the FAQ, but I'm sure that folks besides me would appreciate the insights and advice from the board.

Weather here has briefly cooled and I plan to perform the switch tomorrow AM.
Here are some starter questions that I've got.

Any advice on the compression fittings and the O-rings? I don't want to twist and destroy my aluminum pipes

The compressor is sealed, is there some way to check for internal lubricant? I know some of that lube is in the coolant stream - how can I be sure I'm putting the right amount it? Do I add the lube just like the coolant (via the low-side port? I just successfully recharged and shimmed a similar compressor unit on my C70 so I'm feeling a little bit more confident on how to recharge a system



Thanks as always!