When I got my SL, the A/C compressor belt wasn't on the engine. The previous owner mentioned that it wasn't there when he got the car either, and that A/C wasn't a big deal in MA in a convertible anyway. Needless to say, it isn't a biggie in Canada either.
Anyway, I removed it and checked the clutch on the bench. It holds fine. However, there is no noticeable 'sucking and gurgling' sound when the front part is turned by hand. It turns freely, but there is some scraping of the pulley against the clutch plate (or the part at the front).
I have an old compressor from a '70's Datsun laying around, and when the front is turned, there is a noticeable suction/expel sound from the in/out ports.
Does this indicate that something inside the compressor is bad, and if so, what is it likely to be? Is it repairable?
Could the lack of refrigerant (probably R12) from such a long time of no use allow the compressor to turn freely but not 'compress', like it requires oil to seal and work? This doesn't sound reasonable, as the Datsun compressor has laid there dry for years.

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1986 560SL
2002 Toyota Camry
1993 Lexus