Paul,

That's a good question on the compressor! I believe there is information lurking in this group on buying a seal kit from Toyota. The aftermarket kits are well-less reliable. I was thinking there was a body o-ring which leaks sometimes. If you pull the clutch and replace the seal. The clutch plate clearance is pretty critical for the system to operate correctly. Hence, re-shim the clutch as required.
I haven't been down this road in YEARS, but maybe traveling here soon. Hope this is helpful.

Michael

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Michael McGuire
83 300d
01 vw A4 TDI
66 Chevy Corsa
68 GMC V6 w/oD
86 300E