ac compressor makes clicking noise when ac is off, goes away when ac is on............is clutch and/or bearing servicable independently and in vehicle ? or do i have to replace the entire ac compressor

If this is a Nippondenso unit, the clutch will come off in the car, then remove the snap ring and tap the pulley and bearing off with a plastic hammer. Can be done in car if you have the room to get to it.

New bearing will have to be pressed in after old one is pressed out, then re-install (the bearing and pulley will just push on), re-install snap ring and clutch plate.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!