First, make sure it is the clutch. Connect 12 volts from the battery to the clutch, i.e. direct wire. You can do this without the car running, it's safer that way. Once you have power to the clutch, put a screw driver or something else that is metal near the clutch. If the clutch magnet is working then the screw driver will be attracted to the clutch and the problem is in the wiring and or controls.

If the electro magnet works but the clutch won't engage then you may want to try something like PB Blaster. That's what I did on my BMW earlier this summer and it's continued to work all summer.

You didn't mention which year car you have. I will guess that you have a Diesal Kiki A/C compressor which seems to be the most common from '87 on. I have an old Diesal Kiki that was replaced; bad compressor, that I have been trying to get the clutch assembly off without any luck. Maybe someone on the board can help both of us by describing how to get the assembly off.

Clutches or just the electro magnics are available. Do a search for automobile airconditioning. I bought a new electro magnic from www.rparts.com for a SelTec compressor.

Good luck! Keep us posted.