Hi all, I just completed an R12 to R134a conversion on my 1990 740turbo, My compressor clutch bearing failed, so I found a rebuild compressor for $175, so it seemed worth while to complete the freon conversion. Everything went well except after running for a few hours my compressor clutch will not kick in.
I have measured the voltage going to the clutch, 12 volts as it should be after the time delay relay kicks in, but when I connect the wire to the clutch leads it drops to zero volts, I can jumper the 12 volts directly from the battery and the clutch works fine, so the ground wire is fine. When I jumper from the battery to the clutch the AC system is working fine, plenty of cold air at the vents, I thought it was the wiring but I have jumpered around that and still have the same problem, any ideas???

Thanks Peter