Just to explain, the AC compressor relay has a circuit that compares compressor rpm to engine rpm. If there is a discrepancy, the relay assumes the compressor is dragging and cuts the clutch so as not to compromise the belt and water pump.

And you get today's installment of 86-87 MB Diesels and electronics - losing electronics won't strand you. Don't fear the sixth cylinder.

Sixto
95 S420
87 300SDL