Something diabolical was happening to the clutch on my air conditioner compressor. It would not disengage. The AC compressor continued to turn even after I pulled the 12-volt supply wire to the unit. It seemed possessed!

The AC compressor exhibited no unusual symptoms that would explain the locked clutch, there was no bearing failure, no unusual noise, no smoke, no fire.

On the contrary, the AC continued to work properly. The Jaguar cooled as good or better than the other cars I currently own, all of which have original factory 134a AC systems.

The 1978 Jaguar XJ-S uses the GM A6 compressor, a fairly common compressor used by a variety of General Motor's cars in the US. Based on the resellers I contacted, I was advised not to change the AC clutch. I difficult job I was told. Best left to the professionals. In addition, a rebuilt compressor was, in some cases, cheaper than a new clutch assembly, and darn close to the price of a rebuilt clutch.