My 1991 350 SDL has a tach problem that started intermittently, then generally permanent with only occasional operations.

When it stops, the air conditioner compressor also stops engaging (everything else is OK).

Does this sound like any of the symptoms anyone else is having?

Any advice on where to start? Did the standard fuse thing ... unrelated at that point, I think.

Could be a matter of connections being corroded or loose?

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George Stephenson
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg