The Tach and A/C compressor in my 1985 300SD have finally stopped working completely. For the past year the problem has been intermittent -- when the tach would stop working the A/C compressor would disengage. I searched this forum and found a thread from 1999 that discussed two possibilities. 1) a blown fuse on the overvoltage relay and 2) loose wire that connects to the positive lead of the battery to the EGR control circuit. I have checked both of these and they are OK. Tach and A/C are still dead.

Anyone have any ideas?

Thanks,

Bill