Thanks to M.B. Doc for the Klima relay pinouts. The Kilma in my 1985 300D is not turning on the compressor because the AC (Alternating Curent) signal from the EGR control Unit to pin 2 of the Kilma is missing. I tested the engine speed sensor with a scope and get a good sine wave out. The fault would seem to be inside the EGR control unit and this fault is also suggested by the fact that the tach is not working. In addition the clock is not working but this may be a separate problem. Fuses F2 and F12 are both good.

Has anyone else had a fault in the EGR control unit shut down the air conditioning in a 1985 300D?