OK, so I put in a new servo (aluminum body, $250+tax from Texas European Motors, Austin, TX) and now I only get blower motor and compressor when switch is on "DEF" --no blower in any other switch position. And STILL NO HEAT! Aux water pump is new but only seems to spin when I jump it to the battery. I tested the resistance circuit, and the three components (in-car
temp sensor, the ambient temp sensor, and the rheostat temp selector) all check out.

Sounds like the amplifier, right? Well, I have substituted three different ACC amps, all with the same result. Could they all be fried? Is there some other relay or something that would fry the amps? How can I bench test the amp? I don't want tojust buy a new one and plug it in only to fry it, too...

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1978 300SD 149K miles silver-blue "Maxine" (mine!)
1979 300SD 318K miles red "Helga" (SOLD)
1980 300SD 321K miles yellow "Linda" (younger daughter's)
1980 300SD 148K miles blue (SOLD)
1980 300SD 153K miles green(parts car, SOLD)
Yes, I have a W116 fetish :-)