No voltage to AC compressor, what now? (AKA "I'm melting!!!")

[ThePhoenix]

When I bought my first MB a few months ago ('83 300SD) my wife dubbed her "The Phoenix", because she is gold with a tan interior, chrome wheels, and lots of chrome trim. She says we look like a retired couple from Phoenix driving around in it, and that my constant tinkering is like trying raise the proverbial bird from the ashes.

Anyhow... when I got it the AC didn't work and there was constant warm air coming out of the vents, but it wasn't a problem in February. Now that it's April but it feels like August and every shirt I wear has to be peeled off the MBtex like saran wrap, I think I better do something about it. The PO said that all it needed was the dryer unit to the left of the radiator, so that was the first thing I replaced. No go. Next up was installing a rebuilt main switch unit in the console and a new monovalve. This took care of the constant warm air issue, but still no AC.

Then I tried jumpering 12v to the compressor. This did the trick as a temporary fix, but I can't be telling valets to open the hood and disconnect the red wire running before parking my car. It would embarrass the hell out of the wife, and besides who wants to trust a valet making minimum wage plus tips with such an important task?

Yesterday I installed a new relay (the one with a "J" under it in the fuse box) hoping that would do the trick, but no such luck.

Where do I go from here? I stand waiting with VOM in hand and sweat beading on my brow...