Thanks for posting, though doesn't apply to my 1984 & 85 300D. I understand the 1980 auto-climate system came from an earlier Chrysler system, perhaps late 1950's since my 1965 Chrysler doesn't have it though maybe high-end models did have ATC. Mine is just a manual system, using a pneum-electric push-button switch. In my 300D's, I gave up on the servo-valve. In one, I installed an electric vac switch which controls a vac-water valve, as in later M-B. In the other, I installed the servo-valve from a W124 since good used ones seem more available. Also got rid of the silly aux water pump.

In general, ATC systems are silly. My 2002 Chrysler has a digital one, with dual front and separate rear controls. It works fine, but auto-control is not needed or very useful. Most people just set the temperature setpoint higher (or colder) than they want to get "fast heat" or "fast cold", then change the setpoint later. So, all a car really needs is a hotter-colder knob, like the simple analog manual system in 1996 Plymouth. Don't need a temperature setpoint with a feedback loop.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans