Gave the AC a preliminary glance while I was installing a radio today.
The microswitch on the knob was cracked and falling apart, and the switch itself felt funny, I replaced it with one from my parts car, wrapping the brass wire around the expansion valve, or that area anyway.

I jumped the pressure switch on the drier, no comp, I applied 12v to the comp lead, it came on. Is the comp directly powered through that pressure swtich?
I didn't have time to trace it out today.

So, that switch. I gather clockwise and in the red is supposed to be full cooling, in the blue is adjustable temp, comp cycles on and off at varying rates.
What does that microswitch do though? I observed that the blower fan actually turned off, totally, when the switch was full counter clockwise and the microswitch was clicked. I also observed the car idled even worse than usual in this position, what felt like a dead miss at idle. I was out of diagnostic time, and I'm sure the system is low, and still R12.

What is the deal with the full CCW and bad idle?