Maybe someone can answer this.

First the situation. I'm working on a 1977 240D manual trans, manual Climate Control (AC has twist knob like the blower). I've tested the CC reservoir and it's holding pressure, however the Climate Control circuit (green/yellow line) doesen't hold a vacuum when the AC is off. When I turn the AC on it has a slow but significant leak.

The Question: What diaphrams/vecuum element controls should this system have? Since it is not ACC there should be less of a snake pit, but this far I can only guess that it has the following:

1) AC vacuum control switch
2) Circulating Air Flap Element
3) Legroom Flap Lever & Defroster Nozzle

Any Input?