In my '80 SD, the monovalve crapped out on me in the servo, thankfully, I was able to bypass it to get heat this winter, now that spring approaches, I'd like to revisit that mono valve and try to repair it or come up with some other viable and practical solution.

I have a coolant shut off valve from a Euro 450 SEL. it's vacuum operated.

here's the question part. and please, answer, even if you're not sure, any input is appreciated.

1. Is the monovalve in the ACCII Servo units epectronicallh opened and closed, or is it vacuum operated by a variable vacuum source?
2. is there some OTHER variable vaccum source related to the climate control system that I can use to operate this valve?
3. can't I just buy some monovalve kit for my servo? I have all fan speeds and it makes like it wants to blow cold air (I mean opens the center vents) even thought I have my ACC compressor unplugged for now. Just can't control heat levels.

__________________
RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

____________________________
FACEBOOK: PANZER450

The ACC servo literally contains a servo motor that is controlled by an amplifier box that is inside behind the glove box insert. You are actually in good shape, the "guts" of yours works like it should so you know that the amplifier is good. I would pick up one of the guaranteed good used ones on eBay that you routinely find for $150 and roll the dice with it, or get one of the rebuilds for around $400 since you know the rest of the system works. The ACCII module contains the switches for the blower speeds, vacuum valving, and the hot water valving - all in one unit and its pretty decent when it works. There is also a temperature lock-out switch at the bottom that keeps the blower from operating until a minimum water temp is reached (105 deg F, IIRC) - the lock-out is overriden by the Defrost position or if you have it set to cool temperatures. The system was designed by Chrysler, here is a link to a basic manual on the system as applied to a 71 Chrysler Imperial http://www.imperialclub.com/Repair/Lit/Master/281/cover.htm

More detailed (way detailed, probably approaching 150 pages or more) is available on the W116.org website - start here to access the library
http://handbook.w116.org/matrix6.htm