Seems I have a proper vac leak, while ign is on, climate control system is off. When driving, I can hear it hissing behind the CCU.

Pretty sure it’s a faulty #1 climate control vacuum changeover valve. #1 has switched 12v with the CCU in off mode, when cycling ign on and off. That being part# 0008000478. It’s a 2 pin, 2 port solenoid valve

I disconnected the electrical part of the solenoid, and the vac leak is gone.

Where does one buy this switch over/change over valve?? They’re NLA…

Also, mine are cube shaped, the used ones on EBay are round. This a problem?

What is going to be the effect of running with this valve electrically disconnected??

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

While anything is possible, it is pretty unlikely that the switchover valve itself is the source of a vacuum leak. Have you checked the remainder of the associated vacuum circuit for leaks?

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I’ve read that the change over valves fail often. Not true?
The #1 valve was the first that I found to have switched 12v when turning the ign on/off and leaving the CCU off. Certainly did not go investigating vacuum lines post changeover valve. It’s super tight in there… Any idea where the #1 valve vac lines lead to?? I’d imagine they’d go to a vac pod somewhere, which could be the real culprit…