My defrost is wide open with the AC on on my 1987 W124 300D. I assumed that the pod was bad and ordered a new one. I replaced it this morning, but it still wont shut. it seems like there is no vacuum at the 7 way manifold? All of the other pods work properly and the AC works as it should. The only other thing that may be related is the shifting 1-2 and 2-3 is noticeably harder in the past week or two, but that maybe a different issue.

Any ideas? How do you test the 7-way manifold?

Thanks,

Geoff