I'm having troubles with some of the vaccuum items in my 1985 190D. The locks work. The heating valve, vents, shut-off, etc. don't. Where do I start? Is there a central vaccuum pump that may be shot? How do I test. HELP!!!
Ken

 

You may find that one of the valve diaphragms has torn not allowing vacuum to build up , listen for leaks , i connect a small vacuum pump up to the vacuum line (Electric pump ) let it run and listen for leaks .