[W126 Coupe] main air flap is bass ackwards

[Dick Spellman]

Richard:  one last comment.  You did run a vacuum test on each line at the
vacuum distribution manifold, right?  If any one line has an element with a
bad leak the possibility exists that none of the elements will work properly
because you will draw down the reserve vac pressure on the reservoir under
the fender.  So, a gross leak will cause elements that are actually just
fine to misbehave.

A Mighty-Vac or similar tester will make short work of learning which
element or line is bad by simply disconnecting at the manifold and applying
vac pressure and watching for a drop on the needle over 20-30 seconds.  Then
it's just identifying the line and/or associated element needing repair.
You can also test the vac reservoir at the distribution manifold for leaks.

Dick