[V8] theoretical vacuum questions from the center of my mind.....

[Roger M. Woodbury]

I have a theoretical question about vacuum systems in these cars.  I am
specifically working my way around a vacuum failure in my wife's 100CS, but
I am quite certain that most Audi vacuum systems work in similar fashion.  I
have NEVER had a vacuum failure in any of the cars which I have owned, but
it appears that the 100CS is having a serious vaccum meltdown.  Here's what
is happening.
 
Late sping, 2011:  cruise control turned off.  It just let go, and when
reset, reset for a while and then disengaged again.  When I tried to reset
it, no result.
 
At some point, and perhaps more or less the same time, we began to
experience some unlocking/locking difficulties with the right side doors in
the same car.  Some days the doors would lock and some days they would not.
Some days they would not unlock with the key in the driver's door, and some
days they would. Eventually, neither front nor rear right side door will
lock or unloock properly with the key from the driver's side door.  nor will
the key unlock both front and rear doors on the right side.  The left side
appears uninvolved and both front and rear left side doors will unlock with
the key from the driver's side.
 
The recirculating valve is not working properly if at all, and when it is
cold and damp, the interior surfaces of the window fog badly.  I believe and
have been told on this list that this is a vacuum operated flappy valve.  
 
Now, my questiion:  is there one pump that will provide vacuum to all of
these points on this car?  Or are there multiple pumps?  It seems likely
that the doors and the recirculating flap might be operated by the same
pump/vacuum source.  I do not have a manual, and perhaps I should, but for
now, I'll just post the question.
 
Replacement pumps are crazy expensive or crazy cheap and plentiful for all
sorts of things on this car.  Any comments will be gratefully received.
 
Roger