A/C recirculation/warm air from dash ponderings...

["G. Benedikt Rochow" <rochow@segosf.hlo.dec.com>]

I've got an '84 5kS, but these thoughts and questions probably 
apply to a number of models.

I'm guessing that I'm not the only one to be slightly annoyed
by the presumption that I always want "fresh" air when I want 
heat/cooling, as well as no warm air from the dash vents.
(Tangent: I noticed that Steve Cobram's early US V8 brochure shows 
the same climate control unit, and a separate recirc. button that
nobody appears to have. I remember that when the just-superseded
MB S-class came out, the recirc. switch on the climate control 
was touted as a big-deal feature; maybe Audi was toying with
this revolutionary idea...even my mother's mid-70s Renault 4 had
a continuously-variable inside/outside control on the heater.
But I digress.)
So, besides putting in switches to override the A/C head
unit's idea of where the air should go to,
I'd like to bring my A/C up to the standards of a
lowest-model Renault designed in '61 :) with regard to "fresh" air:

BIG Question: Is the way the air is routed such that it would
work at all to have the recirc. flap open and the fresh air
flap closed, or is "fresh air" the only intake for the blower
motor?
(Considering that I don't know of a mode other than 'off' that
uses recirc. air - is that correct? - I'd guess it doesn't
work. Considering that there's a recirc. flap at all, I'd
guess that the 'knowledge' above is incorrect, as there would 
be no point in having it otherwise, right?)

any ideas/knowledge/experience?
(diagrams? :)

thanks,
-gbr