MASSIVE A/C PROBLEMS! PLEASE HELP!

["Brendan O'Mara" <omarab@peak.org>]

(I have posted on this topic before, but still have
more and more problems! Please read on...)

I am having MASSIVE trouble with my climate control system
in my 84 Audi 5000S with digital climate control.

I have tried all the 'simple' fixes suggested to me
(corroded contacts etc) but this is not the fix.  I have
obtained two additional control heads and none of them
have any display output (no LED indicators, no digital
display whatsoever.)  I have checked voltage and grounds
to the board (by checking at the PC board inside) and
every board related to the climate system has voltage and
a good ground (below .03ohms resistance).  The only
thing on the control head that works is the night illumination
lights.  The other interesting thing is that the original
system 'died' slowly, and intermittently.

I was hoping you could assist me in finding the problem.
I have heard about a diagnostic mode which I have not found
how to use yet.  If you don't have any ideas, do you have
any other suggestions that you can point me to?  Does Delco
have any tech support that you know of?  Any good Audi
electricians that can help me by phone?  I have also seen
mention of Bentley manuals but don't know where to find them.
Would a library have them?

Thank you very much,

Brendan O'Mara
omarab@peak.org