89 100 AC Control Head (Climate Control) Diagnostic

[David_Powell@hqlink.cbsi.com (David Powell)]

Background: 89 100 w/ 114K miles.  I've been to two shops that said they knew
what they were doing.  They did conventional AC system analysis.  My freon is
fine.  The compressor is fine.  They can't find the problem.  Take it to the
dealership they say.  I hate taking things to the dealership.  Finally I open up
my Bentley Manuals.  There's an AC diagnostic built into it.  I follow the
directions.  in the diagnostic pages.  On the 2nd or 3rd page of the diagnostic
pages, it says go to track 17, and look at the value.  The value for me is "no
value".  The diagnosis ends there with "Get a new control head".  

The question(s). 
1.  Is that it?  Is this test conclusive?  or is there something else I could do
to make sure I really need to spend a s__t load of money on a new climate
control?
2. Where's a good place to purchase such a device.  Mine is TEIL-NR
443-830-043F, AUDI 100/200, D.E. MODEL 16123319

3. Does anyone repair these things?

Regards from Hot Virginia,

DPowell