Electrical Problem

[Andreas Budi Dharmawan <dharma@rpi.edu>]

Hi Audi fans,

I'm having a problem with my Audi 5000s 85 Climate Control Unit.
Here is the scope: It started when the blower fan stopped to work.
I followed the guideline specified in the Audi Repair Manual to
check the cause of the problem. The inspection led me to believe
that the blower fan was broken. I replaced the fan and the system
worked perfectly for several days. I checked my old fan and connected
directly to the car battery. To my surprise, my old one still worked.
I rechecked the wiring condition and I was able to veryfy that
there was 12 volts voltage difference between the positive cable and
the ground when I set the climate control at the highest temperature 
and defrost mode. So, it seemed that my new fan was broken too. I did
the same check, that was to connect the fan directly to the car 
battery and as I expected, it worked! I tried to follow the flowchart`
table in the repair manual to find the problem, but I got the same
result: the fan was broken. Could the positive cable have a very
little current which was not strong enough to drive the fan?
If that is the case, which unit I have to replace? 
Having this frustation, I rewired the fan and installed an on/off
emergency button. Thus the fan receives power directly from the
car battery via a toggle switch. I survived with this emergency
fix for several months. I can still control the temperature
via the climate control, I just have to turn the fan on and off
manually. Last night, when I turned the ignition key off and pulled
the key, I noticed that the climate control LED didn't go off. It 
was still on and I heard a noise coming from under the dashboard. 
I suspected that noise came from the vacumm motor which control the
flaps of the air duct. At the end, I pulled the fuse out since
I didn't want to drain the battery. Any idea what unit might be
broken? I can't tell whether the AC unit is still working since
the weather up here has been below 20 degrees Farenheit most of
the time. The heater works though with the exceptions mentioned 
above. 

Does anybody ever encounter this problem? Almost two years ago,
during summer time, the AC didn't work, but the blower fan worked
fine. I brought the car to the dealer and they replace blower
control unit and costed me $100+. 

Thanks in advance