intermittent AC

[Brett Dikeman]

At 6:52 PM -0500 9/12/02, Paul Burgmeier wrote:
>My 1990 Audi 100's AC stopped working today.  This is not the first time
>that the AC stopped working.  It seems to work fine for a long period of
>time and then stop working for a few days.  Any ideas?

Next time it happens, try unplugging the multifunction temperature
sensor.  It's a large brass sensor screwed into the block near the
hose that runs to the upper radiator connection, has a large booted
connector.  The sensor will have either 3 or 4 pins(no functional
difference, just different design.)

If the A/C comes on, tada...your multifunction temperature sensor is
sending a false overheat signal to the A/C controller.

That's the hack-ish way of doing it- the best way is to put the
climate control into diagnostic mode and select the 'channel'
display; each segment of the temperature display indicates an input
or output- one segment, for example, means that the controller is
trying to activate the A/C clutch.  There's a segment for the
overheat signal, as well as the various pressure switches.

I don't remember off the top of my head how to do the diagnostic
mode, but if you have the factory repair manual, it is in there...or
try searching the archives- I did a quick search and came up with:

http://www.audifans.com/archives/1995/05/msg00135.html

Brett
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