intermittent AC

[Paul Burgmeier]

Thanks Brett for the information, it led me to solving the problem!

I tried unplugging the multifunction temperature sensor and that did not
work.  I then looked through the link you sent me and found that the
radiator fan should be turning on when I start the AC. Being an average Joe,
I did not know this. ....the problem was a bad relay.

Thanks again
Paul

90' 100  238,000


----- Original Message -----
From: "Brett Dikeman" <brett at cloud9.net>
To: "Paul Burgmeier" <burgydbq at hotmail.com>; <quattro at audifans.com>
Sent: Thursday, September 12, 2002 9:30 PM
Subject: Re: intermittent AC


> 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
> --
> ----
> "They that give up essential liberty to obtain temporary
> safety deserve neither liberty nor safety." - Ben Franklin
> http://www.users.cloud9.net/~brett/
> http://www.apple.com/switch/
>