AC changes 0n '90 200

[David Michael]

Nick,

I would say almost certainly that the fresh air flap servo has broken loose
and the vacuum hose leading to it has come off. It's a common problem, so
much so that Audi has a repair part. See

http://members.aol.com/c1j1miller/climate.html#Fresh%20air%20flap
and
http://www.sjmautotechnik.com/trouble_shooting/ac.html#recirc

Whats happening is that the "default" position for the flap is recirc - so
when you 1st start the AC, it's in that mode. When it decides to switch over
to "fresh air" the controller switches the vacuum a disconnect hose, big
vacuum leak, dash vents close and you can't get any air out of the dash
vents unless you are coasting downhill creating lots of vacuum.

To test this. you can remove the side panel off the center console and
disconnect the connector that connects the controller to all the vacuum
servos. The red line goes to the fresh air flap servo  - if it will not hold
vacuum, that is your problem.

Installing the Audi repair part is not trivial if you have not done it
before. It took me a while to figure out how to get the screws that hold the
repair bracket in.  I ended up using a pin-vise to pre-dril a pilot hole to
get the screw to grab.

Good luck

Dave
1990 200 QA 220 K



> ---------- Forwarded message ----------
> From: "nick at beol.net" <nick at beol.net>
> To: "quattro at audifans.com" <quattro at audifans.com>
> Date: Tue, 05 Jun 2007 13:09:51 -0400
> Subject: AC changes 0n '90 200
> Vehicle is '90 200 tqa.   Often, in hot weather when the AC is on auto and
> cold air is blowing out of the dash vents, something changes. The fan
> still is blowing, the ac clutch is still clutching, but the air no longer
> comes out the dash vents.  Very likely a door is changing positions.  Can
> happen at idle or at speed. To get the air back out of the center vents
> turn off the ignition and back on.  Turning off/on the climate control
> won't bring it back.
> Has anybody seen this and figured out what to fix?
> Any suspect that the servos simply leak off?
>
> TIA
> Nick
>
>