j14

Air only blows through defroster vents
All air directing flaps in the CC system are actuated using engine vacuum. The default position is "defrost", so if the system is stuck in this mode that it's more than likely that the system isn't getting enough vacuum. Inspect all vacuum lines going to the CC system. Does anyone know if this would be expensive how much are we talking?

SteveJ_in_TX

The AC controller (up under the glovebox)diverts air to the various vaccuum motors in your CC system, they in turn move the flaps and blend doors.

Typically the AC controller as a unit does not fail, it's the individual servos that fail due oil mist getting sucked into the servos and causing the seals to fail from the oil swelling the seals.

The AC controller was a Delco unit used on the big body Oldsmobiles, Cadillacs and Buicks of that era, the common 'el cheapo' fix is to pull one from a GM at a junkyard, de-solder the servos and solder them onto your Audi unit.

I can't remember how to tell if the servos are good or bad, it involves shaking them but I can't remember if hearing a noise/rattle means they are good or bad.

Go to audifans.com and use the Google search on the words AC controller.

Good luck.

-Steve Jensen
87 5kcstq

AndrewsQuattros

Steve,
Are you talking about changing just the control unit by the radio ? Or are the servos in various places or are they all by the glove box ? It might be a stupid question but help me hahha. Thats good that you bring that up cause I thought it was a vaccuum problem also and I was trying to figure it out for a loong time.
Thanks
-Andrew

-84 Audi 5000S
-85 Audi 5000S

crotext

You can pull the AC control unit loose easily. At the top there is a little arm that revolves from a solenoid inside and moves the wire control cable. If it is not moving full swing then there is a problem. Also I learned that a sharp rap on the upper left cover would temporarily shake loose a sticking solenoid. I was lucky enough to find a working replacement in a junkyard. Very easy to change entire unit and with glove box removed it is in view and very accessible. As Steve says, inner components can be changed too.

SteveJ_in_TX

I may not be using the right terminology, but the things I am calling servos are all soldered to the circuit board of the AC controller. The vaccuum motors are at the other end of the vaccuum hoses from the servos and do the actual flap or door movement.

HTH.

-Steve Jensen
87 5kcstq