|
Agree with the previous posts, bt would recommend a disciplined approach going from easiest to hardest sources. I'm assuming you have the same basic ECC as my 1989 765 Tic.
First, there is a black and white check valve near the intake manifold that could be your problem. If the check function had failed, as many do, it would have caused normal ops of dampers only during periods of vacuum in intake manifold. Since this is not your sypmtom, it could have totally failed and may be closed.
Second, there is a vacuum solenoid manifold on the driver's side of the center console that can develop cold solder joints in the multipin connector. This will result in a default condition where all airflow goes to the feet and defrost outlets. (Similar to your problem) Once you gain access to this part, start the car, set the ECC to normal, and flex the connector. On mine, flexing the connector caused everything to start working correctly when in just the right position, clearly identifying the cause. Resoldering the joints has corrected the problem for 50 k miles without return.
Third, you can start thinking about tracing vacuum. You want to begin inide the firewall and verify you have vacuum into the cabin. Then follow the vacuum line into the car and verify at each component that you still have vacuum. This is a real PITA and takes alot of access under the dash. Some shops have an ultrasonic source they put into the vacuum lines under the hood and a detector they use inside the car to find the leaks. Save incredible amounts of labor hours but the tool isn't cheap.
Finally, and I doubt this is your problem, you can verify your vacuum motors (aka: dampers) are functioning. I don't think this is your problem, but it's possible you have a very bad leak through one of them.
Good luck. I found on mine that once I put the time into getting it thoroughly checked out and running well, it is a pretty reliable system.
HTH,
someguyfromMaryland
|
