This car has auto climate control and the center dash air outlets recently started blowing air during heat mode. In heat mode in either Auto Hi or Low, the air flap for the center dash should be closed.
According to the service manual, there is only a single white vacuum line that goes directly from the flap actuator to the climate servo. Under vacuum, the flap is supposed to allow air out, with no vacuum, it closes. What appears to be happening, is the servo applies a full vacuum, about 20 inchs when in cooling mode, as it should. When it switches to heating mode, the pressure drops to 2.5 inchs, as if the servo isn't fully releasing the vacuum, so the flap never closes, which is the problem. If I manually vent the line, it does close fully.
Now, here's the interesting part. From the service manual, it would appear the servo provides or removes the vacuum and the line goes straight to the actuator. However, if I disconnect the line from the servo that goes to the actuator and connect a vacuum gauge to the end of the line, somehow, full vacuum is being developed on the end of the disconnected line.
So, my question is, does anyone know if the center air flap actuator only has a single vacuum line connected as the manual indicates? Is a second line connected to it? Or is something else not shown in the vacuum diagrams in between the servo and the actuator? I traced the white line back, and it disappears headed into the upper dash, in the area where the actuator is located.
For the life of me, I can't figure out how vacuum is appearing on this disconnected line. The problem is either the vacuum is slightly too much for the servo, or the servo has too much air resistance to completely relieve the vacuum. I tried putting in a T fitting in the line and introducing a pin hole leak, and voila! it works perfectly again. Yet, I'm left wondering what is really going on, but don't want to pull the whole dash to find out.
Thanks for any help!