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
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!