AC recirculation flap partial open or closed?
 

on my 1990, I am not sure about the function of my recirculation flap. let me start with a
simple question:

with the car off, I can feel the flap thru the hole under the glovebox. is this the closed or open position?

In the rest position you should be able to push the flap up with your pinky- that is what I refer to as the open position as it lets in fresh air. Then when for instance you select a/c operation the flap should move upwards to the closed position and then it is on full recirculation so you are cooling only the air in the car and not the countryside.

If when you are in a/c mode the flap is only partially closed or fully open then you have a fault in the system- most probably the actuator is knackered.

At rest the flap is completely down: (is down equal to open or closed? would like to use the correct
term so that I am on the same page with everyone.......)

with the AC button on and air at full cold:
AUTO mode, the flap only moves upward slightly
DOWN mode, the flap only moves upward slightly
UP/DOWN mode, the flap moves all the way up
UP mode, the flap moves all the way up
DEFROST mode, the flap is completely down

with the AC on and at full heat on temp slider, the flap is always completely down

since the flap all the way up in both down and up/down, I am thinking that the
actuator is not the problem???

does this sound like a head unit issue???

ALSO: FWIW, with the lever in the defrost position, and the recirculation flap is (correctly) completely down,
when I move the lever back to the up/down position, there is a 5 or more second delay before the flap moves all
the way up. But the flap does move fully up.

the recirculation flap works properly in all positions except AUTO and DOWN.

hoping someone will have similar experience and point me in a direction before I start tearing into the console
and the vacuum lines........

As we talked about on the phone. Your recir flap is closed in the down position. If your actuators are leaking it will never open unless those are fixed. Time to pull the glove box, center console and cluster to replace all 4 of them. The fact your recirc flap is wanting to move shows the head unit is doing what it should but you don't have proper vacuum.

ok thanks

Apologies for creating some confusion in my original post!

A recirc flap has to be open to recirculate air- or so one would think! I have only seen this item referred to as a "recirc flap". I was a bit surprised when I read Sean's post so took a squint at the WSM and duly fell about laughing. In the WSM Porsche call it the "Fresh air/Recirculation flap". To avoid confusion they specifically spell out what they mean by open and closed for this flap operationally so one assumes they probably saw confusion initially- by closed what they mean is where the thing sits when the spring drives it - just as Sean describes.

Rgds

Fred

I accessed the HVAC manifold and mityvac tested all the lines. here is what I found:

Blue recirc flap line: held @ 15 no issue
White heater valve: start @ 15 with quick drop to 10 and slow leak down to 0
Orange center comb: could not pump beyond 5
Green defrost: could not pump about 0
Yellow footwell: also could not pump beyond 5

obviously, I have some issues! lol

but shouldn't I be able to pump all of them up to 15 and then see either a slow or fast leak?
confused about the last 3 readings?? with the defrost, could I have a line not connected to the actuator?

Try pinching off, or plugging, the heater water control valve vacuum hose and re-run your tests.

If the readings change, replace the vacuum module on the heater valve with a new one because it is leaking vacuum. You can test it with your MightyVac before removing just to confirm.

[QUOTE][Try pinching off, or plugging, the heater water control valve vacuum hose and re-run your tests./QUOTE]

not sure why I should recheck the heater valve? I tested each line separately, and certainly the heater valve is bad, and probably the footwell and center comb. I just don't
understand why I can't get a higher reading, and then a drop on the gauge. also the center comb lever drops about 1/3 of the way and then seems to hold.

and the defrost test will not budge off of zero, so I am thinking that maybe the line is disconnected at that actuator?? shouldn't I get "some" reading?

If you can't pump them up, the actuator has failed. Time to tear out the glove box, center console, cluster and replace all 4 actuators.

one step ahead of your Sean: I got the dash all apart!! lol