a/c vent problem

[16again2009]

I have a 1988 porsche 924s. The a/c works fine. The cold air comes out the middle vents at idle. However when the rpms go up the air stops coming out these vents and goes to the floor vent. I have carefully checked and can find no vacuum leaks. I suspect the vacuum reservoir or the solenoid valve. Is there a way to test these parts? Has anyone had the problem?

[djnolan]

Had a similar problem on a 944 and it was a reversed one-way check valve:

https://www.google.com/search?q=vacuum+one+way+check+valve&espv=2&biw=1024&bih=487&site=webhp&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwia84Te6vLLAhWIeSYKHXHzCpcQsAQIPg

[16again2009]

Thanks. I will check that out. That would be way to easy of a fix though. I'm used to things being much harder. Haha.

[16again2009]

The only oneway valve I could find is the one coming from the brake booster. It is facing the correct way. Are there others?

[v2rocket_aka944]

the AC flap door is on the left side, behind the glove box.
there is a vacuum servo attached to it, that closes the flap at certain RPM/throttle conditions to keep the evaporator cold.

check its vacuum line, and the vac control valve on the right side behind the glovebox.