Air Blows thru vents when accelerating e320 coupe

[Fat420]

Just purchased a 94 e320 coupe.

When I accelerate hard my windshield has been fogging up due to air leaking out of the dash vents. This is occuring even though the temp control unit is off (air does not blow during normal driving conditions, only under hard acceleration).

Has anyone else experienced this on a w124? Is it a faulty flap or vacuum?


______________________
SK
94 E320 Coupe
Monotone Pearl Black, 17" AMG Monoblocks, Alpine 9835, JL Audio 500/1 Amp, 10" JL Audio W7 Sub

94 E420 (SOLD)
500E swaybars, 2.82 Diff, Monotone 040 Black, 17" AMG Monoblocks

[Fat420]

Eric,

What is it that is stuck open? How do I get to it?

[sixto]

I'd start with a couple of simple things - the check valve in the line from the intake manifold to the ACC system and the ACC vacuum reservoir. You should be able to check everything with a MityVac at the yellow check valve just ahead of the master cylinder. It'll have one port in front and two ports in the back.

Sixto
95 S420
87 300SDL