Air vents won't shut off

[SalvadorP]

Originally Posted by Rversteeg

I found these pictures on the internet where you can zoom in on the check valves. Yours seem to be orientated the same way. These valves will keep the overpressure in the intake manifold (from the turbo) away from the vacuum system and only let air pass if there is a vacuum in the manifold (eg idling or when engine braking).

You have indeed the ECC system, in which case the shutters are still vacuum operated, but operated by an electric valve unit, controlling the vacuum to the vacuum servo's (did you check fuse 16?).

See enclosed diagrams: as you have been fiddling with check valves item 10 and these are a common point for all valves, it would be my starting point for fault tracing.

Alright, thanks for the info. Is there a way to check these one way valves?
I'll check fuse 16.

I was reading about this the whole afternoon, and I'm pretty convinced at this point that the heater vacuum bellow/servo is probably the culprit, but I'll check the easier to change parts first.
Having said that, is there currently a good way to fix/replace the servo membrane? I found people using a membrane from a GM servo, but it's not available in europe, as it is from a 80s corvette.

Another thing. I know you replaced your matrix with a Nissens, do you know the size? I find 2 different nissens models with vastly different sizes for sale under the same part number.
Does anyone know if these measurements are currect?
width (mm):177
length (in mm):240
thickness (mm):42
original Number:1307236