E36 won't stop whining!

[Major]

Lovely noise my E36 is making at highway speeds with the sunroof open/tilted, but only if the fan motor is off. If I close the sunroof, or turn on the fan, the noise doesn't happen. It's made worse by winds and passing cars. It's coming from the vents on the passenger (left-hand) side, the one closer to the centre of the car.

With the fan on, airflow into the cabin is pretty strong even on the lowest setting, stronger with the sunroof open, so I imagine air is 'pushing' into the car and causing a flap to vibrate, with the help of air being pulled out the sunroof.

Any ideas on what this could be? Haven't seen the whole HVAC unit on an E36, I imagine the recirculation flap is 'leaking'?

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[QikNish]

Are you sure its coming from the vents? I used to get this on my old MCoupe's. Just need new windscreen rubber. To check - run insulation tape over the windscreen rubber (both sides between glass & rubber and glass & body). Then take her for a drive. Worth a check. wont cost you more than a roll of tape to test.

 

[Major]

Are you sure its coming from the vents? I used to get this on my old MCoupe's. Just need new windscreen rubber. To check - run insulation tape over the windscreen rubber (both sides between glass & rubber and glass & body). Then take her for a drive. Worth a check. wont cost you more than a roll of tape to test.

I didn't have a passenger to confirm, but sticking my head on that side of the car I was pretty sure it was coming out the vents/dash area. If you're saying it's the same sound then I'll just give the tape a shot anyway.