Vent Whistle Driving me crazy

[LukeyP]

Hi all, thanks for any help on this, i feel like i dont know what to do next.

A few months back, the Vents in the car started to whistle quite bad with the air on.

If you set the car to re-circulate, it helps a lot but not stop it, air in from outside is much louder, cars go past and it gets louder.

if you slightly crack a window, it totally stops. I have a video here,

https://www.dropbox.com/s/1h9lpudozac4bo0/WhatsApp Video 2023-04-14 at 13.47.37.mp4?dl=0

its a 2015 Audi A7 3.0Tdi.

Someone mentioned the air comes in the front and out the back of the car, and i have a rubber boot lining fitted, thinking that was blocking the air from leaving the car, causing positive pressure, removed all that and its still there.

Removed the intake under the scuttle tray and checked it there, not blocked.

Does anyone have any clues on this?

 

Thanks!!