We have a 2010 TT Coupe 2.0T Quattro. A month ago we began to hear a whistling sound in the dashboard area. I removed the cabin air filter, cleaned it and the whistling is gone, but it now sounds like air blowing into the cabin area, almost like there is a gap in the windshield seal. I have read some incomplete tech articles that suggest there is a valve under the dash that lets outside air into the cabin, but I am not clear where this is located and how to access. Any information would be most appreciated. Thanks.