Air Distribution System
 

Anyone experienced anything like this?
My Golf GT TDi 130bhp has developed a problem with the airflow control. When i put the air recirculation on to circulate air within the car everything is fine. When i select any other airflow ie to the windscreen or through the dashboard vents, i get a strange knocking noise from just behind the passenger airbag. Anybody any ideas?
When you select recirculate again the knocking stops again :confused: