I'm getting a noise coming from behind the glove box on my 2003 Passat.It is only there when the ignition is switched on.The heater diverter vents and other parts of the heater unit are located near the rear of the glove box, so could it be a fault with one of these ?

Any help would be most appreciated.

UPDATE:
I removed the glove box to reveal the unit that houses the air diverter flaps, the lower flap (that directs airflow in to the footwell) is the cause of the noise.It is constantly opening and closing ???