My 1995 525I has started to make a loud buzzing sound. It appears to be coming from near the fan switch between the 2 temp controllers or up behind the radio. It will continue for 10-15 minutes after the car is turned off and eventually stop. I person told me there was a small fan that recirculates air constantly and that was the cause.

Anybody want to take a stab.

Thanks in advance for your replies. This site is great.