There is an intermittent buzz coming from the center console of my 2010 Prius trim level 2. It seems to be coming from the climate control system. It lasts for about three seconds, and it sounds like a fan with a bad bearing or rubbing against something else. The buzz occurs when starting the vehicle after it has been off for several hours, and intermittently while driving (maybe once every couple of days), and exactly one minute after powering off. It began occurring a few months ago. I asked my dealer to fix it but I was unable to duplicate the problem at their service bay. Very frustrating! So what's wrong with my vehicle?