First off I have a Lexus Is300 and have had it since 04. No major problems with it. Recently over the last two weeks or so I have heard a buzzing sound as soon as I put the key in the ignition and turn it (whether the car is started or just the battery is on). The buzzing continues for about 15 seconds. I popped the hood and started the car...could not hear the noise from outside the car...It sounds like it is coming from the dash board. I was wondering if anyone has experienced anything similar to this...I would like to know going into a mechanic so they don't tell me some BS...The only thing I have heard from a mechanic is that it could be the air vents struggling to open as the car is starting...Any other input would be greatly appreciated...

 

It's a module that directs your air flow. This vid will answer your questions. Mine did it too I just unplugged the damn thing