Sounds like it might be the dashbaord vent motors coming to life. The heater box is right back there and it could be the big flaps opening.
My dash buzzes and whirrs for a few seconds after start up, then goes silent once everythings in position. If everythings working I wouldn't sweat it.
My dash buzzes and whirrs for a few seconds after start up, then goes silent once everythings in position. If everythings working I wouldn't sweat it.