I have a 2005 Toyota Sienna XLE Limited which has recently started having a noise coming from under the dash or perhaps through the air vents. When the key is turned on to the start position (engine not started but dash lights are on), and with the radio and heat/AC system turned off, it sounds like an electric motor is running at a slow speed with a bad bearing. It is sort of a rumbling noise. This noise continues even when the engine is started. The noise does not occur when the key is in the accessory position (no dash lights on). Three local dealers have listed to the nloise and they no idea what the problem is. Any one out there have any ideas?