I own a 2011 Mustang GT with about 51,500. I haven't had any real issues until this morning. While driving, a terrible whine/whistling started coming from the passenger side of my car. I determined the sound was coming from the interior fan motor located under the glove box. It's really annoying, especially at lower speeds, the frequency gets REALLY high pitched. The air flow doesn't seem to have changed and the motor appears to be blowing plenty of air.

I looked at the black metal motor housing and there is a small hole in the center of the bottom of the housing. When I cover the hole with my finger, the whine/whistling almost completely disappears! I'm not sure if this sound is indicative of a bad fan motor or if just a small plastic piece that was meant for the hole in the center of the bottom of the motor housing fell off and that piece is supposed to deaden the motor's sound.

I am hesitant to place a piece of tape or other obstruction over the hole in the motor housing to eliminate the sound because I don't know if the hole is meant to be there or not (for motor ventilation, etc).

Does anyone know if a piece of my fan housing is missing or if I need a new one? Perhaps someone could check what their fan looks like (exposed and located directly over the passenger foot well) and see if there is a hole in the bottom of the housing? Providing a pic of interior fan motor housing would also be a HUGE help! I don't want to take it to a Ford dealership or a Pep Boys because I know they're probably going to tell me I need a new fan, whether I need one or not.

Thanks for any help you can provide. :-)