I recently bought a 2007 ford f150 xlt crew cab 4x4 and the next day I noticed that when I turned on the air vent, reguardless of heat/AC/or ventthat there was a whistling/staticky noise coming from underneath my glove box. I took this to the dealer and they said it could be from my blower motor. After they replaced the blower motor it made no difference in the noise. The noise seems to be coming from the box just below the glove box marked "blower motor assembly". The best way I can describe the noise is it sounds like either air being sucked in or leaking out but they could not find any leaks. The noise gets louder the higher faster the fan is set. If there is any advise that you can give me it would be greatly appreciated.

 

Your heating and cooling vents draw in ouside air. At times a leaf or other debris makes its way in and causes a ruckus. Other times a part like the blower wheel gets a little loose or warped and rubs on the housing. Either will usually be missed by the average mechanic who is paid to fly through fixing things.