I bought an 06 Titan King Cab a few days ago and it just started making a whistling noise when my A/C is turned on. The faster I make the fan go, the louder the whistle gets. Also the sound isn't coming out of the vents. It's coming from under the dash on the passenger side. That's where I hear it the loudest. This is very annoying. Has anybody seen this before? Anyone know how to fix it?