I have an 05 1500 4x4. When I turn on the climate control I get a strange whistling sound from the vents. As I turn up the blower fan the whistling gets more and more intense until I get to speed 5, when the sound of the air rush drowns out the sound of the whistling. I've looked for leaves/foreign objects and found nothing. As I search around it sounds like the noise originates somewhere near the area of under the glove box. This occurs whether I'm in heater/AC/or vent. I called the local dealer and they were very helpful in offering to pull my dash apart and look for the problem....should only take a couple of days worth of labor. I've Googled this problem and it seems to be somewhat common. What I can't find is any people who've discovered solutions.
Has anyone had this problem? Is there something I can do to fix it? I don't mind rooting around under my dash but I'd like to know what I"m looking for before I rip it apart. Thanks!

 

Dose it kink of sound like a belt screech? If so its the blower motor not sure whats wrong with youres but i had a work van that did that (I hated that sound so bad) and my buddy just kicked it and it would stop for a few but start up again. I always thought it was just loose.

 

I don't think it's the belt, it sounds like whistling, not screeching.

 

if the whistlingis coming from the blower motor under the dash then it may be junk in there or the little bearing that spins try to lubricate it if nothing is in the fan

 

If the whistling increasing with speed then i would thing that there is something stuck in the blen door.