Ok apparently i cannot catch a break w/ this truck i think it might be the blower motor but i dont know. i was driving down the road a few nights ago with the vent on and all the sudden it starts this whistle sound and and wont stop until i turn the thing to off and i turned on today and it was fine for a few mins then it started again its weird if u guys got n e info would be helpful thank you

-Ricky

My guess is that you have a piece of plastic or something stuck in there.
I would try taking the cover off the vent system (I believe the cover under your wipers, but I'm not sure) and see if there is anything that looks funny under there.

I think i figured it out. It rained really really hard here in connecticut the day before i posted this and being the stupid 17 year old i am. i drove pretty fast through some really big puddles lol i think water got into it some how and then dried out cuz it doesnt make n e more noise. but i still have the oil sender stuck on my truck lol i gotta try and finish changing that
- Ricky

Oh to be young again, where driving through puddles was still fun! Now I usually have to drive for hours just to find those puddles. When 4x4 became more a part of winter life than a toy. I should have known I took a wrong turn somewhere..

Glad that the noise went away, and I hope that the sending unit isn't too hard.