The other day i turned my truck on (2001 2500hd) and it was kinda hot so i turned the a/c on and when i turned the blower up it have some strange vibration somewhere and i turned it to heat and tried changing up all the stuff but it wouldnt quit til i turned off the A/C..... Help?

 

Was the vibration with the engine or the AC?
If engine, you may need to clean the throttle body and or the Idle Air control...

 

It sounded like it was in the vents actually, dont know whats in there, but i think something might be loose. The reason i say that is because when i turned the blower up to 3 then to 4 it kept getting louder with the more air flow. Any ideas?

 

Sounds like the blower (fan assembly) might be out of balance or possibly broken causing it to wobble and vibrate....

 

any idea how to get in there and fix it?