I have 2002 T&C awd.
Van recently started making humming noise when cold and lot of vibrations in gas paddle. When van is moving I dont hear any noise but when idling, noise is very prominent.
I could not point out anything in engine bay which is noisy, only abnormal noise in engine bay is serpentine belt which is due change and alternator but they are not making humming sound.
If anyone faced similar issue before and have some idea's please let me know.

Many Thanks

 

When you change the serpentine belt, inspect the tensioner and idler bearings too. When they wear it can make this sound or vibration.