Plastic rattling sound in car

[black_2.5RS]

I have an 2005 Impreza and for the last 2 weeks, my car has had this mysterious plastic rattling sound which sounds like it is coming from the steering wheel or AC vents. I checked it out and keep seem to figure it out.

The only other thing I can think of is I changed my winter tires to summers around early / mid-March.

Anyone have any ideas what this could be?

[schurchill39]

Take a look at all of your vents. Maybe some one has moved them, in the past little bit, with a littlem ore force then necesary and broke off a little plastic peice of the actual vent itself. If that is the case then you might have to pop then vent out and see if you could retrive the piece. But if its not that then I have no clue