flutter sound in vent

[nodakmp5]

Anyone heard this before? Sounds like leaves or a piece of paper in there. The sound in coming from were the a/c and heater is I think. Is something going out or maybe just some crud in there? I also have some dirt that always blows out the defrost. Are the two related? Thanks.

 

[kboutsider]

Leaves I don't know how they get in there but they do. Mine was blowing tiny bits of leaves into the car when I first starting using the heater (or lack there of with the trouble I'm having) this fall/winter.

 

[Redcoat]

I had a similar problem about a year ago. Got rid of it by just switching the fan speed to the highest setting for a few minutes a few times and I have not heard the fluttering since...

 

[P-Funk!]

Leaves and junk enter the external vents (right behind the hood). Clear them off when you wash.