Weird noise coming out of far right passenger air vent

Does anyone have any idea what this is or how to fix it? it only comes on when i turn the air on. i havent noticed if its just the "head" air or if it comes on with the "feet" or anything. it sounds like a fast clicking noise. like someone put something up to a fan?

 

http://www.tacomaworld.com/forum/2nd-gen-tacomas/7107-tsb-list-2005-toyota-tacoma-33.html

http://www.tacomaworld.com/forum/2nd-gen-tacomas/129253-heater-fan-noise-2.html

now I dont know if this will help but my dad had a problem like this on his "new" truck. (had it 4 years and mom still is not allowed behind the wheel)

 

prob something in the fan

 

Agreed, I'd suspect a leaf, I've had it before. No real harm, just a nuisance.

Whit

 

Have you checked your cabin air filter? They get dirty pretty quick. I clean/Change mine once a year.