About a week ago, a weird noise started happening on the passenger side under the dash. It only occurs when the air is on, not only the air conditioning but whenever i turn on the climate control and air is blowing from the vents. I tried looking and reaching under there but cant seem to find anything loose. Any ideas on what the problem is would be greatly appreciated.

To make this ITR related, here are some pics of me auto-crossing. I had a blast, won second place in my class.

 

Not a clue, could be a number of things man, hard for us to tell you what's loose behind YOUR dash, take it out and look.