So anyways, I just started to notice this. When I have the heat on, and turn the air flow **** to the defrost (either defrost by itself, or with the legs too) I notice I rattle noise coming from inside the dash. But only when its on defrost. Any ideas?

 

You probably have something in one of the front vents, like an M&M or a screw.

 

Haha an M&M, god that would be just great. I'll check. Thanks!