On my way home tonight, I was running the defroster at 80 degrees, on the lowest fan setting, when suddenly it started making a rattling kind of noise, somewhere behind the dash. It sounds like a piece of paper or something stuck in the fan, I dunno. It's dark, so I havn't even attempted to look at anything yet. Anyone have any pointers? If there's something stuck in the system, is there any simple way to clean it out?