2007 Forenza under dash rattle
 

I just bought an 07 Forenza 2 weeks ago. Two days ago a loudrattle developed under the dash directly under the glove box. Glove box is empty.Its intermittent. It ratteled for a whole day and then in the middle of driving it stopped. I called the dealer in Ohio and they said they had heard of this problem in other states but not Ohio yet. It sounds like its coming from the housing unti for the fan or air conditioning. As you increase speed the rattle gets faster. Its prominent at speeds of 50-75 mph.

Does anyone know what this is?
Thanks