What could be causing the rattle in the front of my car?

Question

I have a 2010 Hyundai Elantra Touring. Whenever I'm stopped (either in park or braked in drive) there's a rattle that seems to be coming from the driver side dash. I'm having trouble figuring out what it is. It's louder when the air is on, but still present when it's off.

I've tried/ruled out the following:

• Rear view mirror - I was having this problem too, but it was separate.
• Items in the glove box or other compartments.
• Adjusting the steering wheel position.
• Pressing various portions of the dash and doors to try and find it.

I've also had the hood open while it was running and it didn't seem to be audible from outside.

What else might be causing it?

Update, year or so later: Still happening. Tried removing various portions of the dash and pressing on stuff to see if I could locate it. No luck.

Answer 1

My friend has a similar problem in her car and the only thing that helps is putting a thick stack of papers (parking stubs and tickets, mostly) between the dash and the part of the body that's between the windshield and the right window. It's worth a try.

Answer 2

Something may have gotten into your air vents. I had a leaf in there and it drove me crazy til I one day realised what it was and got it out with a tweazer. It's worth a shot as it won't cost you any money.