Strange noise from dash area

[sabyegrp]

I have a 2002 coupe with 11,000 miles. No problems with anything yet. I am however getting an occasional strange noise from the dash area. Can only describe it as a popping or crackling noise. Does'nt sound like rubbing, and not like electrical cracking. No smell. Almost has a tubular or hollow sound, and not loud enough to hear over the radio. Almost sounds like popping the small bubbles in plastic bubble wrap.
Thought it migh be the ventilation or A/C system. Possibly the air bag system???
Of course it won't happen when I bring it in for service, or when I took the tech around the block..... Can't look under the hood because it only happens when I'm driving.