(Just saw misspelled word in Thread subject. That's Dull, not Dual). This sound started a few days ago. Only heard when the engine is first turned on. Then stops after 30-60 seconds. Sound is like -- this is a very dated reference -- a playing card that has been afixed by a child to a bicycle fender to slap with each passing spoke to make an engine-like sound. The sound does not change in a relation to the heater/AC fan speed. Something tells me it has to do with the cooling opening in the glove box. Anyone come across this?