Recently, right when I turn on the AC for the first time of the drive, I get this super funky smell of BO coming through the vents. I can't seem to get rid of it... although it does go away after the AC has been running for a while. Any ideas of what it might be?

 

Dead rat?

 

Clean the evaporator.

 

Mold or mildew. There are products to spray in the vents but they only mask it, the best way is to remove the evaporator and thoroughly clean or this method work effectively as well