Well my cars vents bring in air that smells of mildew whenever it rains, and I've tried spraying cleaner through the vents but maybe I never put enough, but it never worked.
HOw can I get off the black cover of where the air goes in? I want to wipe down inside there and perhaps remove whatever is buildling up. Its the area adjacent to the windshield, with the little square holes in it. HOw does it come out?

 

Take the big plastic cowl off and you can unbolt the little tray that brings in the air to the cabin.

The stuff in the upper right: