Moldy smell

I get a bad moldy smell after I switch from air conditioning to vent. It goes away after a while, and it only happens after I have run the air conditioner. Any ideas?

Buy a cab of Lysol or the product sold at the auto parts store. Turn on the A/C on high and then spray the can into the vents in front of the windscreen. I would listen to where the sound is the loudest and aim for that.

You might want to try and clean out any leaves that are in there and make sure the drain is working first.