i don't believe the 3rd gens have cabin filters. some methods of getting mildew smell out of ac duct:
1. wait until car is warmed up and while driving, turn the heat to highest it will go and turn fan on high. the heat will dry any condensation left in the airway.
2. with the car parked, turn fan on high using outside fresh air setting (not recycled air). stand outside and spray some lysol into where the air gets sucked into the cabin right below the windshield. (mechanic told me this trick)
3. make sure you use the outside fresh air setting every once in a while and not recirculate all the time.
also as a preventative measure, i always turn my ac off a mile or so before i reach my destination and turn up the fan with fresh air. this helps dry any water in the system before parking the car.
