wet smell when A/C is turned on

You may have some mold build up in the evaporator core of your 2002 Toyota 4Runner. One thing you could try at home is to spray some Lysol disinfectant into the A/C air inlet. Here is how: Turn the a/c on with the fresh air mode active and the blower on medium speed. The air inlet is generally located at the base of the windshield on the drivers side. With the system running as described above, generously spray the Lysol into the air inlet. Turn the system off after spraying is complete and let the vehicle sit for an hour or so to let the disinfectant do it job.