I have a problem when the AC first comes on it smells like mold or mildew

The a/c system's first job is to remove moisture from the air. If precautions are not taken, that moisture will remain on the evaportator, giving micororganisms an ideal growth environment once the evaporator warms up. The smell goes away as the evaporator cools and kills off the organisms. If you use the "auto" function of your a/c exclusively, that will mostly keep the smell away. Also make sure the recirculate is turned off (fresh air is on) when vehicle is shut off so air can circulate from the outside into the evaporator case. If that doesn't completely remedy it, a couple blocks from your destination push the a/c button to shut off the compressor, while keeping the fan on. This will dry the evaporator before you park it and prevent the build up.

here's the deal: A/C is leaking.. happened in my '12 RX350 .. get it repaired under warranty. they're: Fixing the AC, replacing the carpets, removing and replacing all the sub carpet.sound deadening material. get it fixed ASAP because of Mold etc.