Yeah I had the same problem and it seems like Toyota's, BMW, and a bunch of cars have that problem with the AC smelling or just air being brought in by the vents. Apparently most dealership tell you to deal with it or they try to please you by putting in a new cabin filter (although the TC doesn't have one). I believe to get to your problem you would have to basically get to the the evaporator and coil then disinfect and kill the mold/mildew. This is pretty tough because most cars require you to take the dash apart. So the basic problem is that when the AC is used there is condensation that is built up and then mold/mildew starts to grow in there eventually if it does not dried out. A way to try to avoid this is to turn off the AC before you get to you destination and turn on the heat to get rid of most of the condensation. Yeah tough to handle when your in hot weather.
Anyways try this before pull apart the dash. Get a can of lysol disinfectant. Make sure you get something that will smell good or else just the smell of lysol may be worse then mildew. Then start your car and roll all windows down. Turn on the heat to full bast and at the bottom of your windshield on the outside of the car by the wiper arms you will hear and feel the air sucking in through the vents. With Lysol can in hand, spray the mofo into that sucking vent. Make sure you switch up the vents that are open and closed. Hopefully this will kill some of the mildew odor. This worked for me but something tells me that it will be an ongoing battle. Hope that helps