CTScott is correct. Once the air box has debris in it, it (the debris) will always collect condensation from the air condition system and never completely dry out. I pulled the glove box on my 2013 Yaris L & verified it had the cabin air filter installed (it is
supposed to be standard on the 2013 Yaris models) From reading all the posts on water flooding into the passenger compartment, the condensation drain tube gets clogged and the air box will fill with water from the system. If you have purchased a new Yaris, make sure the cabin air filter is installed. It will save you a lot of grief down the road. My cabin air filter already had debris in it after 500 miles.
Older models that have the moldy odor would have to have the box & drain tube cleaned out completely of debris and a cabin air filter installed & maintained.
http://www.yarisworld.com/forums/sho...bin+air+filter