Hey guys. I had an issue a couple weeks ago during a torrential rainfall (which doesn't happen very much at all in south texas).
While driving in the blinding rain my passenger noticed water was pouring on her foot from the glovebox area into the foot well.
After taking out the seats, tearing out the passenger side carpet, and replacing the future moldy carpet padding I took it as a freak incident and didn't investigate the problem much further. The water also took out my ipod nano and isimple cord.
2 weeks later every time I turn the a/c on I can just smell a hint of water and possible mold. I knew the carpet wasn't the source. The next time I gave her a top to bottom cleaning and check I found the problem.
Apparently dirt and foliage had fallen into the compartment that contains the cabin filter under the hood and the one drain hole was clogged. Water was standing at least 4 to 5 inches deep halfway soaking the cabin filter. When those torrential were coming down, it was filling that compartment where the cabin filter was and dumping the over flow through the air vents and into the passenger foot well!
I immediately removed the filter, reached down to remove all the gunk, and reopened the drain hole. Water poured out. Took the hose to it and clean the area the best I could. I bought a new cabin filter an the smell is gone. Thank goodness
I just could not believe how much standing water there was sitting the middle of my car. I assume in the past, since we don't get rain here, that the water would just evaporate due to weather conditions and heat from the engine.
Hope this helps someone avoid the pain I went through worrying about my stang.