Every time it rains I get water on the floor in the front passenger's side. I'm part of a Pontiac Grand Am forum web site and other people have had the same exact problem. There is no real solution for it listed there either. There is one remedy listed, but it's not the problem. The fix listed is to get a foam part from the dealership and install it under the vent cowell (?) at the bottom of the windshield. It involves taking the cowell off after removing the windshield wipers. I went to do this, and noticed that there is no way that peice of foam will help at all because there's no way for rain to be deflected from anywhere it isn't already deflected by other means.

So, it is unknown what is going on or how the rain is getting in, but it's very annoying and it makes my car smell like mold because it can't dry out. I bet the metal underneath the carpet is rusted too. I haven't got the money to fix something like this. I'm worried about the rain getting into the blower motor and/or the blower motor resistor, then I won't have heat in my car for winter. I've already replaced the blower motor resistor three times, and finally have one that has worked for a few years. I don't want anything going wrong again because it's a pain in the ass to replace, one must be a "little person" to get in there and repair it.