[sirmqc]

I had this problem and it was a clogged drain tube. Their is a drain tube that goes from under the windshield on the passenger side to the front passenger wheel-well. In my case, and from other posts I've read on here, it gets clogged with leaves and junk. I tested this by running the hose on my windshield - I could see the compartment filling with water. It eventually fills up enough to flow in through the cabin air filter. If this is your problem, your cabin air filter is probably soaked.