I got a lift to college today and I came home to find water in the passenger footwell. The water is coming from underneath the dash. When I started the car there was a sound off running water from behind the dash. When I revved it there sounded like the water was moving around alot but stopped after awhile. That sounds like the heater matrix doesn't it? It's been raining all day though and the heater still works..getting hot and cold air. Could it be anything other than the heater matrix?