If you have antifreeze in your system the water on the floor will aslo feel somewhat slimy.
Water underneath car carpet.
Car a c systems are actually designed to allow water to drain out of your vehicle.
Especially if your vehicle is not garaged and oft.
Normally condensation in your ac system exits through a small drain tube in the bottom of the vehicle but over time that drain tube can get clogged and cause water to backflow into your car interior.
Use a tool such as a screwdriver to create leverage under the sill to prop it up.
This may be your problem.
Water leaking from under the car can be normal especially on hot days when you ve been cranking the a c at full blast.
The moisture under your carpet has to come from somewhere and that somewhere is almost undoubtedly the air conditioning system.
No matter how much you towel or vacuum off your car s surfaces any fabric and carpeting in your car as well as the chassis beneath will be damp to the touch.
You should also check to see if your vehicle has drain plugs in the floor that you can open up to release any trapped water.
The most common problem when you have water on the pass side carpet is a leaking heater core.
It s often accompied by slight fogging of the windshield and possibly the sweet smell of antifreeze.
The system cools the cabin by pulling humidity from the air and that moisture needs a place to go.
When car carpet gets wet the water seeps down underneath it to the foam backing which can grow mildew on it if it stays wet.