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Q: Water leaking into floorboard

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I need to find out why water is leaking into the passenger's side floorboard of my car. The floor is wet.

Locating water leaks can be tricky. The most common leak I come across is the drain for the AC evaporator that is located inside the car being clogged. The evaporator is the part of the AC system that cools the air. Just like a cold soda can on a hot day, water condenses on it. To combat this it has a drain that leads the water outside. However, if the drain is clogged, the water will spill over onto the floor.

The AC compressor generally runs when the mode selected is defrost, or floor/defrost. The temperature door has no bearing on the compressor turning on which means the compressor will run regardless of the season and temperature.

The next thing to check is any aftermarket add ons. When alarms or remote starters are added, holes are usually drilled in the firewall to route wires to the engine compartment. Finally the leak could be caused by the windshield, sunroof drain, or fresh air inlet.

I would suggest having a certified mechanic, such as one from YourMechanic, come and inspect the origin of the water leak and suggest possible repairs.

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