What Causes Water Accumulation in the Passenger Seat?

[MacBrielle]

Water accumulation in the passenger seat may be caused by air conditioning leaks, sunroof leaks, forgetting to close the windows, or leakage from the small heater core. Below are the specific details: 1. Causes of leaks: It could be due to air conditioning leaks, caused by a blocked air conditioning drain hole, leading to water accumulation in the passenger seat. Sunroof leaks can also cause this, as water from a sunroof leak typically flows through the passenger seat. Another reason is forgetting to close the windows or doors, allowing rainwater to enter or resulting from a flooded car. Water in the passenger seat can also occur if the car has passed through deep water, causing the sponge material in the passenger seat to absorb water. 2. Leakage from the small heater core: There is a small heater core near the footwell on the passenger side, used for heating in winter. It is connected to the engine radiator's coolant circulation system to utilize the engine's heat for winter warmth. If a leak is detected, it is usually due to a leak in the small heater core or loose connecting hoses.