* Faulty weatherstripping around the door or window: Verify the weatherstripping around the passenger side door and window. If it is damaged or cracked, water can leak into the car when it rains.
* Clogged or damaged cowl: Check the cowl, which is the area under the windshield, for any obstructions that may block proper drainage. Clean or unclog the cowl if necessary.
* Damaged A/C evaporator drain hose: Inspect the A/C evaporator drain hose for damage or blockage. If the hose is damaged or clogged, water can accumulate and leak onto the passenger side floorboard.
* Failed heater core: If the heater core is leaking, it can cause water to accumulate on the passenger side floorboard.
Solutions:
1. Inspect and replace weatherstripping: If the weatherstripping around the passenger side door or window is damaged, replace it with new weatherstripping.
2. Clear the cowl drain: Clean any debris or obstructions from the cowl drain to allow proper water drainage.
3. Check the A/C evaporator drain hose: If the A/C evaporator drain hose is damaged or clogged, clear or replace it.
4. Diagnose and fix heater core leaks: If the heater core is leaking, the heater core itself may need to be repaired or replaced.
5. Check other potential leaks: Inspect the car carefully to check for any other potential leaks, like from sunroof, or windshield.
