What are the reasons for water under the driver's side floor mat in the cabin?
3 Answers
The reasons for water under the driver's side floor mat in the cabin are: 1. The sunroof is not sealed tightly, allowing water to leak from the sunroof to the area under the car floor mat; 2. Water from car washing was not cleaned up thoroughly; 3. Rusting in the car's heating system, causing water to leak under the floor mat; 4. Aging of the car's sealing strips. The solutions for water under the driver's side floor mat in the cabin are: 1. Remove the floor mat and clean up any remaining water inside the car; 2. Open the car doors to air and dry the interior; 3. Adjust the vehicle's air circulation switch to internal circulation to drain moisture through the air conditioning system; 4. Replace the floor mat with one that has waterproof properties; 5. Check if the sunroof's drainage pipes are clogged.
I encountered this issue a couple of days ago and after some research, I found there could be several possible causes. If the sunroof drain holes are clogged, water can seep down from the A-pillar and flow directly into the driver's seat. Another possibility is a blocked or cracked air conditioning drain pipe, which would cause condensation water to leak directly into the cabin. Additionally, if the door seals are aged or deformed, water can seep in through the gaps during rain or car washes. A less noticeable cause could be cracked sealant around the windshield edges, allowing rainwater to penetrate and flow toward the footwell. The most troublesome scenario would be a leaking heater core, where coolant could leak into the cabin when using the heater in winter. In my case, after checking the sunroof and doors without finding any issues, I finally discovered that the air conditioning drain pipe connector had come loose. Tightening it fixed the problem. It's best to address such issues promptly to prevent water accumulation from damaging wiring harnesses and flooring.
Having driven for so many years, I've seen plenty of such situations. The issue of water accumulation underfoot deserves attention. Mainly, it needs to be checked from several areas: first, the drainage system on the roof, especially the drainage holes in the sunroof tracks which are easily clogged by leaves and mud. Second, the air conditioning system, where broken or clogged drain pipes under the evaporator are quite common. Third, the waterproof membrane on the doors; if that plastic film is torn or not properly sealed, it will leak. Fourth, the heating device; if the internal water tank leaks, it will spread along the floor mats. Lastly, the floorboard should also be checked, as cars that have been in accidents may have rusted and perforated welding points. I recommend first cleaning the drainage holes under the doors, lifting the floor mats to dry them, then using a high-pressure air gun to clear the drain pipes. If that doesn’t work, it’s best to take it to a professional shop for a thorough inspection.
