Carter Volkswagen Auto Care FAQs: Why is My Passenger Side Floor Mat Wet?
Here in the Seattle area, a little dampness from time to time just comes with the territory. But, if moisture collects in your vehicle (particularly in the passenger side footwell) from seemingly out of nowhere, it can be a little confusing. Where is the water coming from, and how did it get inside my car? The rain is one possible culprit, but there are others that just might surprise you.
Get Down to the Core of the Problem
This problem can seem extra mystifying when your passenger side floor mats are soaking wet, and it hasn't even been raining. But it could be due to a bad heater core.
The heater core is a small, auxiliary radiator located just behind the passenger's side dashboard. It's both a part of your vehicle's engine cooling system and the climate control system. As coolant pulls heat away from the engine, some of the superheated coolant can be diverted to the heater core. At the heater core, heat from the engine is exchanged with the climate control system, and blown through the climate vents when you turn the heat on. If the heater core becomes damaged, corroded or rusted, it could spring a leak -- leaking coolant all over the dashboard, which will collect in the footwell on the passenger side.
If you've got a leaking heater core, you'll want yours replaced or repaired. Otherwise, your vehicle's heater may stop working, and you'll continue to get a damp passenger floor mat.
Additionally, it could be a blocked A/C drain hose. The A/C evaporator collects condensation which normally drips harmlessly onto the road through a drain hose -- but if the drain hose gets clogged with foreign debris, the condensation can back up in the system and leak into your vehicle's interior on the passenger side.
The Sweet Smell of Success (or Coolant)
How do you know which of these two problems your vehicle has? Believe it or not, you can tell with a smell test. If the water just smells like, well, damp floor mat, then it's probably the A/C drain hose that's backing up. However, if the puddle smells sickly-sweet, you know it's the heater core. That's because automotive coolant has a very sweet smell that you should be able to detect -- even if you might look a little strange to passers-by taking a big ol' whiff of your car's floor mat.
Go With The Flow
Water collecting elsewhere in the interior, like on top of the dash or in the back seat? That's more likely to be rainwater seeping past bad window seals, bad sunroof weatherstripping or even leaking in from the doors. Water can get into the door panels, and should drain out onto the road -- but the doors could leak water into the cabin if the drain holes become blocked with debris. You may need the help of a friendly dealership expert at Carter Volkswagen in Ballard to find the source of the leak to keep your vehicle's interior high and dry.