Water leak on passenger side floor

It seems that when I run the A/C for a few minutes there will be soaked carpet on the passenger side. Can’t tell where its coming from.It is water, but why?


There are usually only two sources of water on the floor: coolant from the heater core or water from the air conditioner. It sounds like you know it is just plain water and the fact that it accumulates only while running A/C, attests to that.

You know that little puddle under your car when it is parked while running on a hot day? Water condensing in the A/C unit evaporator under the dashboard is draining to the outside of your car through a drain tube so it doesn’t wet your floor. This is normal. It is drying the air as it enters. That tube passes through the firewall (wall between engine and passenger compartment) and if it clogs, the water can’t get outside (not normal) and you get the puddles inside.

Usually in the spring there are some bugs that will build a nest inside the drain tube.
But as late in the year as it is now, its probably mold preventing drainage. Sometimes,
you can send a wire thru the tube and dislodge the blockage. The water isn’t coming out of the evaporator,
it collects on the fins and drains out the car.
Sometimes the drain falls off and the momentum of the car and the wind against the
fire wall orifice keeps the water from draining.
We did have a case where the drain some how got a crack in it on the interior
side of the wall and leaked, but that was an isolated case of plastic case failure.
Yours should be an easy fix.