Water underneath carpet floor front and rear..

This is normally caused by blocked sunroof drains. Do you have one?

https://www.google.com/search?q=2013+nissan+quest+blocked+sunroof+drain

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If it is equipped with an air conditioner,probable cause would be the a/c cooling coil drain pipe may have come loose or clogged, thus making the condensed water from the cooling coil to spill over on the carpet. Have a look under the box that holds the cooling coil, there should be a drain pipe that goes through the floor towards the front.

You did not indicate what sort of climate you live in or exactly where the carpet in the cabin was most wet...

However, the most common source of water inside a car is a clogged HVAC (heating, ventilation, and air conditioning) drain tube. This tube provides drainage for water condensing on the AC evaporator and any water that enters the HVAC system during rain storms. If the tube is clogged with dirt and debris the water drips from underneath the dash where the heat vents are ... onto the floor instead of dripping onto the road. So usually the wettest place on the carpet is the front passenger foot well.

The drain tube is generally located on the firewall, low on the passenger side. You would probably have to raise the car to see/reach it. I am not sure exactly where the Passport one is ... they can be hard to find at times.

Other possible sources of water are a clogged sunroof drain tube, leaking window seals, torn or missing door seals, and clogged door drain holes.

Also ... buildup of debris (pine needles/leaves) where the windshield wipers retract in to can also block those drains which can sometimes cause overflow into the passenger compartment.

After you find and eliminate the source of the water you will have to lift the carpet and remove the padding underneath in order to dry it. The padding holds water like a sponge and will not dry unless it is removed from the vehicle. Shop vacs won't get the water out of the padding. Even if the carpet feels dry the padding underneath may still be wet, and that is where mold and mildew grows.

Helpful?

Good luck on your troubleshooting

Yes.

soft or hard top? did you check all the floor plugs?

thay didnt replace the heater core??? this should have been done as thats where the water came from. when the carpet gets wet the seal on heater core goes bad causeing this. if you check it in about a week it will prob. be wet agine

We had same--water on driver side rear floor (soaked!). Driver side front floor seemed dry until feeling UNDER rug, was slightly damp. We found the location of TWO leaks causing this.

Leak #1 was through the parking brake line/cable seal; Recaulked with silicone. Removed plastic trim on floor between floor and door to reveal metal channel filled with water.

Leak #2 was where the door meets the car, near the hinge. It was the accordian-looking tube housing the wiring for the door. The big, rubber, circular plug connecting it to the main part of the car had come loose and water ran down through that, into the SAME metal channel filled with water from leak #1; will seal with silicone.

Note: We found that the channel filled extensively near the front door, BUT the carpet edge from the floor near the rear seat was dipping into it, wicking it up to the rear floor. Also, upon acceleration, the water in the channel gushed toward the back, thus soaking the rear carpet.

These leaks were found by removing all plastic trim (covering edges of carpet by doors), then one of us pouring water into specific areas of the exterior of the vehicle, and the other one watching closely with a flashlight for any signs of dripping.

Is your rear window sealed good, does this happen while the car is sitting or while your driving?

Have your ac evaporator deain cleaned out or checked. Without this working the ac water will collect there.

sounds like the air conditioning drain for condensation is plugged