What could cause the floor to get wet on the front passenger side?(98 passport)

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

sounds like a heater core. Does the fluid smell funny? like coolant? anything coming out of the vents when you first start it up?

there is a leak because the foam has disintegrated, or the seal has broken open down by where the feet of the passenger is. Rust stains tell me that the leak may be caused by a break in the body somewhere.

Try spraying expanding foam in the area between the plastic and the metal parts to try to seal out moisture from coming into the passenger compartment.

is it only when the ac is on? there is a pan under the ac unit that has a hole in it to allow the condensation to empty. if that hole gets plugged it could cause the condensation to build up and back into the inside of that car. i unplugged mine and floor stayed dry

prob. the heater core located under the dash the lines go thru the firewall to the engine. on a '98 you gotta take alot of stuff off to get to it air bag, dash etc. alot of time but the parts arent too much $$

Might want to chk. your freeze plugs on that side along with checking the hoses and water pump, paying close attention to the one behind the starter, it can leak there and run along the block to the front.

The problem is with the evaporator drain. There is a, (usually soft flexable), tube that drains condensation from the evaporator to the outside. It is located in the passenger compartment, under the dash. The hose has, (A)-became disconnected from the evaporator. (B)- Has gotten a kink in it. (C)-Became clogged, causing the evaporator to overflow into your passenger floorboard. Your vehicle probably has some covers over these components, you will likely have to remove. Locate the hose, it typically drains just behind and inside your right front wheel. It may be concealed behind a kick panel, or may go thru the floor or firewall. You must find it and follow it to the evaporator and make sure it is not clogged or kinked and is properly connected to the evaporator.

drain pipe from the interior ac unit ,look for rubber outlet pipe outside firewall passenger side and unblock the end

Check the heater core unit located underneath the dashboard on the passenger side of the vehicle. Even though your car's antifreeze is red, it may appear to be clear when there is only a small amount present. Was the liquid in the vehicle sticky and have any smell to it?

Have you by any chance jacked up the passenger side, or got vehicle on a hoist to make sure there isn't any plugs on the underside that may have fell out? They could be round or oval metal or rubber plugs, probably in that area.