If it is wet from water, I would suspect the drain for the condensation water is plugged with crud disturbed while changing the cabin filter. If it is wet from engine coolant, I would suspect a leaky heater core.
The 2003 Ford F1 50 cabin air filter is located behind the dashboard. The air filter will be on the passenger side of the passenger cabin.
Click the link for a video of changing the cabin filter.
The 1995 Sonata cabin air filter is located behind the kick plate on the passenger side of the passenger compartment. You will need to remove the kick plate in order to access the cabin filter.
Purchase a Purolator Cabin Filter. It comes with complete instructions on replacing the filter.
The cabin filter is on the passenger side, near the middle of the dash.
Filters the air entering the passenger cabin through the heating system.
The 2001 Chevrolet S 10 passenger cabin air filter is located behind the dashboard. The air filter is on the passenger side of the dashboard.
Filter installed in some vehicle to filter the air coming into the passenger compartment.
On most S10s, the cabin filter is below the windshield on the passenger side. It is quite easy to remove and replace once it is located. The Chevrolet S10 does not have a cabin filter.
If equipped it is under the dash on the passenger side. There will be an access door if it has a cabin filter.
The cabin filter is accessed under the hood, passenger side, near the base of the windshield.
You won't find one. That van doesn't have a cabin filter.