You probably have a bad heater core.
Find where it is coming from. You probably have debris stopping up the drain below the windshield.
passenger side firewall lower by the strut tower.
in the firewall in front of the evaporator. there is a rubber tube passing through the firewall that allows the fluid to drain. passenger side.
The evaporator drain tube through the firewall is pluggged.The evaporator drain tube through the firewall is pluggged.
unbolts on passenger side on the firewall and pulls out through the interior.
On a 96, it is on the passenger side under dash and pokes through firewall.
The most prosaic explanation is that something spilled there and the water soaked through the carpet.
Check for cracked vaccum line. Small line from engone compartment side through the firewall to the heater doors. The heater doors are controlled by vaccum.
The powertrain control module (PCM) is visible from the engine compartment. It passes through the firewall on the passenger side. The wiring is on the engine side of the firewall and the body of the PCM is inside the Explorer located behind the glove compartment.
The separation between the engine compartment, and you, is called the firewall. The Steering shaft, from your steering wheel runs through the firewall, the heater hoses run through the firewall, the power brake vacuum unit is connected to the firewall, your ignition wires etc run through the firewall.
Through the transmission dipstick tube using a small funnel . It is located by the firewall towards the passenger side of the engine
Adhesion.
See where the coolant overflow tank is on the firewall? Now look to the passenger side and down. It is kinda hard to see cause there is a bracket over it. The adjustment bolt is through the bracket on the firewall side. It sucks to change this belt.