clogged or damaged catalytic converter
Under the floor, mounted to the frame, just forward of the rear passenger side wheel.
If it's the front passenger side ,I would say your heater core is leaking .
Windshield seal? Lower door seal? Hole in floor ?
It could be the heater core leaking.
Heater core has failed.
Heater core
most likely cause is your heater core leaking
Leak in heater core
The ac drain is plugged. The drain hose is on the firewall on the lower passenger side. ...that, or your heater core is leaking.
It fastens to a pass through stud at the passenger floor.
Heater core may be leaking Door seal? Windshield seal?
It could be a door seal or more likely the windshield is leaking.