Moisture - front passenger area

In my 92 DX there's a damp spot in the middle of the front passenger area. I lifted up the floor carpet and there is wetness there. From where could it be leaking?

Well since your car has ac my best bet would be the evaporator drain tube is plugged. It sits under the dash on the passenger side and the tube lets condensation drain out. The evaporator creates quite alot of water.