In that general area could only be two things your weatherstripping around the window or door is cracked and water is entering the cab or your heater-core is leaking. Sometime passengers spill things just thought i would throw that in. Hope this helps....
Crack in the heater core
On the passenger side floor board under your carpeting and a metal plate where you rest your feet On the passenger side floor board under your carpeting and a metal plate where you rest your feet
Heater core leaking?
It's a Dodge thats why.
Heater. Core
The Battery is located in the Floor board between the driver and passenger seats, you will have to remove the rubber floor to access it. Special tools you may need are on the passenger side in the floor, where the jack is.
Heater core failure.
Under the passenger floor board, under the peice of ply wood
Must be a punctured hose. Take it to a shop for a diagnostic.
passenger side floor board
Under the carpet in the front passenger floor board.
Passenger side floor board, where the passenger's feet would be just to the right, behind a cover.