Jeeps - get some gasket goo stuff (technical I know!!)
I had this problem while I was away - Air conditioner condensation leaves the cabin through a small tube (about hose diametre) the foam surrounding the tube in the firewall ages and lets the water dribble back onto the foam and into the passenger side floor.
It is difficult to get your hand in to the tube in the engine bay but I did it and just sealed the foam holding the tube. Worked first shot!
Saves the passengers bitchin!!
not that she would!! would you dear, no of course not, where did I get that from!!