Remove the cover on the side of the trailer. You can see the condensate trough at the front edge and if an original Airstream AC you will see the drain tube going off to the driver side of the trailer and down through the body. This system is below the outer skin of the trailer and would not allow water to reach the outside of the trailer. Even if the drain tube were clogged the overflow water would come directly into the trailer and on the floor.
You may have a after market AC
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles