Could be through the door, could also come in through the telescopic lifters, I was surprised when
I had to remove the fridge in my finch to discover there is nothing to prevent water that gets down
between the telescopic sections entering the camper, it merely seems to drain out the bottom of the lifting
mechanism. Jayco high tech solution seems to be to run a bead of silicon around the mechanism on the floor
to act as dam and drill a small hole to left the water drain away. If you van is not level or the hole has become
blocked it water be quite possible for the water to overflow the bead.
Cheers
Leigh