Passenger floor is wet

Another possibility would be that the A/C evaporator drain hose is draining in to rather than out of the van.

White gunk? did someone spill milk in the car?

---------- Alex

Best guess until garage can work on it is mold. She has no idea how long it was wet under the floormats

There is a body seam under the windshield wiper panel, that water made it's way through. The carpet always was saturated after a rain. I placed some of that waterproof putty over the seam. that stuff is used around roof vent openings in larger vans, worked like a charm.

Otherwise, there is a little donut that mounts around the evaporator drain. That may slip or deterorate. Moulding that same putty material around the drain will work.

Try a high pressure spray at a car wash, around the windshield wiper area, and the cowl under it. See if the leak is there.

Get that carpet up immediately. Clean and dry the area with a blow drier. Pull out any saturated carpet padding. replace with new padding of your choice.