Thank you for using just answer.
Turn on the a/c for 5 minutes and look to see if you have a puddle of water under the passenger side of the van, if not then you most likely have a clogged/restricted a/c drain tube and the water that the system puts off is draining into the van. In this case you will need to crawl under the van and locate the black rubber hose that exits the body on the passenger undercarriage where the firewall and the engine bay meet, clear this hose out with a soft pipe cleaner or VERY LIGHT compressed air. Once you get the water properly flowing out of hte van you need to address the moisture in the van. What I typically do is remove the carpet in teh vehicle and inspect it, if the carpet is wet then I set it out in the sun to dry, if the water has been present for a period of time and the carpet padding is molded/mildewed then I usually REPLACE the carpet and thoroughly clean the floor board.