If your van is like my van, there is a foam rubber mat underneath the carpet. I had a mildew problem in my mini van because the hatch was left open at a game (yes, I was a soccer mom) and rain soaked the carpet. Even after the carpet was dry, the van still had that terrible mildew smell. Nothing seemed to work to get rid of it, either. In despiration I finally pulled the carpet up off the floor and found the foam rubber mat underneath. THAT was the culprit! I cut out the offending area of the mat, went to my local carpet store and got some similar foam rubber mat to replace it, stuck it in the hole I'd cut out, used duct tape to seal the rough edges together, and replaced the carpet over it. Smell was all gone, and it's been fine for years and year and years. Good luck.