For many months, the carpet in the Vanagon was perpetually wet. Was it a window seal leak or unknown rust spot? It wasn't until I used a wet dry vac on the carpet that I noticed a green liquid excreting from the carpet and pad. There had been a long standing leak in the rear heater core.
The entire carpet was moldy and disintegrated. The factory padding was discarded as well. The padding was in the worst shape compared with the carpet. The rubber backing was cracked and saturated with coolant. After the heater core repair, I'm thinking of using truck bed-liner on this floor and maybe covering with a cheap commercial rubber backed carpet.