I think I found the coke canned size electrical box with wires running out. I'm not sure if it's a water pump. It's there, though. And has a white wire. Our AC unit is plugged in nearby that box. The AC unit works great, so at least we will be somewhat comfortable out there.
I guess I can pour bleach water into that hole on the outside? Not sure how to get it back out. That water tank is kind of built-in.