Evaporative coolers work best in dry air.
A neighbor gave one to me when they got an air conditioner.
If I put water into it and ran it, it just made the air/room more humid.
It worked best as a large fan, And I typically used it(dry) to move air into the house at night, then
closed up the windows to keep the hotter air out during the day.
I saved up for a real air conditioner, and that made the room, house, cooler and easier to work through the heat of the day.