Swamp coolers “rely on the flow of air through the building to direct the cool air, and since they always need hot, dry air to evaporate the water, it needs to displace the air already in the ...

If you want, you can use a mild detergent but make sure it's rinsed off thoroughly when you're done. Once you've cleaned off the debris, you can then add the pads back to the swamp cooler.