If you use a swamp cooler, you are probably happy with the lower electrical bills. As I’ve said before, swamp coolers are simple machines, but you can’t just plug them in and forget about them. They will need occasional maintenance.
So when do you know it’s time to replace the cooler pads? Well, that isn’t such an easy question to answer. If you see scale building up on the surface of the pads, it’s a good time to replace them. As water evaporates, what is left behind is the salts that accumulate in the water. You will see many water pumps that will have a bleed outlet to pump out a small amount of water while the pump is running. As water is slowly pumped out, the float drops to a level that allows fresh water to refill the basin. This minimizes the scale that builds up in the cooler (and will help your pads last all season). If you don’t have water in the basin automatically pumped out, you can remove the drain tube and manually drain out a few gallons of water every few days, or oven weekly. Over time you may notice that the temperature of the air may not be what is used to be. So go remove a panel and take a look inside. If your pads are covered in white scale and are hard as rocks, it may help to replace the pads.