Can I save money by running my swamp cooler in the morning and then switching to the central air conditioner when it gets hot in the afternoon?
No! An evaporative cooler will only cool the outside air down 10 to 12 degrees below the ambient temperature. So if it is 110 degrees outside the cooler will below in 100 degree air with at least 80% humidity. When you turn on your central air conditioner it will have to work harder to remove the humidity before it can even start cooling. An air conditioner and a evaporative cooler are not designed to work together. An evaporative cooler produces humidity and a central air conditioner removes humidity.
