Drawbacks If evaporative cooling is common ducted with your heating system, it utilizes dampers to control between heating and cooling. This becomes troublesome in the Spring and Fall when you may need heating in the early morning and cooling in the afternoon, or if you have very nice warm days, and all of a sudden a cold front comes through. Evaporative Coolers cannot be used anytime there is freezing temperatures outside. They must be shut down before it freezes in the fall, and started up after the last freeze in the spring. This can be tricky since you are at the mercy of Mother Nature. Freezing can cause broken parts and water leaks. Since it utilizes water as the cooling medium (which is a corrosive), they can be finicky when pipes get clogged or dirty, or water levels aren't adjusted properly. This affects their cooling efficiency. You must leave your windows, doors or some ventilation open in order for them to operate. This can create a safety issues, noise concerns or an indoor air quality problems in a heavy dust storm. Evaporative coolers can be hooked up to existing forced air duct systems. Because the air delivered by an evaporative system will be warmer than the air supplied by an air conditioner, however, evaporative coolers need to produce more air flow. That means the duct system may have to be larger to handle the volume of air and to effectively cool the house. Evaporative cooling requires water to keep pads wet - a consideration in some areas, especially in drought years. Water consumption can run from three to 15 gallons a day, depending on the size of the swamp cooler and whether or not the water is collected and pumped through the pads more than once. In some areas, discarded water from the unit can be an environmental concern. The cooling effect of an evaporative cooler is dependent on dry air. When the ambient humidity level increases, the cooling effect of an evaporative cooler decreases. The main drawback of swamp coolers is that they depend on dry outside air to operate effectively. On hot, muggy days in the summer, however, swamp coolers will blow hot, humid, soggy air into the house. If the humidity stays high for several days, the moist pads that make the evaporative cooler work can begin to smell, and the musty odor can be blown into the house. This becomes troublesome in the hot monsoon months of July and August. If it is raining outside-don't count on having much cooling.