Anatomy of an Evaporative or Swamp Cooler

  • 01 of 12


    Swamp cooler side panels
    Aaron Stickley

    Evaporative coolers are effective when they are working properly. They work by extremely simple physics: as water evaporates, it effectively "consumes" heat from the surrounding air. It is the same principle as an air fan cooling you as it evaporates perspiration from your skin. The parts of an evaporative cooler are all designed to facilitate efficient evaporation of water.

    Knowing about the various parts of your appliance can make it easier to maintain and repair your cooler. Here is a...MORE rundown of the anatomy of an evaporative cooler. Some cooler parts may need to be replaced often, while others may last the life of the appliance.

    Continue to 2 of 12 below.
  • 02 of 12

    Evaporative Cooler Motor

    Swamp cooler motor
    Aaron Stickley

    Evaporative cooler motors usually range from 1/3 to 1 horsepower. Typically, an evaporative cooler only requires 115/120 volts of power, which is the main reason they use so little electricity. Swamp cooler motors usually work fine until they don't--they don't gradually decline. If you are changing the motor in an evaporative cooler, make sure you take a look at the current motor to see what size it is and how many speeds it has.

    Changing the motor on a cooler is not a difficult project,...MORE but it does require some basic electrical know-how. Don't try this unless you are confident of those skills. 

    Continue to 3 of 12 below.
  • 03 of 12

    Evaporative Cooler Bearings

    The metal bearings are the small round spheres that allow the drive shaft to spin when driven by the motor. Bearings come in high-rise and low-rise bearing assemblies. Also, they usually come either in 3/4" and 1" bore. The shaft spins on the bearings, so if the bearings in the cooler are going bad, it tends to make a horrible squeaking sound. Sometimes this sound can be remedied by lubricating the bearings. If that doesn’t work, the cooler bearings will need to be replaced. If you have...MORE any doubt about which kind you have, make sure and bring the old bearings in when buying the replacements. Again, this is a job possible for a skilled DIYer, but don't tackle it if you're not confident. 

    Continue to 4 of 12 below.
  • 04 of 12

    Motor Pulley

    Swamp cooler motor pulley
    Aaron Stickley

    A swamp cooler has two pulleys: the motor pulley and the blower pulley. The motor pulley sits on the motor shaft and is fastened with a screw. Motor pulleys come in different sizes for different-sized motors. The pulley should match the size and type indicated by the manufacturer of your cooler. Using a different-sized pulley could put unnecessary stress on the motor and can affect how the cooler runs.

    It is a good idea to check the motor pulley condition (look for dents) and alignment...MORE periodically. The pulleys rarely go bad, but if you need to, they can be removed by loosening the Allen screws that hold them in place. When replacing the pulley with an adjustable one, be sure to set the adjustment to the motor specific size.

    Continue to 5 of 12 below.
  • 05 of 12

    Blower Pulley

    Swamp cooler blower pulley
    Aaron Stickley

    The other pulley found in an evaporative cooler is the blower pulley, which is positioned on the blower shaft. As with the motor pulley, the blower pulley must be the correct size to ensure that the swamp cooler works the way it is supposed to. When replacing a blower pulley, make sure to match the pulley to the unit, so that the blower moves enough air to cool effectively.

    Continue to 6 of 12 below.
  • 06 of 12


    Swamp cooler v-belt
    Aaron Stickley

    The V-belt is a long-lasting type of drive belt. Its design creates minimal slippage and it is easy on the bearing, making it a good choice for evaporative coolers. This is important because the V-belt must be aligned straight in order to work effectively. When checking the V-belt, check the pulley positioning and adjust as necessary. Also check the V-belt tension, making sure it matches the manufacturer's recommendations. 

    V-belts come in a variety of sizes, so if you are replacing one, take...MORE care to choose the right size. If the belt is beginning to crack, it may be a good idea to replace it before it breaks.

    Continue to 7 of 12 below.
  • 07 of 12


    The evaporative cooler pump brings the water from the pan to the distribution tubing, and from there onto the pads. The pads need to be saturated to allow the cooler to cool the air, so if the pads are not getting wet enough, it’s possible that the pump may need to be replaced. Upsizing the pump can also help circulate more water;  if the pump does not keep the cooler pads wet enough, you may want to upsize the pump.

    NOTE: Hard water can clog up a swamp cooler pump pretty quickly but there are...MORE some maintenance products that can help prevent or clean out the buildup.

    Continue to 8 of 12 below.
  • 08 of 12

    Drain and Overflow

    The evaporative cooler drain is a pipe that sits in the cooler pan. The drain tube can be removed to drain the water out of the cooler pan. The cooler drain also acts as an overflow to allow excess water to drain out if the float is allowing the pan to fill too high. Excess water will go up and over the drain tube and spill onto the ground, alerting you to the fact that there is a problem.

    Continue to 9 of 12 below.
  • 09 of 12

    Cooler Float

    Swamp cooler float valve
    Aaron Stickley

    The cooler float sits in the cooler pan and regulates the height of the water. The cooler float valve floats up as the water level rises, and it levers the water valve off when it reaches the set level. The water level should be high enough for the pump to be able to draw water up, but not so high that the water flows into the overflow tube. Adjusting the water to the right height is usually just a matter of bending the float rod and waiting to see where the water shuts off.

    A float valve that...MORE doesn’t turn the water off correctly is a common problem, but it is a part that is easy to replace. You can replace a float valve in just a few minutes for just a few dollars.

    Continue to 10 of 12 below.
  • 10 of 12

    Cooler Pads

    Swamp cooler pads
    Aaron Stickley

    Cooler pads come in many types, including foamed polyester, slit expanded paper and wood strips. The most common and cheapest cooler pads are the ones made from woods strips--they seem to work great, but if the strips get loose they can clog up the pump, so placing an extra screen around the pump might be a good idea. Cooler pads also come in a variety of sizes, so take measurements of the inside of the cooler panels when buying new pads.

    Cooler pads need to be changed each year, either when you w...MOREinterize or de-winterize the cooler.

    Continue to 11 of 12 below.
  • 11 of 12

    Distribution Tubing

    Swamp cooler distribution tubing
    Aaron Stickley

    The evaporative cooler distribution tubing, commonly called the spider, distributes the water from the pump to the cooler pads. The tubing can sometimes get clogged and may have to be cleaned out or even changed if you're not getting enough water out of them. It is a good idea to check the distribution tubing regularly, especially if the air doesn’t seem cool enough.

    Continue to 12 of 12 below.
  • 12 of 12

    Evaporative Cooler Electrical Box

    The cooler electrical box is where the main power supply comes with the swamp cooler. The power for the motor, the pump, and maybe even the purge pump comes from the electrical box. There normally is not much repair needed here, except possibly to check the wiring connections.