How to Winterize a Swamp Cooler

A swamp or evaporative cooler is an energy-saving appliance most often used in dry, hot regions as an air conditioner. The swamp cooler works on the simple principle of passing large volumes of air through a wet medium to cool the air in a room as much as 15 degrees F. Even though they are simple devices, you must perform some required steps to winterize them and help them avoid permanent damage.

Close-up of swamp cooler filter pad
  1. Turn off the water and electricity to the cooler. Using the wrench, disconnect the supply line at the source and make sure it drains completely. Again using the wrench, remove the plug from the bottom of the pan and drain the water from the cooler.

  2. Use the screwdriver to remove the side access panels and the front panel holding the filters. Remove the filters and set aside to dry.

  3. Use the flashlight if necessary to inspect the pump screen and water trough, insuring that none of the holes are blocked. Use the towels to push any water remaining in the pan to the drain hole with any loose dirt or debris.

  4. Use the putty knife to gently scrape any stubborn clumps of dirt or debris from the pan. Inspect the pan for cracks and holes. Cover the pan drain hole and pour vinegar into the pan if necessary to loosen calcium or hard water deposits.

  5. Inspect the rest of the interior for any loose parts or critters. Re-install the side panels and the dry filter with its retainer. Cover the entire unit to prevent cold air from coming into the house.


  • Always disconnect electrical power before working on the unit. Water and electricity can be a fatal combination.