Evaporative coolers are a great, low-cost alternative to air conditioning, particularly in arid climates. In addition, since many evaporative coolers are mechanically-simple, you can perform maintenance yourself with just a little know-how. Here are some essential maintenance tasks that you should do to keep your unit running smoothly:

Pad replacement and cleaning

Evaporative coolers use pads that become saturated with water that continuously recirculates inside the cooler. This water trickles down through the pad material, while incoming air flows through the wet pads; the hot, dry air is cooled by evaporation, and a fan forces the cool, moist air into the home.

Evaporative cooler pads are constructed of many materials—wood fiber, metallic strands, plastic, and paper—but basically can be broken into two larger groups: natural fiber pads and synthetic pads. These pads possess different advantages and disadvantages, and their maintenance requirements vary. Below is a brief guide to pad materials and some considerations for use:

  • Natural fiber pads — These pads are typically constructed from Aspen tree wood or paper, and they are an excellent choice due to their cooling ability and modest cost. They will last an entire season before needing replacement, but keep in mind that wood debris can clog components.
  • Synthetic fiber pads — These pads are constructed of plastics and polymers that form a rigid, corrugated structure. They have a much higher cost, but they are excellent performers and can be repeatedly used for several seasons if maintained.

The number one enemy of cooler pads is mineralization, the accumulation of mineral products that are ordinarily dissolved in water. These deposits are damaging because they limit the ability of pads to absorb and evaporate moisture. If allowed to dry or accumulate for a lengthy period of time, these deposits will become difficult or impossible to remove.

Periodically check your cooler pads during summer for mineralization. If you see accumulations, use a brush to gently scrub the "scale" away from the pads. Vinegar applied with a cloth can also help clear away mineralization, but be sure to thoroughly rinse your pads with water after cleaning. 

End-of-summer cleaning

When the summer ends, you should perform a series of maintenance steps to clean your unit and get your evaporative cooler ready for winter. Here are the items that you should address:

  1. Throw away wood fiber pads if they have finished their second season, and thoroughly clean all other types of pads. If you can't get pads completely clean, or if they are showing signs of fraying, tearing or thinning, it is probably time to replace them.
  2. Disconnect the water supply, and drain the unit completely of all standing water.
  3. Scrub the interior of the cooler with vinegar and a cloth to remove any mineral build-up. Pay close attention to areas where blockages can occur, especially where water enters the pump and other narrow places. Use a soft scrub brush to remove any stubborn accumulations. Thoroughly rinse the interior of the cooler to remove vinegar and debris from mineral deposits.
  4. Carefully inspect the interior and exterior of the unit for signs of rust or corrosion. If you see beginning stages of either rust or corrosion, you may want to consider installing a "sacrificial anode." These are small metal objects, constructed of metals such as zinc, aluminum or magnesium, that attach to the interior of the water tray. They "attract" rust and corrosion-causing substances by holding a weak electrical advantage over the cooler's metallic structure. Ask an installer for assistance in purchasing and installing a sacrificial anode.
  5. Once you have finished cleaning the cooler and draining the water, place a cover over the unit to prevent cold air intrusion into your home. You can either use a commercial cover or fabricate one from heavy plastic sheeting that is cut and glued or taped to fit.