How to Fix an Evaporative Cooler: Replacing a Water Pump

Evaporative coolers are an energy efficient way to cool a house in dry climates. They consist of a water reservoir 3-5 inches in depth. This water is sent, via a water pump, to a water distributor, which passes the water over a cooling pad. This cooling pad is basically a large cardboard air filter. Air is pumped through this wet filter, and this water cooled air is then pumped into the house through normal duct work. One of the most common fix-it jobs needed to maintain an evaporativecooler is the replacement of the water pump. Follow the steps below to replace a water pump.

1.    Open the side panel of your cooler. Locate the water pump if you don't already know where it is. There are many reasons a cooler won't work, so diagnosing that the pump needs to be replaced comes first. With the pump turned on, remove the bleed tee cap or the pump hose to see if water is being pumped through the machine. If not, move on to step two.

2.    One of the first orders of business is to assure that the pump is unplugged and the power to the unit is off. Remember, you are working with an electrical appliance and water. Now that it is safe to work with this equipment, check your existing water pump. Do any of the connecting hoses or clamps need to be replaced? If so, you can save yourself a trip by getting everything you need on the first run.

3.  Assuming you will replace the entire pump assembly, the first step will be to remove the pump hose clamp from the end of the pump hose feeding into the water distributor. This is easily accomplished by simply pinching the two ends with pliers and moving the clamp off of the end of the hose. The only other thing which might need to be done is to remove the bleed line from the bleed tee. Many people don't use bleed lines, so this may not be necessary. A bleed line is a 1/4", soft "poly" tubing which runs off the bleed tee, out the drain/overflow pipe in the bottom of the cooler, and off of the roof. (For information about installing a Bleed Line - my Related Articles section)
   

Evaporative air cooler

4.   Now that you have disconnected the old pump, simply place the new one into the water reservoir. It is highly recommended that you set the new pump inside a mesh filter bag or basket. This will prevent bits of scale from clogging or ruining your new pump. Attach the pump hose to the bleed tee and the bleed tee to the pump. Attach the other end of the pump hose to the distributor above the wet cell (pad). Re-attach the bleed line to the bleed tee, and you're all set.

5.   Before you close up your cooler housing, now is a good time to oil your fan, check and adjust your drive belt, and clean out your water tray if need be.