Swamp Cooler Motor Replacement

DEAR MIKE: A while ago, you wrote about an evaporative cooler problem. I have a different problem with my evaporative cooler. The pump works fine, but the cooler doesn't blow any air out. I assume it is the motor, but I am not sure. -- Ryan C.

DEAR RYAN: Your blower problem may be the result of a bad motor, but before you replace it, check some obvious things.

We can assume that the power is on to the unit since the pump works. Remove the panels and filter pads to gain access to the blower (remember to turn off the power before you work on the unit).

The way the air is blown is pretty simple. The motor has a pulley attached to the end of its shaft. A belt (just like a fan belt from your car) revolves around this pulley. The belt is also attached to the fan assembly (most look like squirrel cages). As the motor turns the pulley, the belt turns and drives the fan assembly, which moves the air.

Before you replace the motor, check that the fan belt is still in one piece and is on the pulleys. If it is, then check to make sure that the pulley is not spinning freely on the shaft of the motor. The pulley will be held in place by a bolt that tightens against the motor's shaft. If all this looks good, it may be time to take a trip to the home center for a new motor.

Also, inspect the motor for damage caused by water. It may be that water was dripping or even spraying on the motor. You must repair the leak before you replace the motor or else the motor may die early and/or cause an electrical hazard.

The motor will have a plate attached to it that states the amp rating. Take this information or the motor with you when you purchase a new one. Also, if you are doing repairs to your swamp cooler during the cooler months, you may have trouble finding parts during the off season.
The motor is attached (and also adjusted) using different methods. Your motor will be held in place with brackets. The brackets may swing in an arc or slide on a track. This movement will allow you to adjust the belt to the correct tension once the motor has been mounted.

Removing the motor is simply a matter of loosening the bolts that hold the tension on the belt. The belt can then be lifted off the pulley. Remove the pulley from the motor's shaft by loosening the bolt that holds it on, then pull the pulley straight off the shaft. After that, remove the bolts that hold the motor to the bracket.

Bolt the new motor to the brackets. Getting the pulley in alignment is the trick. If the pulley from the motor is not aligned with the pulley from the blower, the belt will tend to jump or twist off the pulleys.

Place the pulley on the new motor's shaft and align it by using a straightedge. Place the straightedge against the blower pulley and then place it against the motor's pulley. Move the motor's pulley along the shaft until the straightedge contacts each pulley along their outside edges. Lock the pulley into place by tightening the bolt.

Place the belt over each pulley and adjust the tension. Pull the motor back and tighten the fasteners. You will have the proper tension when you can push down on the belt halfway between the pulleys and the belt will move only half an inch. Use about five pounds of pressure to test it.

Finally, wire the motor using the instructions and diagram from the manufacturer. It's a simple wiring job with usually only two wires for a single-speed motor. Replace the panels, turn the power back on, and enjoy the rushing air. 

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