How to Replace a Capacitor on a Swamp Cooler Motor

Replacing a capacitor on a swamp Cooler motor is a simple fix that you can do at home. Naturally, if in doubt, consult a specialist. Capacitors aren’t used in all evaporative coolers, and the presence of one varies from unit to unit.

When a motor is replaced, you should always replace the capacitor as well. A capacitor is a low-cost component that might cause difficulties with a new motor; therefore, it’s best to replace it whenever it is fitted.

There are different reasons why the swamp Cooler motor needs to be replaced, which we will discuss in this article. Again we will discuss the steps followed to replace the capacitor on a swamp Cooler motor.

Reasons for replacing a swamp cooler capacitorReasons for replacing a swamp cooler capacitor

Within a circuit, capacitors store and release energy as needed. Larger capacitors are capable of tolerating higher current loads and have more charge storage capacity. Because some A/C compressor motors require a pulse of energy 300 to 500 percent of normal to start, these features are well suited for air conditioning machinery. This application necessitates the use of a start capacitor. Other electric motors use smaller run capacitors to maintain them spinning at optimum speed.

  • Three motors

The air conditioning system consists of an electric blower motor that circulates cool air within, an electric condenser fan motor that exhausts hot air outdoors, and a compressor motor that pumps refrigerant through the system. Each motor has a capacitor to start when the thermostat turns on the air conditioner and keeps it running at maximum efficiency. Because the compressor consumes far more energy than the other two motors, the compressor capacitor is the largest.

  • Overheating

The moist separator inside the electrolytic A/C capacitor will dry up if the unit gets too hot, resulting in an internal short circuit. If the capacitor’s temperature consistently exceeds 150 degrees Fahrenheit, it may fail.

  • Expected Life Expectancy

Normal wear will eventually cause an A/C capacitor that has been protected from damage, electrical surges, overheating or inappropriate electrical loads to fail. The lifespan of an A/C capacitor varies depending on the temperature and usage pattern, but it usually lasts around six years. The Zettler start capacitor, for example, guarantees a service life of 50,000 starts for ordinary household air conditioning systems.

  • Parts that are worn or damaged

Otherwise, the capacitor will overheat if it is not disengaged within a few seconds. The capacitor may burn up if the compressor or fan motor drags due to damage or worn bearings. By leaving the capacitor in the circuit for too long, a faulty relay switch might cause it to overheat. A capacitor, a compressor, the fan motor, or the unit’s cables can all be damaged by lightning. Even a minor power surge might cause the capacitor to be damaged or destroyed, resulting in compressor overload and failure. A capacitor that is leaking oil is a dead giveaway that it is malfunctioning.

  • Overloading the electrical system

The air conditioning capacitor’s job is to get the compressor and fan motors up to about 3/4 of their maximum speed before disengaging them. It isn’t made to handle a constant electrical load. The capacitor will most likely overcharge and be damaged if the motor becomes physically blocked from turning or if the motor burns out. Voltage exceeding the capacitor’s rated value may also cause it to fail. A power surge from a lightning strike, for example, would cause a significant current spike and likely “fry” the capacitor.

What is a Swamp Cooler Motor Capacitor, and what does it do?What is a Swamp Cooler Motor Capacitor, and what does it do

A motor capacitor in a swamp cooler helps manage the flow of power to the motor so that there are no large up and down spikes. That can assist in extending the motor’s life and maintaining it spinning at a constant speed.

A RUN capacitor is a type of capacitor that aids in the starting of a motor. It can be tested using the appropriate multimeter that can test Microfarads. Many swamp coolers do not use a capacitor, and whether one is installed depends on the manufacturer.

How to Replace a Capacitor on a Swamp Cooler MotorReplace a Capacitor on a Swamp Cooler Motor

1) Unplug the item and turn off the power.

2) Locate the capacitor and jump the legs together to discharge any voltage it may be holding.

3) Disconnect the cables.

4) Remove the screws that hold it together.

5) The wires are connected to the new capacitor.

6) The screws that hold the capacitor in place should be reattached.

7) How to Change a Capacitor in a Swamp Cooler

8) Check the unit, which should now be operational.

What causes the motor to shut down, overheat, and then restart once it has cooled?What causes the motor to shut down, overheat, and then restart once it has cooled

If the sheave on the motor isn’t adjusted correctly, it will overheat and shut off until it cools down. Operating the unit without the front discharge grill on any window or mobile type will cause the motor to overheat and shut off until it cools down.

1. Remove the sidewall cover or pad frame first (Louver)

Remove the screws from the backside panel or push the pad frame up and out of the swamp cooler to gain access to the internal components of your swamp cooler, including the swamp Cooler engine. Once the screws have been removed, or the pad frame lifted out, the back panel should easily slide out to reveal the inside components.

2. Check the Tension of the Belt

The sides of your swamp cooler will easily pull off, revealing the water pump, engine, and belting fan inside. Once inside, check the belt that connects the swamp cooler motor to the fan for tension. It doesn’t have to be too tight or too loose. Your swamp Cooler motor may overheat if the fan belt tension is incorrect. In general, the tension of your fan belt should have roughly 1 inch of play. That can be adjusted using an Allen wrench by altering the motor pulley (sheave).

3. Examine the Shaft Bearings

Two shaft bearings, often known as “squirrel cage” shaft bearings, will be found in your motor. Add an oil port to each of these shaft bearings. Make sure there’s enough oil in these shaft bearings for them to spin freely. If there isn’t enough oil in these bearings, they can seize, causing the swamp Cooler engine to overheat.

4. Examine the Electrical Connections

Ensure your swamp Cooler motor’s electrical wiring and connections are secure and aren’t overheating or shorting out. A faulty switch or fuse in the swamp Cooler motor might also cause the motor to overheat and shut down. To prevent the swamp Cooler motor from overheating, ensure all connections, switches, and cables are correctly fitted and maintained.

5. Verify that the voltage is correct

Your swamp cooler’s motor is tuned to run at a specified voltage or below, preferably below. The motor can overheat if there is too much voltage applied to it. Internal wiring and circuitry can be damaged by too much voltage. To avoid damage and overheating, be sure you’re using the correct voltage for the motor. The motor’s voltage capacity will be printed on the motor’s side. It’s important to note that the motor’s indicated voltage capacity is not the accurate working voltage. The motor should be driven at 55 to 60 percent of its total voltage capacity to ensure optimal operation and avoid overheating.

Read also our another article of:

How to Install a Thermostat on an Evaporative Swamp Cooler

Swamp Cooler Smells Like Fish – What to Do?

Swamp Cooler Spraying Water – What to Do?

Frequently asked questions:

  • How do we test if the capacitor is bad?

Do you want to see if your capacitor is in good working order? A high-quality electrical meter is used to test your capacitor. Microfarad is the unit of capacitance. The microfarad value of a capacitor is indicated on its label. A microfarad number that is too high or too low on your electrical meter indicates that your capacitor is defective.

Before you test your capacitor, use an insulated handle screwdriver to short the terminals. That will assist you in releasing any accumulated energy.

For it to be helpful, the capacitor value must be within the specified range. Remember that capacitors have no polarity; thus, it doesn’t matter which side the wires are connected to. If you have more than two wires running to the capacitor, you must always couple the connected wires on one side.

  1. Reminder on Capacitor Safety

Disconnect the power to the motor before servicing it, and discharge the capacitors before handling them, as with any electrical device.


A competent homeowner with some electrical experience can replace the capacitor on an evaporative cooler. If you need to work on the unit, make sure the power is switched off, and the cooler is unplugged. Capacitors are easy to replace because they only have two legs and two wires.

Ensure you get the correct capacitors for your cooler, as there are many of them, and they have to match the motor. Do you know how to replace a capacitor in a swamp cooler? Let us know what you think in the comments section below.

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