How to Troubleshoot a Fan Motor

How to Troubleshoot a Fan Motor

Fan Motor is a key component of your air conditioning system. Taking the time to understand and troubleshoot this seemingly simple component can help you avoid expensive repairs.

The most common cause of a fan motor problem is dirt or trash build up on the blades. This can throw off the balance of the blades and cause the fan to not work correctly.


Fan blades are a critical part of the centrifugal blower that’s in charge of sucking in, circulating, and pushing out new air. They come in a variety of shapes and sizes, but are all designed to work efficiently for their specific job.

For example, metal blades are typically used for high static pressure fans that require more strength in the material. They may also offer added corrosion resistance or other additives that benefit the specific environment in which they are being installed. Plastics, on the other hand, are a good choice for low static pressure fans and may be colored for aesthetic purposes or contain additives that increase resistance to UV damage.

In addition to examining the fan blades for wear and tear, it’s a good idea to check that the fan isn’t overheating. This could be caused by a variety of things, including an obstructed fan belt or a disconnected or improperly plugged in capacitor. If the motor does overheat, it’s important to shut off the power at the circuit breaker or disconnect switch for safety reasons.

The condenser fan motor keeps outdoor air moving to maintain proper ventilation and cool the refrigerant in an HVAC system. It also transfers the latent heat from the gaseous refrigerant to the surrounding outdoor air. Grainger offers a variety of replacement fan blades and propellers in a range of sizes that fit most popular condenser units.


The bearings that support the rotor are one of the most important aspects of a fan motor. They must be able to hold up to thousands of revolutions per minute and provide a long operational lifespan. This requires a design that is reliable, quiet, and easy to maintain.

The most common bearing types are sleeve or ball. Sleeve bearings are less expensive and work well when noise is a concern. These bearings do not Air conditioner have rolling balls but instead rely on a thin film of oil on metal sleeves. However, sleeve bearings tend to develop a gap between the shaft and sleeve, which can cause the rotor to tilt and wobble.

A specialized solution is the omniCOOL system, which provides a magnetic structure that prevents the gap between the shaft and the bearing sleeve. This minimizes rotor tilt and wobble and eliminates the need for Mylar washers or oil rings. In addition, the omniCOOL system’s enhanced bearing design features specialized grooves that facilitate lubrication.

This is a major benefit of this type of design as it eliminates the need to use additional components and increases the lifespan of the bearings. During installation, it is critical to check the radial clearance between the bearings and the adapter sleeve. This can be done by driving the bearing up the adapter sleeve and measuring its clearance. This ensures the bearings are not loaded before they’re installed, which can damage them before they’re even activated.


A fan motor that’s not working correctly could be due to a number of reasons. For example, it might have a faulty capacitor, or the bearings might be worn out. Regardless of the reason, it’s important to know how to troubleshoot and repair these issues before they lead to a complete breakdown of the unit.

To check the condition of the motor windings, a technician will use a multimeter to test for continuity. The test will measure ohms, which indicates the amount of resistance between the wire terminals. A low reading indicates a closed circuit, while an infinite reading means the windings are open. If the windings are open, the motor will need to be replaced.

Before beginning this step, it’s important to remember that the fan motor is still plugged into power and should be de-energized before testing. This will prevent the possibility of an electrical shock. Afterward, remove both instrument test leads from ground and reconnect them to the motor leads. Ensure that the resistance value is zero megohms (MO) to prevent damage to the test leads.

If any of the connections are loose, retighten them using a screwdriver. However, don’t over-tighten them as this may cause the terminals to crack. In addition, it’s important to inspect the wiring connections for signs of corrosion. If any are found, clean them with a solvent to avoid further problems.


Fan motors are used in a variety of applications, from circulating cool air in your home or office to ventilation in large industrial settings. These motors have a relatively simple design, making them easy to fix when something goes wrong. Regular maintenance and a little preventative testing can help you avoid problems before they start.

The most common reasons that a fan motor stops working are electrical problems and mechanical wear Air conditioner distributor and tear. The motor’s bearings can wear out over time, and the electrical wiring can become worn or disconnected. Incorrectly wired ceiling fans can also burn out and cause a short circuit in the switchboard.

A fan motor can also stop working due to dirt and debris build up on the blades. This can cause the blades to lose their balance and create uneven airflow. It is important to clean your fan motor regularly and keep the blades balanced to prevent this issue.

Another common reason for fan motor failure is a faulty capacitor. The capacitor supplies power to the blower wheel and fan belt. A faulty capacitor can stop the fan from turning or may not be able to supply enough power. If you think your capacitor is faulty, test it using a dedicated capacitor tester to check the microfarad rating. If your capacitor is leaking or not rated correctly, it should be replaced.

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