How to Test a Fan Motor

How to Test a Fan Motor

The fan motor is the part that powers your air conditioner. It can be a complex and dangerous component, so if it stops working, have it checked by a professional immediately.

Being a fan can be quite a lifestyle, with many fans willing to alter their behavior in order to demonstrate their devotion to the object of their interest. However, there are also problems that can arise within the fandom.


Fan blades can be made from plastic, metal, or a combination of both. They can be painted or have additives to increase strength or corrosion resistance. The number of fan blades and their design help determine the amount of airflow produced. For example, fans with higher blade pitches usually move more air than those with lower pitches.

Motor-driven fans use an electric motor to rotate a fan Air conditioner blade, which creates a flow of air that circulates or cools a room or machine. These types of fans are found in a variety of commercial and industrial applications.

Unlike compressors, fans produce air flows with high volume and low pressure. This is why they are suitable for cooling systems in buildings or machinery that cannot tolerate high-pressure changes.

The function of a fan is to move the air, which is why there are many different types of fans with blades that come in a wide range of shapes and sizes. Some are designed to be hung from the ceiling (ceiling fans), while others are built into a window, door, roof, chimney, or other structure.

Many of these fans are made from a material that is durable, corrosion resistant, and able to withstand high temperatures. They can also be made in a variety of colors and textures to match the surrounding décor.


A fan’s bearings are a critical component that impact performance, noise levels and longevity. The wrong bearing type for your application can result in reduced uptime and productivity. This is why it’s important to understand the differences between the different bearing options and how they work in a variety of applications.

One common type of fan bearing is the sleeve-type. This has a series of oil rings and Mylar washers at either end of the bearing bore that retain the lubricant needed to keep the shaft spinning smoothly and quietly. However, the sleeve design also creates friction and traps some of the gas created by rotational friction. Trapped gas solidifies into nitride particles that clog the bearing and hamper movement, ultimately shortening its life.

In contrast, ball bearings in fan motors have a smoother and more even surface than sleeve bearings. They require less lubrication, operate at higher speeds and can be mounted in any orientation. However, they can produce more noise than other types of bearing.

Fluid dynamic bearing variations (also known as hydrodynamic or hydrostatic bearings, vapo or SSO bearings) pump or suck liquids around the sleeve to minimize the abrasion of the sleeve. They offer the quietest and longest-lasting fan bearing option but are typically more expensive than other types of bearing.


Performing regular tests on fan motors can prevent breakdowns and extend appliance lifespans, saving you money in the long run. Testing involves disconnecting power, inspecting wiring, checking continuity, testing capacitors, and assessing bearings. By following these simple steps, you can ensure optimal performance and longevity of your appliances.

Start by turning off your fan and removing the cover. Visually examine the wires for signs of fraying or damage, especially those that connect to the terminals on the motor. If any of the connections are loose, use a screwdriver to Air conditioner manufacturer tighten them. Be sure to check for corrosion, as this can lead to poor conductivity and dangerous conditions.

When a motor local winding burns out, it will create a path for current to travel to the frame or other exposed parts of the machine, resulting in a fire. This is often caused by incorrect wire connection or parallel use of multiple units, causing the motor to be overloaded.

To test the integrity of your motor, switch to the continuity testing mode on your multi-meter and locate the motor winding terminals. If the multi-meter indicates that there is no continuity, this means there is a problem with the windings and your fan will not work. If the multi-meter indicates that there are no shorts, this is a good indication that everything is working correctly.


In an electric motor, a capacitor is used to store electrical energy to help it start. Basically, the capacitor holds onto the positive and negative charges of each of its two plates like magnets attracting one another across a gap. Because of this, when the capacitor is charged up with electricity (which happens when the motor starts up) it has an extra jolt of power to help get the motor spinning. Once the motor is running, it releases this energy to help take the load off of the house’s electrical grid and keep the fans and compressors on a more even energy flow.

To test the capacitor, first you need to discharge it by shorting the terminals together with a screwdriver. Then, connect your multimeter leads to the terminals. You want to check its capacitance — which is listed on the label in microfarads (mF) or sometimes in millifarads, or MFD. Also, look at its voltage rating.

The higher the voltage, the greater the capacitor can deliver. Over time, however, the capacitor’s capacity drops and it loses its ability to deliver the required amount of power. This is why it’s important for technicians to thoroughly troubleshoot and test capacitors before replacing them. See NPTC Tools of the Trade: Testing a Motor Capacitor, extension publication ANR-2783 for details on how to do this.

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