The Importance of Choosing the Right Fan Motor for Your AC System

The Importance of Choosing the Right Fan Motor for Your AC System

The fan motor is a crucial part of your air conditioning system, turning the blades that create the flow of cool air. Its construction is relatively simple and a good understanding of its operation can help you avoid costly repairs or replacements.

Using a multimeter, you can easily check the condition of the motor by measuring its resistance in ohms. A reading of “infinity” indicates a short in the windings, which should be replaced immediately.

Choosing a Fan Motor

The fan motor is one of the hardest working components in your air conditioner. It’s not uncommon for this component to wear out sooner than intended, especially if your AC system is used regularly. The best way to prevent premature failure of this essential part is to choose the right fan motor for the job.

Choosing the proper motor for an application is a meticulous process that involves many factors. For example, the size of the motor is critical as it must be able to handle the required amount of airflow. It’s also important to take into account things like the frame of the motor, which is a very specific measurement. The frame must fit correctly in the equipment that it’s being installed into so that it doesn’t cause any modifications to be made.

Another factor that’s critical to consider when selecting a motor is the size of the fan blade. For instance, a restaurant may decide to switch out an older griddle for a new char broiler, which will require more airflow than the original griddle. This increase in demand can create static pressure in the ventilation system, which requires more fan horsepower to overcome.

The best way to determine the correct size motor is by using the specifications of the existing fan blade. For example, a replacement condenser fan motor will need to match the pitch, diameter, and angle of the original fan blade.


Fan motors are used in a Air conditioner variety of settings ranging from cooling your home as part of your air conditioning system to ventilating large industrial facilities. The basic structure of these motors is similar no matter the application, making them easy to diagnose and repair.

The fan motor in your AC unit powers the blades that blow across the condenser coils of your air conditioner converting the hot refrigerant gas back to a cool liquid. The cooled liquid is then blown throughout your home via ducts. In many cases a faulty fan is the cause of poor air flow and low comfort.

Before replacing a fan motor always remove the old one and inspect it for any signs of wear or damage. Also inspect the electrical connections and wire colors and mark them for reference. If you are unsure of the wiring color you can use a Air conditioner manufacturer multimeter to check for voltage and amperage. Before installing the new motor it is always a good idea to take pictures or make notes of the connection locations so you can refer to them later.

When installing the replacement motor be sure to install it in the proper direction as outlined by its manufacturer. Also be sure to replace the balancing weights on the blades according to the manufacturers instructions. When everything is back in place be sure to test the new fan motor with a multimeter for proper voltage and amperage readings.


If your fan motor isn’t working, there may be a few reasons why. It could be a simple electrical problem, or it could be a mechanical issue such as the pin in the center of the motor case getting too hot or wearing out. There are also times when a fan motor simply stops turning because of debris or dust.

It is possible to troubleshoot a fan motor if you know what to look for and where to start. First, turn off power to the unit at the circuit breaker or fuse box. Then remove the fan blade from the shaft of the motor and inspect the capacitor, which is located inside the fan case (you’ll need to purchase a cap tester for this). A capacitor looks like a large battery with cables attached to it, and it should have a flat top.

If the capacitor is damaged or the pin in the center of the motor case isn’t moving, you can try to fix it by performing an ohm test on the motor windings. To do this, you’ll need a multimeter with an ohms setting. You’ll need to measure the resistance between the white wire and each of the colored wires on the motor, and the reading should be zero if the windings are open or infinite if they’re shorted.


The fan motor is one of the most common parts to fail in your AC system. The good news is that it’s often a relatively inexpensive part to replace. This is a task that many homeowners can complete themselves, although some of you might need to hire a professional.

The first thing you should do is shut off power to the circuit breaker that runs the motor. After that, you’ll want to disconnect the wires from the old motor and carefully replace them with the new one. Make sure that the colored wires match up correctly and that there is no bare metal exposed. If there is, that’s a sign of a bad connection or possibly even a burned out motor.

Once you’ve replaced the motor, reinstall it using the mounting brackets and hardware. Remember to reconnect the wires and make sure that they are properly matched up. It’s also a good idea to clean up the wiring before you leave. No one likes working with a clump of spaghetti wires that have been left behind by other techs.

Be sure to use an OEM replacement fan motor. These are designed by the original equipment manufacturer to fit your specific unit and will help keep your warranty intact. You can also use a universal replacement fan motor for your air conditioner, but that might not be as reliable or have the same cooling capabilities.

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