How to Identify PSC Motors
Dec 17, 2025
Motor Minute™ Technical Tip – How To Identify PSC Motors
Hi, Chris from Regal Rexnord here with your Motor Minute technical tip. Helping you become an HVAC motor pro one minute at a time.
Today’s Motor Minute topic is how to identify PSC motors.
PSC is an acronym that stands for Permanent Split Capacitor. Identifying PSC motors helps you properly diagnose and replace them. The most identifiable component related to a PSC motor is the run capacitor. The run capacitor is electrically connected to the PSC motor. The run capacitor is a necessary component to help the motor start and run.
Below is an example of an HVAC indoor blower motor found in applications such as split system fossil fuel furnace, air handler or package units. Notice the run capacitor mounted on the blower housing near the motor.
Multi-speed PSC indoor blower motors are typically built with two wires dedicated for connection to the run capacitor, separate from the line voltage wires, as seen here on the HVAC unit wiring diagram.
Here is an example of the outdoor fan motor found in applications such as a split system A/C, heat pump or package units. In this application the run capacitor is typically mounted in the electrical box. It is also typically a dual run capacitor that provides a separate run capacitor for the fan motor and the compressor in one component.
Single speed PSC outdoor fan motors are typically built with a 3-wire connection method as seen below. Two wires connect to line 1 and line 2, and the third wire is connected to the (F) or “fan” terminal of the dual run capacitor.
PSC motors are also found in applications such as unit ventilators, attic fans, walk-in coolers and freezers and induced draft blowers just to name a few. Notice in these examples that the run capacitor is mounted directly to the motor and is pre-wired to the motor from the factory.
Industry best practices for replacing PSC motors
Always install a new run capacitor with a new PSC motor. Unless, of course, the run capacitor is pre-wired to the motor from the factory
Always select a run capacitor that matches the rating plate of the new PSC motor as seen here, including the MFD (microfarad) rating and the voltage rating.
Closing comments
- Some universal replacement PSC motors are shipped with a capacitor in the box like the Century® MasterFit Pro® motor. It’s a good practice to ask the distributor if the capacitor is included so you don’t have to make a second trip.
- Genteq® Evergreen® ECM motors are designed to replace PSC indoor blower motors and outdoor fan motors. These motors do not require capacitors making them a great truck stock motor to help you get the job done the first time, every time.
And that’s a wrap on this segment of Motor Minute technical tips. Remember that we provide motor training and product information in multiple formats including videos, literature, podcasts, articles, of course Motor Minute technical tips and classroom education both online and face to face. All of this industry leading training is available at no charge to HVAC professionals at regalmmu.com. Thank you for taking the time to build your motor knowledge.
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