A motor run capacitor continuously supplies voltage to single-phase motors throughout operation, improving efficiency and torque delivery. Unlike start capacitors, run capacitors remain active during the entire motor cycle. These capacitors typically range from 5 to 100 microfarads (µF) and operate at 370V or 440V in residential HVAC equipment.
Performance and Efficiency
Run capacitors increase motor power factor from approximately 60% to 85%, reducing energy consumption and operating costs. They improve starting torque and maintain consistent motor speed under varying load conditions. A properly functioning run capacitor can reduce electricity usage by 10% to 20% compared to operation without capacitance correction.
Maintenance and Lifespan
Run capacitors typically last 10 to 20 years in residential systems, though high ambient temperatures can shorten lifespan to 5 to 8 years. Failed capacitors cause reduced airflow, increased energy bills, and motor overheating. Replacement should occur when capacitance values drop 10% below rated specifications or when physical damage appears, such as bulging or leaking.