Capacitor Failures Can Ruin Your Day . . . and Motors!

The motor run capacitor is an essential component in HVAC systems, but all capacitors are not created equal. Using the wrong capacitor rating or a poor quality capacitor can adversely affect the operation of the motor, the compressor or an entire HVAC system.

Most HVAC systems use a motor run capacitor to run the blower motor, the condenser fan motor and/or the compressor. A capacitor is used to energize a second-phase winding in the motor. It also helps with efficiency by providing the proper phase angle between voltage and current to create the correct rotational electrical field.

If the wrong capacitor rating or a poor quality capacitor is used, then the motor will not have the correct phase angle between the current and the voltage, and consequently the motor torque or rotational force will be affected. Depending on the motor load, this may result in a reduction in the motor’s overall speed.

A wrong capacitor rating or a poor quality capacitor causes an inefficient motor, which causes an under-performing system, which eventually results in either a stopped system, or at the very least, a reduction in the airflow and comfort to the homeowner.

Once a motor has a reduced speed, other issues begin to occur – an increase in overall system noise, greater energy consumption due to the motor’s inefficiency, and an increase in the overall temperature of the motor. The temperature increase reduces both motor life and the overall system life by expediting wear and tear on the motor bearings and a breakdown of the motor insulation.

A wrong capacitor rating or a poor quality capacitor causes an inefficient motor, which causes an under-performing system, which eventually results in either a stopped system, or at the very least, a reduction in the airflow and comfort to the homeowner. The final outcome is a repeat visit by the contractor and an unsatisfied customer.

You can be sure of the quality of the capacitors you purchase by asking the manufacturer for test data that proves its lifespan, quality and reliability. Even though it’s a small, inexpensive component, the capacitor does impact the entire HVAC system.

Anthony Colone is capacitor product manager for RBC Manufacturing Corporation, Genteq.
He can be reached at [email protected]

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