What Are the Indicators of a Faulty HVAC Capacitor?

Indicators

• Capacitors help the compressor, a major component in the system, turn on. If a capacitor is malfunctioning, the compressor may start but make a humming noise. The compressor could also overheat. If the compressor overheats, it may shut down to protect itself. After cooling, it may restart, only to overheat and shut down again. The overheating could eventually cause permanent damage to the compressor. Compressor replacement and installation can be quite expensive. The HVAC system cannot cool effectively with a damaged compressor.

Condenser

• A condenser is a box-like unit housing the compressor and other parts of the HVAC system. The condenser is installed outside the house, usually in the rear of the home. Among its parts is a huge fan that turns when the system starts. A failed capacitor may also prevent the fan from starting. It’s possible that the fan and compressor both may not start if capacitors are faulty.

Repair

• Capacitor troubleshooting should be conducted by a licensed or certified HVAC technician. People without experience repairing HVAC systems risk serious injury such as electrical shock or cuts while working on a compressor or other parts. Trained technicians can test capacitors with special equipment.

Age

• Compressors several years old may require extra power during start-up, and that places additional demands on capacitors. An HVAC technician can install special capacitors offering more starting power for older compressors.

Maintenance

• It’s possible to avoid failed capacitors by scheduling regular maintenance for your HVAC system -- usually every spring. Technicians can alert you to possible failing parts. A Raleigh, N.C., television station reported that annual service calls are usually less than $90, but prices could vary across the country. Service calls and detecting potential capacitor failures before they occur could extend the life of the compressor. Check with a HVAC technician for parts and labor costs on capacitor replacement.