A capacitor is an electrical component that stores and releases energy to help HVAC motors start and run smoothly. In air conditioners and heat pumps, capacitors support the compressor, blower, and fan motors. Start capacitors provide a short power boost for startup, while run capacitors stabilize voltage during operation. A failing capacitor can prevent a system from starting or cause overheating.
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A capacitor is an electrical component that stores and releases energy to help HVAC motors start and run smoothly. In air conditioners and heat pumps, capacitors support the compressor, blower, and fan motors. Start capacitors provide a short power boost for startup, while run capacitors stabilize voltage during operation. A failing capacitor can prevent a system from starting or cause overheating.
What does a capacitor do in an HVAC system?
It stores and releases energy to help motors start and keep running smoothly, supporting the compressor and fans.
Source: The Cooling Company
Capacitors help motors start and run efficiently.
If an AC unit hums but does not start, a failed start capacitor may be preventing the compressor or fan motor from turning on.
Have capacitors checked during routine maintenance, especially before peak summer heat when failures are most common.
“Have capacitors checked during routine maintenance, especially before peak summer heat when failures are most common.”
Extreme heat shortens capacitor lifespan, which is why failures often spike during summer.
Can a bad capacitor stop an AC from starting?
Yes. A failed capacitor can prevent the compressor or fan motor from starting even if the thermostat calls for cooling.
Can I replace a capacitor myself?
It is best handled by a professional due to electrical safety risks and the need for correct ratings.
How do I know if a capacitor is failing?
Signs include hard starting, a humming sound, reduced airflow, or a visibly bulging capacitor.
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