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Air Conditioner Capacitors: Types, Functions, & Signs of Issues

Air Conditioner Capacitors: Types, Functions, & Signs of Issues

An air conditioner (AC) capacitor—sometimes called an HVAC capacitor—is a cylindrical electrical device located near the compressor that stores energy. If you’re wondering why AC capacitors are important for household comfort, view our outline of this critical component.

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How Air Conditioner Capacitors Work

Air conditioning capacitor devices have two electrodes, which are connected to opposite terminals of an alternating current power source. When AC flows through those electrodes, an electric field forms between them and stores energy for later use.

AC Capacitors Are Important Because They:

  • Maintain a steady flow of current
  • Prevent the voltage from dropping so low that it damages the unit
  • Improve system performance by maximizing efficiency

Types of Air Conditioner Capacitors

There are two types of AC capacitors:

Start Capacitor

Start capacitors provide a temporary voltage surge when the power supply is first turned on. The stored charge builds up enough to be released as the electric current starts flowing through the circuit. The initial surge provided by the air conditioner capacitor provides enough power for the circuit to begin operation.

Run Capacitor

Run capacitors regulate the current that flows through it, providing necessary voltage drop and smoothing out any fluctuations in the current’s load.

The difference between start and run capacitors is that start capacitors provide a voltage surge to get the AC system started, whereas run capacitors keep them running after power has been supplied.

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Signs of a Malfunctioning Air Conditioner Capacitor

A faulty AC capacitor will likely become apparent in one of the following problems:

Lack Of Cold Air

An air conditioning system that doesn’t produce cold air could be the result of a malfunctioning compressor, which is powered by the AC capacitor.

High Energy Bills

A malfunctioning AC capacitor can cause your cooling system to short cycle. Short cycling results in higher than normal monthly energy bills because the unit continuously turns on and off in an unsuccessful attempt to reach the set temperature.

Humming Sounds

An AC capacitor that runs too fast or too slow can begin vibrating and cause a humming sound.
AC doesn’t turn on immediately

An AC system should start producing cold air quickly after turning it on. If cold air production is noticeably delayed, a malfunctioning start capacitor may be to blame.

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What Causes An Air Conditioner Capacitor to Go Bad

Keep an eye out for the following factors that cause an AC capacitor to go bad:

Overheating Capacitor

When an AC capacitor’s internal temperature gets too high, it will break down and lose its ability to store an electric charge.

Damaged Parts

Damaged parts will cause an AC capacitor to go bad by making electrical storage less effective and disrupting the flow of current through the system.

Electrical Overload

An electrical overload creates a current that’s stronger than the AC capacitor can handle, which can cause the capacitor to go bad prematurely.

Life Expectancy

Even if the AC capacitor works perfectly, eventually it will break down due to regular wear and tear.

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Air Conditioning (AC) Tune-Up, Repair, & Installation Services

If you are encountering a broken air conditioner capacitor in your system, give our team a call (703) 543-9649 to receive assistance. Our team of technicians offer exceptional air conditioning repair and air conditioning installation services for homeowners in Sterling and other areas in Virginia. Whether you want to tune-up your unit for spring, or need to install a new system, trust an HVAC contractor that has been in the business since 1972. In addition, our staff provides other types of HVAC services such as furnace repair, boiler maintenance, whole-house humidifier replacement, and furnace installation. Start the new season off right by scheduling a service with our team.