What Is an Air Conditioner Capacitor?

Small but mighty, a capacitor is an essential component that plays a huge part in the smooth operation of your air conditioner. A malfunctioning capacitor can lead to warm air blowing from your vents, slow system operation and, in some cases, complete AC failure.

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Scheduling timely air conditioner repairs and regular maintenance can help ensure this tiny powerhouse operates at maximum efficiency when you need it most.

What Is an Air Conditioner Capacitor?

An air conditioner capacitor is an internal component located in the unit's compressor. Its primary function is to ensure the air conditioner maintains a steady voltage as it runs. When you power up your AC, the capacitor creates a jolt of electricity to help get the system going.

The capacitor is located in a central air conditioner unit's outdoor housing. It's contained in a canister that's similar in appearance to a battery. While the capacitor itself looks small, it's actually a high-voltage component that should only be handled by a professional HVAC technician.

What Does an Air Conditioner Capacitor Do?

In a nutshell, the capacitor is connected to the wiring in your outdoor air conditioner, and it provides the power boost your system needs to effectively cool your space. When you start your air conditioner, the capacitor provides the starting jolt of power to the unit's motor.

As your system cycles, the capacitor collects and stores power. It releases continuous jolts of energy during each cooling cycle that are less powerful than the initial starting jolt. Since the capacitor works in conjunction with every component in your air conditioner, system failure can occur if the capacitor malfunctions.

How Does an Air Conditioner Capacitor Work?

Housed in the outdoor condensing unit of central air conditioning systems or heat pumps, the air conditioner capacitor provides power for the air conditioner motor. During the initial startup period, the capacitor works by creating a powerful burst of energy to help prepare the air conditioner for a cooling cycle. As long as your air conditioner is turned on and running, the capacitor continues to provide power bursts with each cooling cycle.

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Signs of a Malfunctioning AC Capacitor

When an AC capacitor malfunctions, it can affect your entire air conditioner. One of the most telltale signs of a failing capacitor is warm air coming from your vents when your thermostat is set to cool. If you smell a strong burning odor coming from your outdoor AC unit, this can be due to an overheating motor triggered by a failed capacitor. Damaged or malfunctioning capacitors can also lead to complete air conditioner failure.

Buzzing sounds can indicate an issue with the capacitor's connection to the air conditioner's fan motor, while slow operation and sudden shut-offs often mean the component is weakening or wearing down. When the capacitor and other internal parts and components begin to fail, they must work harder to effectively cool your space. If your energy bills are unusually high, this can point to a bad capacitor.

Capacitors are high-voltage components that can cause shock and other injuries if handled incorrectly, even when the AC unit is shut off. If your air conditioner exhibits any of the above signs or you suspect an issue with its capacitor or other components, it's always a good idea to schedule a repair service with a licensed HVAC company.