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AC Parts FAQ: What Are Capacitors?

For a system that plays such an important part in your life, chances are that you don’t really know your air conditioning system all that well. Sure, you adjust your thermostat with some regularity, and you see your outdoor unit sitting out there day and day out. For all of the parts that you do see and interact with, though, there are countless others that you’ll never encounter directly. The capacitors in your air conditioner, for instance, are hidden away in the outdoor unit. While you may not see them, though, the importance of their function is immense.

What Is a Capacitor?

Simply put, a capacitor is an electrical component that stores an electric charge. There are two basic types that may be found in an air conditioning system. These are the run capacitor and the start capacitor. In some systems, you may have dual capacitors, commonly found in heat pumps or larger air conditioners.

The Start Capacitor

The air conditioner serving your home may be very efficient, but it is going to require the most energy as it starts up. In order to ensure that your system starts up reliably each and every time, a start capacitor is used. This capacitor basically gives your system a bit of a power boost as it is starting up, providing extra torque to ensure that everything gets going properly. Otherwise, your motor would likely just sit there humming.

The Run Capacitor

A run capacitor, on the other hand, does not jolt a system into action. Instead, this capacitor serves to keep the system up and running once it is operational. It will regulate the current, maintaining the charge and ensuring a smooth, reliable performance from your AC. If your system keeps short cycling, it may be due to a failing run capacitor.


If you need AC services in Holladay, UT, schedule them with Design Comfort.

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