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What Is an AC Capacitor?

What Is An Air Conditioner Capacitor?

A blown capacitor is a common air conditioner breakdown, but what do they even do?

Battery capacitor image

Power Storage

If you happen to know anything about electronic circuits, you’ll know that an air conditioner capacitor is essentially one big battery.

The capacitor stores an electric charge and then releases that charge as needed.

The capacitor itself is made up of two metal plates and “dielectric material” in between them. When a voltage is created over the two metal plates, an electric field is created and stored inside. The energy stored is measured in “micro-farads”. The capacitor also works with the air conditioner’s contactor to supply power.

Dual Run Capacitor Vs Start Run

There are two popular types of capacitors available: dual run and start run. Below are some differences between them.

    Dual Run Capacitor

  • Uses charge stored within to boost the current (power) to the compressor and motors.
  • Used to maintain a charge.
  • Measure at approximately 7 to 9 micro farads.
  • The capacitor must be matched to your air conditioner or it will not work properly.
  • A dead capacitor can be the cause of an air conditioner not turning on.

   Start Run Capacitor

  • Contains a higher storage than a run capacitor.
  • Usually measures between 70-120 micro farads
  • Provides an extra push to get fan started.

Why Do Capacitors Fail?

Air conditioner capacitors can fail for a number of different electrical reasons but mostly it’s just due to age.

Most capacitors are capable of giving you years worth of service assuming you are having annual maintenance completed on your air conditioner. Dirt and dust are the number one causes of HVAC breakdowns.

Need Some Help?

Is your air conditioner not coming on? A blown ac capacitor could be the cause. Give us a call today at 614-475-1800 for 100% Relief!