How to Check the Capacitor of a Home Air Conditioner?

Home and Garden

A capacitor is an essential component of a home air conditioner that helps in starting and running the compressor motor. Over time, capacitors can wear out or fail, resulting in issues with the cooling system. To ensure your air conditioner functions properly, it’s important to regularly check the capacitor. In this article, we will provide a step-by-step guide on how to check the capacitor of a home air conditioner and identify any potential problems.

Understanding the Role of a Capacitor

Before we dive into the process of checking the capacitor, let’s first understand its role in an air conditioner. The capacitor stores electrical energy, which is then used to provide a boost of power to start the compressor motor. It also helps the motor run smoothly and maintain a consistent flow of electricity. A malfunctioning capacitor can lead to issues such as the motor not starting, poor cooling performance, or frequent system breakdowns.

Tools Required

Before you begin checking the capacitor, gather the following tools:

  • Multimeter
  • Screwdriver
  • Insulated gloves
  • Insulated pliers

How to tell if a AC Capacitor is Bad! Visual and Multimeter Testing!

Step 1: Safety Precautions

Prior to starting any maintenance or inspection work on your air conditioner, it’s crucial to take safety precautions to avoid any accidents or injuries. Make sure to turn off the power supply to the air conditioner and disconnect it from the electrical outlet. Wearing insulated gloves and using insulated pliers will provide an extra layer of protection.

Step 2: Locating the Capacitor

Next, you need to locate the capacitor in your air conditioner. Typically, the capacitor can be found in the outdoor unit, near the compressor. It is a small cylindrical or oval-shaped component with wires attached to it.

Step 3: Discharging the Capacitor

Before testing the capacitor, it’s important to discharge any stored electrical energy to prevent electric shocks. Use an insulated screwdriver to short the terminals of the capacitor. Ensure that the screwdriver has an insulated handle to avoid any contact with the metal part.

Step 4: Testing the Capacitor

Now that the capacitor is discharged, you can proceed to test it using a multimeter. Set the multimeter to the capacitance (CAP) mode and touch the leads of the multimeter to the corresponding terminals of the capacitor. The multimeter will display the capacitance value.

If the displayed capacitance value is within the specified range mentioned on the capacitor, it indicates that the capacitor is functioning properly. However, if the displayed capacitance value is significantly lower or higher than the specified range, it indicates a faulty capacitor that needs to be replaced.

Step 5: Checking for Physical Damage

In addition to testing the capacitance, it’s important to visually inspect the capacitor for any signs of physical damage. Look for bulges, leaks, or cracks on the body of the capacitor. Such damage is an indication of a failed capacitor and it should be replaced immediately.

Step 6: Replacing the Capacitor

If the capacitor fails the capacitance test or shows signs of physical damage, it is necessary to replace it. To replace the capacitor, follow these steps:

  1. Make note of the rating and specifications of the faulty capacitor.
  2. Purchase a new capacitor with the same rating and specifications.
  3. Disconnect the wires connected to the faulty capacitor using insulated pliers.
  4. Remove the faulty capacitor by unscrewing it from its mounting bracket.
  5. Install the new capacitor in the same position and secure it with screws.
  6. Reconnect the wires to the corresponding terminals of the new capacitor.

Step 7: Final Testing

After replacing the capacitor, it’s important to perform a final test to ensure proper functioning of the air conditioner. Reconnect the power supply and turn on the air conditioner. Check if the compressor motor starts smoothly and the cooling performance is restored. If everything operates as expected, your air conditioner is now ready to provide optimal cooling.


Regularly checking the capacitor of your home air conditioner is crucial for maintaining its efficiency and avoiding potential breakdowns. By following the step-by-step guide provided in this article, you can easily check the capacitor and identify any issues that may require replacement. Remember to prioritize safety precautions and seek professional assistance if you’re unsure about any aspect of the process. A well-maintained capacitor will ensure your air conditioner operates smoothly and provides cool comfort during hot summer days.

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