“Test Your AC Capacitor with Multimeter: Easy Steps!”

As the summer heat starts rolling in, people tend to rely heavily on their air conditioning systems to keep their homes cool and comfortable. However, it’s essential to understand that air conditioning systems are made up of several working components, such as compressors, fans, and capacitors. Among these components, the AC capacitor is one that is susceptible to failure or malfunctioning with consistent usage. And that can lead to significant problems such as the AC system failing to start or blowing warm air instead of cold air. Hence, it’s crucial to check your AC capacitor regularly to avoid frustrating situations during the hottest months of the year.

In this article, we will guide you through the step-by-step process of checking your AC capacitor with a multimeter. We will also provide some background information on AC capacitors and offer tips on how to identify a faulty capacitor, how to discharge it safely, and how to replace it with a new one. By following this comprehensive guide, you can quickly and efficiently check your AC capacitor yourself and avoid costly repairs.

Why Checking Your AC Capacitor Regularly is Important

Before we dive into the process of checking your AC capacitor, let’s discuss why it’s important to do so regularly. As mentioned earlier, the AC capacitor is responsible for storing electrical energy and helping in the startup process of the AC system. Start capacitors provide an extra boost of power to get the compressor running, while run capacitors provide a steady stream of power to keep it running.

Over time, capacitors can become weak and fail, especially if they are exposed to high temperatures and prolonged usage. A faulty capacitor can cause your AC system to malfunction, leading to significant problems such as no cool air, poor airflow, or a complete system shutdown. And that can be frustrating, especially during the hottest months of the year when you rely on your AC system the most.

By checking your AC capacitor regularly, you can identify any potential problems before they escalate into costly repairs. A simple multimeter test can help you determine whether your capacitor is functioning correctly or not. And if you find that it’s faulty, you can replace it with a new one.

Step-by-Step Guide to Checking Your AC Capacitor with a Multimeter

Now that you understand the importance of checking your AC capacitor regularly let’s discuss how you can do it yourself with a multimeter. Here is a step-by-step guide to help you through the process:

1. Turn off the AC power supply

The first step in checking your AC capacitor is to ensure that the thermal disconnect switch is off and shut off the AC power from the main breaker. This step is crucial to avoid any potential hazards or injury during the testing process.

2. Locate the AC capacitor

The next step is to locate the AC capacitor. The AC capacitor is typically located near the AC compressor and can be identified as a cylindrical object with wires attached. Once you’ve found the capacitor, examine it for any physical damage, such as swelling or bursting, and signs of leakage or damage to the wires.

3. Inspect the Capacitor

Inspecting the capacitor is an essential step in determining whether it’s faulty or not. A faulty capacitor can have a burnt smell, so be sure to check for anything unusual. If you notice any physical damage or leakage, it’s likely that the capacitor is faulty and needs replacement.

4. Discharge the Capacitor

Capacitors can store electrical energy, and if you do not discharge them correctly, they can shock you. To discharge the capacitor, use a screwdriver with an insulated handle to short out the terminals. Once shorted, the capacitor should no longer have any voltage. This step is crucial to avoid any potential hazards.

5. Set the multimeter

The next step is to set your multimeter to read capacitance within the range of the capacitor. You can find the capacitance rating on the capacitor’s label. Alternatively, you can use the multimeter’s auto-ranging feature to set to the correct range automatically.

6. Test the Capacitor

Once you’ve set the multimeter, it’s time to test the capacitor. Touch the multimeter probes to the corresponding capacitor terminals, positive to positive, and negative to negative. The reading displayed on the multimeter should be within the capacitor’s tolerance range. If the reading is significantly below or above the rating, the capacitor is faulty.

7. Replace the Capacitor

If the capacitor is faulty, it needs to be replaced. Capacitors are relatively inexpensive and can be easily found at an HVAC store or online. Ensure that you purchase a capacitor with the same capacitance rating as the old one.


Checking the AC capacitor with a multimeter is a straightforward process that anyone can do. It’s essential to check your capacitor regularly, as it can save you from frustrating AC malfunctions during the hot summer months. By following this step-by-step guide, you can quickly and efficiently check your AC capacitor yourself. Remember to take precautions and discharge the capacitor before testing to avoid any potential hazards or injury. With regular maintenance, you can keep your AC system running smoothly and avoid costly repairs in the long run.

In conclusion, checking your AC capacitor regularly is a critical aspect of maintaining your AC system’s efficiency and functionality. By following our step-by-step guide, you can quickly and accurately test your capacitor’s performance with a multimeter, detect any issues, and replace it with a new one. Don’t neglect your AC maintenance and keep your home cool and comfortable during the hottest months of the year.

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