Everything you need to know about capacitance and how to test it

Capacitance might sound like a super technical term, but it’s actually pretty important when it comes to understanding how your appliances work. Whether you’re fixing something that’s acting up or just want to get a better grasp on electrical systems, knowing how to test capacitance can really come in handy. With a little knowledge and the right tools, you’ll be able to troubleshoot appliance issues and get things running smoothly again like a Pro!

The information in this article may not apply to your specific appliance model. For the most accurate guidance, it’s best to check your manufacturer’s documentation or reach out to us if you’ve got any questions.

What is capacitance?

Capacitance is pretty simple once you break it down. In everyday appliances, capacitors store and release electrical energy to help things like motors run smoothly. You’ll find capacitors in all kinds of appliances with a motor. They help start and run motors efficiently, which is why when something goes wrong with a capacitor, it can affect your appliance’s performance. Even though we don’t usually think about it, understanding capacitance can save you a lot of headaches when troubleshooting appliance issues.

Signs that a capacitor might be failing

Here are some signs to look out for that may indicate a failing capacitor:

1. Appliance not starting or running intermittently. If your appliance struggles to start or only works for a short time before shutting down, it could be due to a faulty capacitor. When capacitors lose their charge, the motor may not receive the power it needs to run properly.
2. Unusual noises, buzzing or humming sounds. This could be a sign that the capacitor is unable to discharge properly or is experiencing strain.
3. Overheating. If you notice that the appliance is getting unusually hot, it could be a sign that the capacitor is no longer functioning properly or is causing other parts to work harder than they should.
4. A burning smell or visible damage. If you see visible signs of damage, like cracking or bulging on the capacitor, it’s time to replace it. A damaged capacitor can also sometimes leak fluid or show burn marks.
5. Frequent tripping of the circuit breaker. The electrical load imbalance caused by a malfunctioning capacitor can overload the system.

If you notice any of these signs, it’s important to test the capacitor using a multimeter to check for continuity or to confirm that the capacitance is within the specified range. Replacing the faulty capacitor promptly will help prevent further damage to your appliance and keep it running efficiently. Remember, always follow safety precautions and refer to your appliance’s manual for specific instructions. 

Steps for testing capacitance with a multimeter

1. Turn off the appliance and unplug it. Always start by disconnecting the appliance from the power source to ensure your safety.
2. Before testing, you need to discharge the capacitor. You can do this by shorting the two terminals of the capacitor with an insulated screwdriver. This will help avoid any electrical shock.
3. Set your multimeter to the capacitance mode. Look for the “Capacitance” symbol (usually a “C” or two parallel lines) on your multimeter dial. If you’re unsure, check the user manual for guidance.
4. Attach the multimeter probes to the capacitor terminals. Place the black probe on the negative terminal and the red probe on the positive terminal of the capacitor.
5. Read the measurement. Your multimeter will display the capacitance reading. Compare it to the value written on the capacitor (in microfarads). If the reading is significantly lower than the value indicated on the capacitor, or if the multimeter shows “OL” (open loop), the capacitor is likely faulty and needs to be replaced.

How to replace a faulty capacitor

If your multimeter test shows that the capacitor is faulty, it’s time to replace it. Here’s a simple step-by-step guide to help you out:

1. Turn off the appliance and unplug it. Make sure the appliance is completely disconnected from the power source.
2. Discharge the old capacitor to ensure no stored energy can harm you during removal. Use an insulated screwdriver to short the terminals and release any stored voltage.
3. Depending on the appliance, the capacitor may be in a motor housing or a control panel. Check the user manual for the exact location, or search for a diagram on the unit if available.
4. Make note of how the capacitor is wired before disconnecting anything. You might want to take a photo to refer to later.
5. Use a screwdriver to remove any screws or clips holding the capacitor in place.
6. Disconnect the wires from the terminals of the capacitor. If the connections are tight, gently wiggle the wire to disconnect it.
7. Take your new capacitor (make sure it matches the specifications of the old one) and place it in the same position as the old one.
8. Reconnect the wires to the new capacitor, following the photo or diagram you took earlier. Make sure the connections are tight.
9. Secure the capacitor using the screws or clips.
10. Before reassembling everything, plug the appliance back in (but don’t fully reassemble yet). Check to make sure the appliance powers up and operates normally.
11. Once you’ve confirmed that everything is working properly, put the appliance back together by replacing any covers or panels you removed.
12. Reconnect the appliance to the power supply and switch it on. It should be up and running smoothly with the new capacitor in place!

Additional information

Thanks for reading! If you still need some replacement parts, grab your model number and head over to AppliancePartsPros.com. We offer over two million parts and most orders arrive in two business days. If you need some help with finding the right part or placing an order, you can contact our team at 1 (877) 477-7278.

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