How To Test A/C Capacitor With Multimeter

When it comes to troubleshooting your air conditioning unit, one of the most common components that may cause an issue is the capacitor. In order to determine whether or not your capacitor is faulty, you’ll need to test it with a multimeter. In this article, we’ll go over the steps to properly test your A/C capacitor with a multimeter.

What is a Capacitor?

Before we dive into the testing process, let’s first discuss what a capacitor is and what it does. A capacitor is an electrical component that stores energy and releases it when needed. In an air conditioning unit, capacitors are used to start the compressor and the fan motors.

What are the Signs of a Faulty Capacitor?

There are a few signs that may indicate a faulty capacitor. These include: – The air conditioning unit won’t turn on – The air conditioning unit is making a humming sound but not starting – The air conditioning unit is turning on and off frequently – The air conditioning unit is running but not cooling the room If you’re experiencing any of these issues, it’s worth testing your capacitor to see if it’s the cause.

Testing the Capacitor

Now that we’ve covered the basics, let’s get into testing the capacitor. Here are the steps: 1. Turn off the power to your air conditioning unit by switching off the circuit breaker. 2. Locate the capacitor. It’s usually a cylindrical shape and can be found near the compressor and fan. 3. Discharge the capacitor by using an insulated screwdriver to short the terminals. 4. Set your multimeter to the capacitance setting. 5. Touch the multimeter leads to the capacitor terminals. The reading should be within 10% of the capacitance rating on the capacitor. 6. If the reading is significantly lower or higher than the rating, the capacitor may be faulty and should be replaced.


Q: Can I test the capacitor while it’s still in the air conditioning unit?

A: Yes, you can test the capacitor while it’s still in the unit. Just make sure to turn off the power and discharge the capacitor before testing.

Q: What if the multimeter reading is zero?

A: If the multimeter reading is zero, it’s likely that the capacitor has failed and needs to be replaced.

Q: Can I replace the capacitor myself?

A: Yes, you can replace the capacitor yourself if you’re comfortable working with electrical components. However, if you’re unsure, it’s best to call in a professional.


Testing your air conditioning unit’s capacitor is a simple process that can save you time and money in the long run. By following the steps outlined in this article and checking for the signs of a faulty capacitor, you can ensure that your unit is running smoothly and efficiently.