How to Test Capacitor with Multimeter? (Helpful Examples)

The importance of capacitors in our daily household appliances is too significant to ignore. The main feature of the capacitor is storing the electric charge, and it plays a crucial role in the charging and discharging of a device.

It plays a vital role in jump-starting the devices by releasing a charge into the circuit with the help of a plate that holds the current. The most usual factors involved in damaging a capacitor include high voltage, heat, moisture, chemical contamination, and moisture.

One of the main reasons for electrical and electronic breakdowns is weak capacitors. They must be tested in time to avoid any electric or electronic breakdown in the future. A multimeter is a troubleshooting device that is used to identify weak capacitors.

Method 1: Using A Multimeter With Capacitance Setting

A digital multimeter with capacitance settings is your perfect choice to carry out this test as it gives the quickest and the most precise results.

The effect of a capacitor is known as “Capacitance “, and the unit of measuring Capacitance is “Farads”. Therefore, a multimeter can measure capacitances as lower as nano-Farads or as higher as micro-Farads.

  • Disconnect the Capacitor: To test your capacitor using a multimeter, the first thing you need to do is disconnect the capacitor from the circuit board.
  • Connect with Resistor: The next step is fully to discharge the capacitor by connecting it to a LED or a powerful resistor.
  • Voltage Rating: Next, the capacitance and voltage rating written on the back of the capacitor should be noted down.
  • Connect the Knob: Use the knob on your digital multimeter to set it to capacitance settings and then attach the probes to the terminals of the capacitor. On an electrolytic capacitor, connect the negative terminal with the black probe and the positive terminal with red to get an accurate reading. The terminals can be connected either way for non-electrolytic capacitors.
  • Check the Reading: Once done with all these steps correctly, check the readings on the multimeter screen and compare them with the given ratings.

A minor difference in the readings and the given rating is acceptable as electrolytic capacitors tend to dry up, but a significant difference should indicate that the capacitor is defective and the potential root cause of your troubling device.

Method 2: Using A Multimeter Without Capacitance Setting

Some multimeters might not have capacitance settings, but they can still be used to test your capacitors.

  • Discharge the Capacitor: Discharging the capacitor is the first step in this type of multimeter too.
  • Connect to ohms: Unlike the previous method, this time the multimeter should be set to ohms to measure resistance and the setting should be adjusted to measure for a high range.
  • Connect with Electrolytic: Connect the positive terminal to the red probe and the negative terminal to the black probe for the electrolytic capacitor. You can connect the probes either way if you have a non-electrolytic capacitor.
  • Check the Reading: Quickly note down the reading of the resistance displayed on the screen quickly before it changes to the resistance of an open circuit which is infinity.
  • Disconnect from Capacitor: Finally, disconnect the probes from the capacitors and repeat the process many times. If each test shows a different reading of the resistance, it should be sufficient to prove that the capacitor is working properly, but if it displays the same results every time, your capacitor is damaged.

How to Test Capacitor with Multimeter on Central Air Units?

Central air or HVAC units mainly use two types of capacitors, namely “run capacitors” and “start capacitors”.

Run Capacitors: The “run capacitors” are used in fan motors and compressors

Start Capacitors: The “start capacitors” are used in Air Conditioners and heat pumps.

To test these types of capacitors, the power supply should be turned off and the terminals should be disconnected with the help of a screwdriver.

After that, the wires on the capacitors should be disconnected and the probes of the multimeter should be connected to get a reading on the multimeter screen.

How to Test Microwave Capacitor with Multimeter?

Microwaves are also powered by capacitors. If you are going to test your microwave capacitor, firstly, you need to disconnect the power. Then, remove the cover of your microwave and note the wire connected to the terminals of the capacitor.

Check for a bleeder resistor in your microwave; if installed, you need to remove it before testing. Now, place each of the multimeter’s probes to each terminal of the capacitor and note the reading and then reverse the probes so that they are each touching the other terminal. Do the same process repeatedly, and note the reading.

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