Most electronic appliances you have at home have a capacitor. A capacitor is an electrical machine that holds an electrical charge primarily found in the HVAC system and fan motors. But there are times when your capacitor isn’t working, and the engine starts producing some funny noise. When this happens, you don’t need to dispose of your device but rather check on the capacitor if it’s working and save some money.
Read on and understand how to test an HVAC capacitor using a multimeter
Testing a Capacitor with a Digital Multimeter In 5 Steps
Discharge Your Capacitor
Before you work on any electrical connection, it’s advisable to disconnect it from the power supply. This will make the work environment safe and also prevent unseen dangers.
Step 1: Identify the capacitor’s location on the appliance, which is found next to the motor. Then use a screwdriver to open the machine to reach the capacitor. Ensure you use the insulated needle nose pliers when removing the wires for safety purposes.
When discharging the capacitor, observe the following safety measures;
- Use the insulated screwdriver to prevent shock or any harm when working on electricity. Also, ensure the screwdriver handles are crack-free to avoid electric current traveling through the metal to your hands.
- But don’t forget to put on gloves for additional protection. Avoid oversize gloves as they provide less dexterity while at work.
- Another thing you should be cautious with is the metallic parts of the screwdriver. Please don’t touch it but rather maintain a firm grip on the insulated handle whether you’ve got the gloves on.
Step 2: After taking the precaution measures, put the screwdriver’s shaft on the positive terminal. Lower the screwdriver in a position that its shaft touches the terminal by 2.5 cm from the tip. But ensure the screwdriver isn’t in contact with the terminal on the capacitor.
Step 3: Then use the tip of the screwdriver to touch the negative terminal. But don’t stop the contact with the positive terminal; instead, tilt the screwdriver to contact the negative terminal. Immediately the two terminals connect, you’ll hear a pop sound while the screwdriver will produce some sparks on its tips. Note that this is not a cause for an alarm but instead showing that you’ve discharged the capacitor.
Step 4: It would help if you again connected the terminals to get rid of the remaining charge. Do this by maintaining the screwdriver on both ends of the terminals, then tap the negative side with the tip at least twice.
Step 5: The Next Step Should Be Involving the Multimeter
If you’re using a digital multimeter, work with the capacitance setting to get accurate results.
- Put the red probe on the positive terminal, and the negative terminal has the black probe. Make sure you don’t touch the metallic pins with your hands but rather hold the probe’s base.
- After the two probes connect with the capacitor’s terminals, you’ll see the readings on your multimeter changing. To be safe from residual charge, put on gloves while using the multimeter.
- You shouldn’t remove the probes until the numbers stop changing, which will take a few seconds if your capacitor is in good shape. Note down the capacitance number after you’re done with the measurements to act as a reference. If you notice no change in the numbers, the capacitor is open and ready for replacement.
- The next thing you should do is ensure the reading is equal to the numbers on the capacitor. You’ll see the maximum and minimum capacitance on the sides of the capacitor, and it entails all the information. The accepted capacitance range will depend on the kind of capacitor you’re using. Note that if the capacitor is below or above the range, you need to replace it. Also, if the capacitance number went more than your HVAC multimeter’s limit, it means the capacitor has shorted out and needs a new replacement. For example, if the reading is more than 6% of the rating, it should be replaced.
Using an Analog Multimeter to Test for HVAC Capacitor
if you’re using an analog multimeter to test for capacitor, set it to test for resistance. But ensure you switch off the power supply, discharge the capacitor, and remove the wires on it. Then select the multimeter to the highest resistance setting and place the leads on the capacitor terminals. Note that the resistance reading will start from zero and rise to the maximum. When the unit is bulging or oil is leaking from it, that’s a sign that you need to replace it.
Conclusion
If your HVAC system has a faulty capacitor, it will not have a power supply as this is the powerhouse of the unit. However, you can test the system capacitor using an HVAC multimeter and replace it when need be. Replacing a faulty capacitor isn’t hard as you only need to get the right replacement part with the right voltage rating and microfarad rating. After that, you should disconnect the wires, put the new part and reconnect the wires. Doing this will help you save costs as you’ll not hire a technician to work on the system.
