AC capacitors play a vital role in ensuring the proper operation of air conditioners, and that’s why you should know how to test air conditioner capacitor devices. However, an AC capacitor can get damaged at the time when your HVAC technician is not around. But before you think of replacing the capacitor, you must test it to see if it’s failing.
Testing air conditioner capacitors is quick and easy when you understand the entire procedure. Besides, you will need all the testing tools and equipment to get the job done faster and safely. The good news is that this guide explores everything you need to know about testing AC capacitors, including the signs of a bad AC capacitor.
But before we dive into the facts, let’s look at the role of capacitors in air conditioners.
What is an AC Capacitor, and How Does it Work?
A capacitor is a small cylindrical device that stores energy to energize the AC’s motors. For example, it can send a jolt to start the AC motor or keep it running when it’s time to cool off your home. Note that the capacitor is among the most frequently used and replaced parts in an air conditioner. If it malfunctions, your AC system can fail to work.
An AC capacitor works with the air conditioner’s motors, compressor, and outside fan. It stores electricity and can send it to the AC motors in powerful bursts to rev up the unit when starting the cooling cycle. The capacitor will then reduce its energy output once the AC is running. However, it will still supply a steady power current for the cycle.
AC capacitors get measured in microfarads and voltage. The latter shows the amount of electrical current moving through the capacitor. So, the higher the voltage in a capacitor, the faster an electrical current moves through it. On the other hand, microfarads indicate the amount of electrical current a capacitor can store and are abbreviated as “MFD.”
Pro Tip: Don’t mistake capacitors for batteries; although capacitors look like batteries, they do not hold charge in any significant measure to power things independently. These high-voltage devices are part of the AC’s wiring systems, so it’s not recommended that you attempt to replace them yourself without technical knowledge.
How to Test an Air Conditioner Capacitor
Now that you understand what an AC capacitor looks like and how it works, you can test if your AC capacitor is working as it ought to. Here are the steps to follow.
Step 1: Check Your AC Capacitor Ratings
An AC capacitor has several ratings, but you should only focus on the working voltage and capacitance value. Understanding these ratings can help you determine if your AC capacitor is performing as rated or not.
Capacitor’s Working Voltage
The working voltage indicates the maximum amount of voltage that can pass through an AC capacitor. Many AC capacitors have voltage ratings of 370V and 440V. However, most manufacturers consolidate their stock to 440V only. Besides, it’s always ideal to use higher voltage capacitors to protect them from breaking down faster.
Capacitor’s Capacitance Value
The capacitance value of an AC capacitor gets measured in microfarads. It indicates the maximum amount of energy a capacitor can store, so expect to see capacitance ratings like 50+5 MFD or 50+5 μ on your capacitors. Note that a higher capacitance value means that the AC capacitor can store more electric charges when a voltage is applied.
Step 2: Turn Off the Power Supply to the AC Unit
Turning off the AC’s power supply is the most important before handling your AC capacitor. It reduces the risk of getting electrocuted during the process, so don’t proceed before switching off the AC’s power supply.
You can turn off the power supply to your AC unit at the breaker panel, often mounted outside the house around the outdoor condensing unit. Then, you can double-check to be sure that the power to your AC unit is successfully disconnected using a circuit alert device. Thankfully, there are affordable circuit alert devices on the market.
Step 3: Discharge the AC Capacitor
Ac capacitors are high-voltage devices you must handle carefully during testing. Despite shutting off your AC power supply, the capacitor may still have power stored in them. Touching its two terminals with your hands will discharge the stored energy and result in an electric shock.
The best way to discharge an AC capacitor is by placing a screwdriver across the AC terminals. However, the screwdriver must have an insulated handle to prevent possible shocks. After that, disconnect the wires from the capacitor.
Step 4: Obtain the Capacitor Readings Using a Multimeter
Using a multimeter is essential in testing an air conditioner’s capacitor. To take the readings, place the meter’s leads on the terminals of the discharged AC capacitor. Your reading should fall within six percent of the rating indicated on the capacitor. You should replace the capacitor if the reading is more than six percent lower than the rating.
Signs that Your AC Capacitor is Bad or Failing
Now that you understand how to test a capacitor on an air conditioner, you should know the signs of a failing capacitor. The signs will help you determine that it’s time to test your capacitor. Here are the signs your AC capacitor is failing.
Your energy bills get unreasonably higher. The AC unit produces smoke or a burning smell. You cannot feel cold air in your house despite the AC running. Your AC produces a clicking or humming noise when it’s running. The AC takes longer to begin a cooling cycle, or it won’t start at all. The air conditioner randomly shuts off by itself without you doing anything
So far, you understand how to test air conditioner capacitor devices. But remember to handle your AC capacitor carefully during testing because they store energy. If you discover that the high-voltage device is failing, consider hiring a reputable HVAC contractor to help you replace it. Replacing it by yourself may pose significant risks.
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