How to Test AC Capacitor: A Comprehensive Guide

How to test AC capacitor? We all know that AC capacitors play a crucial role in the functioning of our air conditioning systems. Over time, these capacitors can weaken or fail. This results in inefficient cooling or even total breakdowns. It’s essential to know how to test your AC capacitor to ensure optimal performance and avoid unnecessary expenses.

In this comprehensive guide, we will walk you through the step-by-step process of testing an AC capacitor. But first, let’s understand what a capacitor is and why it’s vital for your AC system.

What is an AC Capacitor?

An AC capacitor is an electrical component that stores and releases energy. This helps start your air conditioning unit’s compressor and fan motors. The capacitor creates an electric field between two conductive plates, allowing it to store electrical charge.

Why Test Your AC Capacitor?

Testing your AC capacitor is important for several reasons:

• Preventing Breakdowns
  Regularly testing your capacitor can identify any weaknesses before they cause complete breakdowns. Minimizing the risk of expensive repairs or replacements.
• Increasing Efficiency
  Weakened capacitors can reduce the efficiency of your AC system, leading to higher energy bills. Testing lets you detect and address any issues. This ensures optimal performance and energy savings.
• Extending Lifespan
  Timely testing and maintenance can extend the lifespan of your AC capacitor, saving you money in the long run.

(Related: AC Line Frozen? Here’s Everything You Need To Know)

How to Test AC Capacitor

Step 1: Safety First

Before starting any tests, it’s crucial to focus on safety. Turn off the power supply to your AC unit from the main circuit breaker. Ensure that all electrical connections are secure. Working with electrical components can be dangerous, so take necessary precautions.

Step 2: Discharge the Capacitor

Capacitors can store electrical charge even when the power is off, posing a risk of shock. Make sure to discharge the capacitor before testing it to avoid any accidents. Use an insulated screwdriver to bridge the terminals of the capacitor. This safely discharges the stored charge.

Step 3: How to Test an AC Capacitor with a Multimeter

To test an AC capacitor, you’ll need a multimeter – a versatile tool for measuring electrical properties. Set your digital multimeter to the resistance (ohms) setting before proceeding.

• Identify the terminals of the capacitor – typically labeled “C” or “+” for the common terminal and “FAN” or “HERM” for the fan or hermetic terminal, respectively.
• Attach the multimeter’s probes to the corresponding terminals of the capacitor.
• Read the resistance value on the multimeter display. A functioning capacitor should have a low resistance reading that gradually increases and settles.
• If the resistance reading remains high or infinite, it indicates a faulty capacitor that needs replacement.

Step 4: Dual Capacitors Testing

If your AC unit has a dual capacitor (combining start and run functions), you can follow these extra steps:

• Discharge the capacitor, as mentioned earlier.
• Set your multimeter to the capacitance (farads) setting.
• Connect the multimeter’s probes to the common terminal (“C”) and the fan (“FAN”) or compressor (“HERM”) terminal.
• Note the capacitance value displayed on the multimeter. Compare it to the manufacturer’s specifications. If the reading deviates significantly, it shows a faulty capacitor.

Step 5: Assessing Physical Condition

Lastly, visually inspect the capacitor for any signs of physical damage, such as bulging or leaking. Damaged capacitors often show a failure or impending failure.