How To Discharge Ac Run Capacitor

5 min read Jun 26, 2024
How To Discharge Ac Run Capacitor

How to Discharge AC Run Capacitor: A Step-by-Step Guide


An AC run capacitor is an essential component in air conditioning and refrigeration systems. It helps to improve the efficiency and performance of the compressor motor. However, when servicing or replacing the capacitor, it's crucial to discharge it safely to avoid electrical shock or injury. In this article, we'll provide a step-by-step guide on how to discharge an AC run capacitor.


Before you start, make sure to take the following precautions:

Turn off the power

Switch off the main power supply to the AC unit or system. Verify that the power is off using a voltage tester or multimeter.

Wear protective gear

Wear rubber-insulated gloves, safety glasses, and a non-conductive apron to protect yourself from electrical shock.

Ensure the capacitor is not under pressure

Check if the capacitor is not under pressure or stress, which can cause it to short circuit or explode when discharged.

Discharging the Capacitor

Short the terminals

Use a discharge tool or a shorting wire (a wire with a switch or a fuse) to short the capacitor terminals. This will allow the stored energy to be safely discharged.

Note: Never use a screwdriver or any metal object to short the terminals, as it can cause a spark and lead to electrical shock.

Monitor the voltage

Use a multimeter to monitor the voltage across the capacitor terminals. The voltage should gradually decrease as the capacitor discharges.

Wait for the voltage to drop

Wait until the voltage drops to a safe level, typically around 0 volts or a very low voltage (less than 1 volt).

Verify the capacitor is discharged

Double-check that the capacitor is fully discharged by measuring the voltage again. If the voltage remains low, you can proceed with the repair or replacement process.

Additional Tips

Use a capacitor discharge tool

Consider investing in a capacitor discharge tool, which is specifically designed for this purpose. These tools can make the discharging process safer and more efficient.

Be cautious of expired capacitors

Old or expired capacitors can be more prone to electrical shock or injury. Exercise extra caution when working with them, and consider replacing them with new ones if possible.

Follow manufacturer guidelines

Always refer to the manufacturer's instructions and guidelines for discharging and handling capacitors specific to your AC system.


Discharging an AC run capacitor is a critical step in ensuring your safety while servicing or replacing the component. By following the steps outlined in this guide and taking necessary precautions, you can safely discharge the capacitor and avoid electrical shock or injury. Remember to always follow manufacturer guidelines and take necessary safety measures to protect yourself and others.