Replacing Your A/C Capacitor

Replacing your A/C capacitor is a common repair you may experience over the course of your A/C’s lifespan. Since this repair does involve electrical components, we recommend calling an expert at Chas Roberts to do the replacement. Learn more about the steps to replace your A/C capacitor.

What is the function of the capacitor? 

The capacitor acts as a battery, storing electricity to start the system’s multiple motors, including the compressor, blower motor, and exterior fan.

Depending on your unit type, some air conditioner models use a single capacitor to power all three motors, while others may use separate motors.

Issues to look out for when your capacitor is failing 

When your capacitor begins to fail, you may notice a few symptoms.

  • A clicking noise within the cabinet. This issue indicates immediate replacement because the unit is hard starting and can damage the compressor.
  • A buzzing or humming noise. The humming noise results because the air conditioner motor attempts to turn on but cannot, meaning your capacitor has completely died
  • Starting but quickly shutting off. When a compressor begins to deteriorate, the air conditioner strains to start but then shuts off immediately, indicating a weakened compressor

Replacing your A/C capacitor 

It’s not difficult to replace a capacitor, and you probably already have most of the equipment and materials needed to do the replacement on your own. However, because it deals with electrical currents, we recommend calling in a technician to do the repair. Capacitors are made to store electrical current, and there is a risk of shock if you touch or attempt to disconnect it without releasing any stored electricity. To discharge, run a screwdriver across the two metal contacts. Failure to do this correctly increases the possibility of a shock. If you do decide to move forward with replacement, use the following steps to ensure it is done correctly.

Step 1: Make sure you turn your power off before starting any maintenance 

If you look around your A/C unit, you should see the circuit breaker box nearby. If there is not a box near the unit, it may be located in inside your circuit breaker panel. In addition to turning off your power, make sure you also turn off your home’s thermostat. This will stop the capacitor from receiving brief bursts of low-voltage current while you are working.

Step 2: Take off your A/C’s access panel 

With your tools, pry up the access panel of your air conditioner and remove the screws. This panel is often found on the upper corner of the air conditioner.

Step 3: Buying a new capacitor 

Locate the existing part inside your unit to find the correct capacitor you need. In most cases, there will be an informational sticker. If you do not see a sticker on your old capacitor, it is best to take the part with you to your local maintenance store along with the name/model of your A/C unit.

Step 4: Remove the existing capacitor 

Reminder: The capacitor might still be storing electricity even if the power is off, and this current needs to be drained before you can operate it securely.

To do this, you must discharge the current from the capacitor. Hold the blade of a screwdriver that is insulated across the metal terminals that extend out from the capacitor. This effectively discharges any electricity that is left.

Before un-attaching the wire from the capacitor, make sure you note where the wires go. That way, when you install the new capacitor, you are clear about where the wires attach. Where each wire goes should be marked on the top of the old capacitor.

Step 5: It’s time to install your new capacitor!

Place the capacitor in the exact location as the old one. Ensure the connections are correct. After installing the new capacitor, you can turn back on your power and thermostat to see if everything is working correctly. If you run into issues, you may have mixed up the wires attached to the capacitor, which should be double-checked.


Replacing an A/C capacitor can be done quickly and safely by a Chas Roberts expert technician. We are always available for repairs, big or small.

Chas Roberts is the oldest and largest residential HVAC company in Arizona and has been family-owned and operated for over 75 years. Contact us for reliable, quality service.