How to Replace an AC Capacitor

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Updated September 10, 2022

As the summer heat rolls in, it’s super important to have the best air conditioner possible if you want to stay cool. If your unit isn’t cooling as it should, one of the main things to do is test the AC capacitor to make sure it’s in good condition. However, sometimes, they break altogether. So, if this has happened to you, read on. We’ll show you how to replace a capacitor on an air conditioner.


  • An AC capacitor is what provides the initial burst of energy that powers a central AC unit.
  • When purchasing a new capacitor, make sure that it shares the same specs as the one you are replacing.
  • Rewiring a capacitor is a simple task and can be accomplished with a screwdriver and basic electrical knowledge.

How Do You Replace the Capacitor on Air Conditioner?

Before getting started, it can be good to know what a capacitor does concerning the air conditioner motor. It might also be a good idea to read up on how to fix an air conditioner compressor.

Because the capacitor provides the initial surge of energy that powers the air conditioning unit, you’ll need basic electrical knowledge and some tools to replace it. Also, once you’ve completed the task, you’ll need to reset the air conditioner. 

Insider Tip

The labels on the capacitor should have three letters: F, C, and H. The “F” is for the fan, the “C” is for common, and the “H” is for herm (which is the one for the compressor).

And for more of our guides on air conditioner repair, you can check out our article on how to fix an air conditioner compressor.


Turn the power off, first at the thermostat and then at your AC’s electrical disconnect box.


On the outdoor part of the AC, unscrew the unit’s access panel.


Check what type of capacitor you have, and then buy a new one with the same voltage, capacitance, and tolerance.


Using an insulated screwdriver, hold the metal part of the two terminals of the old capacitor. This step is called “discharging.” Discharging removes any excess charge that might be stored in the old capacitor.


Unscrew the harnesses of the old wires and make sure to label each one as you detach. There should be three wires: fan, common, and compressor. Sometimes the capacitor will have labels to indicate where each wire should go.


Install the new capacitor. First, put the capacitor in the same spot as the previous one. Then, place each wire into the capacitor terminals. If any of the wire straps or harnesses are old or corroded, buy new ones and replace them.


Turn on the power outside and inside at the thermostat. If everything seems to be working correctly, replace the access panel.


Failing to discharge the capacitor before removing it can result in electric shock.


How long do AC Capacitors last?

The average AC capacitor is said to have about ten years of life.

How do I know if I have bad capacitors?

Some common symptoms of a broken capacitor are if your AC takes a long time to start, it’s making a strange humming sound, or your energy bills are oddly high.

What Is a Capacitor Rating?

The capacitor voltage rating signifies the maximum voltage it can handle and still work safely.

STAT: It’s said that 80% of all central AC issues derive from electrical malfunctions. (source)

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