A capacitor (not a flux capacitor) is one of the essential parts of your AC unit. And when it doesn’t work as it should, your central air conditioning system fails to function correctly.

How do you know that your central air system isn’t working because of problems with your capacitor? We’ll give you some of the signs. But first, let’s discuss the role of the capacitor in your central air conditioner system.

What is a capacitor, and how does it work in central air conditioners?

A capacitor stores up electricity, kind of like a rechargeable battery. It supplies a small burst of energy to a motor when needed.

There are two kinds of capacitors found in a central AC unit: start capacitors and run capacitors.

The start capacitor provides the extra voltage needed to start the compressor or fan motor. A run capacitor provides energy to keep them running. While a start capacitor is only required at the beginning of each cooling cycle, the run capacitor is engaged throughout the entire process. Heat pumps and air conditioners typically use these dual-run capacitor systems.

Why do capacitors fail on cooling systems?

Alas, nothing lasts forever. But one of the reasons capacitors generally fail is that they are sensitive to overheating. This is especially true for commercial units stored on rooftops. However, residential air conditioners can also overheat when running too hard for too long.

Capacitors can also fail as a result of power surges. Of course, lightning strikes can cause a substantial power surge, thus damaging your capacitor. However, smaller power surges caused by fluctuations in the electrical grid can also affect the capacitor over time.

Finally, a capacitor may fail because it loses its ability to store and release energy over time.

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What are the signs that my capacitor is going bad on my central air conditioning system?

Here are some signs that your capacitor is going bad on your cooling system:

  • The air conditioner’s compressor has trouble starting and then shuts off quickly.
  • The air conditioner will repeatedly stop and start.
  • You hear humming or clicking noises coming from your HVAC unit.
  • Your air conditioner cannot provide enough cool air even when outdoor temperatures are moderate.
  • Your energy bills are higher than usual.

How can I prolong the capacitor’s life on my new central AC unit?

Here are four tips for keeping cool air blowing through your house:

  1. Install an HVAC surge protector to reduce the effect of power surges on your system.
  2. Turn the temperature on your air conditioner UP during the hottest days of summer to keep your system from overheating.
  3. Improve the energy efficiency of your home (cover east and west-facing windows, avoid using your clothes dryer and oven during the heat of the day, etc.).
  4. Have a professional maintain your system.

Can I replace my own capacitor?

You’ll see many guides and videos online detailing how to replace your own capacitor. However, while we applaud do-it-yourselfers for many home projects, we do NOT RECOMMEND that you replace a capacitor on your own.

The capacitors on AC units carry a high charge. So if you choose to work on your own system, never touch the terminals on the end of a capacitor. Also, don’t use any tools with metal handles to discharge the load on a capacitor. And (of course) make sure your AC unit is disconnected from power before touching the system.

Key Points About the Capacitor in Your AC Unit

  • A capacitor is an essential electrical component of your air conditioning system.
  • You may have more than one capacitor in your AC unit.
  • One of the most common symptoms that your capacitor may not be functioning properly is that it turns off and on repeatedly.
  • Install an HVAC surge protector, turn up the thermostat on the hottest days of the year, and make your home energy efficient to prolong the life of your air conditioning system.
  • Professionals should maintain and service your HVAC system.

Contact HOP Energy for Air Conditioner Service or Maintenance

Do you have questions about how your air conditioner? Contact HOP Energy’s HVAC affiliates to schedule a visit from a certified, professionally-trained HVAC technician.

We will replace the capacitor on your unit if that is what is causing the problem. If it’s time for a new air conditioner, we will discuss your options, including a high-efficiency heat pump, split system air conditioners, and air quality systems.

Contact us today