As a homeowner, it’s a good idea to spend some time learning about the various systems throughout your home and their components. Your AC system is a somewhat complex system that relies on various parts to function correctly. When something goes wrong with it, the problem may just be the internal capacitor.

What Is an AC Capacitor?

An AC capacitor is a cylindrical metal container that is typically located within your outdoor compressor unit. This capacitor works much like a battery. When your air conditioner needs to start running, its capacitor helps to supplement your home’s electrical system to adequately start your entire air conditioning system. When your air conditioner is running, it collects and stores energy.

Diagnosing a Faulty AC Capacitor

The typical capacitor can last up to 20 years. However, just like other internal components of your home’s air conditioning system, it can go bad at one point or another. Since the capacitor is responsible for powering various components of your air conditioning system, there can be a variety of symptoms that you may experience when it goes bad.

The most common symptoms associated with a faulty AC capacitor include:

  • Burning smell from outdoor unit
  • Humming noise
  • Shutting off randomly
  • Taking a while to start
  • Not creating cool air

As soon as you notice any of these issues, it’s best to replace the capacitor before it causes more damage to the internal components of your home’s air conditioning system.

Why Does an AC Capacitor Fail?

While AC capacitors do last a long time, they can fail due to a number of reasons. The most common are associated with power surges, lightning strikes, short circuits, and overheating of the system’s circuitry. Even very high outdoor temperatures can mess with your capacitor and cause it to fail prematurely.

Examining Your AC Capacitor

When you believe that your AC capacitor has failed, it’s a good idea to give it a physical examination. In some cases, you can verify its failure by its exterior look. For example, it may have bulging, cracking, or a liquid oozing out of it. All of these problems indicate a malfunctioning capacitor that needs to be replaced.

If you don’t immediately notice any defects in the cylindrical container of the capacitor, you can test it with a multimeter. This helps to verify that the capacitor is indeed the issue. You’ll want to start by turning off the power to your entire air conditioning system.

Next, use a screwdriver to touch both of the capacitor terminals at the same time. You’ll want to use a screwdriver with an insulated handle and touch the HERM and FAN terminals. This works to discharge any energy left in the capacitor before you touch it.

Testing Your AC Capacitor

You’ll want to turn your multimeter to read Ohms, which looks like an omega symbol. Hold one of your probes on the Common terminal and one on the Fan terminal. On a well-functioning capacitor, the reading should go high and then jump back to infinity Ohms.

You’ll want to repeat this testing on the Fan and Herm terminals as well. If you don’t notice this jump, then it’s an indication that your AC capacitor has failed and needs to be replaced.

How to Replace an AC Capacitor

Start by ensuring that all of the power is killed to your air conditioning system. Next, remove the access panel for your outdoor compressor unit and locate the capacitor. Make a note of the wiring setup, and then disconnect the wires.

The capacitor will either be screwed in or held in by snap compression. Once you remove the old capacitor, it’s time to replace it with a new one. Make sure that you get a capacitor with the same model number so that it will work properly in your system. Simply screw or snap your new capacitor in place. Reconnect your terminal wires based on the documentation that you made earlier. Once everything is reconnected, it’s time to turn your system back on and test out your new AC capacitor.

Professional AC Service

HB Home Service Team offers professional AC service for the entire Central PA region. We’re also here for all of your heating, plumbing, oil, propane, duct cleaning, indoor air quality, electrical, and home safety needs. Contact us today to schedule an appointment.

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