Capacitor for AC: What They Are and When to Replace Them

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Capacitor for ac unit

Your AC features a collection of components that must work together to cool your home. One of them is a compact unit known as the capacitor.

Why do you need a capacitor for AC? How do you know when it’s time to change yours? We’ll answer these questions and more.

What Is a Capacitor?

A capacitor is a small object that stores electricity and sends kicks of energy required to start a motor and keep it running. A capacitor for AC works with the compressor, outside fan, and blower motor to cool your home. In an AC, it powers the fan motor and blower motor.

Most capacitors have a cylindrical shape.

What Is the Difference Between Start Capacitors and Run Capacitors?

Start capacitors deliver the energy your AC motor needs to kick off the cooling cycle. In contrast, the run capacitor provides the energy required to keep the motor going and your AC functioning.

Many AC units don’t feature both capacitors separately. Modern units have a single capacitor serving that dual function.

You can swap both the run capacitor and the start capacitor for a double-action unit when necessary. They are easier to replace, and they don’t take up much space in the HVAC unit.

Why Do You Need a Capacitor for AC?

Although your AC unit or heat pump runs on your home’s electrical connection, it requires a stronger boost to work effectively. Air conditioners are power-guzzling machines that require more energy than your home’s wiring can supply. The capacitor solves the energy problem by assisting the unit.

A capacitor’s job is crucial. Unfortunately, a failed capacitor is one of the most common reasons for air conditioner malfunction. A worn-out AC causes several problems and will affect your comfort in the hot summer months.

What Are the Main Causes of a Failed Capacitor?

Some of the common causes of a bad AC capacitor include:

  • Power surges
  • Overheated system circuitry
  • Lightning strikes
  • Cooling system short circuits
  • Equipment wear
  • Extreme temperatures
  • Over cycling

Most capacitors for AC will last 20 years or more. However, the issues listed above can significantly reduce your unit’s life expectancy.

How Does a Bad Capacitor Affect Your AC and Fan Motor?

AC-heater unit

If a capacitor fails, the system’s performance will take a huge hit. If the exterior components don’t get adequate power, the air conditioner can’t cool your home effectively—if at all. The capacitor is integral to the cooling process.

Inadequate voltage delivery to the components will force the system to work harder while cooling your home. The result is faster wear and tear and a bloated cooling bill.

When to Replace Your AC Capacitor

Your AC capacitor may not cause your air conditioner to quit completely. However, some signs tell you it’s time to change the capacitor. They include the following:

  • Smoke or burning smell from outside components when the air conditioner is working
  • A louder than usual hum from the air conditioner
  • Extremely slow progression to a cooling cycle after you turn on your air conditioner
  • Random air conditioner shutdowns
  • Higher than usual energy bills
  • Lack of power in the air conditioner unit
  • Visible cracks, bulging or oozing liquid from the capacitor

Your AC capacitor needs to be replaced if you notice these signs. However, you need to speak to a qualified contractor for definitive confirmation.

HVAC contractors confirm a problem with the capacitor for AC by testing it using a voltmeter. Capacitor ratings are in microfarads, often with a range of plus or minus ten. If your capacitor has a 40 microfarads rating and the multimeter shows a reading lower than 30, it’s time to replace it.

Should You Replace Your Air Conditioner Capacitor on Your Own?

You shouldn’t replace your AC capacitor on your own. Many DIY tutorials exist online discussing how you can change capacitors. However, that’s a risky venture you should avoid unless you’re a qualified professional.

A quick search online will bring up examples of people who experienced severe electric shocks while attempting to change the capacitor in their cooling system. This is one DIY project that can land you in the emergency room.

Capacitors are dangerous because they retain a lot of energy long after turning off the air conditioner. A qualified HVAC technician knows how to handle capacitors safely and effectively.

Additionally, you could void your warranty by working on the air conditioner without the right qualifications.

Should You Change Your AC Due to Capacitor Problems?

Air conditioning unit

You don’t have to change your AC due to capacitor problems. Replacing the capacitor with a newer one is often enough to correct any problems the AC unit might have. However, if the capacitor problem lasted too long before you found out, you may have other types of damage that would require changing the AC unit.

A professional HVAC contractor will take a comprehensive look at your system and offer the right guidance. Typically, it’s often cost-effective to replace units over a decade old if you can afford the upfront costs. These units are more efficient and will cool your home faster.

Branded vs. Generic Capacitor for AC: Which Is Better?

Branded and generic AC capacitors play the same role in the function of an air conditioner. There’s no difference between them if you choose the right capacitor size for your unit.

However, some AC manufacturers may insist on sticking with their branded capacitors to prevent voiding the warranty.

Get Professional Help with Your Heat Pump and AC Capacitor Problems Today

If you suspect any problems with your AC capacitor, call Confident Comfort Heating & Cooling for immediate help. Our team of professionals will diagnose the problem quickly and provide repairs to reduce the air conditioner downtime.

You don’t have to endure the hot Arizona summer weather for too long. We offer free estimates and can send a technician to your home in minutes.

Contact Confident Comfort Heating & Cooling, Flagstaff, AZ, to discuss any capacitor for AC problems.