What causes a capacitor to go out on an AC unit?

Author: Ms. Eliane Wuckert  |  Last update: Saturday, November 22, 2025

Power Surge or Overload Minor power surges or other fluctuations in power also overload the capacitor and may cause it to fail. Your AC capacitor may also fail if the fan motor burns out or is somehow impeded from spinning freely.

What makes an AC capacitor go bad?

Overheating. If your air conditioner is constantly running or is too old, this can cause the capacitor to overheat and fail. To prevent this, it's helpful to give your system a break every now and then by turning it off for a few hours. This will help prolong your air conditioner's life and its parts.

What is the common cause of capacitor failure?

Power outages or surges and excessive heat are also common concerns. Aging can also cause capacitor failure. Electrolytic capacitors fail due to leakage or vaporization of the electrolyte inside. This can be caused due to heating in operation.

What is the life expectancy of an AC capacitor?

On average, AC capacitors last 10 years, but their life span can range anywhere from five years to 20.

What damages an AC capacitor?

Heat exposure: Heat may be one of the most damaging elements for air conditioner capacitors. Exposing these units to high heat for extended periods shortens their lives and can cause significant damage to your unit.

5 Misunderstood AC Run Capacitor Facts

Is it OK to run AC with bad capacitor?

While your AC will still work with a bad capacitor, it will struggle to function correctly. Eventually, the system will stop working altogether. Extended use can cause further damage internally. We recommend contacting a professional to handle the repairs so that you don't risk any damage to your air conditioning.

How much does it cost to replace a capacitor in an air conditioner?

The average cost to replace an AC capacitor is $180. Prices usually range from $200 to $400 depending on the type of capacitor and system you have. Photo: Courtesy of Angi member Kathy W.

Can AC run without a capacitor?

When you switch on your AC, numerous components work together to cool your space effectively. Among these, capacitors play a crucial role. These components are essential for powering your air conditioner, enabling it to operate efficiently. Without capacitors, your system simply couldn't function.

How often do capacitors go out on an AC unit?

Capacitors provide the power that certain A/C parts need to do their job. The average capacitor can last around 20 years, but in places like Arizona, things can be a little different, thanks to extreme heat.

Can I replace an AC capacitor myself?

Since AC capacitors are high-voltage components that might cause significant injury to you even if the power is out, it is strongly recommended against changing them yourself. Follow any instructions provided with your new unit purchase if you're thinking about replacing your own AC capacitor filter.

Why does the capacitor on my AC unit keep going out?

A fan motor or compressor with worn-out bearings may cause the capacitor to work harder and fail. If the relay switch on your air conditioner malfunctions, it may cause the capacitor to overheat. Damage from lightning or power surges also affects the capacitors, causing them to fail.

What are the 2 typical signs that a capacitor is bad or has failed?

Bad AC Capacitor Symptoms Checklist
  • Smoke or a burning smell from exterior air conditioning components.
  • A humming noise from your air conditioner.
  • Your air conditioner takes some time to start a cooling cycle once you turn it on.
  • The air conditioning system shuts off at random.

Can a bad capacitor cause a fire?

In the worst case, the capacitor may ignite, resulting in a fire hazard.

What blows a capacitor on an AC unit?

Several things can cause a capacitor to blow, including: A power surge or lightning strike. If your home is struck by lightning or encounters a power surge, the surge can overwhelm your capacitors and cause them to blow. A short circuit.

How long does it take to replace a capacitor on an air conditioner?

In most cases, replacing an AC capacitor will take between 1 and 2 hours. However, some more complex cases could take up to 4 hours.

How to prevent capacitor failure?

Temperature Control: Keeping the HVAC system in a well-ventilated area and maintaining proper airflow can prevent overheating and extend the capacitor's life. Surge Protection: Installing surge protectors can safeguard the system from sudden power surges, preventing overload and capacitor failure.

Is it bad to run AC with bad capacitor?

If the start capacitor malfunctions or wears out, it usually prevents the HVAC unit or the blower from turning on. A bad run capacitor won't prevent the unit from starting, but it can lead to the unit shutting down prematurely, overheating or making more noise than usual.

What is the lifespan of an AC capacitor?

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

How do I know if I need a new AC capacitor?

How To Recognize a Failing AC Capacitor
  1. Loud humming sounds coming from the AC condenser.
  2. Having your air conditioning shut off without warning.
  3. Burnt odors or smoke coming from the outdoor condenser.

Is it common for AC capacitor to fail?

It's inevitable that capacitors will eventually wear out. As long as you catch the failing capacitor early, it's relatively easy and inexpensive to fix.

Will the fan still work if the capacitor is bad?

Will AC fans run if the capacitor is bad? The answer is a resounding no. An air conditioning unit will stop working with a faulty capacitor unless you get hold of Coral Springs' air conditioning repair experts.

Is replacing AC capacitor easy?

Can You Replace an AC Capacitor Yourself? Replacing a capacitor is a relatively simple task that most people can do themselves with a little bit of research. However, it is important to remember that capacitors store a lot of energy, so it is necessary to discharge the capacitor before working on it.

How do you tell if a capacitor is bad on a AC?

Most common first signs of a bad AC capacitor:
  1. Vents Not Blowing Cold Air. ...
  2. Higher Than Usual Energy Bills. ...
  3. Unusual Compressor Humming Noises. ...
  4. Older HVAC System. ...
  5. Independent Shutdown. ...
  6. Sluggish Turn On and Operation. ...
  7. AC is Inoperable.

How many capacitors are in an AC unit?

Depending on how your HVAC system is built, there may be two single capacitors or one dual capacitor in your outdoor unit. Systems requiring two single capacitors need a start capacitor and run capacitor to function properly.

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