What blows an AC capacitor?

Author: Frankie Boehm  |  Last update: Thursday, October 23, 2025

What causes a blown capacitor in your air conditioner? A power surge from something like a nearby lightning strike. A short circuit in an air conditioner's control board. Overheating of a capacitor due to hot weather and/or too much stress.

What breaks 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.

What damages an AC capacitor?

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. The capacitor continues to send power to try and operate the fan but eventually overloads and burns out.

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.

Can a dirty filter cause a capacitor to go bad?

Dirty Filters

Clogged air filters reduce airflow from the return ducts to your evaporator coil. If you ignore the dirty filters long enough, the capacitor will overheat.

5 Misunderstood AC Run Capacitor Facts

What would make a capacitor blew up?

High temperature, poor ventilation, high operating voltage, excessive voltage harmonic components, and operating overvoltage are additional factors that may contribute to capacitor explosions. System designers must consider these factors to create environments conducive to capacitor longevity.

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 causes run capacitor to burn out?

Included in these categories are intermittent opens, shorts or high resistance shorts. In addition to these failures, capacitors may fail due to capacitance drift, instability with temperature, high dissipation factor or low insulation resistance.

Is it okay to run AC with a 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.

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.

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.

How much is it to replace an AC capacitor?

For AC capacitor replacement, anticipate spending between $150 and $400, depending on the capacitor's type and accessibility. A bad AC capacitor is a fairly minor repair, and most HVAC technicians will recommend a repair rather than replacing the unit when the capacitor is the problem.

Will a bad capacitor trip a breaker?

Once the unit is running, the run capacitor then takes over and continues to supply additional current to keep the motors moving. If either the start capacitor or run capacitor fails, the motors will start drawing much more current and lead to the circuit breaker tripping.

Can an 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.

What blows a capacitor?

What causes a blown capacitor in your air conditioner? A power surge from something like a nearby lightning strike. A short circuit in an air conditioner's control board. Overheating of a capacitor due to hot weather and/or too much stress.

What burns out a capacitor?

The capacitor's ability to store and release energy can cause it to overheat and wear out eventually. This can happen when the whole system runs for long periods of time. Capacitor failure can also be the result of a power surge, a lightning strike or fluctuations in the electric grid.

What kills an AC capacitor?

Power surges can cause a capacitor to fail, too.

Obviously a lightning strike from a summer thunderstorm can overload and burn out your HVAC's electrical system., Also weaker power surges can cause damage to capacitors over time. Those weaker surges can be caused by fluctuations in the electrical grid.

Will the fan turn on if the capacitor is bad?

A faulty capacitor typically prevents the fan motor from getting enough power to start or maintain operation. In some cases, you might hear the motor humming but see no movement. This occurs because capacitor failure leaves the motor without its needed power boost.

Can a power surge damage an AC capacitor?

A power surge will overload and burn out your electrical system, putting every capacitor in your electrical appliances at risk of damage. The most effective way to protect your air conditioner's capacitor, as well as your other appliances, is to install an HVAC surge protector.

Will a compressor run with a bad capacitor?

While it may still turn on, weak or degraded capacitors can't always provide enough electrical oomph to get those blower and compressor motors running at full force. You'll likely notice the air from your vents just doesn't have that same crisp, robust flow. Rooms may feel stuffy and take forever to cool down properly.

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.

What causes a capacitor to catch fire?

Film capacitors may ignite due to increased leakage current caused by a defect in the dielectric film or poor connection of the counter electrodes *20. In addition, there is a possibility of open failure in evaporated metallized type capacitors. The dielectric of the film material is not flame retardant.

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.

Should I turn off AC if capacitor is bad?

If the capacitor is damaged or worn out, it can cause the compressor to work harder than it should, which can lead to a humming noise coming from the access panel of the condenser unit. Such a sound may also be coming from the AC's motor, so try turning the AC unit off and on once to see if that's the case.

What does it cost to replace an AC capacitor?

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.

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