How often should I replace the capacitor on an AC unit?

Author: Duane Schumm DVM  |  Last update: Wednesday, April 23, 2025

For most ACs, this is about 15 to 20 years. However, even though your air conditioner might be rated to last this long, this doesn't mean that all of its components will. In most households, AC capacitors need to be replaced approximately twice throughout an air conditioner's lifespan.

How long does an AC capacitor last?

Generally, AC capacitors will last for around 20 years. However, this range can be shortened or lengthened depending on factors like usage frequency, local climate conditions, and how often your air conditioner has received regular tune ups.

How do you know when to replace an AC capacitor?

Your capacitor is rated with microfarads. By using a voltmeter, an HVAC technician can determine how many microfarads your capacitor has. A value under 25 is a sign that your capacitor is bad and must be replaced. Although you might own a voltmeter, you shouldn't measure the capacitor yourself.

Is it worth replacing the capacitor on an AC unit?

All AC and heat pump capacitors fail eventually.

Capacitors are one of the most common parts that need to be replaced on residential air conditioning systems. They typically provide several years of service, but you'll need to replace them at least once if you keep the same air conditioner for more than ten years.

How do I know when my AC capacitor is bad?

A sure sign of a bad AC capacitor is a humming sound from within the access panel. Any humming noises indicate a problem with the air conditioning system or the components of the AC unit. Try turning the power on and off again to see if it was a one-time issue with the motor or a recurring problem.

Was Quoted $400. I Fixed It For $11.72! AC Capacitor Testing and Replacement

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.

Will an AC fan run if the capacitor is bad?

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 average cost to replace a 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.

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 is the most common part to fail on an AC unit?

#1 Most Common Air Conditioning Repair – Bad Capacitor

The fan of course makes a whirring noise, the compressor is like a deep buzz like a refrigerator running. Holding your hand above the fan should feel warmer than the outside air.

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.

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.

What is the average lifespan of a capacitor?

Over time, capacitors degrade due to normal wear and tear. When combined with heat exposure, a capacitor's average life span of 20 years can plummet. Improper voltage.

Can a bad AC capacitor cause a high electric bill?

Failure to blow enough cold air into the room is the most obvious sign that the capacitor is faulty. Other possible signs of a faulty AC capacitor include: High electricity bills: Your energy bills may surge simply because the capacitor is not operational.

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.

What kills an AC capacitor?

These are some of the factors that may be affecting the lifespan of AC capacitors: 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 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 do I know if my AC capacitor is going to be replaced?

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.

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.

Is it OK to run AC with bad capacitor?

Capacitors may seem like an insignificant part of your HVAC System, however, if you have a failing AC capacitor, your unit will not be able to properly turn on as it was designed to.

How long does it take to replace capacitor on AC unit?

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.

Can a fan run without capacitor?

Well, it is needed to have one capacitor installed on each single phase motor of a fan to generate net positive magnetic flux. However, in the absence of a capacitor, there will be a complete shift in magnetic flux for each current cycle; that leads to net-zero magnetic fields that would not make the fan rotate.

What damages 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.

Why is AC not blowing cold air?

First, check your filters and coils for dirt and debris that may be impeding airflow. Once you've cleaned the filters and coils, run the air conditioner with just the fan so that the ice accumulation can melt off. If the AC still doesn't blow cold air, it could be that refrigerant levels are too low.

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