How Long Should Your Home’s AC Capacitor Last and Why Does It Cost So Much To Replace?

Kenneth Wilson

AC Capacitors are a common replacement item and like every machine, there's a peculiarity to them. In this guide, we'll cover everything you need to know about AC Capacitors and its replacement cost!

What are AC/Air Conditioner Capacitors?

An AC capacitor, also called a run capacitor, is a small, cylindrical object that sends energy to the motor that powers an air conditioning system. The AC capacitor gives your AC system the initial boost it needs to turn on and also provides continuous power for it to keep running.

The air conditioner capacitor is an electronic component inside your unit that is used to store charge in an electrostatic field. In a nutshell: it’s a temporary storage device for electricity. The air conditioner capacitor is used to stabilize voltage and start the motors in your cooling system.

It is also necessary for the air conditioner to run, as the motors inside your air conditioner are powered by the capacitor. The capacitor is just one component that makes up an air conditioning system. This small but mighty piece is a true workhorse, and like all parts of an air conditioning system, isn’t prone to malfunctioning. Without a properly-working capacitor, your system won’t be able to function as it should.

The air conditioner capacitor starts the various air conditioner motors and keeps them going by building up a store of electricity that can be used to provide continuous power. In this role, it acts as a sort of temporary battery so that there is a constant supply of power to keep the system running smoothly.

If you suspect your air conditioning system’s capacitor is bad, here is everything you need to know about the part and how to troubleshoot and replace a broken one.

In general, capacitors don't wear off. All they do is receive power, store it up, and wait for the signal to discharge. However, a small percentage of these capacitors do burn out unexpectedly.

This can happen for any number of reasons, and there is not much you can do to prevent it from happening. Capacitors are built to live as long as the unit they are installed in, but changing outside temperatures and extreme conditions can cause them to break down sooner. The best thing to do is have your system regularly maintained by a certified technician who can inspect for signs of damage or wear before the capacitor really burns out.

AC Capacitor Types

There are two types of AC capacitors: run capacitor and start capacitor. An AC run capacitor have two categories:

  1. 1
    Single run capacitor – has 2 terminals and starts one motor at a time.
  2. 2
    Dual run capacitor – has 3 terminals and can start multiple motors. Dual AC capacitor cost is expensive than single run capacitor as most HVAC technicians prefer using it because it saves space and is simpler to replace.

How long should AC Capacitors last?

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.

AC Capacitors last between 10 - 20 years. How often should you replace an AC capacitor?

To make sure your A/C unit is always running at its peak performance and to make sure you get the full lifespan out of that capacitor, be sure to routinely schedule preventative maintenance every six months, look out for the signs of a bad capacitor, and if all else fails, give us a call.

How do you know you need a new Capacitor?

Your HVAC guy says your capacitor is on the fritz. Here's how you know he's right:

  • The voltmeter says there are too few microfarads. All capacitors are rated in microfarads. For example, yours might be rated for 35 microfarads with a range of plus or minus 10. If it dips below 25, a voltmeter will tell your HVAC technician that it's time to replace it.
  • It's swollen like a balloon. When the capacitor is really far gone (and by the time we find them, they often are), it will swell up. Your capacitor might be bad even if it isn't swollen, but it's common for a bad capacitor to swell. It will look like someone packed too much material into the tube and it's bulging at the sides.
  • The capacitor leaks oil. This doesn't always happen, but bad capacitors frequently have oil leaking out of them. (Related: Home AC Compressor Replacement Cost and Consumer Guide) A leaky capacitor = a capacitor that's past its prime.

A note of warning: Capacitors can be dangerous. Even after you disconnect the power to the AC, the capacitor still holds a lot of charge. If you touch it, it might electrocute you. And it can hurt you really badly. So you must leave it to the experts.

Why Changing your Capacitor is a Good Idea

Capacitors are small, but they do play a big role and sometimes they fail. More often than not, they will eventually. Here are some reasons why they fail.

Heat Exposure

Especially living in the valley of the sun we know about being exposed to heat. Now for capacitors being exposed to the heat for long periods of time it really takes a toll on them. So, make sure you can shade your unit as much as possible, so it spends fewer hours in the sun to maximize the life of the capacitor.


Usually a capacitor is designed to last somewhere between 10-20 years, but a lot of different things play a role in the lifespan of them, such as we discussed earlier, like exposure to heat, if the capacitor is undersized, or even if it was built with wrong parts, a number of things play into how long they will last, the good thing is capacitors are not that expensive.

Voltage Rating

A lot of the time homeowners tend to find they have bad capacitors and take it amongst themselves to change them. Sometimes they pick the wrong one for their unit just trying to save a few bucks. It might seem like an easy fix but in reality, it’s best to have an experienced professional take care of it.

Each A/C unit calls for a specific capacitor with a specific voltage rating and when changed themselves, some homeowners don’t always get the one intended for their unit. That can cause the capacitor to short or work even harder and shorten the lifespan of the capacitor. The wrong capacitor can even cause parts to break down and that can lead to system failure.

Replacement Rules for Capacitors

  1. 1
    The voltage rating of the replacement capacitor must be equal to or greater than the original capacitor.
  2. 2
    The microfarad (strength) rating of a replacement run capacitor may vary plus or minus 10% from the original run capacitor.
  3. 3
    The microfarad (strength) rating of a replacement start capacitor must be equal to or no greater than 20% of the original start capacitor.
  4. 4
    If capacitors are wired in parallel the total capacitance (microfarad rating) is equal to the sum of the individual capacitors. The voltage rating of each capacitor must be equal to or greater than the original voltage rating.
  5. 5
    If capacitors are wired in series then the total capacitance is equal to the reciprocal of the sum of the reciprocals of the individual capacitors. The formula 1/CT = 1/C1 + 1/C2 + 1/C3 + … can be used to determine the total capacitance.

Some AC Capacitor Facts

  • The Voltage Rating is what it can handle, not what it will produce. Many techs think they must replace a 370v capacitor with a 370v capacitor. The voltage rating displays the “not to exceed” rating, which means you can replace a 370v with a 440v but you cannot replace a 440v with a 370v. This misconception is so common that many capacitor manufacturers began stamping 440v capacitors with 370/440v just to eliminate confusion.
  • You can test a capacitor while the unit is running. You simply measure the current (amps) of the motor start winding coming off of the capacitor and multiply it times 2652 (on 60hz power 3183 on 50hz power) and then divide that number by the voltage you measure across the capacitor.
  • Current doesn’t flow through the capacitor, just in and out of it. Techs notice that the one side of power is connected to the C terminal or the side opposite the run winding. Many techs imagine that this power “feeds” into the terminal, gets boosted or shifted, and then enters the compressor or motor through the other side. While that may make sense, it isn’t actually how a capacitor works.

A typical HVAC run capacitor is just two long sheets of thin metal, insulated with an insulation barrier of very thin plastic and immersed in an oil to help dissipate heat. Just like the primary and secondary of a transformer the two sheets of metal never actually touch, but electrons do gather and discharge with every cycle of the alternating current.

For example, the electrons that gather on the “C” side of the capacitor never go “through” the plastic insulation barrier over to the “herm” or “fan” side. The two forces simply attract and release in and out of the capacitor on the same side they entered.

Why does it cost so much to replace AC Capacitors?

To replace capacitors, we must know the price range of replacing other parts.

According to collated fiscal reports, here is the complete list of how much an AC owner would expect to pay to rectify an air conditioner’s issues.

  1. 1
    Detection and repair of leakage in a Refrigerant – $220 to $1,500
  2. 2
    Recharging an AC refrigerant – $110 to $850
  3. 3
    Replacement of a circuit board – $125 to $650
  4. 4
    Replace circuit breakers, relays, and fuses – $20 to $350
  5. 5
    Replacement of a thermostat – $110 to $480
  6. 6
    AC compressor repair hard start kit – $120 to $270
  7. 7
    Replacement of a capacitor – $95 to $470
  8. 8
    Replacement of a home air compressor – $1,350 to $2,300
  9. 9
    Replacement of an evaporator coil – $630 to $1,250
  10. 10
    Replacement of a condensing unit fan motor – $100 to $700

Therefore, from this nationally recognized list, the cost of replacing an AC capacitor ranges from about 100 to 500 dollars. This comes in addition with the re-installation costs and technicalities that hinge in location, availability of materials and expertise.

So why does it cost so much to replace AC Capacitors though?


Labor is a big part of the cost of any home repair and installation. The cost of labor is the biggest part of the price tag for an AC capacitor replacement. Generally, people spend $30-$50 for the part itself, and $100- $200 total, including the labor.

That means that $70 - $150 of the cost of installation comes from labor and supplies. Installing an AC capacitor only takes up a total of 30 minutes, and a maximum of 1 hour. If you go online, you can see that many homeowners were shocked to receive bills over $200 for a capacitor replacement.  During a busy time of the year, an invoice for $500 is not to be expected.  Remembers you're paying for the time that technician spent learning the trade, the ability to diagnose it quickly, and to have the right part on hand for fast replacement.

Shelf Life

They say that you can get between 10 and 20 years out of an AC capacitor. That is quite a long shelf life, but there are many variables that affect it. As mentioned above, there are several problems that can render a capacitor useless before that time.

However, the 10-20 year lifespan attributed to AC capacitors is based on a usage limit. You can start most capacitors 50,000 times in their lifetime. So technically, the timeline has less to do with the years and more to do with your own usage.


The cost of maintaining an AC is not fickle. It comes with several demands that test endurance, the need for top-notch quality and financial strength. AC capacitors conserve charge and have a lifespan of about 10 - 20 years.

They may develop faults even before the lifespan as a result of differences in types and environmental influences however, the cost of replacement varies in line with the best of capacitors. This cost carries the personnel cost and the equipment cost.

Kenneth Wilson
August 24, 2021
Cost Guides, HVAC

Kenneth Wilson

Retired contractor. Currently residing in Southwest Florida. Now in semi-retirement, I write and manage this blog focused on helping home owners make savvy decisions when it comes to finding contractors and getting their projects done. I also operate remodeling design service for homeowners.

Ask The Author Your Questions In The Comments!

  • Should my capacitor wear out in 3 yrs? Keep my air on 75 in Silver Springs Florida. New air conditioner.
    Only 3 yrs old.

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