How many capacitors does an HVAC system have?

Author: Mr. Adam Davis Jr.  |  Last update: Wednesday, September 10, 2025

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.

How much does it cost to replace a capacitor in a HVAC system?

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.

How do I know if my HVAC capacitor is bad?

Air Conditioner Not Blowing Cold Air

When the capacitor is bad, warm air blowing through your vents and not cold air is one of the first signs of trouble. You can try turning your condenser unit on and off again, but you may be dealing with a failing capacitor if the problem persists.

Why do I have two capacitors on my AC unit?

A dual capacitor powers both the fan and the compressor, which is the big pump housed in your outdoor cabinet that circulates refrigerant between the indoor evaporator and outdoor condensing unit.

Where is the capacitor located in HVAC?

Central Air

The outdoor system is often called the “condenser.” Inside are the circuit board, compressor, and heat exchange coil. The AC capacitor is inside the compressor. It's a cylinder-shaped component that looks like a big battery. To find it, you'll need to remove the unit's side panel.

5 Misunderstood AC Run Capacitor Facts

How many capacitors does an HVAC unit have?

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.

What happens when HVAC capacitor goes out?

A bad capacitor forces the motor to work harder than usual, leading to overheating and a burning smell. However, you may fail to notice the electrical odor because the capacitor sits outside. If your air conditioner isn't working, look at the condenser unit to ensure the motor isn't overheating.

How often do HVAC capacitors need to be replaced?

AC capacitors are designed to last for many years, but eventually, they will need to be replaced. On average, an AC capacitor might last between 5-20 years. However, some factors can affect the lifespan of your AC capacitor.

Will an AC fan run 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. In Florida's hot and muggy climate, the air conditioner needs to be in top condition.

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.

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.

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.

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.

What is the life expectancy of a capacitor in a HVAC system?

While the lifespan of HVAC capacitors can vary, ranging from 5 to 20 years, it is important to be aware of warning signs that indicate a failing capacitor. Such signs include longer startup time, strange noises, lack of airflow, and inadequate cooling of the home.

How do you diagnose a bad HVAC capacitor?

If your unit does not turn on immediately, this likely is a symptom of a bad capacitor. Additionally, if the air conditioning typically takes several seconds to kick in once powered on, this indicates a weak capacitor. An HVAC technician will be able to tell you if your system requires a new capacitor or not.

Why do HVAC capacitors fail so often?

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.

Should I turn off AC if the 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.

How many capacitors are in an AC unit?

ACs have two different types of capacitors. The start capacitor delivers the burst of energy it takes to start the motor. Once the motor gets running, the run capacitor stores and releases energy to maintain the motor. Some ACs have two single capacitors, while others have a dual capacitor system.

What are the two 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 I run my AC without a capacitor?

These components are essential for powering your air conditioner, enabling it to operate efficiently. Without capacitors, your system simply couldn't function. There are two main types of capacitors within your AC unit: start and run capacitors.

How long does it take to fix AC capacitor?

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. Our Alternative Heating & Air professionals can help diagnose the problem and get your air conditioner up and running quickly and efficiently.

What is the life expectancy of an AC compressor?

Your air conditioner compressor should last the whole lifespan of your air conditioner, about twelve years or more if you choose a ClimateCare air conditioner. However, it might not last that long if your air conditioner is too small for the space it's cooling, or if you don't keep your air conditioner well-maintained.

How much does it cost to replace a HVAC capacitor?

AC capacitor replacement cost varies based on several factors, but the national average is around $180. Typically, homeowners can expect to spend between $100 and $400 for air conditioner capacitor replacement from a professional HVAC technician during a preventative maintenance visit.

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 a bad capacitor cause a fire?

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

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