What Causes a Capacitor to Fail in an Air Conditioner?

 AC Capacitor


Your air conditioner’s capacitor is among its most essential components. If it doesn’t work properly, your unit will lack the power necessary to start up and run efficiently. But what causes a capacitor to fail in an air conditioner that’s fairly well-maintained?

As Hodgkin’s reliable AC repair company, our technicians at JC Heating & Cooling have years of experience in handling this issue. Below, you’ll discover how a capacitor functions, why it typically malfunctions, and what you can do to prevent failure.

What Is a Capacitor?

An air conditioner’s capacitor is a cylindrical component that resembles a battery. Like a cell, it stores an electrical charge that allows your air conditioner to start upon command. Historically, most air conditioning units contain a few different types of capacitors.

For example, the start capacitor does what its name suggests, providing enough power to startup the system. However, when it doesn’t deliver energy to enable your system to efficiently cool your home, the motor may not kick off as it should. 

#1 Overheating Capacitor

Some air conditioning capacitors harbor a damp separator within their inner workings. As hot Florida temperatures rise in the summer, the separator may lose its moisture, causing a short circuit when the internal temperature climbs too high. Overheating can also occur if your system works too hard for long periods of time. 

In either case, you need to call an HVAC technician like JC Heating & Cooling to inspect your unit. Don’t wait long to schedule our services—an overworked system results in more than just normal wear and tear and can lead to many other components failing in quick succession. 

#2 Faulty Components

Old or damaged components are common reasons for capacitor failure. They also cause the unit to overheat from working too hard to reach your temperature setting. 

Parts like fan motors or compressors have bearings, which become damaged or worn if the system works too hard. Any dragging fan motors and compressors can eventually destroy a capacitor. A faulty relay switch may also cause problems by forcing your capacitor to circuit too much energy.

#3 Electrical Surge

Did you know that your air conditioner can only handle a certain amount of electricity at any given time? So, a power surge or a lightning strike will send an electrical swell of energy to the unit that no capacitor can handle. It might kill your capacitor or damage other air conditioning components.

Has a power outage or surge affected your home? Check your fuse box for flipped switches, and switch them back into the ‘On’ position. If you reset the system, but the air conditioner doesn’t turn on again after a few minutes, be sure to call for professional repairs.

#4 Capacitor Overload

What causes a capacitor to fail in an air conditioner that’s otherwise well-maintained? One reason might be an overload of energy. Capacitors should only function for a few short moments when your unit starts, providing just enough energy for the air conditioner to begin cycling.

However, occasionally, debris or mechanical problems may prevent the motor from running. Your capacitor will continue sending power and then fail entirely.

#5 Outdated Capacitor 

Most capacitors only last between five and six years. Like other components, they eventually stop working. However, their lifespan typically depends on how often the air conditioner starts up and what state the other parts of the system are in long-term.

Do you have to replace your capacitors? If you have an otherwise working system that doesn’t want to startup, you might need a replacement for your capacitor. 

Signs of Capacitor Failure

  • Your unit makes odd sounds that resemble buzzing or clicking. 
  • Your air conditioner doesn’t power on when it should. You may turn it on manually or notice that your temperature rises above your thermostat setting. 
  • Your air conditioner stops producing crisp, cool air. Instead, the air feels lukewarm or moist. 
  • The air conditioner powers on before quickly powering down again. This could indicate a capacitor that lacks an appropriate charge.

Let JC Heating & Cooling Solve Your Capacitor Problems

Do you want expert solutions to your air conditioning situation? Reach out to our team of skilled technicians at JC Heating & Cooling. We can assist you with any HVAC issue, from learning how to reset the air conditioner to helping you choose a new unit that fits your needs and budget.

What causes a capacitor to fail in an air conditioner? Find out more when you call JC Heating & Cooling at (708) 968-3131 today to schedule our services.