How to Tell If Your Furnace Capacitor Is Faulty

Posted on: February 2, 2021

How long do furnace capacitors last The capacitor is a small, yet important component of your furnace. It is designed to ‘jumpstart’ the unit by giving the furnace blower motor an extra jolt of energy and getting the fan running. Just like any other part of the furnace, a capacitor may break down and cause your furnace to stop working.

If you are wondering whether you need to contact heating system repair experts in San Diego County to inspect your furnace capacitor, you’ve come to the right place. In this article, we discuss the common signs of a faulty furnace capacitor to help you determine whether you need a replacement.

How long do furnace capacitors last?

Modern furnaces have capacitors that are designed to last anywhere between 10 and 20 years. However, a variety of factors may decrease the lifespan of a capacitor, such as:

  • Prolonged heat exposure: if a capacitor is exposed to heat for a long period of time, it may become susceptible to damage. To prevent this, place your furnace under the shade, minimizing the time it spends in the sun, maximizing durability.
  • Incorrect voltage ratings: homeowners may attempt to replace their furnace capacitors themselves, and sometimes choose a cheaper capacitor that doesn’t match their unit’s correct voltage rating. This may greatly decrease the lifespan of the capacitor and even lead to system failure.
  • Improper installation and sizing: a capacitor that is undersized or installed with the wrong parts may not last long and cause problems with the entire unit. This can be avoided by relying on experienced HVAC technicians for the installation.

What are the signs of a bad capacitor?

Your furnace has a blower motor that blows the hot air into your home via ductwork. In a way, a furnace capacitor functions as a battery, storing the energy required for the blower motor to work well. If a furnace capacitor is faulty, the blower motor won’t function properly and may compromise your family’s comfort.

A faulty furnace capacitor may exhibit several signs, including:

No power

A broken furnace capacitor will prevent the functioning of the blower motor, causing the unit to stop working completely. Before you can determine whether the capacitor is the root cause of the problem, you should check the fuse controlling your furnace and see if it’s on. Once your furnace receives power, increase the thermostat settings and see whether the blower motor starts working within a couple of minutes. If there’s no response, the capacitor is most likely the cause.

Inconsistent blower motor operation

The capacitor needs to be in good condition for the blower motor to function properly. If the capacitor is bad, the blower motor may run slowly or inconsistently, or overheat easily. If you notice that your blower motor works strangely or short cycles, make sure to contact professionals to inspect your capacitor.

What does a bad furnace capacitor sound like?

You can also tell whether your furnace capacitor is working properly by listening to the sounds it creates. If a capacitor produces humming sounds, it may be a sign that is experiencing electrical issues. To check if this is the case, make sure to turn up the furnace thermostat and wait for the blower to start working. Next, use a screwdriver to open the access panel and lean near the blower housing to listen for a humming sound. If you hear it, make sure to reach out to HVAC professionals to inspect the unit.

How often should capacitors be replaced?

Capacitors are actually one of the most common components that are replaced on furnaces. They are usually designed to provide 10-20 years of service, but various factors discussed in this article may decrease their lifespan. If you’ve had your furnace for more than 10 years, it is likely that you’ll have to replace the capacitor at least once.

Testing the furnace capacitor

Start by shutting off the power to your unit at the fuse. Remove the housing of the blower motor to gain access to the capacitor. Even if there’s no power, the capacitor still holds a charge. Make sure to remove the wiring from the terminal and follow the manufacturer’s instructions for your furnace to discharge the capacitor. Use a voltmeter and set it to the X1 setting. You can find the voltage rating for your capacitor on its side, in most cases. Touch the voltmeter probes to the capacitor terminals and check if the voltage matches its rating. If it doesn’t match, you’ll need to have the capacitor replaced.

If you notice any of the signs of a bad capacitor discussed in this article, contacting professionals should be your next step. Not only are experts better qualified to size and install a new capacitor properly, but they may also check your furnace for any other potential issues, such as a faulty furnace transformer. We strongly advise you against trying to perform any furnace repairs yourself as this may result in more serious damage.

Your go-to professionals for heating system repair in San Diego

What are the signs of a bad capacitor If your home heating system isn’t working properly and it has compromised your indoor comfort, look no further than Action Air Conditioning, Heating & Solar. We are a team of experienced professionals committed to meeting the needs of our customers across San Diego. If you need us to ensure the comfort of your home near Old Town Temecula or Double Peak Trail, our NATE-certified technicians will be at your location fully equipped to resolve any issues with your HVAC system with efficiency and ease.

Whether you need us for HVAC repair, maintenance, or installation, rest assured that we’ll do everything in our power to ensure your optimal comfort and safety. Our team relies on proven methods and equipment to keep your cooling and heating systems in peak condition all year long. Get in touch with us today at 760-727-4152, and see why we are the favorite HVAC company in San Diego County.