Bad Capacitor on a Gas Furnace Blower

The Telltale Signs of a Bad Capacitor on a Gas Furnace Blower

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The furnace in your home is one of your home’s hidden gems keeping your family comfortable during any kind of weather Mother Nature throws at you. And the truth is you probably pay very little attention to your furnace.

Until you wake up one morning and your house is freezing cold and you suspect you might have a furnace issue. Or maybe you feel like your furnace isn’t quite keeping up with keeping your rooms warm.

If you’re concerned you might have a furnace problem, one key thing to consider is the capacitor.  A bad capacitor can either reduce or eliminate heat from getting from your furnace into your home.

How will you know if the problem is related to a capacitor? Read on for these signs you might have a bad capacitor in your furnace.

What Is a Capacitor and How Does It Work?

A capacitor is a key part of your furnace’s function that helps to get the warm air moving into your home. Gas comes into your furnace where it is ignited by the pilot light. This creates the warm air you need to heat your home.

Yet, the warm air has to have a way to get into all the different rooms in your home. Your furnace has a blower that will kick on to send that warm air created by your furnace through the ducts and into your home.

The blower requires a significant amount of energy to work. This is where the capacitor comes in. It is the part of your furnace, similar in shape to you a soda can, that stores energy up. When the furnace needs to kick on, it uses the energy from the capacitor to run the blower and move the heat.

Your furnace has three important parts, the compressor, blower, and outdoor fan. Most furnaces are set up so each of these three components has a pair of capacitors working for them. The first capacitor uses the energy stored to get the furnace part it’s connected to going. Then the second one uses the stored energy to keep it running.

Signs of a Faulty Capacitor

You will definitely notice when your furnace isn’t running. But prior to that there may be some signs of trouble you should pick up from your furnace.

Imagine your capacitor showing your symptoms that something is amiss. Let’s take a closer look at some of the symptoms a faulty capacitor might show.

Humming Sound

You know what your car sounds like when it’s running normally, the same can be true for your furnace. You know what your furnace sounds like when it kicks on and the blower is going. It’s highly likely you’ll recognize when something sounds amiss.

If you are concerned about a potential capacitor problem, try this. First, turn up the heat forcing your blower to kick on. Remove the front panel of your furnace. Often when a capacitor is failing, there will be a humming sound coming from the furnace as it tries to kick on the blowers.

No Power

Another more obvious problem is if the blower won’t kick on at all. Firsts, check your fuses for the furnace. Make sure they are getting the appropriate power and that isn’t the root of the problem.

Then turn up your heat so as to force the blower to kick on. If nothing happens once you kick up the heat, you definitely need to call a furnace professional. It is likely the capacitor is not functioning properly forcing the blower to kick on when the heat is turned on.

Inconsistent Output

Remember, the capacitor holds the energy needed to kick on the blower and push heat out of the furnace into the vents. If you have a bad capacitor, you might find that the blowers are working inconsistently.

If the capacitor isn’t holding a charge to turn on the blowers, they might not run properly. It might be that the blower turns on and then quickly turns back off again.

Often a capacitor won’t fail completely, it just starts to not run as well. This means you will get inconsistent output from your furnace. This is a sign it’s time to have the capacitor inspected.

Aging HVAC System

The job of turning on the blower in your furnace over and over again can over time simply wear out the capacitor. It gets worn from all the use it gets performing its job.

If you have an older furnace and have not had it inspected recently, you should. If you know the capacitor has never been replaced and you are getting some of the above warning signs, it’s likely time to have it looked at by a professional.

How Can You Test to See If the Capacitor Is Kaput

If you are concerned you have a bad capacitor, it’s likely you will need to call in an HVAC professional. But you can do some investigating yourself to see if you have any warning signs.

Again, you want to start by cranking up your heat, so you know your furnace will kick on. Then get close to the furnace and listen. Any unusual humming or clicking indicates a problem.

Often when a capacitor is failing, it will get overheated. This may cause the wires that run from the capacitor to fray causing a burning smell. If you have an unusual smell near your furnace, call a home heat repair professional right away.

Know the Signs of a Bad Capacitor

Most homeowners pay very little attention to their furnace, expecting it to do its job and keep the house warm. But a furnace has parts that work hard over time. A  bad capacitor can be a relatively common furnace problem if you aren’t getting heat from your furnace.

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