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Why Does My Furnace Keep Turning Off/Short Cycling?

When the weather gets colder, homeowners across the country start cranking up their thermostats to keep themselves warm and cozy. After all, heating systems are a must during the chilliest months of the year. But have you noticed your furnace turning on and off frequently? If so, you’re not alone. This problem, known as “short cycling,” is unfortunately common and can have various causes.

So, why does your furnace keep turning off — especially when you need it most? This issue could be related to your thermostat, air filter, furnace blower motor, and more. We’ll discuss what causes a furnace to short cycle in more detail below.

How to Tell if Your Furnace Is Short Cycling

What does a short cycling furnace look like, exactly? This particular issue is usually easy to spot. However, there are some signs of short cycling that you might be surprised to learn about.

If you’re unsure whether you’re dealing with this problem, use this guide to learn more about short-cycling:

How to Tell if Your Furnace Is Short Cycling infographic

Thermostat Problems

It’s no secret that a short-cycling furnace is frustrating to deal with. You’re probably struggling to stay warm, which can be a serious problem when temperatures dip at night. The good news is that furnace short cycling can sometimes be easy to fix.

First and foremost, you’ll want to start by checking your thermostat to see if the problem lies there. It’s possible that your thermostat needs new batteries. If the batteries have gone bad, this can disrupt your thermostat’s ability to work correctly.

If you’ve checked the batteries and the problem persists, there’s a chance that your thermostat has been installed in a bad location. Reconsider the location of your thermostat if it’s been installed near the furnace or in an exceptionally warm room.

Does it seem like your thermostat is working properly and installed in a decent location? If so, you’re probably ready to move on to the next potential reason for this problem. Let’s continue to discuss what causes a furnace to short cycle below.

Dirty Air Filter

If you’re dealing with short cycling, checking the furnace’s air filter should be one of the first steps you take.

Why does your furnace keep turning off because of a dirty air filter? In most cases, the reason has to do with insufficient airflow. A dirty or clogged air filter can prevent the proper circulation of air through your heating system. Poor airflow can cause the heat exchanger to overheat, which may lead to the furnace shutting down completely.

Dirty air filters can lead to many heat and air conditioning-related problems. For example, a dirty filter can also have a negative effect on your furnace’s energy efficiency, which can result in higher energy bills.

So if you’re experiencing short cycling woes, don’t forget to check the air filter. Replacing the filter could be the simple fix you need to get your furnace running smoothly again. As a general rule of thumb, you’ll want to replace the filter once every 90 days.

Blocked Air Vents

Although a clogged air filter can lead to poor airflow, it’s important to mention that blocked air vents can also lead to this particular problem. As an extra precaution, you should go throughout your home and check that the air vents are open and free of obstructions. If these vents are closed or blocked by furniture, this can also be what causes an overheating furnace.

Faulty Flame Sensor

Your furnace’s flame sensor has an important job in that it’s responsible for detecting a flame within the heating system. When the sensor detects a flame, it will open the gas valve. If the sensor doesn’t detect a flame, it will close the gas valve so that gas doesn’t flow into the home.

Unfortunately, a dirty flame sensor could be why you’re dealing with a short-cycling furnace. So, why does your furnace keep turning off due to a dirty flame sensor? Essentially, when the flame sensor becomes covered in a layer of grime, it’s unable to discern whether or not a flame is present. As a result, the flame sensor will malfunction, and your furnace will turn on and off quickly.

Malfunctioning Blower Motor

When your furnace heats up the air, the blower motor is responsible for sending this warm air out into your home. Unfortunately, this critical component can malfunction and lead to short cycling.

Why does your furnace keep turning off with a malfunctioning blower motor? The reason is pretty simple to understand. If the blower motor is unable to complete its job, the heated air inside your furnace will have nowhere to go. This heated air will build up, and eventually, your furnace will shut down as a safety precaution to prevent overheating.

Fortunately, professional furnace repairs can help fix this problem. You’ll want to address this issue ASAP, so don’t hesitate to call your local heating experts to schedule a furnace repair in Benson, AZ.

Blocked Flue

Overheating can also be caused by a blocked flue. As you may or may not know, your furnace’s flue pipe is in charge of venting the combustion gases from the heat exchanger to the exterior of your home. This pipe is incredibly important, as it helps prevent carbon monoxide from entering your living spaces.

Are you still asking yourself, “Why does my furnace keep shutting down?” Unfortunately, a blocked flue could be the culprit. This pipe can become clogged with various types of debris and foreign objects. If your furnace detects a clog, it will shut down to prevent overheating and harmful carbon monoxide leaks.

Poor Furnace Installation

Believe it or not, a poor installation can be what causes a furnace to short cycle. When installing a heating system in your home, it’s important to make sure that the unit fits your home’s size and accommodates your heating needs.

If you install a furnace that is too big for your home, this can lead to several problems, including frequent stopping and starting. An overly-large furnace will heat your home much quicker than it should, and once it’s completed its job, the system will shut down.

Unfortunately, an oversized furnace can also lead to higher utility bills and excessive wear and tear, so you’ll want to address the issue as soon as possible.

Choose Rite Way AC for Your Next Furnace Repair!

It can be helpful to know what causes a furnace to short cycle, especially if you’re dealing with this issue in real-time. If you need to schedule a repair, turn to the experts at Rite Way AC! Our knowledgeable team can help with all of your needs, including a high-quality furnace installation in Tucson, AZ.

Contact us today to learn more about our services!