Furnace Short Cycling: Causes and Troubleshooting

AirPoint technician repairing short cycling furnace

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In the chill of winter, your home’s heating system becomes your best ally. But what happens when this trusted friend starts acting up? A common problem many homeowners encounter is furnace short cycling. This article aims to help you understand what furnace short cycling is, its causes, troubleshooting techniques, and when it’s time to call in the professionals.

Understanding Furnace Short Cycling

What is Furnace Short Cycling?

Furnace short cycling refers to when a furnace starts and stops repeatedly in quick succession. It’s like a car engine that keeps stalling and restarting – frustrating, inefficient, and potentially damaging in the long run.

Signs of Furnace Short Cycling

If you notice that your furnace turns off before your home is adequately heated or that it starts and stops more frequently than usual, you may be dealing with a case of short cycling. Other signs include unusually high energy bills and inconsistent temperatures throughout your home.

Causes of Furnace Short Cycling

Thermostat Issues

Thermostats regulate your furnace’s operation. If it’s malfunctioning, it can signal the furnace to turn off prematurely, leading to short cycling.


Overheating can cause the furnace’s safety devices to shut it down to prevent damage. If your furnace consistently overheats, it may be short cycling.

Dirty Air Filters

Clogged or dirty air filters restrict airflow to your furnace, causing it to work harder, overheat, and eventually shut off prematurely.

Inadequate Furnace Size

If your furnace is too small for your home, it will struggle to maintain the desired temperature, resulting in short cycling.

Troubleshooting Furnace Short Cycling

Checking the Thermostat

Check if the thermostat is set to the right temperature and if it’s functioning properly. If it’s old or malfunctioning, you may need to replace it.

Inspecting Air Filters

Regularly inspect and replace your air filters to maintain optimal furnace operation. A clean filter can significantly reduce the chances of short cycling.

Evaluating Furnace Size

Ensure your furnace is correctly sized for your home. If it’s too small, it may require upgrading to a larger model to stop short cycling.

When to Contact a Professional

While some issues can be resolved with simple troubleshooting, some situations require professional assistance. If your furnace continues to short cycle despite your efforts, or if you’re unsure about any part of the process, it’s best to call in a heating expert.

Preventive Measures for Furnace Short Cycling

Regular furnace maintenance can help prevent short cycling. This includes frequent checks and cleaning of the filters, ensuring the thermostat is functioning well, and a professional review of your system at least once a year.

Trust AirPoint to Fix Your Short Cycling Furnace

Furnace short cycling can be a frustrating issue, leading to energy inefficiency and a less comfortable home environment. But by understanding its causes and how to troubleshoot it, you can take proactive steps to maintain a reliable and efficient heating system. Remember, when in doubt, it’s best to consult with professionals, such as AirPoint, a Carrier factory authorized dealer and NATE certified in Toronto. Awarded the HomeStars Best of the Best 2023 and rated 5 stars on Google and HomeStars, AirPoint’s technicians are fully certified by TSSA, HRAI, and CSA

To learn more about how to fix a troubleshooting furnace, watch this video by AC Service Tech LLC

Frequently Asked Questions About Furnace Short Cycling

Causes can range from thermostat issues, overheating, dirty air filters, or a furnace that's too small for the home.

Troubleshooting steps include checking the thermostat, inspecting and cleaning air filters, and ensuring your furnace is correctly sized for your home.


If your furnace continues to short cycle despite your troubleshooting efforts, or you're unsure about the process, it's best to call a professional.

Regular furnace maintenance, including regular checks and cleaning of the filters, ensuring the thermostat is functioning well, and an annual professional review can help prevent furnace short cycling.

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