6 Reasons Why Your Furnace Keeps Turning Off and How to Repair It 

Your furnace keeps your house warm during the frigid winter months, so it’s frustrating when something is off. One frequent issue is a furnace that continually turns on and turns off over and over. This problem is known as short cycling. It stresses your furnace and might result in expensive repairs or even early failure. 

Short cycling can be the result of for a few reasons. Before you request furnace repair, research the possible causes and how to resolve the issue. 

1. Dirty Air Filter 

The HVAC filter catches airborne dust, hair and other substances that could wreak havoc on furnace. If you don’t replace the filter frequently, it can get dirty and decrease the airflow. When this occurs, a safety feature switches off the furnace to stop getting too hot. Inspect the filter, and if it’s dirty, get a new one. Going forward, replace the filter every 30 to 90 days to keep your furnace from short cycling. 

2. Obstructed Air Vents 

A dirty filter isn’t the only issue that can lower airflow and overheat your furnace. Walk around your home and look for shut or blocked air vents. For adequate system balance and performance, keep all registers open, even in unoccupied rooms. 

3. Dirty Blower Wheel 

The furnace blower has blades that move air through the ductwork. If they are covered in dirt, the air won’t move correctly, causing overheating and short cycling. Frequently replacing the filter is the simplest method to avoid a dirty blower wheel. If the blades are already dirty, request furnace maintenance to have them cleaned. 

4. Faulty Thermostat 

Check your thermostat next. This is the core of your HVAC system and instructs the furnace on what to do. Ensure the thermostat is on heating mode and auto fan with the desired temperature showing on the screen. Try replacing the batteries. Also, check whether the thermostat is in full sunlight or near a heat source that could affect the temperature reading. If you use a smart thermostat, go to the manufacturer’s site for troubleshooting tips. 

5. Sooty Flame Sensor 

The flame sensor turns off the gas valve when no burner flame going. The sensor can’t find the flame if it’s coated in soot, so the gas switches off sooner and the furnace shuts off. Leave the work of repairing a dirty flame sensor to a pro like Service Experts Heating, Air Conditioning & Plumbing. 

6. Oversized Furnace 

When it involves heating and cooling equipment, larger isn’t always best. A larger system warms up your house too fast, causing unpleasant temperature changes and short cycling. The only way to resolve this issue is to request new furnace installation

If you try the resolutions we mentioned here and nothing has changed, it’s time to contact the pros at Service Experts Heating, Air Conditioning & Plumbing. We’ll review the situation, figure out the cause, and provide the necessary service. Our aim is to bring back indoor comfort, energy efficiency and dependable furnace performance for all season long. And our services are supported by a 100% Satisfaction Guarantee for a year.* For more details about furnace short cycling, or to request HVAC repair, reach us at 866-397-3787 now! 

— 

*Not applicable to the Advantage Program. See your signed Advantage Program Agreement for full details and exclusions. 100% Satisfaction Guarantee is subject to certain restrictions and limitations as set forth in the applicable Terms and Conditions. 

Enjoy our blogs!

Keep checking back for more!

© 2025 Service Experts, Service Experts Heating & Air Conditioning, and the Service Experts logo and design are registered trademarks of Service Experts LLC and used under license by SE Canada Inc. All Rights Reserved. *Not applicable to the Advantage Program. See your signed Advantage Program Agreement for full details and exclusions. 100% Satisfaction Guarantee is subject to certain restrictions and limitations as set forth in the applicable Terms and Conditions.