6 Reasons Why Your Furnace Keeps Switching Off and How to Resolve It 

Your furnace keeps your family comfortable during the chilly winter months, so it’s annoying when something is off. One routine complaint is a furnace that continuously turns on and shuts back off over and over. This issue is referred to as short cycling. It strains your heating system and may cause pricey repairs or even early replacement. 

Short cycling can be caused by for varying reasons. Before you book furnace repair, review the possible causes and how to resolve the problem. 

1. Clogged Air Filter 

The HVAC filter traps airborne dust, hair and other debris that could cause problems for furnace. If you don’t replace the filter often enough, it can get filthy and reduce the airflow. When this occurs, a safety mechanism turns off the furnace to prevent getting too warm. Check the filter, and if it’s dirty, install a new one. Going forward, get a new 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 restrict airflow and overheat your furnace. Walk around your house and be on the lookout for for unopened or blocked air vents. For recommended 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 dirty, the air won’t travel correctly, creating overheating and short cycling. Frequently replacing the filter is the simplest approach to avoid a dirty blower wheel. If the blades are already dirty, schedule furnace maintenance to have them cleaned. 

4. Faulty Thermostat 

Check your thermostat next. This is the cortex of your HVAC system and tells the furnace what to do. Make sure the thermostat is in heating mode and auto fan with the desired temperature shown on the screen. Try putting in new batteries. Also, check whether the thermostat is in bright sunlight or near a heat source that could influence the temperature reading. If you have a smart thermostat, visit the manufacturer’s site for troubleshooting tips. 

5. Sooty Flame Sensor 

The flame sensor turns off the gas valve when no burner flame is present. The sensor can’t sense the flame if it’s sooty, so the gas shuts off sooner and the furnace shuts down. Leave the job of cleaning a faulty flame sensor to a professional like Service Experts Heating, Air Conditioning & Plumbing. 

6. Oversized Furnace 

When it comes to home comfort equipment, larger isn’t always better. An oversized system adds warmth to your home too rapidly, causing uncomfortable temperature swings and short cycling. The only way to resolve this issue is to do new furnace installation

If you try the fixes we went over here and you’re still having problems, it’s time to reach the professionals at Service Experts Heating, Air Conditioning & Plumbing. We’ll take a look at the situation, diagnose the cause, and do the necessary service. Our priority is to bring back indoor comfort, energy efficiency and trustworthy furnace performance for the rest of the season. And our repairs are backed by a 100% Satisfaction Guarantee for a year.* For more info about furnace short cycling, or to book HVAC repair, reach us at 866-397-3787 today! 


*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. 

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