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

Your furnace keeps your home warm during the harsh winter months, so it’s disconcerting when something is off. One frequent issue is a furnace that continuously turns on and turns off all the time. This operating error is known as short cycling. It stresses your heating system and may cause expensive repairs or even early replacement. 

Short cycling can be the result of for several reasons. Before you book furnace repair, consider the probable causes and how to fix the situation. 

1. Clogged Air Filter 

The HVAC filter attracts airborne dust, hair and other substances that could cause problems for furnace. If you don’t get a new filter often enough, it can get clogged and block the airflow. When this happens, a safety feature switches off the furnace to stop overheating. Check the filter, and if it’s dirty, get a new one. Going forward, change the filter every 30 to 90 days to keep your furnace from short cycling. 

2. Clogged Air Vents 

A dirty filter isn’t the only thing that can restrict airflow and overheat your furnace. Walk around your residence and look for shut or crowded air vents. For recommended system balance and performance, keep all registers open, even in unoccupied rooms. 

3. Dirty Blower Wheel 

The furnace blower uses blades that push air through the ductwork. If they are caked with dirt, the air won’t move correctly, causing overheating and short cycling. Routinely replacing the filter is the simplest way to stop a dirty blower wheel. If the blades are already dirty, request furnace maintenance to have them cleaned. 

4. Faulty Thermostat 

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

5. Sooty Flame Sensor 

The flame sensor switches off the gas valve when no burner flame on. The sensor can’t detect the flame if it’s covered in soot, so the gas switches off too soon and the furnace shuts off. Leave the job of repairing a dirty flame sensor to a professional like Service Experts Heating, Air Conditioning & Plumbing. 

6. Oversized Furnace 

When it involves heating and cooling equipment, bigger isn’t always right. A bigger system warms up your residence too rapidly, creating intolerable temperature changes and short cycling. The only way to fix this situation is to request new furnace installation

If you try the fixes we mentioned here and you’re still having problems, it’s time to reach the professionals at Service Experts Heating, Air Conditioning & Plumbing. We’ll review the situation, figure out the cause, and do the necessary repair. Our aim is to restore indoor comfort, energy efficiency and trustworthy furnace performance for all season long. And our services are upheld by a 100% Satisfaction Guarantee for a year.* For more info about furnace short cycling, or to book HVAC repair, call us at 866-397-3787 right away! 


*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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