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

Your furnace keeps your home warm during the harsh winter months, so it’s disconcerting when something is wrong. One frequent issue is a furnace that continually switches on and turns off over and over. This issue is referred to as short cycling. It stresses your heating system and may lead to expensive repairs or even early breakdowns. 

Short cycling can be the result of for a few reasons. Before you schedule furnace repair, consider the potential causes and how to resolve the problem. 

1. Filthy Air Filter 

The HVAC filter catches airborne dust, hair and other debris that could damage the furnace. If you don’t change the filter often enough, it can get dirty and block the airflow. When this happens, a safety mechanism switches off the furnace to avoid overheating. Inspect the filter, and if it’s dirty, get a new one. From now on, change the filter every 30 to 90 days to keep your furnace from short cycling. 

2. Blocked Air Vents 

A dirty filter isn’t the only thing that can reduce airflow and overheat your furnace. Walk around your house and check for closed or crowded air vents. For proper system balance and performance, keep all registers open, even in empty rooms. 

3. Dirty Blower Wheel 

The furnace blower consists of blades that move air through the ductwork. If they are dirty, the air won’t flow properly, causing overheating and short cycling. Routinely changing the filter is the easiest approach to stop a dirty blower wheel. If the blades are already dirty, book 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. Double-check the thermostat is in 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 direct sunlight or near a heat source that could affect the temperature reading. If you have a smart thermostat, go to the manufacturer’s site for troubleshooting tips. 

5. Soot-Covered Flame Sensor 

The flame sensor is responsible for turning off the gas valve when no burner flame on. The sensor can’t find the flame if it’s sooty, so the gas turns off too soon and the furnace shuts off. Leave the job of cleaning a faulty flame sensor to a professional like Stallion Heating and Air Conditioning. 

6. Oversized Furnace 

When it involves heating and cooling equipment, oversized isn’t always better. A larger system adds warmth to your home too fast, leading to unpleasant temperature swings and short cycling. The only way to resolve this issue is to schedule new furnace installation

If you try the solutions we mentioned here and nothing has changed, it’s time to reach the professionals at Stallion Heating and Air Conditioning. We’ll examine the situation, diagnose the cause, and do the necessary work. Our priority is to bring back indoor comfort, energy efficiency and trustworthy furnace performance for the rest of the season. And our services are upheld by a 100% Satisfaction Guarantee for a year.* For more information about furnace short cycling, or to request HVAC repair, give us a call at 215-259-5850 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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