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

Your furnace keeps your house cozy during the frigid winter months, so it’s frustrating when something is wrong. One common issue is a furnace that continuously kicks on and switches off all the time. This operating error is called short cycling. It stresses your furnace and could lead to costly repairs or even early replacement.

Short cycling can happen for a few reasons. Before you schedule furnace repair, research the potential causes and how to resolve the problem.

1. Clogged Air Filter

The HVAC filter traps airborne dust, hair and other pollutants that could cause problems for furnace. If you don’t get a new filter frequently, it can get filthy and block the airflow. When this takes place, a safety device turns off the furnace to stop getting too warm. Check the filter, and if it’s dirty, get a new one. From now on, get a new 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 blocked air vents. For recommended system balance and performance, keep all registers open, even in unused 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 right, leading to overheating and short cycling. Routinely replacing the filter is the best approach to prevent 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 gives the furnace instructions on 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 full sunlight or near a heat source that could affect the temperature reading. If you use a smart thermostat, check the manufacturer’s site for troubleshooting guides.

5. Sooty Flame Sensor

The flame sensor turns 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 down. Leave the work of fixing a faulty flame sensor to an Expert like Golden Seal Service Experts.

6. Oversized Furnace

When it includes HVAC equipment, larger isn’t always better. A bigger system adds warmth to your house too rapidly, causing uncomfortable temperature swings and short cycling. The only way to fix this situation is to schedule new furnace installation.

If you attempt the fixes suggested here and nothing has changed, it’s time to reach the pros at Golden Seal Service Experts. We’ll take a look at the situation, diagnose the cause, and perform 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 630-246-2698 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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