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

Your furnace keeps your you comfortable during the chilly winter months, so it’s annoying when something is wrong. One routine complaint is a furnace that continually switches on and shuts back off over and over. This problem is known as short cycling. It stresses your heating system and could cause costly repairs or even premature failure.

Short cycling can be the result of for a few reasons. Before you book furnace repair, research the potential causes and how to take care of the problem.

1. Dirty Air Filter

The HVAC filter traps airborne dust, hair and other substances that could wreak havoc on furnace. If you don’t get a new filter often enough, it can eventually be clogged and block the airflow. When this happens, a safety mechanism switches off the furnace to stop getting too warm. Check the filter, and if it’s dirty, replace it. Going forward, get a new filter every 30 to 90 days to stop your furnace from short cycling.

2. Blocked Air Vents

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

3. Dirty Blower Wheel

The furnace blower uses blades that distribute air through the ductwork. If they are caked with dirt, the air won’t travel properly, causing overheating and short cycling. Frequently replacing the filter is the best way to avoid a dirty blower wheel. If the blades are already dirty, book furnace maintenance to have them cleaned.

4. Faulty Thermostat

Inspect your thermostat next. This is the cortex of your HVAC system and gives the furnace instructions on what to do. Double-check the thermostat is on heating mode and auto fan with the desired temperature showing on the screen. Try changing the batteries. Also, check whether the thermostat is in bright 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 guides.

5. Dirty 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 covered in soot, so the gas turns off prematurely and the furnace shuts down. Leave the work of cleaning a sooty flame sensor to a professional like Norrell Service Experts.

6. Oversized Furnace

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

If you go through the solutions we mentioned here and you’re still having issues, it’s time to call in the pros at Norrell Service Experts. We’ll examine the situation, diagnose the cause, and provide the necessary service. Our goal is to bring back indoor comfort, energy efficiency and dependable furnace performance for all season long. And our repairs are upheld by a 100% Satisfaction Guarantee for a year.* For more info about furnace short cycling, or to schedule HVAC repair, call us at 205-267-0023 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.

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