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

Your furnace keeps your home cozy during the frigid winter months, so it’s annoying when something is off. One routine situation is a furnace that continually turns on and switches off all the time. This problem is referred to as short cycling. It strains your heating system and may cause costly repairs or even early replacement.

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

1. Filthy Air Filter

The HVAC filter attracts airborne dust, hair and other pollutants that could damage the furnace. If you don’t change the filter frequently, it can eventually be clogged and decrease the airflow. When this happens, a safety mechanism turns off the furnace to stop overheating. Inspect the filter, and if it’s dirty, replace it. From here on out, replace 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 unopened or obstructed 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 push air through the ductwork. If they are dirty, the air won’t travel right, leading to overheating and short cycling. Routinely changing the filter is the easiest method to stop a dirty blower wheel. If the blades are already dirty, request furnace maintenance to have them cleaned.

4. Faulty Thermostat

Examine your thermostat next. This is the brain of your HVAC system and tells the furnace what to do. Double-check the thermostat is on heating mode and auto fan with the desired temperature displayed on the screen. Try changing the batteries. Also, check whether the thermostat is in direct sunlight or near a heat source that could impact the temperature reading. If you have a smart thermostat, check the manufacturer’s site for troubleshooting instructions.

5. Soot-Covered Flame Sensor

The flame sensor switches off the gas valve when no burner flame going. The sensor can’t sense the flame if it’s sooty, so the gas turns off sooner and the furnace shuts down. Leave the work of fixing a dirty flame sensor to an Expert like Aramendia Plumbing, Heating and Air.

6. Oversized Furnace

When it includes heating and cooling equipment, bigger isn’t always better. A larger system heats up your residence too rapidly, leading to unpleasant temperature changes and short cycling. The only way to fix this issue is to request new furnace installation.

If you attempt the fixes we mentioned here to no avail, it’s time to call in the professionals at Aramendia Plumbing, Heating and Air. We’ll review the situation, pinpoint the cause, and do the necessary service. Our priority 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 details about furnace short cycling, or to book HVAC repair, call us at 210-404-4233 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.