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

Your furnace keeps your family cozy during the harsh winter months, so it’s frustrating when something is wrong. One frequent issue is a furnace that continuously kicks on and shuts back off over and over. This problem is known as short cycling. It strains your heating system and may cause pricey repairs or even earlier than normal breakdowns.

Short cycling can be the result of for varying reasons. Before you schedule furnace repair, read about the probable causes and how to fix the issue.

1. Clogged Air Filter

The HVAC filter attracts airborne dust, hair and other substances that could wreak havoc on furnace. If you don’t change the filter regularly, it can eventually be clogged and reduce the airflow. When this takes place, a safety device turns off the furnace to avoid overheating. Pull Out the filter, and if it’s dirty, replace it. Going forward, change the filter every 30 to 90 days to prevent your furnace from short cycling.

2. Blocked Air Vents

A dirty filter isn’t the only thing that can restrict airflow and overheat your furnace. Walk around your home and be on the lookout for for closed 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 push air through the ductwork. If they are dirty, the air won’t flow properly, causing overheating and short cycling. Regularly putting in a new the filter is the best method to avoid a dirty blower wheel. If the blades are already dirty, request 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 on heating mode and auto fan with the desired temperature showing on the screen. Try replacing the batteries. Also, check whether the thermostat is in direct sunlight or near a heat source that could influence the temperature reading. If you use a smart thermostat, go to the manufacturer’s site for troubleshooting tips.

5. Dirty Flame Sensor

The flame sensor switches off the gas valve when no burner flame going. The sensor can’t detect the flame if it’s coated in soot, so the gas turns off sooner and the furnace turns off. Leave the job of fixing a sooty flame sensor to an Expert like San Antonio Air Service Experts.

6. Oversized Furnace

When it includes HVAC equipment, bigger isn’t always best. A larger system adds warmth to your residence too quickly, causing intolerable temperature swings and short cycling. The only way to take care of this situation is to request new furnace installation.

If you go through the fixes we went over here and you’re still having problems, it’s time to contact the professionals at San Antonio Air Service Experts. We’ll examine the situation, diagnose the cause, and provide the necessary work. Our goal is to reintroduce indoor comfort, energy efficiency and reliable furnace performance for all season long. And our repairs are supported by a 100% Satisfaction Guarantee for a year.* For more details about furnace short cycling, or to schedule HVAC repair, give us a call at 210-570-9705 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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