Why Does My Furnace Keep Running?

Jan 26, 2020 | Blog, Furnace, Heating, Winter

Anyone would be concerned if their furnace wasn’t working the way it should be when winter weather arrives. It’s never a good idea to ignore your HVAC system until there’s a problem. Preventive maintenance is important. Before the onset of the cold-weather season, give Xenia Heating & Air a call and schedule an appointment to have one of our fully trained and licensed HVAC technicians conduct a comprehensive inspection and cleaning of your entire HVAC system. That way, you will know your system is ready to face whatever the winter weather has in store, and that it will be able to keep your home and your family warm and toasty all season long. The term “short-cycling” refers to your furnace running for a few minutes and then shutting off again repeatedly. Short-cycling means that your furnace is not completing its full operating cycle. This indicates that there is a problem with your HVAC system. There are several reasons this may happen.


Reasons Why Your Furnace Won’t Stop Running

Your Thermostat Has Been Changed To A Higher Setting 

You may not even think of this because it’s an easy issue to correct. It is also the most common reason for short cycling. If the temperature setting on your thermostat is turned up, it will cause the furnace to come on more than usual. When you realize your furnace is running more than usual, check the setting on your thermostat first. If it is something this simple, then you will be relieved that it isn’t a more serious issue. Adjust your thermostat down to a lower temperature setting and see if it operates run normally again. If it continues to short-cycle, then another problem exists. 


The Air Filter Is Clogged With Dirt 

When the furnace’s air filter becomes clogged with dirt, the airflow through it is restricted. Your furnace will short cycle because it is trying to work and warm your home properly. The restricted airflow keeps the furnace’s heat exchanger from getting adequate air, resulting in the heat exchanger becoming overheated. The furnace’s fan will run nonstop, blowing cold air to cool down the heat exchanger. This can be easily corrected. It is also easy to avoid. Simply check and replace your air filter before the cold-weather season arrives. This may fix the problem. Keeping a clean air filter in your furnace at all times is essential to the performance and longevity of your HVAC system. Mark your calendar as a reminder to check the air filter once a month during the time your system is being used the most and replace it at least one time during the season. 


The Fan Switch is In The ‘On’ Position 

There is a switch on your thermostat that has two settings marked ‘Auto’ and ‘On.’ The switch controls the fan located inside the furnace. When the switch is in the ‘On’ position, the furnace’s blower will run nonstop. This is a waste of energy as well as an added strain on your HVAC system. The constant activity can result in your furnace becoming overworked and overheated, which could damage your entire HVAC system. Switch the fan setting over to ‘Auto.’ This will keep the furnace’s fan working only when it needs to circulate warm air into your home. 


A Faulty Fan Limit Switch 

Your furnace will short cycle if the fan limit switch becomes defective, such as if a short develops in the wiring or if the switch simply becomes worn out. The fan limit switch is underneath the hood of your furnace. Its purpose is to control the furnace’s blower. The fan limit switch contains a device that acts as a probe. This probe-type device turns the fan on of the burner assembly begins to overheat. Once it has cooled down, the probe shuts the fan off again. If either the limit switch or the probe becomes damaged or stuck in the ‘On’ position, then the furnace’s blower will run continuously. Call us for help, and one of our professional HVAC technicians will locate and repair the problem with your furnace right away. 


An Extinguished Pilot Flame 

Short cycling combined with cold air coming through your heating vents could mean that the furnace’s pilot light has been extinguished. If this happens, the furnace will run endlessly in an attempt to heat your home properly. If you know how to re-light the pilot light and feel comfortable doing so, you can re-ignite the flame on your own. However, if you would like to have a professional deal with the issue, feel free to call us, and we will be happy to send one of our HVAC technicians to light it for you. 


Still Need Help With Your Furnace?

If your furnace is short-cycling, call Xenia Heating & Air at 937-708-8451 or visit our website at https://www.xeniaheatingandair.com/schedule-now/. We will set up an appointment for you at your convenience with one of our skilled HVAC specialists. Our technician will find the problem and correct it quickly. We are available 24 hours a day, seven days a week, 365 days a year to help with all of your HVAC needs and to answer all of your questions.