Why Won’t My Furnace Stay On?


The click of your furnace kicking on in the fall and winter months is a reassuring sound, letting you know that it may be cold outside, but inside, your home will stay toasty warm. But as soon as it starts, it kicks off again. At first you don’t think anything about it, but you notice it continuing to happen. When your furnace turns on and off in short bursts, this is called “short cycling.” It’s a common issue for homeowners, and our heating and air conditioning repair company in Garner is going to walk you through what the problem might be and how you can fix it.

Lack of Airflow Causes Furnace Short Cycling

One of the biggest issues that causes your furnace to short cycle is a lack of airflow. If the furnace can’t pull air into the heat exchanger, it can overheat, triggering the temperature sensor and tripping the high limit switch to keep the furnace from overheating. The good news is that it’s generally easy to determine why your furnace isn’t getting proper airflow, and you can check with these measures:

  • Check your air filter – Your filter prevents dirt, dust, and dander from clogging up your furnace, but if you don’t change or clean the filter regularly, air can’t circulate into the exchanger, causing it to short cycle.
  • Check the return vents – Make sure there’s nothing blocking air flow into your return vent, like a piece of furniture or curtains.

If overheating is causing your furnace to kick off and on, you’ll want to reach out to a furnace repair company immediately because overheating can lead to cracks in the heat exchanger and leak carbon monoxide into your home.

Check Your Thermostat

Your thermostat sends the signals to your furnace letting it know when it’s time to get to work, so it may be the cause of your heat’s short cycling. However, there are many things that could be going on with your thermostat, including:

  • Check your temperature setting – Your furnace kicking off and on could simply be because it doesn’t have far to go to reach the programmed temperature. If it’s programmed or a smart system, make sure the setting is updated to reflect your home’s current needs.
  • Thermostat is too warm – If your thermostat is in a sunny, warm area of the house, it’s not getting the opportunity to cool down enough to send the signal that it’s time to kick on. If you see a sunbeam landing on it, or there’s a lamp right under the sensor, it may be time to find a new spot for it or minimize the heat of that location.
  • Batteries may be dying – If the batteries are going out, it may be causing the signals to not get sent properly, so try changing them and see if that fixes the issue.

If these don’t fix the short cycling issue, it may still be a problem with the thermostat, such as a short or other issue, but that would most likely require diagnostics from a professional furnace repair technician.

Furnace Blower Is Malfunctioning

If you hear the furnace kick on, but nothing happens after that, it may not be short cycling, but there is simply no heat being pushed out of the furnace. This is most likely due to the blower malfunctioning in your heating unit and will need to be fixed or replaced by a professional.

The Furnace Is Too Large

A furnace that’s too big for your house will put out heat faster than your house really needs. It will run for two minutes or so, then it will turn off simply because it hit the desired temperature. This isn’t efficient for your home and could lead to the unit wearing out more quickly than a properly-sized system. Having a furnace that’s too large is typically a problem that is discovered either after you’ve recently purchased a new heating system or bought a home and have only recently turned on the heat.

Contact Our Furnace Repair Company in Garner

If your furnace is kicking off too fast, and changing the filter or the thermostat batteries aren’t fixing the problem, it’s time to reach out to our heating repair company in Garner. Short cycling can wear out your system and overwork core components, leading to a more intensive repair. Our experienced, NATE-certified repair professionals will get to the core of what’s wrong with your system, whether it’s a simple repair or a more complicated malfunction, and get it working again quickly with a reliable, effective solution. Call us at 919-772-2759 or fill out our form below to schedule service, today!