Why Does My Furnace Kick On and Off?

When your furnace kicks on and off, this is a system malfunction called short cycling. Short cycling conditions create a lot of problems for homeowners – you need to address this issue right away to prevent system damage and discomfort. Hans Heating and Air shares more information on short cycling, its causes, and how to take action.

What Is Short Cycling?

When your thermostat signals it’s time for heat in the home, your furnace fires up and runs a heating cycle, which operates for several minutes to add warmth indoors. Often, homeowners here a minor click from the thermostat when the cycle starts and stops, or may notice the sound of air flowing through the vents then coming to a stop. 

When a furnace kicks on and off too soon, this indicates a system issue. When a heating system is short cycling, the furnace kicks on and off in just a few seconds up to a minute or two after a heating cycle begins. This leads to multiple heating cycles over the course of an hour – a typical furnace runs about three to eight heating cycles in an hour, though this varies based on outdoor temperatures and the temperature you wish to maintain indoors.

What’s to Blame When a Furnace Kicks On and Off

A few different issues commonly cause furnace short cycling. Some are easily resolved with a few DIY steps, while others require an HVAC technician’s help. The top causes to blame when a furnace kicks on and off are:

  • Air filter needs changed
  • Thermostat batteries need replaced
  • Blower motor malfunctions
  • Incorrect furnace size

Time to Change Your Furnace Filter

When a furnace doesn’t receive adequate airflow, it heats up. This is commonly caused by a dirty air filter. Once high temperatures are reached within the equipment, the limit switch shuts down the heating cycle for safety reasons. Then the furnace must cool down before another cycle starts – but the issue just happens again.

If your furnace kicks on and off, the first thing you need to check is your filter. If it is dirty and covered in contaminant matter, change it and see if a fresh filter solves the short cycling issue.

Change Thermostat Batteries

If a thermostat’s batteries are dying, this issue may disrupt the signals sent to the furnace to start and stop heating cycles. Your thermostat may not read temperatures indoors correctly, and trigger the heating system to start then stop too soon. Check the thermostat batteries and replace them with fresh ones and see if this stops the short cycling.

Malfunctioning Blower Motor

While less common, sometimes a furnace fires up but the blower motor does not. The blower motor is the component responsible for pushing air through the system and into the indoor spaces. When the blower isn’t running, the heat created by the furnace quickly builds in the system, and the limit switch will end the cycle for safety.

If your furnace kicks on and off quickly, check your vents for airflow. No air during a heating cycle or a weak airstream are indicators of blower motor issues. Contact Hans for furnace repair in Montgomery, AL in this situation.

Oversized Furnace Problems

Short cycling is a tell-tale sign of a furnace that is too big for your home. Large furnaces rapidly heat the space, resulting in a shorter heating cycle. When the furnace kicks on and off quickly every time it operates, components wear out faster, leading to more frequent repairs, not to mention energy waste. The furnace needs to be replaced with the right size unit – a job for an HVAC professional.

End Short Cycling When You Call Hans

Don’t let a short cycling furnace stand in the way of your comfort this season, or cost you extra money in repairs! When your furnace kicks on and off, call Hans for quick and reliable furnace repair.

Return back to all blogs

Stay In Touch

Keep up with the latest tips and special deals - 
subscribe to our monthly newsletter.