Here's Why Your Furnace Won't Turn Off


The short answer is your furnace won’t turn off due to some kind of error or malfunction within your furnace, thermostat, or HVAC system. It could be the wrong thermostat setting is being used, a clogged air filter or your thermostat itself is no longer working properly.

When you have a heating system not shutting off, this issue makes it difficult to maintain the desired temperature inside the home. Your furnace or heating unit is likely wasting energy, and this problem could raise your heating bills.

When you experience problems with the furnace inside your home, you can always give us a call at Williams Comfort Air for Indianapolis furnace repair service. However, this particular heating issue is sometimes solvable without professional HVAC repair. Our technicians share the reasons why your gas furnace keeps running and doesn’t shut off, as well as what you can do to fix minor issues without calling for service. Year-round, trust our team of NATE-certified heating and air conditioning technicians to stop your HVAC problems and make your home more comfortable.

Why Your Heating Unit Keeps Running and Doesn’t Turn Off

When a furnace or heater continues to run and doesn’t stop when the room reaches your desired temperature, or it runs longer than expected, a few issues could be the problem.

Improper Thermostat Setting

If it is getting too hot in your home and your furnace is still running, the problem may be simpler than a broken system. Someone else in the home may turn the thermostat setting up without your knowledge, setting the heat well above your desired temperature. Make sure the thermostat is set properly before looking into more complex issues.


Check the Thermostat Controls Setting for the Temperature

Make sure the thermostat is set according to your preferences and not too hot, as you may need to adjust the temperature down.

Try to Switch the Temperature Setting Below the Current Room Temperature

This should trigger your furnace or heater to turn off. See that it does cause the heating equipment to stop, then set the temperature properly according to your preferences.

Incorrect Fan Settings

Sometimes, the furnace or heater isn’t actually running, but it sounds as if it is because the furnace blower motor continues to run. If this is the issue, you need to check the fan switch on the thermostat to make sure the correct fan setting is in use – you may need to switch it.

It is likely that the fan has been set to run all the time rather than only during a heat cycle. The blower is capable of running independently of the furnace or air conditioner, but you typically want to use the setting that only allows it to run with your HVAC unit to save energy and better control room temperature.

Check Your Thermostat Settings for the Fan

Your thermostat may have a toggle switch to adjust the fan settings between ON and AUTO, or this setting may be adjusted on the display if you have a digital thermostat.

Make Sure the Thermostat Is Set to the AUTO Fan Setting

This setting allows the blower fan to run only as the furnace heats. With the ON setting, the blower fan runs around the clock and will blow cool air into your home when the heat is not on, which can disrupt the temperature and waste energy. 

Dirty Air Filter


The job of your thermostat is to read the room temperature and communicate heating needs to the furnace or heating unit. For example, the thermostat reads cold air is present and is below the desired temperature setting; therefore, hot air flow needs to be produced, and the furnace turns on.

If there is a problem with the thermostat, it may not communicate properly and make your furnace to endlessly run and heat the home. A loose wiring connection is one of the common causes of problems with thermostats, and you may need to tighten the wiring.

  1. Turn off power to your furnace or heater at the circuit breaker.
  2. Remove the thermostat cover to access its wiring panel.
  3. Check the thermostat wiring connections to see if any are loose. Tighten wiring connections with a screwdriver.
  4. Replace the thermostat cover and restore power to your heating unit.

It may be possible for a professional to fix the issue if you cannot, but thermostat replacement may need to be replaced through repair services from your HVAC contractor. Occasionally, sensors will go bad, or a switch will break. In this case, you are due for a thermostat upgrade – your technician can help you select a unit that offers the energy efficiency and control you desire.

When You Need to Call For Furnace Repair

Some issues that cause a furnace or heat pump to continue running and fail to turn off cannot be corrected through simple troubleshooting. A faulty limit switch or compressor contact within the heat system can cause this issue, which require professional repair to fix the system properly.

If you have tried each step above and your furnace is still running, trust Williams Comfort Air to get your furnace working properly. Our certified HVAC technicians are standing by to service you. Give us a call or schedule repair services online.

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