Why Won’t My Furnace Turn Off?

Your furnace is designed to come on when the temperature inside your house drops below the level that you program into your thermostat. Once the desired comfort level is achieved, the furnace should automatically turn off. If your furnace stays on or the blower motor continues to run, your system is experiencing a problem that requires immediate attention. A malfunctioning furnace or blower wastes energy, which can significantly increase your utility bill.

The Furnace Will Not Stop Running

One of the first things you should check is the temperature that is programmed into the thermostat. It may have been accidentally set too high. You should also check your filters. When filters are clogged, they restrict the movement of air through the system, preventing warm air from reaching the thermostat and stopping the unit from turning off as designed. Leaky ductwork permits conditioned air to seep inside walls, and insufficient insulation permits the loss of warm air generated by your furnace. Both situations can cause the unit to run continuously.

Another potential issue is that the limit switch could be defective. This component turns the heating element on and off in response to signals that it receives from the thermostat. If this part is malfunctioning, it must be replaced.

In order to control the furnace properly, the wires in the thermostat must be attached to the correct terminals. The thermostat could also be malfunctioning, wired incorrectly or require calibration.

An undersized furnace must run longer to warm your home, especially when the outdoor temperatures are extremely cold. Undersized equipment does not have the ability to produce enough BTUs to properly heat a space.

Furnace Blower Will Not Turn Off

You may also encounter a situation in which the heating element turns off, but the blower motor continues to run. The blower circulates air, which gives the impression that the furnace is running even though it is not producing heat.

Check the settings on your thermostat. The fan may be set in the "On" position. While this position uses more energy, it can create a more comfortable environment by circulating warm air. If you do not want the fan to run continuously, reposition the switch to the "Auto" setting. Another potential reason that the furnace blower runs continuously is a faulty control switch.

If none of the troubleshooting tips serves to solve your furnace concerns, be sure to contact a heating professional for assistance. Tempco Heating & Air Conditioning has been serving Naperville, Palatine , Arlington Heights and other nearby communities for more than 20 years.