It’s mysterious and concerning when the furnace won’t turn off, but this issue usually has a simple explanation. Here are four explanations that’ll help you and other Kildeer, IL, residents solve the mystery.

Problems With the furnace Fan Limit Switch

An electrical malfunction in the fan blower can prevent the thermostat from communicating with the furnace. A faulty limit switch or the “always running” manual override setting causes this malfunction. If the limit switch has a faulty wire or an incorrect setting, the blower will ignore the thermostat’s command to turn off after the burners have cooled.

The fan won’t cycle off until you rewire or reset the limit switch. Constant operation could damage the heat exchanger and cause a breakdown. So, you must address this issue immediately with professional rewiring and furnace repair.

Loss of Power to the Furnace Thermostat

Loss of power prevents a thermostat from communicating with the HVAC system. Old batteries cause a thermostat to constantly lose power, which prevents it from sending the shutoff command. Change your thermostat’s batteries every few months.

Thermostat Damage or Malfunction

Damage, dust accumulation and non-calibration confuse the thermostat’s internal sensors, causing mixed signals between the device and the heating system. This makes it so the heating system won’t turn off after it receives the signal or may perform another action.

Incorrect Furnace Thermostat Setting

Certain thermostat settings make your furnace run continuously. For example, if your system is set to “On” instead of “Auto,” the fan won’t turn off no matter what temperature your home reaches. The “On” setting is only effective in temporary situations.

Continuous furnace operation damages the fan motor, blower and heat exchanger, reduces energy efficiency and increases energy bills. However, sometimes the heater runs continuously because it can’t reach the set temperature. In this case, your system likely needs professional furnace maintenance from Martin Enterprises Heating and Air Conditioning, so give us a call today.

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