Before You Panic – Here’s Why Your Furnace Won’t Turn Off

During the winter, you want your furnace to be blowing hot air. However, if your furnace is overactive, it can create problems for your home.

Your heating system should run through a natural cycle, turning on and off regularly. But if your furnace won’t turn off, it can lead to damage and costly repairs.

Why the Heater Won’t Turn Off

There are several reasons why your furnace won’t shut off. Many times, the thermostat is the culprit. It may be set too high or at the wrong temperature, or it may have damaged wiring. If that is the case, your furnace might not automatically shut off.

Other reasons your furnace does not turn off when the desired temperature is reached might include:

  • Dirty furnace filters
  • Leaky air ducts
  • Bad furnace blower motor
  • Electrical sensor issues

Continue reading to learn a few troubleshooting tips. These can help solve your furnace problem or let you know when to call in the professionals.

Check the Thermostat Setting

When your furnace won’t shut off after reaching the temp you set it at, the first thing you can do is check the thermostat. If it is set to ON, try switching it to Auto. This will signal the fan to shut off when the room reaches the desired temperature.

Another issue could be the desired temperature setting. If it is too high, your furnace might struggle to keep up. A setting of 80 degrees puts stress on any type of furnace, especially in a big house or in winter weather.

The last thing to check is the current temperature of your home. If it is below the set temperature, your furnace may be working too hard or have a clogged air filter. If your furnace can’t heat your home to a reasonable temperature, you may have a more severe problem and need to call the professionals.

Check for Clogged Air Filters

A clogged air filter might contribute to why your furnace won’t turn off. Air filters help regulate the furnace’s air supply. They cause your furnace to overwork when they’re dirty.

When the furnace turns on, the return ducts begin circulating the air to heat your house. These ducts send air through the filters, removing dirt, dust, and other harmful particles. When a filter is clogged, your furnace cannot get the needed air supply. It works harder to make up for the lack of air, becoming less effective as the air filter becomes dirty.

An air filter should be changed at least once every three months. If your air filter is dirty or clogged, you can change it and wait an hour to see how your furnace responds.

If you would like help choosing and replacing an air filter, or if changing your air filter doesn’t solve the problem, call an HVAC technician near you for help.

After a Power Outage

If you’ve recently lost power, your furnace might not kick back on immediately. You should check that the thermostat is in heating mode and at an appropriate temperature. If that doesn’t work, check the circuit breaker. A power outage might have caused the breaker to trip.

The last thing to try is resetting the furnace. Locate the reset button and press it to ensure the furnace is ready to run again.

When to Call the Professionals

Any problem that extends beyond switching the thermostat setting and changing dirty air filters requires the attention of an HVAC professional.

Broken Fan Blower Motor

Every furnace has a fan that gets its power from a motor. The fan pulls in the cool air moving through your home and pushes out heated air to make your home a comfortable temperature.

Like a car, these motors can have mechanical failures that cause them to run incessantly. The problem is usually caused by a faulty fan limit switch, which tells your furnace fan when it is time to switch off. An HVAC expert can repair issues with your blower motor, typically by installing a new switch or fixing the wiring.

Malfunctioning Thermostat

Sometimes the furnace won’t shut off even when the thermostat is off! This can be the result of a faulty or broken relay switch.

With age, the wiring in a thermostat can malfunction. The wiring that usually signals the furnace to shut off can short-circuit or wear out. This problem involves electricity and is best left to an expert.

Leaks in the Ductwork

If your heating won’t turn off and runs for a long time, the problem could be leaky ductwork. Your home has two types of ductwork: supply and return. Supply ducts move warm air through your home, while return ducts pull cool air into the furnace to be heated.

Any leak in the supply duct allows heated air to escape, leaving your home feeling cold. Your home will never reach the desired temperature, forcing your furnace to constantly run to heat your home.

Call TSS Home Comfort for Furnace Repairs

If your furnace won’t shut off, it’s essential to hire a licensed technician to make any necessary repairs. A skilled professional will know the ins and outs of your HVAC system and quickly work to restore your comfort.

For quality work by trusted technicians, call TSS Home Comfort when your furnace won’t turn off, is blowing cold air, or won’t heat your home to your desired temperature.