What to Do When Your Heater Won’t Turn Off!

It’s not unusual for heating systems to have a problem once in a while. It could be as simple as a broken thermostat or an electrical problem. If your gas furnace won’t turn off, here are a few steps you can take to get a correctly working furnace again.

Examine the Air Filter

A dirty air filter creates problems for numerous homeowners and their HVAC system. Here’s why. It limits airflow, making your furnace work harder and run longer to satisfy your ideal temperature.

This increases usage on your furnace, as well as the odds of a breakdown and premature failure.

It can also make your furnace get too hot and shut off for a time to cool down. Then it will keep duplicating this process when your furnace switches on. This is known as short cycling. In addition to wearing out your furnace more quickly, it can drive up your heating bill and make your home feel uncomfortable.

We recommend replacing flat filters each month and pleated filters every three months. If you can’t remember the last time you got a new furnace filter, remove it and hold it up to the light. If you can’t see light through your filter, it’s too dirty and you should get a new one.

If the matter was connected to a clogged air filter, replacing it with a new filter should fix this common problem when your heat won’t turn off. If not, we suggest checking your thermostat settings next.

Check Out the Thermostat

Your thermostat runs your furnace and basically informs the unit when to turn on and off. It’s often the problem when your furnace won’t stop running.

At times having the heat turn off is as simple as adjusting an incorrect thermostat setting.

Ensure Your Thermostat is Set to “Auto”

Your thermostat includes two settings, “auto” and “on,” that manage your heating system’s blower motor.

“Auto” means the furnace blower will only operate when the furnace does.

“On” means the furnace blower will run constantly. This constant air flow can help with heat circulation but will also increase your power bill and increase wear and tear on your furnace.

If your thermostat is switched to “on,” it will seem like your furnace is not turning off, but it’s really just the furnace blower you’re hearing. Changing it to “auto” should solve the problem. It will also help you save money on your energy costs.

Confirm Your Temperature Setting

If your thermostat won’t turn off heat, compare the temperature setting to the area temperature. If it’s greater than the room air temp, your furnace will keep operating until it hits your desired temp.

Remember that if it’s extremely cold outside, your furnace will have to operate much longer than usual to keep your home cozy. This is because of a large temperature difference between the cold air outside and the warm indoors.

As a test, you can try decreasing the thermostat to correspond with the room. Then, wait a few minutes. This should make the furnace shut off momentarily.

Replace the Batteries

If you use a programmable thermostat, it’s probably battery powered. You can test replacing the batteries to see if that resolves the issue. If it doesn’t or if there’s wiring to your electrical system, shift it to “off.”

If your furnace won’t turn off after you move it to “off,” you will need to cut the power.

Cut the Power

Thermostat seems to be working fine but your furnace still won’t turn off? There are two spots you can shut off the power to your heating unit: at the breaker box and at its dedicated power switch.

1. 1. Go to your breaker box and locate the breaker marked “furnace.” Move the breaker switch to the right to cut power.

2. 2. Next, search for the specific power switch to your heating system. It’s similar to a light switch and can be found on or close to your furnace. Push the switch down to cut power.

3. 3. Your furnace should be shut off now.

If you had to switch off your system at the breaker, call us at for professional service, as you may require furnace repair.

What Causes a Furnace to Keep Running?

Sometimes fixing this problem can be as simple as changing your air filter or changing thermostat settings. In other situations, you might need a professional when your heater won’t turn off.

Fan Limit Switch Needs to Be Replaced

The furnace fan limit switch controls your furnace’s blower motor. If the switch goes out, it might sound like your furnace running nonstop, even though just the blower is running.

You might see a furnace error code if there’s an issue with the limit switch. Your furnace will speak through a flashing red light on the front of your heating system.

Our Experts can diagnose and correct any issues you’re having with your furnace blower motor. Often this can involve replacement parts, such as the control board, faulty wiring or the fan switch itself.

Defective Thermostat

Like anything else in your home, your thermostat can wear out over time and need to be replaced. If it’s time for a new one, ask us about getting a smart thermostat.

These thermostats make it simple to save energy, since they develop an energy-efficient heating and cooling schedule according to your needs. Additionally, you’ll be able to adjust and monitor your thermostat from just about anyplace with your phone.

Leaky Air Ducts

Your furnace relies on ductwork to distribute hot air to vents throughout your home. If your home or ductwork is older, your furnace might be running constantly since the ductwork is leaking hot air in the attic.

Identifying this leaky ductwork and other airflow problems can be difficult to resolve on your own, since it’s hidden behind walls and ceilings. Our Experts can help with identifying and handling any air duct repair service that you need.

Rely on Our Experts for All Your Furnace Repair Needs

Troubleshooting furnace problems can be inconvenient, particularly when it affects your comfort, energy efficiency and heating bill. When it involves furnaces, there’s a reason why we say we’re Experts in our field. You can depend on our ACE-certified technicians to resolve your problem quickly and affordably. And what’s even better, we stand behind our HVAC system repairs with a 100% satisfaction guarantee for one year.* Call us at to book your appointment now.