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

It’s not uncommon for heating systems to have a glitch every now and then. It could be as simple as a broken thermostat or an electrical issue. 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 causes problems for numerous homeowners and their HVAC system. Here’s why. It restricts airflow, making your furnace work harder and run longer to meet your ideal temperature.

This multiplies wear and tear on your furnace, as well as the odds of a breakdown and early failure.

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

We recommend replacing flat filters once a 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 dusty and you should get a new one.

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

Check Out the Thermostat

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

At times having the heat turn off is as easy as changing an incorrect thermostat setting.

Make Sure Your Thermostat is Set to “Auto”

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

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

“On” means the furnace blower will operate continuously. This constant air flow can help with heat circulation but will also increase your power bill and lead to 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 noticing. Switching it to “auto” should resolve 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, check the temperature setting to the room temperature. If it’s higher than the room air temp, your furnace will keep running until it reaches your desired temp.

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

As a check, you can try lowering the setting to match the room. Then, wait a few minutes. This should make the furnace turn off in a few minutes.

Replace the Batteries

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

If your furnace won’t shut off after you switch it to “off,” you will need to turn off 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 specific power switch.

    1. Head to your breaker box and locate the breaker labeled “furnace.” Push the breaker switch to the right to cut power.
    1. Next, look for the specific power switch to your heating system. It’s similar to a light switch and is located on or close to your furnace. Push the switch down to cut power.
    1. Your furnace should be shut off now.

If you had to switch off your system at the breaker, contact us at for professional service, as you may need 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 seem like your furnace running nonstop, even though just the blower is going.

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

Our Experts can identify and fix any problems 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.

Faulty Thermostat

Like anything else in your home, your thermostat can break down over time and need to be replaced. If you’re due 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 based on your needs. Plus, you’ll be able to set and keep tabs on your thermostat from just about anyplace with your phone.

Air Ducts Are Leaking

Your furnace uses ductwork to circulate hot air to vents across your home. If your home or ductwork is older, your furnace might be running all the time 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 diagnosing and taking care of any air duct repair service that you require.

Rely on Our Experts for All Your Furnace Repair Needs

Troubleshooting furnace issues can be inconvenient, particularly when it impacts your comfort, energy efficiency and heating bill. When it comes to furnaces, there’s a reason why we say we’re Experts in our field. You can count on our ACE-certified technicians to solve 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.