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

It’s not unheard of for heating systems to have a problem once in a while. It could be as straightforward as a bad thermostat or an electrical problem. If your gas furnace won’t turn off, here are a couple steps you can take to get a properly working furnace again.

Check the Air Filter

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

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

It can also make your furnace overheat and shut down for a time to cool off. Then it will keep duplicating this process when your furnace turns on. This is known as short cycling. In addition to wearing out your furnace more quickly, it can increase your heating bill and make your home feel unpleasant.

We recommend replacing flat filters monthly and pleated filters every three months. If you can’t remember the last time you replaced your furnace filter, pull it out and hold it up to the light. If you can’t detect 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, putting in a fresh filter should solve this common problem when your heat won’t turn off. If not, we suggest checking your thermostat settings next.

Check the Thermostat

Your thermostat runs your furnace and simply tells the unit when to turn on and off. It’s usually the problem when your furnace won’t stop running.

Sometimes having the heat turn off is as simple as changing a wrong thermostat setting.

Make Sure Your Thermostat is Set to “Auto”

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

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

“On” indicates the furnace blower will operate continuously. This constant air flow can help with heat circulation but will also drive up your power bill and lead to wear and tear on your furnace.

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

Check Your Temperature Setting

If your thermostat won’t turn off heat, compare the temperature setting to the area 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 operate much longer than normal to keep your home cozy. This is due to a big temperature difference between the cold air outside and the warm indoors.

As a test, you can try lowering the temperature to correspond with the room. Then, wait a few minutes. This should make the furnace shut off in a few minutes.

Put in Fresh Batteries

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

If your furnace won’t shut off after you move 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 places you can cut the power to your heating unit: at the breaker box and at its dedicated power switch.

    1. Head to your breaker box and find the breaker marked “furnace.” Move the breaker switch to the right to shut off power.
    1. Next, search for the specific power switch to your heating system. It looks like a light switch and is located on or near 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 correcting this problem can be as easy as changing your air filter or changing thermostat settings. In other situations, you might want a professional when your heater won’t turn off.

Fan Limit Switch Needs Replacing

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 a problem with the limit switch. Your furnace will communicate using a blinking red light on the front of your heating system.

Our Experts can identify and correct 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.

Bad Thermostat

Like anything else in your home, your thermostat can break down as time passes 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, because they develop an energy-efficient heating and cooling schedule based on your preferences. Additionally, you’ll be able to set and keep tabs on your thermostat from just about anywhere with your phone.

Leaky Air Ducts

Your furnace relies on ductwork to distribute hot air to vents across your home. If your home or ductwork is older, your furnace might be operating all the time because the ductwork is leaking hot air in the attic.

Diagnosing this leaky ductwork and other airflow issues 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 require.

Rely on Our Experts for All Your Furnace Repair Needs

Troubleshooting furnace problems can be annoying, 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 industry. You can rely 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 schedule your appointment today.

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