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

It’s not uncommon for heating systems to have a glitch once in a while. It could be as simple as a bad thermostat or an electrical issue. If your gas furnace won’t shut off, here are a few steps you can take to get a properly working furnace again.

Examine the Air Filter

A dirty air filter creates issues for numerous homeowners and their HVAC system. Here’s why. It limits airflow, forcing your furnace to work harder and run longer to meet your desired temperature.

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

It can also make your furnace get too hot and shut down 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 faster, it can increase your heating bill and make your home feel unpleasant.

We recommend replacing flat filters each month 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 see light through your filter, it’s too dirty and you should replace it.

If the matter was connected to a clogged air filter, replacing it with a clean filter should solve 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 usually the problem when your furnace won’t stop running.

Sometimes having the heat turn off is as simple as changing an incorrect thermostat setting.

Ensure Your Thermostat is Set to “Auto”

Your thermostat has 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 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 set 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 solve the problem. It will also help you spend less 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 greater than the room air temp, your furnace will keep running until it reaches your desired temp.

Remember that if it’s very cold outside, your furnace will have to run much longer than normal to keep your home warm. 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 setting to correspond with the room. Then, wait a couple of minutes. This should make the furnace turn off in a few minutes.

Put in New Batteries

If you use a programmable thermostat, it’s likely battery powered. You can try putting in new batteries to see if that solves 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.

Turn Off the Power

Thermostat seems to be working fine but your furnace still won’t turn off? There are two spots 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 locate the breaker marked “furnace.” Push the breaker switch to the right to shut off power.
    1. Next, search for the specific power switch to your heating system. It’s similar to 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 turn off your system at the breaker, call us at for professional service, as you may need furnace repair.

What Causes a Furnace to Keep Running?

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

Fan Limit Switch Needs Replacing

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

You might notice a furnace error code if there’s a problem with the limit switch. Your furnace will speak via a blinking red light on the front of your heating system.

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

Faulty 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 installing a smart thermostat.

These thermostats make it easy 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.

Air Ducts Are Leaking

Your furnace uses ductwork to circulate hot air to vents throughout your home. If your home or ductwork is older, your furnace might be running all the time because the ductwork is leaking hot air in the attic.

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

Depend on Our Experts for All Your Furnace Repair Needs

Troubleshooting furnace issues can be annoying, especially 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 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.* Contact us at to schedule your appointment today.

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