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 broken thermostat or an electrical problem. If your gas furnace won’t shut off, here are a few steps you can take to get a properly working furnace again.

Check the Air Filter

A dirty air filter creates problems for many 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 increases wear and tear on your furnace, as well as the likelihood of a malfunction 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 repeating 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 uncomfortable.

We encourage replacing flat filters monthly and pleated filters every three months. If you can’t remember the last time you got a new 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 linked to a clogged air filter, replacing it with a fresh filter should fix this common issue when your heat won’t turn off. If not, we suggest checking your thermostat settings next.

Check the Thermostat

Your thermostat controls your furnace and simply informs the unit when to turn on and off. It’s usually to blame 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 has two settings, “auto” and “on,” that control your heating system’s blower motor.

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

“On” indicates the furnace blower will operate continuously. 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 set to “on,” it will sound 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 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 area temperature. If it’s higher than the room air temp, your furnace will keep operating until it reaches your desired temp.

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

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

Put in New Batteries

If you use a programmable thermostat, it’s likely battery powered. You can test replacing the batteries to see if that solves 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. Go to your breaker box and find the breaker marked “furnace.” Move the breaker switch to the right to cut power.
    1. Next, search for the specific power switch to your heating system. It looks like a light switch and is located on or close to your furnace. Move the switch down to shut off 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?

Sometimes correcting this problem can be as simple as replacing your air filter or adjusting 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 regulates your furnace’s blower motor. If the switch goes bad, it might sound like your furnace running continuously, 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 communicate through a flashing red light on the front of your heating system.

Our Experts can diagnose and fix any issues 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 over time and need to be replaced. If you’re due for a new one, ask us about installing a smart thermostat.

These thermostats make it easy to save energy, since they create an energy-efficient heating and cooling schedule according to your preferences. Plus, you’ll be able to adjust and keep tabs on your thermostat from just about anyplace with your phone.

Air Ducts Are Leaking

Your furnace relies on ductwork to circulate hot air to vents across your home. If your home or ductwork is older, your furnace might be operating all the time since 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 hidden behind walls and ceilings. Our Experts can help with diagnosing and handling any air duct repair service that you need.

Rely on Our Experts for All Your Furnace Repair Needs

Troubleshooting furnace issues can be annoying, especially when it affects 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.* Call us at to book your appointment now.

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