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

It’s not unusual for heating systems to have a glitch every now and then. It could be as straightforward as a broken thermostat or an electrical issue. If your gas furnace won’t shut off, here are a couple steps you can take to get a correctly working furnace again.

Examine the Air Filter

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

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

It can also make your furnace overheat and shut down for a time to cool off. 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 faster, it can increase your heating bill and make your home feel uncomfortable.

We encourage 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, 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 replace it.

If the matter was connected to a clogged air filter, putting in a clean 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 a wrong 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 run when the furnace does.

“On” means the furnace blower will operate constantly. 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 shutting off, but it’s really just the furnace blower you’re noticing. Changing it to “auto” should solve the problem. It will also help you spend less money on your energy costs.

Check Your Temperature Setting

If your thermostat won’t turn off heat, check the temperature setting to the area temperature. If it’s greater than the room air temp, your furnace will keep operating 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 big temperature difference between the cold air outside and the warm indoors.

As a check, you can try lowering the thermostat 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 have a programmable thermostat, it’s probably 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 shut off after you move it to “off,” you will need to cut the power.

Turn Off the Power

Thermostat seems to be working fine but your furnace still won’t shut 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. 1. Head to your breaker box and find the breaker labeled “furnace.” Move the breaker switch to the right to cut power.

2. 2. 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. Move the switch down to shut off power.

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

If you had to turn 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 easy as changing your air filter or changing thermostat settings. In other instances, you might need a professional when your heater won’t shut off.

Fan Limit Switch Needs Replacing

The furnace fan limit switch regulates 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 blinking red light on the front of your heating system.

Our Experts can identify and correct 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.

Defective Thermostat

Like anything else in your home, your thermostat can break down as time passes 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, because they develop an energy-efficient heating and cooling schedule according to your needs. Additionally, you’ll be able to adjust and keep tabs on 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 all the time because the ductwork is leaking hot air in the attic.

Diagnosing this leaky ductwork and other airflow issues can be challenging to resolve on your own, since it’s concealed behind walls and ceilings. Our Experts can help with diagnosing and taking care of any air duct repair service that you need.

Rely on Our Experts for All Your Furnace Repair Needs

Troubleshooting furnace problems can be annoying, 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 solve your problem quickly and affordably. And what’s even better, we back our HVAC system repairs with a 100% satisfaction guarantee for one year.* Call us at to book your appointment now.