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

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

Check the Air Filter

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

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

It can also make your furnace overheat and shut down for a time to cool down. Then it will keep repeating this process when your furnace switches on. This is called 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, remove it 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 linked 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 Out the Thermostat

Your thermostat runs your furnace and simply tells 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 includes 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 run constantly. 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 noticing. 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 area temperature. If it’s greater than the room air temp, your furnace will keep operating until it reaches your desired temp.

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

As a test, you can try lowering the temperature to match the room. Then, wait a couple of minutes. This should make the furnace shut off momentarily.

Replace the 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 problem. 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 set it to “off,” you will need to turn off the power.

Cut the Power

Thermostat appears to be working fine but your furnace still won’t shut off? There are two places you can shut off 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, look for the specific power switch to your heating system. It looks like a light switch and can be found on or near your furnace. Move the switch down to shut off 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 require furnace repair.

What Causes a Furnace to Keep Running?

Occasionally correcting this problem can be as easy as replacing your air filter or changing thermostat settings. In other situations, you might want 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 out, it might sound like your furnace running nonstop, even though just the blower is running.

You might notice a furnace error code if there’s a problem with the limit switch. Your furnace will communicate via a flashing 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. Sometimes 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 it’s time for a new one, ask us about getting a smart thermostat.

These thermostats make it easy to save energy, because they create an energy-efficient heating and cooling schedule according to your needs. Plus, you’ll be able to set 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 operating all the time since 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 concealed behind walls and ceilings. Our Experts can help with identifying and taking care of 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 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 now.

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