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 broken 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.

Check the Air Filter

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

This multiplies wear and tear on your furnace, as well as the likelihood of a breakdown and premature 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 turns 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 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, remove it and hold it up to the light. If you can’t detect 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 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 basically 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 easy as adjusting an incorrect thermostat setting.

Ensure 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 run when the furnace does.

“On” means the furnace blower will operate constantly. This constant air flow can help with heat distribution but will also drive up your power bill and increase 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. Changing it to “auto” should solve the problem. It will also help you save money on your energy costs.

Confirm Your Temperature Setting

If your thermostat won’t turn off heat, compare the temperature setting to the area temperature. If it’s greater than the room air temp, your furnace will keep operating until it hits your desired temp.

Remember that if it’s very cold outside, your furnace will have to run much longer than usual to keep your home cozy. This is due to a big temperature difference between the cold air outside and the warm indoors.

As a check, you can try reducing the setting 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 probably battery powered. You can test replacing the batteries to see if that solves the problem. 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 set it to “off,” you will need to turn off the power.

Turn Off the Power

Thermostat appears 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 specific power switch.

    1. Head to your breaker box and locate the breaker labeled “furnace.” Push the breaker switch to the right to cut power.
    1. Next, look for the dedicated power switch to your heating system. It looks like a light switch and is located on or close to your furnace. Push 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 need furnace repair.

What Causes a Furnace to Keep Running?

Sometimes fixing this problem can be as simple as replacing your air filter or adjusting thermostat settings. In other situations, you might need a professional when your heater won’t turn off.

Fan Limit Switch Needs to Be Replaced

The furnace fan limit switch controls 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 a problem with the limit switch. Your furnace will speak using a flashing 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. Sometimes this can involve replacement parts, like the control board, faulty wiring or the fan switch itself.

Bad Thermostat

Like other things in your home, your thermostat can wear out 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, because they develop an energy-efficient heating and cooling schedule according to your preferences. Plus, you’ll be able to adjust and monitor 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 running all the time since the ductwork is leaking hot air in the attic.

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

Depend on Our Experts for All Your Furnace Repair Needs

Troubleshooting furnace problems can be inconvenient, 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 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.* Contact us at to schedule your appointment today.

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