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

It’s not unheard of for heating systems to have a glitch every now and then. 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.

Check 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 satisfy your ideal temperature.

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

It can also make your furnace overheat and shut off for a time to cool down. Then it will keep duplicating this process when your furnace switches on. This is called short cycling. In addition to wearing out your furnace more quickly, 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 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 get a new one.

If the matter was connected to a clogged air filter, putting in a clean filter should fix this common problem when your heat won’t turn off. If not, we recommend 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 often the problem when your furnace won’t stop running.

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

Make Sure 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 operate when the furnace does.

“On” indicates the furnace blower will run constantly. This constant air flow can help with heat distribution but will also increase 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 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 running until it hits 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 cozy. This is due to a big temperature difference between the cold air outside and the warm indoors.

As a test, you can try reducing the thermostat to match the room. Then, wait a couple of minutes. This should make the furnace turn off momentarily.

Put in New Batteries

If you have a programmable thermostat, it’s probably battery powered. You can try replacing the batteries to see if that resolves 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 move 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 shut off? There are two places you can cut 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’s similar to a light switch and can be found on or near your furnace. Push 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?

Occasionally fixing this problem can be as simple as replacing your air filter or adjusting thermostat settings. In other instances, you might want 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 out, it might seem like your furnace running continuously, even though just the blower is going.

You might see a furnace error code if there’s a problem 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 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.

Bad 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 simple to save energy, because they develop an energy-efficient heating and cooling schedule according to your preferences. Plus, you’ll be able to set 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 throughout your home. If your home or ductwork is older, your furnace might be operating constantly since the ductwork is leaking hot air in the attic.

Diagnosing this leaky ductwork and other airflow problems can be difficult to troubleshoot 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.

Depend on Our Experts for All Your Furnace Repair Needs

Troubleshooting furnace issues can be annoying, particularly when it impacts your comfort, energy efficiency and heating bill. When it involves furnaces, there’s a reason why we say we’re Experts in our industry. You can count on our ACE-certified technicians to resolve your problem quickly and affordably. And what’s even better, we back our HVAC system repairs with a 100% satisfaction guarantee for one year.* Contact us at to schedule your appointment now.

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