My Furnace Won’t Turn Off – Why?

image of homeowner adjusting programmable thermostat since furnace won't turn off

Furnaces present homeowners with reliable and dedicated heating services for many years. However, the systems aren’t infallible and could experience some issues. A typical heating problem is when the furnace won’t turn off as expected. Reviewing common problems helps determine when to hire an HVAC professional for heating system services. In this article, we discuss some common causes and solutions for a furnace that won’t shut down.

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Furnace Won’t Turn Off: Causes & Solutions

Keep reading to explore more about this heating system issue.


A simple thermostat issue that prevents the furnace from shutting down, especially if the thermostat is set to ON instead of AUTO. Under the circumstances, you can adjust the switch to AUTO.

Wrong Temperature Setting

thermostat settings for hvac system

A furnace will continue running without shutting off if you set the thermostat at a temperature that is unnecessarily too high. Suppose the problem is that the temperature setting is too high. In that case, you can consult an HVAC professional about appropriate temperature settings for your unit. Many homeowners believe setting the thermostat higher than necessary will heat the home faster.

Unfortunately, all this practice does is run up energy costs. If the homeowner forgets to lower the temperature, it could become too hot in their home. The furnace’s temperature setting shouldn’t exceed 75 degrees in most areas.

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Damaged Thermostat Wiring

The component could have damaged wiring if the thermostat is over ten years old. Pest infestations, such as rodents in the walls, could also damage wires that connect to the thermostat. A wiring inspection by an HVAC professional reveals if there is any existing wiring damage.

You should never attempt to test or repair your thermostat’s wiring as it is dangerous. If you complete the task incorrectly, you could damage the component and prevent it from ever operating again. The thermostat wiring connects to your home’s wiring system. It could cause electric shock or electrocution if you come in contact with it.

Air Filters

image of a dirty furnace filter and hvac air filter replacement

Dirty or clogged air filters cause the furnace to run continuously. Changing out the air filter as needed prevents this issue. However, if the air filter isn’t easily accessible, contact an HVAC professional to help change the filter. Consulting an HVAC provider about the correct filter size improves airflow. In addition, it ensures that you use the right air filter for your system.

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Related Article: Top Signs Your Furnace Is Overheating

The Furnace Relay Switch

A furnace that won’t shut off is a sign that the relay switch needs resetting or the switch has become stuck. An HVAC technician can assess the switch, reset it, or replace a stuck relay switch to improve the furnace’s performance.

Another relay switch problem is when the contacts arc weld themselves and become pitted. The issue prevents the contacts from opening correctly and shutting down the furnace as expected. A sign that this has happened is if you see a spark inside the furnace.

Furnace Gas Valve

gas furnace repair

Over many years of use, the gas valve could become stuck. When the valve is stuck, the furnace continues burning propane or natural gas and produces heat. Even though the furnace has been shut down, heated air circulates through the home, and temperatures increase. As a result, your home could become too hot regardless of the current temperature settings.

If this issue accompanies a gas leak, dangers to you and your family are imminent. A higher flow of gas through the system could cause higher gas costs, but there is a greater risk of fires, explosions, and carbon monoxide risks. Contact an HVAC technician to quickly correct this gas valve issue and protect your family and home.

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Related Article: Why Does My Furnace Pilot Light Go Out After Heating?

Leaky Air Ducts

hvac technician repairing leaky ductwork

Leaky air duct indicators start with uneven heating in the home, and each room becomes a different temperature without consistent heating services. Next, you’ll notice a higher accumulation of dust in your home. And finally, sudden and unexplainable increases in energy costs reveal that the ductwork is damaged, leaking, or requires replacement.

These problems happen because of ductwork that is the wrong size for the heating unit or the home. Pests or animals that break into the ductwork to build dens for reproduction cause air leaks and heat loss. The best way to manage these problems is to contact an HVAC provider for an inspection and replace or set up repairs as needed.

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How to Reduce Common Furnace Problems

There are essential steps to follow to decrease furnace problems. Hiring an HVAC professional to complete these services ensures that they are completed correctly and don’t nullify your warranty. All maintenance and repair services must follow the manufacturer’s instructions in the product warranty. In addition, an HVAC professional is trained to perform the services correctly the first time.

Annual Heating Maintenance Services

image of an hvac contractor performing a gas furnace repair

Setting up annual heating maintenance services helps you find problems before you start your furnace for the season. The technician completes inspections and tests all the components in the heating systems. They inform you if there are any existing problems and recommend repairs. If the system is too old, they suggest you replace it with an updated, more energy-efficient heating system.

During an HVAC tune-up, HVAC technicians open up the entire furnace and give it a thorough cleaning. All dust and debris on the components are removed to provide a fresh and clean system. Adding ductwork cleaning addresses debris in the ductwork, registers, and vents.

During seasonal cleaning services, the service provider changes out the air filter and removes any debris around it. They’ll also check the air filter size and tell you how frequently to change out the air filters.

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Addressing Heating Problems Promptly

Contact your preferred heating service provider at the first sign of any furnace problem. Fixing issues faster lessens wear and tear on the heating system and prevents other components from failing prematurely. In addition, if you set up heating inspections and repairs sooner, it will save you time and money.

Constantly running furnaces present many problems for homeowners, and professional HVAC services are critical to maintaining the systems. Several issues prevent a furnace from shutting down as expected, which drives up heating costs. Contact an HVAC professional and schedule a service appointment at the first sign of these issues.

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McAllister Energy

McAllister Energy offers high-quality HVAC services in Camden County, New Jersey. We hire only the best, professionally certified technicians who conduct superior heating and cooling services. Some of our HVAC services include HVAC maintenance, heating and cooling installations, repairs, ductless systems, energy audits, and much more. All our techs provide accurate HVAC services on time, every time.

Our company guarantees affordable heating and cooling service rates. Our maintenance services can increase your home’s comfort, energy efficiency, and cost-effectiveness. We can also provide you with a highly energy-efficient HVAC replacement system that fits your budget. Your satisfaction is important to us, so all our work comes with a guarantee. Book a service appointment with McAllister Energy today. We provide free, in-home estimates.

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