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What Can Cause a Furnace to Stop Working

Aug 22, 2022Furnace Repair

What Can Cause a Furnace to Stop Working?

When a furnace filter becomes clogged, the furnace may shut off. Dirty filters often cause furnace problems. Occasionally, dust and dirt will obstruct the airflow, causing the heat exchanger to overheat. Additionally, your house won’t be heated if the exchanger shuts down too soon.

Here’s a list of the most common problems that can cause the furnace to stop working:

Thermostat Is Set to Off

The thermostat controls heat in your home. If your furnace’s settings have been changed or its electronic components have been damaged, this can be one of the reasons it won’t shut off.

You should check the thermostat first if your furnace ceases to work. Make sure the thermostat is set to HEAT mode before turning it on.

Flipped Circuit Breaker

Your heating system can be cut off by a circuit breaker that has tripped. Check the circuit breaker if your furnace is not coming on. You may need to reset any tripped breakers to resolve this issue.

The underlying problem at hand will likely continue to occur if the issue persists. Diagnosing and solving the problem requires the help of an HVAC technician.

Blocked Air Filter

The airflow through the furnace becomes restricted if the air filter becomes clogged. The system may then shut down because of overheating because the safety switch shuts down the unit at high temperatures.

Make sure the air filter is not covered in debris and replace it if it is. Check to see if your system starts up again after it has cooled down.

Furnace Access Panel Is Not Properly Activated

A safety switch on some furnaces can cause the furnace to stop working. An access panel in a furnace that is not installed correctly can prevent the furnace from starting.

Check that all access panels on the furnace are in the correct positions and secure all access panels to the furnace.

Furnace Air Flow Obstructed by Dirt or Other Items

The airflow through and into the furnace gets blocked by dirt, debris, furniture, rugs, and other items – causing overheating.

Ways of making sure that debris won’t block the airflow:

Make sure the air filter is clean and replace it if it is dirty.

Make sure that you leave a minimum of 6 feet of clearance around your furnace.

Air needs to circulate, so make sure all your vents are open freely.

Dirty Burners

Heat is lost from your furnace as dirt and rust accumulate on its burners.

Follow this procedure to clean your burners:

Close the gas valve leading into the furnace and turn off the electricity at the breaker box.

Take out the access panel and the small access panel for the burner chamber, if applicable, from the furnace.

Disconnect all burners by removing the metal clip.

Remove any debris on the burner’s surface with a vacuum and soft brush. To clear the burner’s interior debris, blow compressed air in the burner and turn the burner to loosen debris.

The burners should be replaced, and clips should be attached.

Access panels should also be replaced.

Put the furnace back on by re-restoring electricity and gas.

Furnace Not Lubricated Properly

Grinding noises when your furnace is running are an indication its bearings need lubrication. A furnace that is not adequately lubricated will wear down its components, which can ultimately cause it to shut down.

A furnace tune-up will take care of this issue. Keep your furnace off until repairs are made, and you have avoided causing damage to the unit. You can schedule a furnace repair technician to perform maintenance, including lubrication for your furnace’s motor bearings. Call us today.

Faulty Limit Switch

The limit switch monitors temperatures within the furnace for your safety. Furnace furnaces stop working if the switch malfunctions. A technician needs to replace this component.

Igniter Not Working

An igniter malfunction can stop your furnace from working. Heat won’t be created by igniting fuel. You can determine whether an igniter needs to be replaced by:

Remove the access panel and switch off the furnace.

Finding visible damage like cracks, dents, and damage due to warping or fraying.

Use an ignition plug multimeter. You need to replace the igniter if the gauge indicates zero or infinity.

Furnace Cycles Off and on

During a short cycling pattern, a furnace may cause damage. Clogged filters and obstructed airflow due to short cycling can be rectified by checking and replacing the filters and ensuring all vents are unblocked.

The problem is also the result of faulty components and wrongly sized systems. Consult an HVAC technician to troubleshoot your furnace and determine whether short cycling is the cause.

Faulty Control Board

A furnace can shut down when its control board malfunctions. A sudden temperature rise could be an indication of this problem. A professional must resolve this problem as it requires knowledge of a specific component.

Cleaning Flame Sensors

When using a flame sensor, the furnace’s pilot light works with an ignition system that ensures fuel can be burned. The device ensures that a flame is present for combustion. When the furnace is dirty, it cannot detect a flame, so it stops working.

The Gas Pipeline Is Closed

If the furnace’s gas supply line is closed, the furnace will not receive fuel and won’t keep the home warm. Verify that this gas valve is open on this line.

Cracked Heat Exchanger

Your furnace’s heat exchanger transfers heat from combustion to the air. Over time and years of regular use, cracks or other damage can cause your furnace to consume more energy. Gases accumulate between cracks in your home and cause dangerous leaks of carbon monoxide. A heat exchanger malfunction can pose a safety threat, so it’s vital to get a technician out to assess the situation.

Licensed HVAC technicians can resolve the issue. A qualified technician will determine whether or not your heat exchanger’s damage can be fixed or whether or not it needs to be replaced altogether.


  • Steve Ireland

    Steve owns Ireland HVAC, which specializes in residential and commercial air conditioning repair and installation, as well as furnace repairs and air filtration systems in the central Indiana area. Steve and his crew have decades of experience in heating and cooling repairs for practically every air conditioning and heating system in use today, allowing them to diagnose and repair residential and commercial systems quickly. Ireland HVAC is also committed to ensuring that every household and business owner receives nothing but excellent service from any AC repair company they select. Ireland Steve