You’d be surprised how easy it can be to get your finicky furnace up and running. Before you reach out to a pro, why not give these troubleshooting tips a try? They could be just the ticket to having your heating system purring along again.

If your furnace not turning on, you should first check whether the air filter is clean. Dirty or clogged filters can restrict airflow and prevent the furnace from starting up. Other common reasons a furnace may fail to ignite include improper thermostat settings, forgetting to turn on the gas line, or a faulty pilot light.

How Does a Furnace Work?

Your furnace is a complex machine with many interconnected components, including a blower motor, flame sensor, pilot light, power switch, ignitor, thermostat, and air ducts. The thermostat in your home (or multiple thermostats if you have a zoned heating system) measures the temperature and signals the furnace’s control board when it’s time to begin the heating cycle.

When the temperature drops below the set target, the control board receives the signal and opens the gas valve, igniting the burners. The flame sensor then activates the blower motor, which circulates the heated air through the ductwork and into your living spaces. The combustion byproducts then travel through the heat exchanger and out of your home via the flue pipe.

Why is My Furnace Not Turning On?

There are several possible reasons why your furnace may not be igniting. Let’s take a closer look at some of the most common issues:

Thermostat Issues

Although this may seem like an obvious first step, be sure your thermostat is set to the “heat” mode and that the target temperature is lower than the current room temperature. Verify that the thermostat is receiving power and that the batteries (if applicable) are not drained. If the thermostat appears to be functioning properly, move on to the next potential problem.

How To Fix

• Check that the thermostat is set to “heat” mode and that the target temperature is below the current room temperature.
• Replace the thermostat batteries if applicable.
• Ensure the thermostat is receiving power at the electrical circuit.
• Consult the thermostat manual for any additional troubleshooting steps.

Power Supply Problems

If the thermostat checks out, the next step is ensuring the furnace receives power. Locate the circuit breaker or fuse that controls the furnace and verify it has not tripped or blown. If the power supply appears to be functional, move on to the next potential issue.

How To Fix

• Check the circuit breaker or fuse controlling the furnace and reset or replace it if necessary.
• Inspect the furnace’s power cord for any damage and ensure it is securely plugged in.
• If the furnace has a power switch, make sure it is in the “On” position.

Gas Line Issues

The first and most important step for gas-fired furnaces is to ensure the gas supply is turned on. You can check this by examining the shut-off valve, which is typically located outside the home near the furnace. Another way to test if the gas is flowing properly is by starting up another gas-powered appliance, like the stove.

How To Fix

• Verify that the gas shut-off valve is in the “Open” position.
• If the gas is turned off, carefully turn the valve counterclockwise to open it.
• Try igniting another gas-powered appliance to confirm the gas is flowing.
• If the gas line appears to be functioning, move on to the next potential problem.

Dirty Air Filter

Changing the air filter is one of the easiest solutions for a non-functioning furnace. If routine filter changes have not been performed, and the vents and registers are completely clogged, this can severely restrict the furnace’s airflow and prevent it from starting up.

How To Fix

• Locate the furnace’s air filter and remove it.
• Inspect the filter and replace it if it appears dirty or clogged.
• Ensure the filter is installed correctly in the proper orientation.
• Clean any dust or debris from the filter compartment.

Ignition Problems

Some furnaces light the burners with an electronic spark or hot surface igniter. The furnace may fail to ignite if these components become dirty or damaged. You can try cleaning the igniter with compressed air and a soft brush, but you’ll need to replace it if it’s beyond repair.

How To Fix

• Inspect the igniter and clean it with compressed air and a soft brush.
• If the igniter appears cracked or damaged, you’ll need to replace it.
• Consult your furnace’s manual or a professional technician for the proper replacement part and installation instructions.

Blower Motor Issues

The furnace blower motor is responsible for circulating the warm air throughout your home. If there are problems with the blower motor, the entire heating system won’t function properly. Common blower motor issues include a failed capacitor, worn bearings, or a malfunctioning control board.

How To Fix

• Check the blower motor’s power supply and ensure it’s receiving electricity.
• Inspect the blower motor for any visible signs of damage or wear.
• If the blower motor appears faulty, you’ll need to replace it.
• Consult a professional HVAC technician for proper diagnosis and replacement.

Safety Features

Your furnace is equipped with various safety features, and any that have been triggered or malfunctioned can prevent the unit from starting. These include:

• Limit switch – Shut off the furnace if the heat exchanger gets too hot.
• Flame sensor – Detects the presence of a flame and shuts off the gas if it’s not present.
• Pressure switch – Ensures proper airflow before allowing the furnace to operate.

How To Fix

• Inspect the limit switch, flame sensor, and pressure switch for any issues.
• Clean the components with a soft brush and compressed air, if possible.
• If the safety features appear damaged, you’ll need to replace them.
• Consult a professional HVAC technician for proper diagnosis and repair.

Control Board Issues

The furnace’s control board manages all the electronic functions, including ignition, blower operation, and safety features. If the control board is malfunctioning, it can prevent the furnace from starting up.

How To Fix

• Inspect the control board for any visible signs of damage, such as scorch marks or loose connections.
• Try resetting the control board by turning off power to the furnace, waiting a few minutes, and then restoring power.
• If the control board appears faulty, you’ll need to replace it, which is best done by a professional HVAC technician.

How Do I Avoid Issues With My Furnace in Canada?

To prevent furnace problems and ensure reliable heating throughout the cold Canadian winters, it’s essential to schedule regular maintenance. The service experts at TaskPro can handle any level of maintenance or repairs, including cleaning, tune-ups, and part replacements.

If your furnace is quite old, consider a replacement. A newer, more energy-efficient furnace can save you money in the long run by requiring less maintenance and fewer repairs.

Learn about the best types of heating systems for your home in Canada and compare heat pump vs. furnace.

When should I call a professional to fix my furnace?

If you’ve tried the troubleshooting steps outlined above and your furnace is still not turning on, it’s best to call in the experts. The team at TaskPro Service Group Inc. can diagnose the problem and recommend the most appropriate solution, whether that’s a simple repair or a full furnace replacement.

We offer emergency heating services to address urgent heating issues, especially when freezing temperatures pose a health and safety risk. Call us at 604-245-5524 or fill out our contact form to schedule an appointment and get your furnace back up and running as soon as possible.

FAQs

Why is my furnace suddenly not turning on?

If your furnace is not turning on, the most common culprits are a dirty air filter, improper thermostat settings, or gas supply or electrical power issues. Checking these basic components is the first step in troubleshooting a non-functioning furnace.

How do I force my furnace to start?

Checking your thermostat is the best place to start. Make sure it’s set to “heat” and that you’ve set the temperature higher than the current room temperature. If that doesn’t resolve the problem, try switching your fan to “on” to force the furnace to start working.

Will a furnace reset itself?

A malfunctioning furnace might repeatedly trip a reset and in circumstances where the unit isn’t overheating. Here are just a few reasons why your furnace might keep resetting itself: Overuse faulty wiring within your home.