Furnaces | 5 Min

What to Do if Your Furnace Won’t Turn On

Written by Chris

furnace wont turn on

As the temperatures drop outside, there’s nothing more frustrating than coming home to a cold house because your furnace isn’t turning on. It’s important to have a properly functioning furnace not only for your comfort but also for the safety of your home. In this guide, I’ll walk you through some common reasons why a furnace won’t turn on and how to diagnose the issue.

The Importance of a Properly Functioning Furnace

A properly functioning furnace is essential for your home’s safety and your comfort. Without a working furnace, your home could be at risk for frozen pipes, which can cause costly damages. Additionally, a malfunctioning furnace can release carbon monoxide, a dangerous gas that can be deadly.

Aside from safety concerns, a properly functioning furnace is necessary for your comfort during the winter months. A non-working furnace can leave you and your family in the cold and uncomfortable.

Common Reasons Why a Furnace Won’t Turn On

There are several reasons why a furnace may not turn on. Here are some of the most common issues:

Checking the Thermostat

The thermostat is the control center for your furnace. If it’s not working properly, it can prevent your furnace from turning on. First, check to see if your thermostat is set to the “heat” mode and set to the desired temperature. If it’s not, adjust it accordingly.

If the thermostat is set correctly and the furnace still isn’t turning on, check the batteries. If the batteries are dead, replace them and see if that fixes the issue.

Checking the Furnace Filter

A dirty air filter can cause your furnace to shut down. The filter collects dust and debris over time, and if it’s not cleaned or replaced, it can restrict airflow, causing the furnace to shut off.

To check the filter, turn off the furnace and locate the filter. If it’s dirty, replace it with a new one. It’s recommended to replace the filter every one to three months to ensure proper airflow.

Inspecting the Furnace for Visible Damages

If your furnace won’t turn on, inspect it for any visible damages. Look for cracks or holes in the furnace, as well as any loose wires or connections. If you notice any damages, it’s best to call a professional to make the necessary repairs.

Checking the Pilot Light

If your furnace has a pilot light, it may need to be relit. First, locate the pilot light and follow the manufacturer’s instructions to relight it. If the pilot light won’t stay lit, it may be a sign of a more significant issue, and you should call a professional for assistance.

Testing the Furnace’s Electrical Components

If your furnace’s electrical components are malfunctioning, it can prevent the furnace from turning on. First, check to see if the furnace is receiving power by checking the circuit breaker or fuse box. If the circuit breaker has tripped, reset it and try turning on the furnace again.

If the circuit breaker isn’t the issue, check the furnace’s electrical components, including the blower motor, igniter, and control board. If you’re not comfortable checking these components yourself, it’s best to call a professional.

Troubleshooting the Furnace’s Gas Supply

If your furnace is powered by gas, it’s essential to ensure that the gas supply isn’t the issue. First, check to see if the gas valve is turned on. If it’s not, turn it on and try turning on the furnace again.

If the gas valve is on, check to see if the gas line is obstructed or damaged. If you notice any damages, call a professional to make the necessary repairs.

When to Call a Professional for Furnace Repair

While some furnace issues can be easily fixed, others require the expertise of a professional. If you’ve attempted to diagnose the issue and still can’t get your furnace to turn on, it’s time to call a professional.

Additionally, if you notice any damages to your furnace, such as cracks or holes, it’s best to call a professional to make the necessary repairs. Attempting to repair a damaged furnace yourself can be dangerous and cause further damage.

Preventative Maintenance for Your Furnace

To prevent future furnace issues, it’s essential to perform regular maintenance. Here are some preventative maintenance tips:

By performing regular maintenance, you can catch any potential issues before they become major problems.


A non-working furnace can be frustrating and dangerous. By following the steps outlined in this guide, you can diagnose the issue and determine if you need to call a professional for repairs. Remember to perform regular maintenance to prevent future issues and ensure your furnace is running properly.

Don’t let a non-working furnace leave you in the cold this winter. Take action to diagnose and fix the issue today.

Schedule annual furnace maintenance with SmileHVAC to ensure your furnace is running properly and avoid potential issues in the future.


What could be causing my furnace to not turn on?

There are several potential causes for a furnace failing to turn on, including a malfunctioning thermostat, a clogged air filter, a tripped circuit breaker, a faulty ignition system, or a lack of fuel supply.

How can I tell if my furnace issue requires professional repair?

While some simple issues like a tripped circuit breaker or a clogged air filter can be resolved with DIY solutions, other issues like a faulty ignition system or gas supply require professional repair. It's always best to consult with a licensed HVAC technician to diagnose and fix any furnace problems.

Can I troubleshoot my furnace if it won't turn on?

How often should I have my furnace serviced to prevent issues like not turning on?

It's recommended to have your furnace serviced by a licensed HVAC technician at least once a year, ideally before the heating season starts. Regular maintenance can help prevent issues like not turning on and ensure that your furnace operates efficiently and safely.

What should I do if my furnace still won't turn on after troubleshooting?

If you've checked the thermostat, air filter, and circuit breaker and the furnace still won't turn on, it's time to call a licensed HVAC technician. A professional can diagnose and fix any issues with your furnace, ensuring that it runs safely and efficiently.