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How To Fix a Furnace That’s Not Turning On (2024 Guide)

Typical Cost Range: $150 – $500

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By Brenda Woods 02/03/2024

When the weather cools and the leaves change, it’s time to fire up your furnace for the cold winter months. But what do you do when your furnace won’t turn on

We at the This Old House Reviews Team will walk you through the necessary steps to fix a non-running furnace and help you identify when to hire a professional. With just a few tools and some basic knowledge, your furnace will be running like new in no time.

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Typical Cost Range: $150 – $500
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Installation costs for common air conditioning units range from $500–$2,500.

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Depending on the repair, the typical cost ranges from $100–$2,000.

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Installing an electric furnace will typically cost $1,600–$9,700.

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Your furnace’s malfunction may be due to something simple, such as a blown fuse or tripped circuit breaker, or it could be more complicated and require professional repair. Here are some of the most common reasons why a furnace won’t turn on.

1. Power Supply Interruptions

Your furnace won’t work properly if its power source is interrupted. A blown fuse, tripped circuit breaker, or even a bad wire connection can interrupt your power supply. If your furnace stops working, check your home’s electrical panel before calling an electrician.

2. Thermostat Issues

Your furnace won’t turn on if the thermostat isn’t set correctly. Make sure your desired temperature is set above your home’s ambient temperature (typically 68 degrees Fahrenheit), and that the “on” switch is engaged. If this doesn’t solve the issue, you may need to replace your existing thermostat with a modern, programmable thermostat.

3. Ignition Problems

Some furnaces rely on an electronic spark or hot surface igniter to ignite the burners. If these parts become faulty or dirty, the furnace may fail to catch. You can try to clean these components with compressed air and a brush, but if they’re damaged beyond repair, you’ll need to replace them.

4. Dirty Air Filter

An air filter clogged with dust or debris will restrict airflow into your furnace, possibly preventing it from turning on. Check the filter for blockages and replace it if necessary.

5. Malfunctioning Pilot Light

The pilot light is responsible for lighting the furnace’s burners in older gas water heaters. If the pilot light goes out, the furnace won’t turn on. In this case, you can relight the pilot yourself. Call a repair service for a tune-up if that doesn’t work.


Signs You Need To Repair Your Furnace

Is it time to repair your furnace? Check for these signs:  
The furnace is making strange noises. Banging, popping, or humming noises can indicate a motor issue.
The furnace does not produce heat. If the furnace is not producing any heat, it could be a sign of a broken component or worn-out parts.
The furnace runs constantly without shutting off. This can indicate a problem with the thermostat or the limit switch, which turn off the burner when the desired temperature is reached.
The pilot light won’t stay lit. This means there’s a problem with the pilot light itself, the gas line, or the thermocouple, which is a temperature measuring device.
The furnace is emitting odd smells such as gas, dust, or burning wires. If you detect any of these smells, turn off your furnace immediately and call for professional help.

How To Fix Your Furnace

Try these troubleshooting tips if you suspect something is wrong with your furnace.

Check the Thermostat

Make sure the thermostat is set correctly. If it’s battery-powered, replace the old batteries with fresh ones. It may need replacing if you’ve set the thermostat correctly and it still won’t turn on. 

Check the Power Supply

Are all the breakers turned on? If your furnace runs on a fuse, is the fuse still in good condition? If the power supply appears to be OK, move on to the next step.

Check the Pilot Light

Older gas furnaces have a pilot light that helps ignite the gas for heating. Make sure the pilot light is lit. If it’s not, try to light it yourself following the instructions in your furnace’s user manual. 

Check the Filters

Dirty filters can block your system’s airflow. Check your furnace filters and replace them if they appear to be clogged. This should help get your furnace running again. 

Check the Gas Line

If you’ve gone through all of these steps and your furnace still won’t turn on, it could be a gas line problem. Look for leaks, blockages, or bad connections in the line. If there are any issues with the gas line, contact a professional immediately.

Get Estimates from HVAC Experts in Your Area
Typical Cost Range: $150 – $500

When To Hire a Professional

You’ll want to hire a pro if you face complex repairs such as replacing the heat exchanger, motor, or other major components. Also, make sure to call an expert if your furnace is under warranty, as the manufacturer may cover your bill. Incorrect repairs may void the warranty, so it’s best to leave it to the experts who can ensure the job is done correctly.

Homeowners can do many other less challenging repairs themselves. This includes cleaning or replacing filters, checking electrical connections, or cleaning the blower wheel. If you can diagnose and identify the problem, you may be able to make repairs without having to call a professional.


DIY vs. Professional Furnace Repair

Do-it-yourself (DIY) furnace repair can be a great way to save money, but it’s important to understand the limits of your skills. When in doubt, contact a professional.

Professional Furnace Repair

DIY Furnace Repair

Furnace repair technicians can accurately diagnose and repair your furnace in a timely manner. This service is more expensive than DIY repairs, but there are benefits:
  • Cost: Though pricier, professional furnace repair often comes with a guarantee that puts a cap on your total expense. You’re also less likely to need repairs in the future.
  • Time: A furnace repair technician can complete the job quickly, saving time compared to DIY repair. 
  • Safety: DIY repair can be dangerous if you lack knowledge and proper safety equipment. Assess the risks associated with each project before attempting it yourself.
Professional furnace repair costs vary depending on the job’s complexity. Expect to pay an average of $150–$500 for a service call. This price includes repair parts and labor. Additional services, such as cleaning or part replacement, will cost more.
If you’re looking to save money and don’t mind getting your hands dirty, DIY furnace repair might be a good option. However, it can be a dangerous project, causing injury or even death if done improperly. 
It’s important to have basic electrical and mechanical knowledge for DIY furnace repair. You should also have access to the necessary tools and supplies. Be sure to refer to the owner’s manual for specific furnace model instructions.
The biggest benefit of performing your own furnace repair is the potential savings. The biggest risk is that you might do it wrong. Making an error could lead to further damage or create a dangerous situation. You could also miss an underlying issue that only a trained professional can detect.
The cost of doing your own furnace repair depends on the repair needed and the tools and supplies required. You may only need to purchase a replacement part for a few dollars, or you may need to purchase additional tools and supplies that can add up quickly.

Our Conclusion

The key to fixing a furnace that won’t turn on is correctly diagnosing the underlying issue. If you’re having difficulty pinpointing the cause, we highly recommend seeking professional help. DIY furnace repair can be risky and could result in further damage if done incorrectly. Professional furnace repair is usually more expensive than doing it yourself, but will provide long-term solutions and peace of mind. 

It’s important to schedule regular maintenance checks with a reliable technician to ensure your furnace is working properly. These maintenance checks will allow you to catch any furnace problems before they become serious, saving you money and hassle in the future.

Get Estimates from HVAC Experts in Your Area
Typical Cost Range: $150 – $500

FAQ About Fixing a Furnace That Won’t Turn On

Where is my furnace reset button?

Your furnace reset button will usually be located inside the blower compartment. It’s a safety feature that shuts down the furnace when a problem is detected and before the circuit breaker trips.

How do you fix a furnace that won't start?

Furnaces won’t start for all sorts of reasons. Maybe it’s the circuit breakers. It could be the pilot light. Check both of these if your furnace stops working. Also, make sure the drain pan and air filter are clean, and check your natural gas or oil supply.

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

If your furnace won’t turn on, make sure the filter is clean before assuming the worst. Other potential causes can stem from improper thermostat settings, forgetting to turn on the gas line, or a defective pilot light.

How do I know if the problem is with the thermostat?

If the problem is your thermostat, you should notice one or more of these signs:

  • Your HVAC system refuses to start.
  • Your heating system or air conditioner runs without stopping.
  • You get different room temperature readings in different sections of your home.
  • Your programmed settings keep disappearing.
  • You change the temperature settings but the system doesn’t respond.

What does it mean when the furnace blower is not turning on?

If the furnace blower doesn’t turn on, the issue may be in the wiring or in the motor. This must be addressed by a technician with access to tools and schematics. Your thermostat may have caused the issue, but an HVAC technician should confirm. 

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