Why Is My Furnace Not Turning On? (2025 Guide)
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Realizing your furnace won’t turn on is frustrating—especially during the chilly winter months. Luckily, if your furnace has been properly maintained, you can take a few simple steps to get your home comfortable again and avoid a costly furnace replacement.
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Central AC unit costs range from $3,800 to $7,700.
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Reasons Your Furnace May Not Be Turning On
We’ve outlined different steps you can take to fix your furnace depending on the problems you’re encountering. If you’re not trained to perform any of the troubleshooting techniques or are uncomfortable completing them, contact an HVAC contractor for professional assistance.
When the Furnace Thermostat Won’t Turn On
Here are a few steps to take when your thermostat isn’t working.
Check the Electrical Panel
Check your circuit breaker panels to ensure the furnace switch is in the “on” position. If not in the “on” position, pop the breakers back into place. Close the furnace door so the safety switch can activate the furnace.
Check the Batteries
If your thermostat doesn’t seem to have power or won’t activate the furnace, the batteries may be dead. If your furnace doesn’t heat your home consistently, consider using AA lithium instead of standard alkaline batteries. AA lithium batteries help extend the life and consistency of your heating system.
Check the Thermostat Position
If your furnace struggles to get the room temperature above 60 degrees Fahrenheit, check that your thermostat is in the heating position. You might want to change your thermostat‘s physical location so it isn’t near sunlight and drafts. This will provide a more accurate reading and improve the thermostat’s heating capacity.
When the Furnace Doesn’t Blow Warm Air
If you notice that your furnace is turning on but not blowing warm air, try the following repairs:
Check the Filter
Dirty air filters cause insufficient airflow, preventing the furnace from starting. Inspect the furnace’s filter, located in either the uptake (the duct or channel that leads air upward from below) or inside the furnace itself. Check if there’s dust or debris buildup. If you need to replace the filter, ensure your furnace is off before doing so. Filters should face the same direction the furnace blows air.
When the Furnace Won’t Ignite
There are some fixes you can try if you notice your furnace doesn’t ignite, but they’re more complicated than the steps above.
Check the Ignition Sensor
The ignition sensor is a small, short metallic rod that creates electricity to confirm the presence of a burning flame. If this sensor gets dirty, the furnace won’t stay or will blow cold air. The furnace’s heat exchanger—the part that heats the air—must sense an ignition to power it. We recommend contacting a trusted furnace repair company for furnace flame sensor replacement.
Inspect the Pilot Light
Another more complicated repair is for a furnace pilot light. If the furnace’s pilot light doesn’t remain lit, it won’t run properly. In older furnaces, the pilot light is typically a small, blue flame used to ignite the natural gas being pumped into the main burner.
First, switch the furnace’s power on and off. If the furnace still doesn’t turn on after resetting the pilot, power down the furnace and inspect the element for any damage. If all else fails, call a professional to come and perform gas furnace maintenance as soon as possible.
Our Recommendation
You can handle some small furnace problems, such as fixing your thermostat settings or power switch, on your own. However, it’s usually best to hire a professional HVAC technician to properly diagnose and resolve the issue.
Working with a furnace can be dangerous if you’re not adequately prepared or experienced. You’ll undoubtedly want to work with a professional furnace repair service if you require an entire HVAC system replacement.
Use our tool below to schedule a service call from a nearby furnace repair company to get your home back to normal.
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Furnace Not Turning On FAQ
Do all furnaces have a reset switch?
Yes, all furnaces feature a reset switch. These are generally red or yellow and are located inside the blower compartment. The reset button is a safety feature that will shut down the furnace when a problem is detected—often a hot or overheating furnace—before it trips the circuit breaker.
Can you hear your furnace click on but not fire up?
If your furnace is making a clicking noise but not providing heat, it’s most likely because the spark igniter is trying to ignite your pilot light or burners but failing. In other words, thereu0026#8217;s an ignition system malfunction that needs to be fixed.
How long do furnaces usually last?
A well-maintained furnace can last 15 to 20 years, but common furnace issues such as blockage and clogging in your air ducts can shorten its life span. We recommend scheduling annual tune-ups to ensure you get the most out of your furnace.