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Why Is My Furnace Not Turning On? Understand The Cause And What To Do

By Travis Baugh
 
When the temperature drops and your furnace won’t turn on, it can be a stressful and uncomfortable situation. Understanding the common causes can help you troubleshoot and get your home warm again quickly. Keep reading or reach out to your local Bryant dealer for immediate help.
a homeowner asks a bryant dealer about his furnace not turning on

12 Causes Of A Furnace Not Turning On

If your furnace isn’t turning on, it can be due to a variety of issues. Here are some common causes to check:

1. Thermostat Issues

A faulty thermostat could be preventing your furnace from turning on. It might be set incorrectly, have dead batteries, or be malfunctioning entirely. Try resetting the thermostat, replacing the batteries, or testing it with a different temperature setting.

2. Tripped Circuit Breaker

If the circuit breaker for your furnace has tripped, the system won’t receive power.

3. Blown Fuse

Some furnaces have an internal fuse that can blow and prevent the system from operating.

4. Pilot Light or Ignition Problems

If your furnace uses a pilot light, check to see if it has gone out. Modern furnaces often have electronic ignition systems, and problems with the igniter or gas valve can also prevent the furnace from lighting up.

5. Dirty Air Filter

A clogged or dirty furnace filter can restrict airflow, causing the furnace to overheat and shut off as a safety measure.

6. Gas Supply Issues

If your furnace runs on gas, check to ensure the gas valve is open and the gas supply is intact. A gas supply issue could prevent the furnace from igniting.

7. Dirty or Blocked Flame Sensor

The flame sensor ensures that the furnace’s flame is operating correctly. If it’s dirty or malfunctioning, the furnace might fail to ignite. 

8. Faulty Limit Switch

The limit switch is a safety feature that shuts down the furnace if it overheats. If this switch is faulty or malfunctioning, it could prevent the furnace from turning on, even if the temperature is normal.

9. Condensate Drain Clog (For High-Efficiency Furnaces)

High-efficiency furnaces have a condensate drain that collects moisture produced during the heating process. If this drain becomes clogged, the furnace might shut down as a safety precaution.

10. Electrical Problems

Other electrical issues such as a damaged wiring or malfunctioning control board can prevent your furnace from operating. 

11. Bad Blower Motor

If the blower motor is malfunctioning or burned out, the furnace may run but fail to circulate warm air through the system. This can prevent the furnace from functioning properly.

12. Closed or Blocked Vents

If the air vents or ducts are blocked or closed, the furnace could overheat or fail to get the airflow it needs, causing it to shut down.
a woman shivers in house with furnace not turning on

What To Do If You Have A Furnace Not Turning On

If your furnace isn’t turning on, it can be frustrating, especially during colder months. Here's a step-by-step guide on what to do if you find yourself in this situation:

Check the Thermostat

Ensure the thermostat is set to "heat" and the temperature is higher than the current room temperature. Replace the batteries if the thermostat is battery-powered. Reset the thermostat or adjust the temperature settings to see if it triggers the furnace to start.

Inspect the Circuit Breaker

Go to your electrical panel and check if the furnace’s circuit breaker has tripped. If the breaker has been tripped, reset it by flipping it off and back on. This can restore power to your furnace. 

Check the Furnace’s Power Switch

Some furnaces have an on/off switch near the unit itself. Make sure this switch is in the “on” position.

Ensure the Gas Supply is On

If you have a gas furnace, check that the gas valve is open. If the valve is off, open it to allow gas to flow to the furnace. Also, ensure that your home’s gas supply is intact, and there are no outages or interruptions.

Look for a Faulty Pilot Light or Ignition System

If your furnace uses a pilot light, check if it’s lit. If it’s out, follow the manufacturer’s instructions to safely relight it. For modern furnaces with electronic ignition, ensure the ignition system is functioning properly. If it’s faulty, you may need professional help to diagnose and repair it.

Replace a Dirty or Clogged Air Filter

A clogged furnace filter can restrict airflow and cause the furnace to overheat or shut down for safety reasons. Replace the air filter if it’s dirty.

Inspect the Furnace’s Flame Sensor

If the furnace ignites but shuts off quickly, the flame sensor may be dirty or malfunctioning. Clean the flame sensor carefully with a soft cloth, or contact a professional if it needs to be replaced.

Clear Any Blocked Vents or Registers

Ensure all air vents are open and not blocked by furniture or other objects. Blocked vents can prevent proper airflow and cause the furnace to shut down.

Check for a Clogged Condensate Drain (High-Efficiency Furnaces)

If you have a high-efficiency furnace, a clogged condensate drain can cause the furnace to shut down as a safety precaution. Check the drain for blockages and clear it if necessary.

Check for Error Codes or Strange Noises

Many modern furnaces have a display panel that shows error codes. If you hear unusual sounds or notice error codes, note them down and refer to the owner’s manual or call your local Bryant dealer to diagnose the issue.

Call a Professional HVAC Technician

If you’ve gone through the troubleshooting steps and your furnace still won’t turn on, it’s time to call your local Bryant dealer. Problems like a faulty control board, blown fuse, or broken blower motor require professional expertise to repair safely and effectively.
 

Connect With A Bryant Dealer When Your Furnace Won’t Turn On

When you choose a Bryant Dealer, you’re working with a trusted professional who will handle the furnace repair with care and expertise. Bryant dealers are highly trained and experienced in working with furnaces, ensuring they understand the unique features and potential issues specific to your system. They can diagnose the root cause of the problem and provide the most effective solution. This gives you peace of mind that the job will be done right the first time, ensuring your home stays warm and comfortable.
 
Besides fixing the immediate issue, a Bryant dealer can offer regular maintenance services, which can prevent future furnace problems. Annual furnace maintenance can help ensure that your furnace is running efficiently and avoid costly repairs down the road.
 
Schedule an appointment with your local Bryant dealer today.
 

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