Disclosure: We may get commissions for purchases made through links in this post.
The outside temperature is dropping and you're expecting the furnace to kick on at any minute. But the appliance remains dormant, leaving household members and guests to deal with the cold weather. So what could be wrong? We researched the possible reasons why a furnace may not start, and here’s what we found.
A furnace may not kick on because of the following possible causes:
- Faulty circuit breaker
- Dirty furnace filter
- Broken blower motor
- Furnace ignition switch malfunction
- The pilot light is out
Understanding these potential reasons why a furnace isn't providing comfortable heat can help users apply the correct troubleshooting, repairs, or parts replacements to the appliance. Continue reading as we talk about these possible causes in greater detail. We’ll also tackle some solutions you may try to recover your furnace’s serviceability.
Why Is My Furnace Not Kicking On?
Applying the correct steps to restore your furnace's working condition requires you to find the source of the issue. Some of the potential reasons why your furnace isn’t kicking on are:
Faulty Circuit Breaker
A circuit breaker connected to a furnace may trip or become damaged because of different reasons, such as:
- Short circuit: An improper switch setup may cause its connections to cross, causing the error.
- Electricity overload: A sudden surge in electricity, such as a thunderstorm, can cause a damaged or tripped switch.
- Arc fault: Generally occurs because of corroded or loose wires.
- Defective fuse: The switch used is faulty from the beginning.
- Ground fault surge: Similar to a short circuit, this type of electricity surge happens when the fuse’s hot wire gets into contact with its ground wire.
Dirty Furnace Filter
Furnaces have filters that can catch dust, dirt, and other unclean airborne particles. That way, the appliance can work as efficiently as possible. But the filter can become overridden with filth over time, causing the appliance to lose efficiency. If left unchecked, the furnace may fail to start.
Also, certain cases exist wherein the furnace filters get dirty faster than usual. Some of these instances are:
- The fan setting is always in the ‘On’ position and not on ‘Auto.’
- The property is in a fairly dusty locale.
- Pets and their shedding hair may also increase the rate at which filters become clogged.
- Air duct holes can bring more dirt and dust to the furnace filter than usual.
Our post on how to adjust the fan speed on a furnace may help in reducing the dirt and dust buildup in that appliance’s filter.
Broken Blower Motor
A furnace blower functions by blowing hot air through the air ducts. It’s an integral part of the heating system as the module also helps in generating heated air. If the blower is broken or damaged, the appliance may not kick on when needed.
Certain cases may also require homeowners to replace their furnaces’ faulty blower motors. You’ll know when to change these components when:
- Poor to no airflow moves from the HVAC air vents.
- Increased costs from energy bills.
- A weird smell is coming from the furnace.
- Unknown noises when the furnace operates.
Furnace Ignition Switch Malfunction
Also called a furnace ignitor, the ignition switch is generally a small metal piece surrounded by a ceramic container. It functions by lighting the gas to provide sufficient heat in a house.
This part is also one of the starting points for the appliance to supply heat. So the furnace can’t deliver comfortable warmth to the home if this component malfunctions or is broken.
Homeowners may know if their furnace's ignitor is faulty if:
- The appliance trips the circuit breaker frequently.
- Automatic and frequent power cycles.
- Clicks to try to start but nothing happens.
- The furnace stops blowing warm air after running for some time.
Pilot Light is Out
Gas furnaces typically have pilot lights, which are small burning flames found in the appliance’s combustion chamber. It’s an ignition source that also provides consistent warmth to the household. If this flame goes out, the furnace might not start delivering hot air to the HVAC ductwork.
How Do I Get My Furnace To Kick On?
In this section, you’ll learn about a couple of possible solutions that might restore your furnace’s ability to ignite properly.
Replace the Circuit Breaker
If you deem that the circuit breaker is at fault for your furnace failing to ignite, make sure you have the necessary knowledge and confidence to go through with this task. Otherwise, contact a certified electrician to take advantage of expert help.
Keep in mind that fiddling with the circuit breaker panel without sufficient understanding of electronics may result in expensive mistakes. Also, you might put yourself at risk of acquiring injuries from mishandling electrical equipment.
Here’s a quick look at how to replace the circuit breaker connected to your furnace:
What You’ll Need
- Non-contact voltage detector
- Needle-nose pliers
- Flathead screwdriver
- Electrical tape
- Replacement circuit breaker
- Open the panel and verify the location of the tripped or faulty circuit breaker.
- Turn off all the circuit breakers in the panel to avoid accidental activations or deactivations.
- Use the non-contact voltage detector to ensure that no electrical current is presently going to the breakers.
- Place the black probe of the multimeter on the circuit breaker panel to gain ground. Then, place the red probe on the furnace’s fuse. Continue with the next step if the tool doesn’t get electricity readings.
- Label the wires with electrical tape to avoid confusion during reinstallation.
- Use the flathead screwdriver to remove the wires attached to the faulty breaker.
- Install the wires to the new circuit breaker. Make sure to follow the same setup with the old fuse
- Take out the damaged circuit breaker from the panel and replace it with the new model.
- Turn on the electrical circuits and check the furnace if it runs properly.
Ensure that the replacement circuit breaker is the same model as the faulty unit. Don't mix different circuit breakers in one panel or it might cause an imbalance in the delivery of electricity.
You can also watch the video below to learn more details about this process:
Clean the Furnace Filter
Unlike replacing a damaged circuit breaker, cleaning a furnace filter is generally a DIY-friendly job. Check your owner’s manual for the specific steps to locate and remove the filter from the appliance.
Once you know the procedure to remove the furnace filter, continue this project by following these steps:
What You’ll Need
- Garden hose
- Turn off or disconnect the furnace from its main power source.
- Unscrew the panel covering the filter.
- Take out the filter and bring it outside.
- Wash the dust and dirt buildup from the filter with the garden hose.
- Set the wet filter under a shaded area and let it air dry.
- Reinstall the filter to the furnace and test the appliance to see if it turns on as intended.
You may also need to replace the filter if you see damage. If so, you can skip the cleaning process and only change the old filter with the new unit.
You can also read our post on how to clean a Rheem furnace filter if you have a heating system from that brand.
What Are The Common Problems With Furnaces?
Aside from a furnace not kicking on, the appliance may also become susceptible to other relatively common problems. Some of these issues are:
- The heat setting on the thermostat fails to make the furnace supply comfortable heat.
- Visible damage in the furnace's heat exchanger.
- Frayed blower belt.
- Faulty limit switch.
- Worn ball bearings.
Homeowners may call for professional assistance to help with furnace repairs. If so, expect to pay about $100 to $2,000, depending on the seriousness of the issue. The overall overhead may reduce if some DIY repairs are complete before the certified technician arrives.
Is It Worth It To Replace A Furnace?
It might not be ideal to repair a furnace if the costs to fix the appliance outweigh the expenses for its replacement. For example, choose to replace an old furnace with a new model if you need to spend over $1,000 to fix the aged model. On the contrary, buying and installing a new model might only make you spend about $900.
A furnace not kicking on might occur because of some underlying problems. Some potential causes of this issue include a faulty circuit breaker and a broken blower motor. Owners should identify the source of the problem to know and apply the appropriate solution.