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January 21, 2023

Your Furnace Won’t Turn On? Here’s a Quick Fix!

Problem with the Furnace Not Turning On - LG Home Comfort

Like most homeowners, you probably feel frustrated when your furnace won’t turn on. While it may feel overwhelming to determine why your furnace is not working, you can take a few steps to figure out what is wrong and how to fix it.

Here is a guide for diagnosing and fixing the issue so you can enjoy a warm, comfortable home.

Most Common Reasons Why Your Furnace Won’t Start

Fixing a furnace can be a tricky process, and it often helps to have an idea of where to begin troubleshooting. Below are the five most common reasons your furnace is not starting:

There Is an Issue with Your Thermostat

The thermostat is the control center for your home’s heating system. If something has gone wrong with it, this could lead to your furnace not turning on. This could be due to the following:

  • Lost programming or reset
  • The setting is incorrect
  • Loose connections
  • Frayed wires
  • Aged wires

There Is an Issue with Your Gas Line

If you have a gas-powered furnace, you may have an issue with your gas valve or gas line. While it’s rare, this could include anything from clogs in the line to a disruption in service from the utility company. Mostly, the problem with a gas line is a leak. In this case, call a technician for a professional furnace repair.

Your Furnace Is The Problem

If none of the above issues are present, there may be an issue with the actual furnace itself rather than any external factor such as wiring or fuel supply lines. Common furnace problems include clogged burners, faulty blower motors, or even worn-out parts like belts or bearings that need to be replaced for your unit to function properly.

Something Is Restricting Air Flow

Another potential cause of a failing furnace is an accumulation of dust or debris within your air ducts or vents. This can result in decreased efficiency levels and eventually lead to failure if left unchecked for too long, so ensure that all areas are clear and free of obstructions before trying to fix any other issues with your furnace unit.

You Need To Change Your Air Filters

The air filter ensures clean air is circulated throughout your home by trapping dust particles and other contaminants before they enter circulation through the system’s vents and ducts.

However, over time these filters become filled with debris which can lead to decreased airflow levels and ultimately cause failure if not changed regularly enough (generally every three months).

You Have a Faulty Ignition Sensor

If all else fails, there could be a problem with the pilot light itself that will require professional assistance from a qualified technician to repair it appropriately and safely without damaging any other components of your system.

What to Do When Your Gas Furnace Won’t Turn On?

When your gas furnace fails to turn on, it can make your home icy cold and uncomfortable. Before you call an HVAC system technician to come out and diagnose the problem, try these quick tips that can often solve the issue:

Tip #1: Check Your Circuit Breaker

While gas furnaces are powered by gas or propane, some components, such as the ignition systems and blower motor, need electricity.

If the circuit breakers in your home are not correctly configured, it could be why your gas furnace won’t turn on. Check each one for a tripped circuit breaker or one turned off. If you find either of these, reset them and then try to turn on your furnace again.

Tip #2: Check Your Thermostat

Many thermostats have batteries inside them that need to be replaced periodically. If they are old or dead, they can prevent your furnace from turning on properly. Try replacing the batteries and see if that solves the problem. You should also ensure all settings are correct. If any of them are set incorrectly, this could cause an issue with starting up your furnace.

Tip #3: Check the Drain Pan

An overflowing drain pan is another common reason a gas furnace fails to start up correctly. Too much water in the drain pan can create a short circuit and prevent your furnace from turning on at all times. Empty any excess water from the pan and then try powering it up again.

Tip #4: Check Your Air Filter

The furnace of your HVAC system may not start if the air filter is dirty because the heat pump can’t receive the required air to warm your house due to clogging. It can also cause the heat exchanger to overheat and shutdown.

Make sure you check the air filter once a month and change it when needed. Remember that a clean air filter will help your unit operate efficiently and improve indoor air quality, improving overall health for your family.

Here are simples steps on how to clean your air filter:

  • Remove the existing filter from the system. In most cases, this requires simply opening a door or panel in front of the unit.
  • Inspect the filter to determine if it needs to be cleaned or replaced. If there is visible dirt or debris on the filter, it should be taken outside and gently tapped against a hard surface to remove any loose particles.
  • Clean the filter using a vacuum cleaner with an attachment hose if needed. Ensure not to damage the material while cleaning the filter, as this will reduce its effectiveness in filtering pollutants from your home’s air.
  • Reinstall the filter, ensuring it fits snugly into place so that no air can bypass it and enter your home without being filtered first.
  • Close all doors or panels and switch on power again at the main breaker panel or fuse box.

Tip #5: Check the Furnace Pilot Light

The pilot light is essential for a gas furnace to work properly. If it is not lit, your unit will not turn on. Be sure that the flame is lit consistently. If it doesn’t work, relight it according to the manufacturer’s instructions or contact a professional HVAC technician for help safely and correctly.

Tip #6: Check Your Natural Gas Supply

Ensure there is no gas leak or enough natural gas or oil in the supply lines leading to your home before attempting to start a gas furnace again. No matter how many other things are checked first, sufficient fuel supply available for use by natural gas furnaces is necessary for them to run. These levels should be adequate before hitting the power switch back online.


Furnaces are complex systems and can experience many issues due to wear and tear over long periods of use. Problems can also arise if there is a lack of maintenance, especially in winter when the demand for heat is higher than usual. Consider following the tips above if your furnace won’t turn on.

If everything else fails, call qualified HVAC professionals who understand how these systems work and what steps need to be taken to get them running again without too much trouble or cost.

Terms and Conditions

  • Once an initial service has been completed, the customer will be on a one-year commitment
  • After the initial 12 months, the contract will be renewed on a month-to-month cadence
  • If a service is completed for the next year, it automatically renews the commitment for an additional year
  • Customers can cancel at any time after the 12-month initial commitment as long as the following year’s service has not been completed.
  • Customers need to provide 30 days written notice in order to cancel their plan