Furnace Not Kicking On When Temperature Drops: Troubleshooting Tips

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As the temperature drops during the cold winter months, it’s crucial to have a properly functioning furnace to keep your home warm and cozy. However, if your furnace fails to kick on when the temperature drops, it can be frustrating and uncomfortable. In this article, we will discuss some common reasons why your furnace may not be turning on and provide troubleshooting tips to help you resolve the issue.

1. Thermostat Settings

Start by checking your thermostat settings. Ensure that the thermostat is set to “heat” and the temperature is set higher than the current room temperature. If the thermostat runs on batteries, replace them to ensure accurate readings and proper functioning.

2. Power Supply

Check if your furnace is receiving power. Inspect the main circuit breaker or fuse box to see if the circuit breaker has tripped or the fuse has blown. Reset the breaker or replace the blown fuse, if necessary. Additionally, make sure that the furnace switch, usually located near the unit, is in the “on” position.

3. Air Filter

A clogged or dirty air filter can obstruct airflow and cause the furnace to shut down. Check the air filter and replace it if it appears dirty or clogged. Regularly changing the air filter every 1-3 months can prevent future issues and improve the efficiency of your furnace.

4. Gas Supply

If you have a gas furnace, ensure that the gas supply is turned on. Locate the gas shut-off valve near the furnace and verify that it is in the open position. If you suspect a gas leak, immediately leave your home and contact a professional for assistance.

5. Pilot Light

For older furnaces with a pilot light, check if the pilot light is lit. If it has gone out, relight it according to the manufacturer’s instructions. If the pilot light keeps going out, there may be an underlying issue that requires professional repair.

6. Ignition System

If your furnace has an electronic ignition system, listen for clicking sounds indicating that the system is attempting to ignite. If you don’t hear any clicking, there may be a problem with the ignition system that requires professional attention.

7. Overheating

Furnaces have safety features to prevent overheating. If your furnace overheats, it may shut off to protect itself. Check if the furnace is excessively hot to the touch. If so, turn off the furnace and wait for it to cool down before attempting to restart it. Clean the furnace and ensure proper airflow to prevent future overheating issues.

8. Blower Motor

If the furnace is receiving power but the blower motor is not running, there may be an issue with the motor or its components. Contact a professional technician for a thorough inspection and repair.

9. Professional Inspection

If you have gone through the troubleshooting steps and your furnace still does not kick on when the temperature drops, it’s time to call a professional HVAC technician. They have the expertise and specialized tools to diagnose and fix more complex issues that may be causing the problem.

10. Regular Maintenance

Prevention is key to avoiding furnace issues. Schedule regular maintenance for your furnace to ensure optimal performance and to catch any potential problems before they escalate. A professional technician can clean and inspect your furnace, making necessary adjustments and repairs to keep it running smoothly.


A furnace not kicking on when the temperature drops can be a frustrating experience, especially during the cold winter months. By following these troubleshooting tips and seeking professional help when needed, you can ensure that your furnace operates efficiently and provides the warmth and comfort your home needs.