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Why Won’t My Furnace Come On?

Why Does My Furnace Make a Weird Smell When I Turn It On?
Why Does My Furnace Make a Weird Smell When I Turn It On? from www.allproplumbers.com


During the chilly winter months, a malfunctioning furnace can be a major inconvenience. If you find yourself asking, “Why won’t my furnace come on?”, there could be several potential reasons behind it. In this article, we’ll explore some common issues that may prevent your furnace from turning on and provide some troubleshooting tips to help you identify and resolve the problem.

1. Thermostat Settings

Start by checking your thermostat settings. Ensure that it is set to “heat” mode and the temperature is set higher than the current room temperature. Sometimes, the problem can be as simple as the thermostat not being properly set.

2. Power Supply

Check if the furnace is receiving power. Look for any tripped circuit breakers or blown fuses in your electrical panel. If you find any, reset the breaker or replace the fuse and see if that resolves the issue. Additionally, make sure the furnace switch is turned on.

3. Pilot Light

If you have a gas furnace, check if the pilot light is lit. If it’s not, relight it according to the manufacturer’s instructions. If the pilot light keeps going out, there may be a problem with the thermocouple, which should be inspected and replaced if necessary.

4. Gas Supply

Ensure that the gas supply valve to the furnace is fully open. If it’s partially closed or completely shut off, your furnace won’t be able to ignite. If you suspect a gas leak, immediately turn off the gas supply and contact a professional technician.

5. Air Filter

A clogged or dirty air filter can restrict airflow and cause your furnace to shut down as a safety measure. Check the air filter and replace it if it appears dirty. Regularly changing the air filter can also improve the efficiency and lifespan of your furnace.

6. Condensate Drain

If you have a high-efficiency furnace, it may have a condensate drain line that removes excess moisture. If this drain line gets clogged, it can trigger a safety switch that prevents the furnace from operating. Clear any blockages in the drain line to restore proper functioning.

7. Ignition System

If your furnace has an electronic ignition system, check if it’s working correctly. If you hear clicking sounds but the burners don’t ignite, there might be an issue with the ignition system. In such cases, it’s best to seek professional assistance to avoid any potential hazards.

8. Overheating

Furnaces have safety mechanisms that shut them down if they overheat. Check if the furnace is excessively hot to the touch. If it is, turn off the power and wait for it to cool down. Dirty air filters, blocked vents, or problems with the blower motor can cause overheating. Address these issues and then try restarting the furnace.

9. Faulty Blower Motor

If your furnace’s blower motor is malfunctioning, it won’t be able to distribute warm air throughout your home. Listen for any unusual noises coming from the motor or check if it’s running at all. If you suspect a problem with the blower motor, it’s advisable to contact a professional technician for inspection and repair.

10. Professional Assistance

If you’ve tried the above troubleshooting steps and your furnace still won’t come on, it’s time to seek professional help. A licensed HVAC technician can diagnose the problem accurately and provide the necessary repairs or replacements to get your furnace up and running efficiently.


When your furnace fails to turn on, it can be frustrating and uncomfortable, especially during cold weather. By checking thermostat settings, power supply, pilot light, gas supply, air filter, condensate drain, ignition system, overheating, and the blower motor, you can often identify and resolve the issue on your own. However, if the problem persists, it’s always best to consult a professional to ensure the safety and longevity of your furnace.