7 Reasons Why Your Furnace Won’t Turn On

Brr.. time to turn the furnace on.. but wait, why isn’t it working?

Your furnace isn’t working because of a tripped circuit breaker, dirty filter, the thermostat is broken, a broken blower motor, you’re out of gas, or your drain pan is full or clogged.

Below you’ll find out how to fix these issues and why your furnace isn’t responding to your thermostat.

Let’s get started.

7 Reasons Why Your Furnace Won’t Turn On

1. Circuit breaker is tripped

While it is true that combustion furnaces use gas or oil, they still have electrical components within that need electricity to run.

Check your circuit breaker and look for where it says “HVAC” or “FURNACE” and ensure that it’s on the “on” setting.

You can try turning it off and on again to see if that helps.

2. Filters aren’t clean

A dirty filter can lead to low airflow, which can cause your furnace to not function properly.

A clogged filter will cause your furnace to work harder and longer, and may not even work at all.

You may also smell a burning smell, which is indicative of a dirty filter.

You should change out your filter every 90 days, or you may suffer from restricted airflow and your furnace not turning on.

3. Thermocouple is damaged

If your pilot light won’t stay lit, then it may be the thermocouple. Dust can build up and block the sensor, causing your furnace not to turn on.

Try cleaning the thermocouple and then the pilot light. If it still doesn’t stay on, then you’ll need to replace the thermocouple.

4. Broken blower motor

Your blower motor sends air to each room in your home through ductwork. If your blower motor or fan isn’t operating correctly, then you won’t be receiving any hot air in your home and your furnace will cease to operate.

It could also be that your blower motor is dirty.

If your heat exchanger isn’t receiving the proper amount of airflow from your blower, the heat exchanger may overheat causing your furnace to shut down.

5. Thermostat is set incorrectly

Something simple as your thermostat being set incorrectly may cause your furnace not to turn on.

Ensure that it’s in the “ON” position and that your thermostat is on. You may have to replace the batteries for your thermostat to operate again.

It may be that the wiring has become loose or dust/debris has disrupted your thermostat from working.

If you aren’t sure how to diagnose your thermostat, it’s best to consult with an HVAC technician.

6. You’re out of gas or oil

A simple solution for why your furnace won’t turn on is to check if you have natural gas or oil.

If you run out after constant use, then you won’t be able to light your furnace and heat your home.

7. Drain pan is full

When your drain pan is full, it triggers the float switch which prevents your furnace from turning on.

Your drain pan should drain automatically, but if there is a clog then it won’t be able to do so.

Ensure that the drain pan is clear and can drain by itself.

Why is my furnace not responding to the thermostat?

If your furnace isn’t responding to your thermostat, it’s indicating that the thermostat is lacking power, might be set wrong, has bad firmware, the wiring may be faulty or you have a dirty filter that needs to be changed.

The most probable cause is that the battery inside your thermostat has died, so try to change the battery before you jump to any conclusions.

When to Call Professional HVAC Technicians?

If you have tried the 7 fixes for why your furnace won’t turn on and nothing has worked, our local HVAC technicians can help service your furnace.

They’re ready to help at any moment, and all you need to do is click the button below and you’ll be on your way to getting a free quote in a jiffy.

If it’s in the middle of winter and your furnace breaks, it’s even a better time to call an HVAC specialist to prevent frozen pipes.

Don’t forget you can also try resetting your furnace. Remember, if your furnace won’t stay lit, that’s an entirely different problem.

Image credit: Flickr.com

About Roy Cohen

Roy Cohen has a burning passion for heating, cooling, and ventilation. He aims to help you save money on expensive repairs and bring you the best HVAC products. He has years of experience behind him in HVAC repair and garage maintenance.

You can find Roy at his LinkedIn or his email: [email protected]

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