Why My Furnace Won’t Turn On? Here’s How To Fix It!


We’ve all been there – it’s freezing outside and our furnace decides to go on strike. It can be frustrating and downright uncomfortable, but fear not!

In this article, we’ll explore the possible reasons why your furnace may not be turning on and how to repair your furnace. From thermostat malfunctions to clogged air filters, we’ll cover it all.

Thermostat Malfunction

You might want to check if your thermostat is working properly. Sometimes, the issue with a furnace not turning on lies with the thermostat rather than the actual unit itself. We’ve encountered this problem before and it can be quite frustrating, but luckily it’s usually an easy fix.

First things first, make sure that your thermostat is set to the correct temperature. It’s possible that someone might have accidentally changed it or bumped it out of place. If that doesn’t solve the problem, try replacing the batteries in your thermostat. Low battery power can cause all sorts of strange issues.

If neither of those solutions works, you may need to take a closer look at your thermostat itself. Check for any loose wires or connections that could be causing a malfunction. If everything looks fine, you might want to consider calling a professional HVAC technician to come and inspect your system.

Pilot Light or Ignition Issues

The most common issue with a furnace that won’t turn on is a problem with the pilot light or ignition. When this happens, it can be frustrating and uncomfortable, especially during cold winter months. However, there are a few things we can check before calling for professional help.

Here are four steps to troubleshoot the pilot light or ignition issues:

  1. Check the gas supply: Ensure that the gas valve is open and that there is an adequate supply of gas reaching the furnace. If the gas supply is interrupted or turned off, the pilot light will not ignite.
  2. Inspect the pilot light: Look through the small window on your furnace to see if the pilot light is lit. If it’s out, try relighting it according to your manufacturer’s instructions.
  3. Clean the flame sensor: Over time, dirt and debris can build up on the flame sensor, preventing it from detecting a flame. Gently clean it using fine-grit sandpaper or steel wool.
  4. Test the ignition system: If you have an electronic ignition system, make sure it is functioning correctly by listening for a clicking sound when you turn on your furnace.

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Electrical Problems

Inspecting the electrical connections and wiring is essential in troubleshooting furnace issues related to electrical problems.

When our furnace isn’t turning on, it’s important for us to:

  • Check if there are any loose or damaged wires. We start by turning off the power supply and then carefully examining all the electrical connections.
  • Look for any signs of frayed or burnt wires, as these could be causing a short circuit or preventing proper electricity flow.
  • Make sure that all the switches and breakers related to the furnace are in the correct position.
  • Sometimes, a simple switch being turned off can be the cause of the problem.
  • Inspect other electrical components such as relays and control boards.
  • Use a multimeter to test for continuity and resistance in these parts.
  • If we find any faulty components during this process, we replace them accordingly.
  • Call a professional HVAC technician who specializes in furnace repair if none of these steps resolve our issue. They have advanced tools and expertise to diagnose complex electrical problems more accurately.

Lastly, remember always to prioritize safety when dealing with electrical systems by disconnecting power before inspection or repair attempts.

Gas Supply Problems

To ensure proper heating, make sure you have enough gas supply for your furnace. Gas supply problems can often be the cause of a furnace not turning on. If there is not enough gas flowing into the furnace, it won’t be able to ignite and produce heat.

There are a few possible reasons for this issue:

  • Firstly, check if the gas valve supplying your furnace is fully open. Sometimes, due to accidental movement or maintenance work, the valve may have been partially closed, restricting the gas flow. Ensure that it is entirely open to allow sufficient gas into the system.
  • Secondly, check if there are any issues with the gas line itself. A leak in the line can lead to a decrease in gas pressure reaching your furnace. If you suspect a leak, contacting a professional immediately for repairs is crucial.
  • Lastly, if you use propane as fuel, check that your tank has enough propane left. Running out of propane will obviously prevent your furnace from operating correctly.

Furnace Not Turning On – FAQ

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How do I know if my thermostat is malfunctioning?

If your furnace isn’t turning on, it’s important to check if the thermostat is malfunctioning.

To determine this, you can try a few troubleshooting steps:

– First, make sure the thermostat is set to heat mode and that the temperature setting is higher than the current room temperature.
– Next, check if the display on the thermostat is functioning properly and if it’s receiving power.
– If these steps don’t solve the issue, it may be time to call a professional for further assistance.

What could be causing my pilot light to go out frequently?

There could be several reasons why the pilot light on your furnace is going out frequently.

Some possible causes include a malfunctioning thermocouple, a dirty or clogged pilot orifice, insufficient gas supply, or even draft issues.
It’s best to have a professional HVAC technician inspect and diagnose the problem to ensure it gets resolved properly.

They will be able to identify the specific issue and provide the necessary repairs or adjustments.

Can electrical problems cause my furnace not to turn on?

Yes, electrical problems can definitely cause a furnace not to turn on. Faulty wiring or a blown fuse could prevent the furnace from receiving power.

Additionally, a malfunctioning thermostat or control board may also be to blame. It’s important to have an HVAC technician diagnose and fix any electrical issues to get your furnace up and running again.

How often should I change my air filters to prevent clogging?

To prevent clogging, we should change our air filters regularly. The frequency depends on several factors such as the type of filter, the level of pollutants in our area, and the usage of our furnace.

Generally, it is recommended to replace air filters every 1-3 months. Regularly changing air filters can improve airflow, reduce energy consumption, and extend the lifespan of our furnace.

What are some signs that my gas supply may be the issue with my furnace not turning on?

Some signs that the gas supply may be the issue with a furnace not turning on include:

– A lack of gas smell near the furnace
– No pilot light or ignition sound
– Other gas appliances in the house also not working

It’s important to address these signs promptly as they could indicate a potentially dangerous situation.

Contacting a professional HVAC technician is recommended to diagnose and resolve any issues with the gas supply.


In conclusion, when our furnace is not turning on, there could be various potential problems to consider. It could be a thermostat malfunction, issues with the pilot light or ignition system, electrical problems, clogged air filters, or even gas supply issues.

To determine the exact cause and resolve the problem, it is essential to consult a professional HVAC technician. They have the expertise to diagnose and fix any issues efficiently and ensure our furnace operates smoothly again.

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North York