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Furnace Won’t Kick On

Furnace Won't Kick On? Troubleshooting Tips to Restore Warmth

Discovering that your furnace won’t kick on can be a chilly surprise when cold outside. Don’t worry! Walker Heating & Air Conditioning is here to help. Before you rush to call the pros, let’s dive into a quick and easy guide to try to fix this common issue. Learn how to bring your furnace back to life and restore warmth to your home with these expert tips.

furnace won't kick on

Top 5 Easy Reasons Why Your Furnace Won't Start

  1. Thermostat – Ensure the thermostat is set to the right temperature with heating mode ON. Sometimes, the furnace won’t kick on if the temperature is set below the home’s temperature. Make sure the batteries are brand new.
  2. Power Supply – It could be a power issue if the furnace is not responding or doing nothing. Check the furnace switch. Usually, it looks like a regular light switch near the furnace. Also, check the electrical panel to ensure the breaker is ON and not tripped.
  3. Air Filters – If a clogged air filter restricts air, your furnace will turn off after running for a few minutes. The furnace can’t breathe, and it overheats, causing a safety to turn it off.

Troubleshooting Why the Furnace Won't Kick On

If you’ve checked all the reasons above and the furnace still won’t kick on, here’s how to troubleshoot.

6 Sequences of Operation for Gas Furnaces

  1. The first thing that happens is the furnace gets a signal from the thermostat to the W and C connections.
  2. Next, if the circuit board and relays work, they send power to the inducer motor. Note: If you have a standing pilot that won’t light, here’s a video on how to light a pilot on a furnace.
  3. The next sequence closes the PSIG switch if the inducer motor runs. Note: If you have an ancient furnace that is 20+ years old, it may not have an inducer motor. These are natural draft furnaces. You can skip the inducer and PSIG switch and will go straight to this next step.
  4. The ignitor will get power if the PSIG switch closes and all other safeties stay closed. Note: If any safeties like the PSIG switch, roll-out, limits, etc., the inducer motor will continue to run. When this happens, the ignitor can also be bad if it gets power with all the safeties closed.
  5. The next step is the gas valve will receive 24v and push gas through the manifold to the burners. If the gas valve receives 24 volts and no gas comes out, you most likely have a bad gas valve.
  6. Next, if the flames are coming on, congratulations, you don’t even have to worry about the first five steps. The flame sensor is the 6th and last reason the furnace won’t kick on. The flames must be present, or the flame sensor will kick the gas off. Remove and clean the flame sensor if the flames light for a few seconds and then cut off. You can use a dollar bill, steel wool, or light sandpaper.

Furnace Repair - Blower Motor Replacement


Facing a furnace that won’t kick on stinks, but with these troubleshooting tips, you may stand a chance. This guide helped you navigate common furnace issues and restore your heat.
If DIY solutions fall short, contact Walker Heating & Air Conditioning. Call Today! (703) 483-2400

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