Why Won’t My Furnace Turn On? A Michigan Tech Explains

It’s frustrating and inconvenient to deal with your furnace not turning on during a cold day so we’re here to help you troubleshoot the problem.

The only way you can know exactly what’s wrong with your furnace is to have a professional diagnose your system. However, the four main issues that could be causing your furnace to not turn on include:

• Your thermostat is on the wrong settings
• A tripped circuit breaker
• A dirty air filter
• Your condensate drain pipes are clogged

In this blog, we’ll look at each of these issues in more detail as well as let you know which of these issues can be fixed by you, and which require a professional’s help.

Want a professional HVAC technician to fix your furnace ASAP? Contact Thornton & Grooms. We provide same-day furnace repairs so we’ll get your heat up and running again in no time.

Your furnace may not be turning on if your thermostat is on the wrong settings.

If your thermostat is on the wrong settings, it may not trigger your furnace to turn on. To ensure your thermostat is on the right settings, start by:

• Making sure your thermostat is powered on. If the display is off or unresponsive, try switching out the batteries.
• Confirming that the thermostat is set to HEAT and ON. If your thermostat is set to COOL, your thermostat won’t tell your furnace to turn on even if the temperature you’ve set on your thermostat is higher than the temperature in your home.

If your furnace isn’t turning on, you’ll want to check if your furnace’s circuit breaker isn’t the issue. If the breaker has tripped, power to the furnace will be cut and the furnace won’t be able to start up again until the breaker is reset.

To fix a tripped circuit breaker, you’ll want to find your home’s electrical panel and search for the circuit breaker labeled “furnace.” If the switch is in the middle position, it has tripped. You’ll want to reset the breaker by:

1. Flipping the breaker OFF (to the right)
2. Waiting 30 seconds
3. Flipping the breaker ON (to the left)

WARNING: If you’ve reset the breaker already and your furnace still isn’t turning on, do not reset the circuit breaker again. Call an HVAC technician for assistance. If the breaker keeps tripping, you might have deeper electrical problems that need to be addressed.

A dirty air filter can block the flow of air to your furnace, causing it to overheat and shut down.

To determine whether or not a dirty air filter is your issue, you’ll want to start by inspecting your air filter. If your air filter looks like the image below, it’s dirty and you should replace it. Once your air filter has been replaced with a clean one, your furnace should start up again. If not, contact an HVAC professional for help.

To prevent your furnace from shutting down due to a dirty air filter in the future, you should switch out your air filter every few months (or when you notice that the filter is dirty).

Most furnaces produce condensation that needs to be drained out of your home so the condensation doesn’t leak into your home. The condensation is drained out of your home via two condensate drain pipes.

However, if the condensate drain pipes get clogged with mold or slime, the condensation will back up and potentially cause water damage to your furnace. Luckily, your furnace has a safety device called a float switch that will shut down your furnace to prevent damage if it notices that your condensate drain pipes are clogged.

In order to get your furnace to turn on again, your condensate drain pipes will need to be unclogged. To unclog your drain pipes, contact a professional HVAC technician to inspect the drain pipes and clear any clogs so the float switch stops shutting down the furnace.

When you schedule a furnace repair with Thornton & Grooms, we’ll assign you a tech based on your desired date. After you’ve made an appointment, your assigned HVAC technician will text you a courtesy ETA before they arrive at your home. We aim to make furnace repairs simple and convenient for you.