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Ecobee Furnace Not Turning On? 4 Common Causes + Fixes

An Ecobee furnace not turning on equals a cold home just as winter strikes. If you’re facing this issue right now, it’s time to get to the bottom of the problem to get your furnace back up and running again.

Your Ecobee furnace isn’t turning on because of a tripped breaker switch, blown fuse, overheating problems, or thermostat problems. Fix the problem by checking for tripped circuit breakers, inspecting the fuse box, lowering the temperature on the thermostat, and inspecting the thermostat’s wiring.

This article will help you find why your Ecobee furnace isn’t getting power. We’ll walk you through the steps to diagnose the problem and tell you how to fix each issue. 

Tripped Breaker Switch

You might have a habit of jumping to the worst conclusion when your Ecobee furnace stops turning on. Maybe it’s broken and needs to be repaired. 

And sure, there are situations where that’s the case — but, more often than not, the problem is very easy to fix. 

Always start with the basics. You can save yourself a lot of time, effort, and money to get the furnace working again.

Let’s begin the diagnostics by looking at the breaker switch. 

Power runs through this switch, which serves as a safety mechanism for your furnace (and other home appliances, too). If there’s a power surge, the breaker switch trips. When the switch trips, your furnace will no longer be receiving electricity. This means the furnace won’t be able to turn on at all. 

How To Fix

Have you experienced a power surge in your home recently? If your furnace was off throughout the summer, there might’ve been a power surge that went undetected. 

It’s usually easy to reset the breaker switch. However, you must know where your furnace’s breaker switch is located. In most cases, it’s close to the power box. If you open the box, you should see a tripped breaker switch. If this is the case, simply switch it ON and restart your furnace. 

The video below guides you through the procedure of resetting a tripped breaker switch:

Blown Fuse

Your home’s fuse box is another safety precaution protecting the circuit board. It’s significantly cheaper to replace a fuse than a broken circuit board — these small parts play a significant role in preventing severe damage to the furnace. 

If there’s a sudden spike in power, a fuse in your Ecobee furnace can blow. Your furnace won’t turn on until you replace the blown fuse when this happens.

How To Fix

There’s a specific box that houses the fuse for your furnace. This is called the fuse box. 

You should see a small switch there. It acts as a power switch for the furnace. On the inside, there should be a single fuse. The fuse will have a power rating between 3–5 amps.

Here’s what you need to do to fix a blown fuse:

  • Cut power to your furnace at the breaker switch.
  • Open up the fuse box. You may need to use a screwdriver.
  • Check the fuse. If the fuse is blown, the wire inside will be broken. If the wire is still intact, the fuse should work normally. 
  • If the fuse is blown, replace it. Ensure that the amp rating matches on the replacement fuse.
  • Remove the old fuse and insert the new one. 
  • Close the fuse box and return power to the furnace. 

The video below offers a quick guide on replacing a fuse in a furnace:

Overheating Furnace

Furnaces have multiple safety features that protect critical components, such as the transformer and the circuit board. Apart from the fuse and breaker switch, there’s also a temperature limit switch. 

The limit switch constantly monitors the temperature of the furnace. It also checks the temperature settings on your thermostat. If the furnace continues to run for an extended period, there’s a risk of overheating. 

When the furnace gets too warm, the temperature limit switch trips. This causes the furnace to stop producing heat. The switch ensures the furnace doesn’t overheat, as it could spell trouble for the components on the inside. 

How To Fix

There are two possible solutions to this problem. Sometimes, the temperature limit switch is tripped. Other times, it’s stuck or faulty. 

With this in mind, your initial step here is to determine why the switch is causing problems with the furnace. Did the furnace overheat recently?. This should give you an indication that the temperature limit switch tripped. Here’s what you need to do:

  1. Turn off the furnace.
  2. Find the temperature limit switch in the furnace.
  3. See if the switch is tripped. If it is, reset it.
  4. Take a look at why the switch tripped. If you had the furnace running continuously for a very long time, this could’ve caused it. In other cases, it’s due to a dirty filter that needs replacing. 

Replace the temperature limit switch if it’s faulty or stuck. Follow the instructions in the video below:

Thermostat Problems

Another potential problem may lie with the thermostat. If the thermostat has no power, it can’t tell your Ecobee furnace to turn on. You won’t be able to change the temperature either.

The problem is often due to dead batteries. If the thermostat gets its power from the furnace, this might be the issue. Also, the thermostat or wiring could be faulty. 

How To Fix

Start by determining if dead batteries are behind the issue. Remove the thermostat and change the batteries. See if it comes on now. If the thermostat doesn’t use batteries, make sure there are no problems with the power line that runs to the thermostat.

If the thermostat still doesn’t work, check the wires using a multimeter. Ensure they sit snugly in the thermostat. If the thermostat still isn’t working, you may need to replace it.


When the breaker switch trips or a fuse blows, your furnace can’t receive power from the main supply. Overheating and thermostat problems can also lead to a non-functioning Ecobee furnace. Check for all the possible issues, and look for other signs of problems with the furnace setup.


  • Chris Hewitt

    Chris is a Texas-based freelance writer who loves the outdoors and working in his garage. When he's not enjoying the Texas sun, he can be found tinkering with all sorts of things in his workshop.

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