Ecobee Thermostat Has No Power? (Possible Causes & Fixes) (2023)

It’s frustrating when you take time to install an Ecobee thermostat only to have it not power on. It’s even more frustrating when the thermostat was already working and suddenly loses power. In either case, there is always a reason.

For newly installed Ecobees with no power, check the thermostat’s placement on the backplate. There may be loose or incorrect wiring or no C wire. If you have a Power Extender Kit, check that it’s installed correctly. Lastly, you could be having problems with voltage.

If your Ecobee was previously working, check for a tripped circuit, float switch, or temperature sensor. There may be a blown fuse on your furnace control board.

The following information relates to the Ecobee3 Lite, the Ecobee4, and the Ecobee SmartThermostat.

If your Ecobee isn’t placed correctly on the backplate, it won’t power on. Oftentimes, the thermostat wires get in the way of the Ecobee properly connecting to the backplate.

Tuck in any protruding wires to allow the thermostat pins to fully insert into the backplate. You’ll hear a click when the thermostat is completely connected. There will be no gaps or spaces between the thermostat and the backplate.

In order to power the thermostat, the R/Rc/Rh wire must be connected to the Rc terminal. This is true for all Ecobee thermostats except the Ecobee3 Lite.

Check that all wires are inserted into the correct terminal (both the wires and terminals are labeled). Gently tug on each wire to ensure they are snuggly inserted. The tabs next to each terminal should be pressed down to properly secure the wires.

Ecobee makes it very clear that you need a C wire for your thermostat to work. If you have a C wire, make sure it’s connected to the C terminal.

Not all thermostats require a C wire, so it’s possible you have one but weren’t using it. Check your junction box for a spare wire that was pushed to the back. It may be blue or black. Make sure this spare wire is also attached to the C terminal on your HVAC board.

If you don’t have any spare wires but have an R, G, and Y wire, you need to install a Power Extender Kit (PEK). The PEK makes it possible to power an Ecobee thermostat if you don’t have a C wire.

• R wire to RC terminal
• G wire to C terminal
• W wire to W1 terminal
• Y wire to PEK terminal

• Check that the power is turned on at the circuit breaker.
• Check for a blown fuse at the circuit breaker.
• Make sure the cover panel to the furnace is closed completely. Some HVAC systems have a safety feature that cuts power to the equipment if this panel isn’t closed all the way.
• There may be a short in your C wire, which is usually indicated by a clicking sound at the thermostat. Try installing a PEK or using a spare wire as the C wire. If the Ecobee turns on after trying those options, the problem was with your C wire.

If your Ecobee was previously working but has suddenly powered off, it usually means the thermostat is receiving insufficient voltage. The furnace powers the Ecobee. Any disruption at the furnace may result in the thermostat powering off.

Test the voltage at the RC and C wires to make sure the thermostat is receiving 24VAC. If it’s not, check for any of the following issues.

The float switch is a safety feature on an air conditioner. When the AC drain pan becomes too full of water build-up, the float switch automatically cuts power to AC to avoid overflow. No power to the AC means no power to the thermostat.

The float switch is located either on the side of the drain pan or at the bottom of the furnace. Completely empty the drain pan before resetting the float switch. This should restore power to your Ecobee.

Every furnace has an internal temperature limit. Similar to the float switch, a sensor trips once the temperature limit has been met and cuts power to the heater. The thermostat can’t turn on in this scenario.

A furnace overheats when it runs for long periods of time or if the filter is dirty which reduces airflow. You can try lowering your heat temperature set point. Once the furnace reaches the set point, the system shuts off and begins to cool down. If the air filter is dirty, swap it out for a fresh one. Changing it every few months ensures maximum airflow.

In the event you lose power, your Ecobee will continue to run on whatever power it has stored in its rechargeable battery. However, once the battery dies, your HVAC system will stop running until the battery is able to recharge.

All of your settings are safely stored and will be remembered once the power goes back on.

You may find you need to reset your Ecobee after it loses power. This could be due to a power outage or any of the above scenarios that cause the Ecobee to shut down.

To reset your Ecobee, go to the Home screen and press Menu > Settings > Reset > Reset All Settings, then confirm by pressing Yes. In this instance, your Ecobee will be restored to its factory setting. Any personal information or programs you had will need to be reset.

If your Ecobee becomes disconnected from the Wi-Fi, remove it from the wall for at least two minutes. Then, place it back on the wall. This process is known as power cycling. To reconnect the thermostat to the Wi-Fi, go to Main Menu > Settings > Wi-Fi > Network > Select Wi-Fi Network.

Related Guide: Why Is My Ecobee Not Responding?

If your Ecobee won’t power on, you first have to determine whether you’ve just installed it or whether it’s been working for some time.

If you just installed the Ecobee, there may be an issue with how it was installed.

Try adjusting how it sits against the backplate. Make sure all the wires are installed in their proper terminals and tighten any loose-fitting wires. Ensure that you have a C wire and that it’s installed and working properly. If you don’t have a C wire, make sure your PEK is installed correctly. Lastly, ensure that the thermostat is receiving a sufficient amount of voltage,

If your Ecobee suddenly stopped working, it’s usually due to a power issue from your HVAC system.

Check for a blown fuse at the furnace control board. Replace if necessary. Turn on any circuits that have been tripped. If your float switch has been tripped, first empty the drain pan and then reset the switch. Check that your furnace hasn’t overheated due to long runtime or clogged air filters.