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

Ecobee Thermostat Has No Power? (Possible Causes & Fixes) (1)

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.

Do You Need Your Thermostat Repaired or Reprogrammed?

Get free, zero-commitment quotes from pro contractors near you.

Ecobee Thermostat Has No Power? (Possible Causes & Fixes) (2)

(Video) New ecobee smart thermostat not powering on Fix!

No Power to Newly Installed Ecobee

You’ve just installed your Ecobee, and now, it won’t power on. It’s possible something happened during installation that’s causing a power issue. Check the following areas to see if you can correct the problem.

Incorrect Backplate Placement

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.

Loose or Incorrectly Installed Wires

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.

No C Wire

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.

Incorrectly Installed PEK

You only need a PEK if you don’t have a C wire. Make sure your PEK is installed in this configuration:

  • R wire to RC terminal
  • G wire to C terminal
  • W wire to W1 terminal
  • Y wire to PEK terminal
(Video) Ecobee turned off? A/C cooling Thermostat issue solved.

On the other end of the PEK, you’ll notice a C wire. This should be connected to the C terminal in your HVAC control board.

Problems with Voltage

The Ecobee needs 24VAC to power on. Using a voltmeter, test the voltage between the RC and C wires. If it’s reading less than 24VAC or if you have no voltage, the following scenarios could be the cause:

  • 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.

An Ecobee SmartThermostat with voice control has a green flashing light to indicate 24VAC power is going to the thermostat. If the light is flashing green but there is no power, you need to contact Ecobee’s customer support.

No Power to Previously Working Ecobee

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.

Tripped Circuit

Check your breaker panel to ensure that all circuits are on. If the circuit to your furnace has tripped, switch it back on to re-establish power to the furnace. This should also allow your Ecobee to power on.

Blown Fuse on Furnace Control Board

Open the control panel on your furnace where your thermostat is connected. Check for either a purple 3 amp or an orange 5 amp fuse as they are the most common. If it’s blown, it has to be replaced. After replacing it, the Ecobee should power on without a problem.

Tripped Float Switch

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.

(Video) New Ecobee 3 not powering up. C wire problem

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.

Tripped Temperature Sensor

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.

Related Questions

We’ve discussed a lot of ways to troubleshoot your Ecobee if it won’t power on. But maybe you have more questions. Below are some things other people asked regarding the power functions of their Ecobee thermostat.

Does Ecobee work when the power is out?

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.

How do I reset my Ecobee after a power outage?

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.

(Video) How to fix a blank thermostat

How do I get my Ecobee back online?

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?

Does the Ecobee screen turn off?

Yes, you can configure the Ecobee thermostat screen to automatically stand by when not actively heating or cooling. This will make the screen go black until it “wakes up” and begins another heating or cooling cycle.

Do You Need Your Thermostat Repaired or Reprogrammed?

Get free, zero-commitment quotes from pro contractors near you.

Ecobee Thermostat Has No Power? (Possible Causes & Fixes) (3)

Summing It Up

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.

(Video) No power to Honeywell thermostat? Here's a fix.


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

An unexpected power outage can cause your Ecobee to shut down abnormally and not work after power comes back. If your thermostat suddenly stops working after a power outage, fixing the power supply should bring it to life. Otherwise, you may want it checked by a professional to advise and repair it if necessary.

How do I reset my ecobee thermostat after power outage? ›

Here's an easy four step process to resetting your thermostat after a power outage.
  1. Turn off your thermostat. Before doing any other troubleshooting, start by finding your thermostat and turning it off. ...
  2. Locate and reset circuit breaker. ...
  3. Wait 30 minutes. ...
  4. Turn the thermostat back on.

What happens to ecobee when power goes out? ›

An unexpected power outage can cause your Ecobee to shut down abnormally and not work after power comes back. If your thermostat suddenly stops working after a power outage, fixing the power supply should bring it to life. Otherwise, you may want it checked by a professional to advise and repair it if necessary.

What voltage is the C wire on ecobee? ›

Also known as the common wire, the C wire enables the continuous flow of 24VAC power that ecobee thermostats need to operate.

Does the ecobee have a battery? ›

Your ecobee room sensor is powered by a single 3 Volt CR-2032 battery.

Why does my ecobee thermostat have no power? ›

If your ecobee was previously powered on and working fine, a sudden black screen usually indicates insufficient voltage going to the thermostat. The ecobee draws power from the furnace, so any disruption to this power source will result in a loss of power at the thermostat.

How do I get the power back in my thermostat? ›

Follow these four easy steps to troubleshoot a thermostat not getting power.
  1. Make sure the thermostat is turned on. ...
  2. Replace the batteries. ...
  3. Check the circuit breaker panel. ...
  4. Open the thermostat housing and make sure it's clean.

What happens to thermostat when power goes out? ›

Yes, the thermostat stores the set point and schedule. When power is lost to the thermostat, the only information it "loses" is the current time. Once power is restored, the thermostat will resume its previous settings and configuration. It will also automatically reconnect to the WiFi network.

What happens to smart thermostat when power goes out? ›

The Nest comes with a battery backup, which it switches to once the power goes out. This battery backup is a rechargeable lithium-ion battery. Once the Nest switches over to its battery backup, it will have enough battery power to last just a couple of hours. Then, it will completely shut down.

What 2 wires are used to power the ecobee? ›

ecobee thermostats require a C (common) wire to power on. If your current thermostat uses only two wires (R and W, or T and T) or three wires (R, W, and G), a few installation options are available.

Will ecobee work without c wire? ›

Please download the ecobee app (available for Apple and Android devices) and follow the step-by-step installation guide. If you're lacking a C wire and have at least four wires at your thermostat to work with (refer to this article if you only have two wires), you'll want to install the Power Extender Kit (PEK).

Does the C wire power the thermostat? ›

A C-wire, or a common wire, runs from your low voltage heating system (24v) and carries continuous power to your thermostat. In today's electric market, most newer heating and cooling systems have C-wires, which guarantees compatibility for the installation of all smart thermostats.

How does ecobee thermostat get power? ›

ecobee thermostats require a C (common) wire to power on. If you only have two wires at your current thermostat, there are a few installation options available.

What is the battery life of ecobee? ›

Amazing battery life

SmartSensor is powered by the long-lasting CR2477 battery and uses a secure, energy-efficient radio frequency (915MHz) for up to five years of battery life.

What voltage does ecobee power? ›

ecobee thermostats are designed to work with most 24-volt systems, even older ones. Take a look at your thermostat. If your system is high-voltage, the thermostat should be labeled with 120 V or 240 V or have L1/L2 labels and thick wire nuts. High-voltage systems like electric baseboard heaters are not compatible.

Do you need to reset thermostat after power outage? ›

While it might seem time-consuming or tedious, it's important not to do anything with the thermostat, circuit breaker, or AC unit for 30 minutes after switching the breaker back on. The circuit breaker inside the actual AC unit needs a reset as well, and that's what it'll do during the 30-minute break.

How do I get my ecobee thermostat back online? ›

My ecobee is not connecting to ecobee servers
  1. Try power-cycling the ecobee by removing it from the wall and leaving it off for two minutes.
  2. After two minutes, place the ecobee back on the wall.
  3. To reconnect to Wi-Fi, go to MAIN MENU > SETTINGS > WI-FI > NETWORK > SELECT WI-FI NETWORK.

Can a power outage reset a thermostat? ›

If the power was out for a long time, the thermostat may have automatically reset to the factory default. If this is the case, you'll need to consult your owner's manual to reprogram it—or give us a call and we'll handle it! Power outages can trip breakers, but they're very easy to reset.

Does the thermostat reset when the power goes out? ›

When power is lost to the thermostat, the only information it "loses" is the current time. Once power is restored, the thermostat will resume its previous settings and configuration. It will also automatically reconnect to the WiFi network. Once reconnected, all features are accessible again.


1. Ecobee 3 Thermostat troubleshooting. Unit not powering up. C wire problems
(Peace Peace)
2. Still no power to Honeywell thermostat? Here’s another check.
(Chris McDowell)
3. Ecobee not working
(steven powell)
4. How To Reset Ecobee Smart Thermostat
(One Hour Smart Home)
5. How To Check Power at Thermostat - Furnace & AC Won't Start - Finding Loose Electrical Connection
(Benjamin Sahlstrom)
6. One of the Problems with Smart Thermostats - ecobee3 Extra
(ScottDot Extras)
Top Articles
Latest Posts
Article information

Author: Melvina Ondricka

Last Updated: 10/08/2023

Views: 6666

Rating: 4.8 / 5 (48 voted)

Reviews: 87% of readers found this page helpful

Author information

Name: Melvina Ondricka

Birthday: 2000-12-23

Address: Suite 382 139 Shaniqua Locks, Paulaborough, UT 90498

Phone: +636383657021

Job: Dynamic Government Specialist

Hobby: Kite flying, Watching movies, Knitting, Model building, Reading, Wood carving, Paintball

Introduction: My name is Melvina Ondricka, I am a helpful, fancy, friendly, innocent, outstanding, courageous, thoughtful person who loves writing and wants to share my knowledge and understanding with you.