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Typically, a blinking light on your Nest thermostat or Heat Link signifies that critical data is being exchanged between these devices.

When it comes to a combination of yellow, green, and orange lights, the device may be stuck in pairing mode, trying to reset or trying to update its firmware. 

Rectifying these issues can get your device back up and running, so keep reading to learn more.

At SmartHomePerfected we always advise readers not to undertake any work they are not competent in performing and if in any doubt, it is best to seek the assistance of a professional.

In my experience, the combination of yellow, green, and sometimes orange, blinking light combinations occurs in the 2nd generation Heat Link. 

In this device, there can be two blinking patterns:

  • Blinking rapidly: during a factory reset
  • Blinking slowly: during pairing mode

When the Heat Link is blinking yellow and green rapidly, this indicates the device is undergoing a factory reset procedure. Usually, you can wait it out until the reset is complete but the device can get stuck in this mode.

On the other hand, the Heat Link may start blinking yellow and green slowly, this occurs during pairing mode when the device is trying to connect with your Nest thermostat.

You can fix this issue by bringing the thermostat closer.

However, these simple solutions might not fix the problem and you might need to troubleshoot further. 

Nest Heat Link
Regardless of whatever mode it's stuck in, you can get the Heat Link back up

During this troubleshooting process, you might have to unplug the thermostat and replace the batteries or check the wiring. Live wires can be dangerous so we highly recommend following the necessary safety precautions or getting help from a certified professional.

If your 2nd generation Heat Link or Nest thermostat doesn't exit pairing mode or the reset process, it might be stuck or running into issues with maintaining a stable connection with the thermostat. 

In whatever case, you can try the following troubleshooting steps. 

The first thing you can do is to reposition the thermostat so it's closer to the heat link. So try bringing it as close as possible during the pairing process. 

You might have to move the stand or unplug the thermostat from the wall mount (if it runs on batteries) so be prepared to tackle that as well.

After pairing is complete, you can move the thermostat to a more convenient location but make sure you don't keep it too far apart. I recommend a maximum distance of 10-30m with minimum obstructions.

Also, make sure your Heat Link isn’t hidden away behind your heating equipment, it needs a good amount of breathing room so its antennas can pick up the Thread signal.

If the app can't detect the Heat Link or the device is stuck in pairing mode, you can try carrying out a manual restart. 

Simply press and hold the center button on your heat link for more than 10 seconds. The yellow and green light combination will start flashing rapidly after ten seconds, indicating that the device is restarting. 

After the restart, follow the instructions on the app so you can add your heat link to the app and try to pair it with the thermostat.

Step 3: Force Restart The Thermostat

If the issue lies in your Nest thermostat, you can try to resolve a frozen screen by carrying out a quick restart.  

Similar to the Heat Link, you can restart the device by:

  1. Holding the thermostat ring button for 10 seconds
  2. Letting go and pressing the ring button again
  3. Waiting until the screen lights back up

Step 4: Replace or Recharge Batteries

The batteries might be dead or loose so make sure to reinstall them, or replace them entirely, without failing to install them in the correct polarities.

However, if your Nest thermostat has internal batteries, recharge the device using a Mini-USB or Micro-USB cable and let it charge overnight or for a good couple of hours. 

You can find the USB port on the back of the thermostat.

Also, make sure the battery voltage is up to par, by checking the power information in the technical information menu. 

Final Step: Get Help from a Professional

If the above steps won’t fix your Nest thermostat or Heat Link, they might be defective and in dire need of replacement or rewiring. 

In that case, it’s better to get help from a professional. 


The blinking light combination is mostly apparent in 2nd Generation Nest Thermostats and Heat Links with the issue related to the pairing mode or a stuck reset procedure. 

Usually, these lights go away after a couple of minutes but you can always troubleshoot the issue by following the guide mentioned above.

So try it out and drop us a comment if you have any questions.


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