Why Is My Nest Thermostat Blinking Red Light? [6 Easy Fixes]

Are you worried because your Nest thermostat has suddenly started blinking red light, and you don’t know what to do about it? Your Nest may often blink lights of different colors at certain inconveniences, which may direct you to act accordingly.

So, what does the red flashing light on the Nest thermostat mean?

The red flashing light on your Nest thermostat indicates that it has low-powered batteries. Thus, it may no longer work efficiently. Therefore, to tackle this situation, all you need to do is replace its battery, charge it, or look for any defect in the wiring that creates such a hindrance for it to work well.

Keep reading to learn all about Nest blinking red light. We shall also list some quick workarounds to fix this issue in no time.

why is my nest thermostat blinking red light

What causes the blinking red light on Nest thermostat?

The low battery is the primary cause of the red blinking light on the Nest thermostat. However, there may be several reasons that may result in such a cause.

Here are the causes for the blinking red light on the Nest thermostat:

  • The low-powered battery of your Nest thermostat may not enable it to perform its functions well.
  • Wiring problem which may create hindrance for your Nest to charge when needed.
  • Power issue or no power to the r-wire may not provide sufficient energy for your thermostat to charge.
  • Outdated software may also disrupt your thermostat’s functioning and may blink red light in return.

How to fix the Nest thermostat flashing red light?

To fix the Nest thermostat flashing red light, you first need to rule out the main cause concerning it. As discussed earlier, low battery is the main culprit; however, there are various reasons. Therefore, follow the most suitable fix concerning the main problem.

Below are the fixes for your Nest thermostat flashing red light:

1. Replace your Nest’s battery

Its low-powered batteries are the most common cause of the red flashing light on your Nest thermostat. Therefore, the first thing that should come to your mind while dealing with such a situation should be to charge these batteries.

If you have a built-in battery system in your thermostat, then this fix may not be a suitable option for you. However, if your batteries are replaceable, head to the nearby store and get 2 AAA alkaline batteries as soon as possible. Then, simply remove the old ones and insert these new ones for efficient results.

Below are the steps to replace your Nest’s battery:

  1. Firstly, pull out the Nest’s display off the base.
  2. Next, remove the old batteries from the back of your Nest’s display.
  3. Now, insert 2 AAA alkaline batteries, ensuring their right position.
  4. Lastly, place the Nest’s display back and press it gently until you hear a clicking sound.

2. Charge your low-powered battery

If you have a built-in battery system within your Nest thermostat and have a low battery issue, then charging them is your only option. To charge your Nest thermostat, you need to get a USB cable to connect it to the back of your system at the USB port.

Here are the steps to charge your Nest thermostat:

  1. Firstly, pull out the Nest’s display off the base.
  2. Next, connect it to the USB port of your laptop, computer, or the main switch using a USB cable, just like how you charge your mobile phone.
  3. You’ll soon see a blinking light on the front of the Nest thermostat, indicating that it’s charging, and soon, you will resolve your red blinking light problem. Note that usually, Nest takes half an hour to charge.

However, if the battery has drained completely, it may take two hours to charge fully.

3. Check the R-wire on your Nest thermostat

The R-wire on the Nest thermostat powers your HVAC system completely. So, your Nest thermostat may simply stop functioning if there is anything wrong with the R-wire.

Therefore, you simply need to check the power of the R-wire on your thermostat to rule out any sort of problem with the R-wire.

Simply start by checking the wire itself, then check the power system is on. Further, check your thermostat’s wiring, ensuring it won’t have any problem. Lastly, ensure the drain pan isn’t clogged, and the float switch is on and not tripped.

4. Check the wiring of your Nest thermostat

If none of the above hacks helps you in any way, then the next step is to check the wiring of your Nest thermostat. Before checking your thermostat’s wires, turn off your system to prevent any faulty wire from damaging your Nest.

Below are the steps to check the wiring of your Nest thermostat:

  1. Firstly, head to the Settings on your thermostat.
  2. Next, go to the
  3. Now select the option Wiring Info.
  4. You’ll now see a map of wires connected to the Nest thermostat.

Note that all the wires should be in color. If you see any grey wire, then this indicates that a particular wire is not sending power to the Nest. Likewise, if all the wires appear grey, then it means you’re facing any power issue.

You may then contact the technician if you need any help to fix this wiring issue if you’re not aware of the electrical components of your Nest thermostat.

Also read: How to fix Nest no power to Rh wire

5. Reset your Nest thermostat

If the wiring system of your Nest thermostat is completely fine, then the next step is to reset your system. As you know, resetting simply refreshes your system clearing all the bugs, errors, glitches, and stored data in no time.

Here are the steps to reset your Nest thermostat:

  1. Firstly, head to the main menu.
  2. Next, go to Settings.
  3. Now select
  4. Lastly, move to the Factory reset option and select it.

6. Contact the customer support team

If none of the above hacks supported you, then the only option is to contact the customer care support team. Simply explain to them the problem you’re facing then they’ll guide you accordingly.

They’ll help you recognize the main cause behind the problem you’re facing and then guide you on getting rid of it by following simple steps.

They may also send their team to your place to fix the issue if you cannot solve it yourself. So, feel free to contact them for the best results.

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Nest thermostat blinking red light primarily indicates low battery. There may be certain issues concerning this problem. All you need to do is either charge your thermostat or its battery. However, if it has any issue with its wiring or the main power, then fix it accordingly.

This blog will help you recognize the main reason behind your Nest thermostat blinking red light in no time. So, follow this guide step-by-step to get rid of the Nest blinking red light issue without any hurdles.

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