nest thermostat flashing red light

Confused by the Nest Thermostat flashing red light? We’re here to clear it up for you!

The different patterns of blinking on the Nest thermostat, give away certain error codes with the device.

By learning more about the blinking of your thermostat, you’ll be able to tell right away what’s going on with the device and how to fix it.

Let’s learn more!

To fix a red blinking light on the Nest thermostat, start by waiting for the device to charge up its battery capacity.

After that, perform a Power Cycle on the unit, before testing with different charging equipment and replacing the backup batteries.

Keep reading to learn more about the issue with the Nest thermostat and how to fix it!

My Nest Thermostat Flashing Red Light – Explained!

If the Nest thermostat is flashing in red light, that doesn’t certainly mean that there’s a problem.

why is thermostat blinking red

We shall first mention that the red blinking light is usually associated with the battery level of the Nest thermostat and that it is currently being charged.

Once the Nest thermostat gives off the “Low Battery” message on its home display, it means that it’s time for a recharge! In other words, the red blinking light indicates charging.

Flashing Red Vs. Solid Red Light on Nest!

Our ability to rule out the blinking patterns of the Nest thermostat will give you an idea of what’s going on with the device.

In total, there are two patterns of red blinking lights:

  • Flashing Red Light – Low internal battery, but the thermostat is charging
  • Continuous/Solid Red Light – The Thermostat is soon to shut down due to low battery

The solid or continuous red light is more likely to occur with older models of Nest thermostats, however, it still indicates an issue with the battery level.

Let’s learn how to address this problem and fix the blinking red light on the Nest thermostat!

Flashing Red Light Nest Thermostat – Fixed in Minutes!

wait until the battery is charged

After reviewing what exactly has been causing the red light on the Nest thermostat and the patterns of blinking, it’s time to do something about it!

In the guide you’re about to see, we’ve included a variety of solutions that’ll help with the troubleshooting of the Nest thermostat!

Solution #1 Wait Until the Battery is Charged

Before we get into some advanced troubleshooting, you should simply wait it out.

If you’ve just connected your Nest to the charger and it blinks in red, that’s totally normal. In fact, it means that the device is currently charged and should be ready to go after 30-40 minutes.

In that set of thoughts, if you’ve just plugged in the Nest device with a charger, give it an hour!

Note: Although Nest has an operational battery, it has two AAA batteries as a backup charge.

That’s why your thermostat is likely to take longer to charge, especially if the backup batteries got drained too, as a result of continuous usage at low battery levels.

If your Nest has been blinking in red for the past 2-3 hours and there doesn’t seem to be any change in the patterns of blinking, keep reading further!

Solution #2 Power Reset the Nest Thermostat

pull off thermostat from wall

Next, we’ll be trying something known as “Power Reset” on the Nest thermostat!

As the name of the method suggests, we’ll be resetting the power of the thermostat, by removing its backup batteries for a certain amount of time.

By doing this, we’ll achieve a software and a hardware refresh of the Nest thermostat, which is convenient.

Follow these instructions to Power Reset the Nest thermostat in easy steps:

  1. Pull the thermostat off the wall base.
  2. Take out the backup battery compartment latch.
  3. Eject the 2 AAA batteries from inside the thermostat.
  4. Insert the pair of AAA batteries back into the Nest thermostat.
  5. Put the battery compartment back together.
  6. Push the thermostat back onto its wall base.
  7. Test the device…

To completely perform a Power Reset on the Nest thermostat, the least amount of time that the device must be kept without batteries remains 5 minutes. 

Alert: Re-installing the batteries right away after removing them, will not power reset the device!

Solution #3 Use Different Charging Equipment

use different charging equipment

Perhaps, this is a problem caused by the Charging Equipment, used for filling the thermostat’s battery.

If the device has been standing connected to a charger for a while now, and still blinking red, it’s probably that the microUSB cable cannot properly recharge the battery of the unit.

  • Get another microUSB cable with an adapter, and connect the thermostat!

In addition, you should also install the charging equipment of the Nest Thermostat into a different electrical outlet, to address two issues at once.

If there has been a problem with the power source where you’ve connected the thermostat, it won’t charge either.

Note: Let your thermostat charge up with its new equipment, for at least 30 minutes!

Solution #4 Reset the Nest Thermostat

reset the nest thermostat

Another way to fix the “Nest Thermostat flashing red light” problem is to Reset the thermostat.

It’s another simple and effective method for the common user to try and also a great approach for addressing software issues.

Although the red light is caused by the batteries of the thermostat, it wouldn’t hurt to reset the software of the unit and check how that would go.

Here’s how to reset the Nest thermostat easily:

  1. Press on your thermostat’s ring.
  2. Choose the Settings tab.
  3. Turn the thermostat’s ring to the right and press Select on the “Reset” option.
  4. Choose your option from the rest options.
  5. (Optional) Select “Erase All”.

Although you’ll be able to choose from multiple reset options, we suggest selecting the complete factory reset feature “Reset All”.

It’ll wipe all settings and data from your thermostat, that could’ve been causing the problem.

Note: Once your thermostat starts resetting itself, do not interact with the device.

Solution #5 Identify HVAC System Wiring Issues

check for damages in wiring

Inspecting the wiring installation of your HVAC System definitely requires at least a bit of technical knowledge and a common electrician’s sense, but don’t worry, we’ll help!

There’s an easy way to access the wires in the Nest thermostat and try to spot any faults with the wires, which you could later report to a specialized technician.

After all, only someone specialized, or Nest technician themselves could repair your HVAC system installed properly.

Here’s how to identify HVAC-to-Thermostat wiring issues:

  1. Take off the thermostat from its base.
  2. Cut the power from the circuit breaker to your HVAC system temporarily.
  3. Locate the 4 screws, holding the thermostat’s mounting base to the wall.
  4. Undo the screws and pull out the base.
  5. You should be seeing 2 or 3 wires, based on the type of your HVAC system.
  6. Try to spot any cuts, damages, or rips, inflicted on the thermostat’s cables.

If you did see fatal damages to the cables, then your next step is to call a technician right away, to take a look and repair the fault.

Alert: We strongly suggest not fixing the wires by yourself, since you could mess up the system.

Solution #6 Replace the Backup Batteries

replace the backup batteries

This whole problem could go away, by inserting fresh batteries in the Nest thermostat.

We’ve tried to save some of your time by just power resetting the thermostat back in the second solution, but if the problem seems to persist, it’s likely that the batteries have finally died.

  • Before proceeding with the steps, purchase a pair of new AAA batteries! 

Here’s how to replace the backup batteries of the Nest thermostat easily:

  1. Take off the thermostat from the wall stand.
  2. Remove the battery compartment cover on the back of the device.
  3. Eject the old batteries of your thermostat.
  4. Insert a fresh set of AAA batteries inside the device.
  5. Re-install the components of the battery compartment.
  6. Place the thermostat back on the wall.
  7. Try powering on the device…

If the thermostat is now fully functional after replacing its batteries, the red light on the device should stop blinking soon.

The thermostat may keep blinking in red for several seconds after replacing the batteries, but that’s just leftover electricity, left by the old battery pack.

Note: The batteries must be inserted correctly, or the Nest thermostat won’t power on!

Quick Recap:

When Nest Thermostat flashing red light, connect the device to the charger and wait for it to reach full battery capacity.

If that didn’t work, power reset the thermostat by removing its backup batteries, check the HVAC system’s wiring, and try with a different charger.

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