Nest Thermostat Not Getting Power? (6 Instant Solutions)

Wondering why is the Nest thermostat not getting power? Stay with us throughout this guide!

The power supply of the Nest thermostat may have sustained functionality impairment due to a severe power outage or damaged terminal wiring.

This guide will help you identify the exact cause of the power faults with the Nest thermostat and produce helpful solutions to try at home.

Whenever the Nest thermostat is underpowered, verify that the power source of the “C” wire and the backup batteries are in proper condition. If the issue persists, reconnect the terminal wires of the unit’s base.

There is much more to discuss, so let’s get started!

Why is the Nest Thermostat C Wire Not Getting Power?

The power supply of the Nest thermostat consists of replaceable or rechargeable backup batteries (based on the model) and the primary C-wire power supply.

If either of the power sources fails to transmit electricity sufficiently, the Nest thermostat may run into a power error.

Here are the possible causes for the power insufficiency of the Nest thermostat:

Those can be the possible reasons for the power malfunction of the Nest thermostat.

Hence, to uncover all potential solutions, advance to the complete guide and solve the issue in minutes!

Nest Thermostat Not Getting Power – Here’s How to Fix!

Tip: Follow the proven solutions below to fix the issue efficiently!

1. Reinsert the Nest Backup Batteries

The first step to address power-related issues with the Nest thermostat is to reinsert the internal batteries, as long as they are replaceable.

Only the standard Nest thermostat models run on two triple-A backup batteries, while the Nest model “Learning” and model “E” use rechargeable.

Here’s how to take out the batteries of your standard (Google) Nest thermostat:

1. Take off the front plate of the Nest thermostat.
2. Expose the battery compartment on the side.
3. Remove the compartment cover from the dock.
4. Eject the replaceable batteries from the Nest.
5. Wait for 15 seconds and reinsert the batteries.

Tip: If the batteries have not been replaced recently, insert a fresh set of two triple-A batteries!

2. Install an External New Power Supply

What’s revolutionary about Nest thermostats is that they are configured to function without a C-wire in most homes.

The C-wire adapter is designed to be installed in case of an electrical insufficiency of the thermostat to supply additional voltage and stabilize the Nest’s functionality.

The “Nest Power Connector” is available for purchase within the Google Store and can be installed without professional knowledge about the installation but with the correct guidelines!

How to Install Nest External Power Supply?

Installing an external power supply is a process that can be completed in a few steps.

However, before starting it, turn off the power to the HVAC system and open the face of the thermostat. 

Here’s how to install an external power supply to a Nest thermostat:

1. Locate the wires between the thermostat and the HVAC.
2. Identify the wire connected to the “RC” and “RH” terminals.
3. Disconnect the wires by undoing the attachment screws.
4. Connect the new external power supply to your HVAC.
5. Connect the thermostat with the new “C” power supply.
6. Finally, turn on the power at the breaker and test the Nest.

If you’ve followed the steps correctly, the C-wire connector of the Nest thermostat should be fully functional and supply the unit with extra voltage.

If the issue persists, double-check the C-wire connector’s leads and verify they are correctly installed on both ends.

Important: The RH terminal goes with the red wire and RC or C with the black one!

3. Check the Primary Circuit Breaker

If the Nest thermostat is not getting power, another solution you must attempt is to reset the power supply of the system by switching off the circuit breaker.

A potential voltage fault or overloading of the HVAC system could also impact the thermostat’s functionality.

Notice: Resetting the circuit breaker will only help if the Nest thermostat has a “C” wire!

How to Identify a Tripped Circuit Breaker?

A tripped circuit breaker moves to the center of the panel, neither supplying nor deactivating the power supply of the system.

Hence, the next step is to reset the circuit breaker by pushing it to the “OFF” side first and then restoring the power supply of the system by setting it to “ON.”

Here’s how to reset the circuit breaker of the HVAC system in easy steps:

1. Open the circuit breaker panel and find the “HVAC” switch.
2. Push the switch downwards to deactivate the HVAC power.
3. Wait for 60 seconds while the system’s power is turned off.
4. Next, push the system switch back up to the “ON” position.
5. Wait until the Nest thermostat reboots and loads the system.

Note: Your Nest thermostat may take up to 5 minutes to load the system!

4. Inspect the Nest Thermostat’s Wiring

If the Nest thermostat is not getting power after resetting the circuit breaker, the issue could be with the terminal wires’ installation.

There are specific preferences as to how the wiring of the Nest thermostat must be hooked up, so it’s vital to verify that everything is connected correctly.

Here’s how to access the terminal connections of the Nest thermostat:

1. Turn off the power to the HVAC system. 
2. Then, remove the thermostat’s display. 
3. Inspect the wiring for any damage signs.
4. Check the wires’ connection to a terminal.

How to Set Up Nest Thermostat’s Terminal Wires?

• The Yellow wire plugs into the “Y1” terminal.
• The Gray wire plugs into the “Y2” terminal.
• The Green wire plugs into the “G” terminal.
• The Orange wire plugs into the “OB” terminal.
• The Red wire plugs into the “RC” terminal.
• The Brown wire plugs to the “W2/AUX” terminal.
• The Blue wire plugs into the “C” terminal.

If you’ve identified defective thermostat equipment or damaged wire during the inspection, contact the Google Nest support team at 1 (888) 525-3050.

Important: Turn on the power only after you’ve installed the faceplate of your Nest thermostat!

5. Factory Reset the Nest Thermostat

A change in the thermostat’s settings could cause the Nest thermostat not to get enough power, resulting in advanced issues with the software.

To eliminate potential misconfigurations in the Nest thermostat’s power behavior, it is recommended to conduct a factory reset.

Here’s how to perform a factory reset on the thermostat:

1. Access the Nest settings menu on the display.
2. Scroll down and select “Reset” or “Factory Reset.”
3. Next, confirm the “Reset” action when prompted. 
4. Wait for the Nest thermostat to complete the reset.
5. Then, set up the Nest thermostat’s system initially.

The HVAC system will treat the factory reset on the thermostat as a new device installed.

It will reset the voltage settings, setup schedules, and other user-customized options, prompting you to set up the device from scratch.

So, shortly, you must see the “Initial Device Setup” prompt.

Alert: Do not interact with the Nest thermostat while the factory reset continues!

6. Test the HVAC System Voltage

The Nest thermostat isn’t getting power could occur whenever the thermostat is not receiving enough voltage from the power supply or is not within the expected range.

The unit relies on a stable voltage supply to operate efficiently, as Over/Under voltage impacts the functionality.

Note: To perform a voltage test, a Multimeter will be required!

Here’s how to test the voltage on the Nest thermostat:

1. Set the Multimeter to the AC voltage setting.
2. Insert the probes into the R and C terminals. 
3. Then, turn on the A/C to the HVAC system. 
4. Observe the readings from the Multimeter.
5. Note down the readings of the multimeter.
6. Turn off the HVAC and reinstall the display.

If your multimeter’s voltage arrow does not move, it means there’s a fault with the main power supply of the HVAC.

In such a case, it is strongly advised to consult with an HVAC technician or contact Google Nest support for further association regarding the issue.

Note: If the multimeter reading is between 24-30 volts, the thermostat receives enough voltage! 

Quick Recap:

Whenever the Nest thermostat not getting power, ensure the power supply isn’t damaged and inspect the internal “C” wire connector.

If the fault is still there, you must correct the terminal wires installation of the thermostat and perform the factory restoration process!

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