"No Power" but then power.

[GBCheval]

My Nest device will shut down and come up with "No Power" for several hours during the day, at times it will be intermittent. It will miraculously recover, usually late in the evening and continue to run just fine, all wiring once again detected, no error messages, only to once again continue the cycle later.  There is no rhyme or reason to it, no "set" schedule.  Any help would be appreciated. Yes I have tried a different Nest, switched with one upstairs that has never had that issue.

[luciaaa]

Hi, @GBCheval!

Thank you for reaching out to the community. I'm sorry your thermostat is repeatedly shutting down and displaying 'No Power,' only to recover seemingly at random. I really appreciate you trying to swap the thermostats and checking for any available schedule. I'd be happy to help you!

To provide the most accurate troubleshooting steps, please answer the following questions:

• What is the model of your thermostat? Here’s a helpful article about how to identify your thermostat model. 
• Do you have a conventional system (furnace and AC unit) or a heat pump system (single unit for heating and cooling)?
• What was the result after swapping the thermostat's display?
• What other unusual symptoms have you noticed since the issue began?
• Is this a new installation? If not, when was the thermostat installed?
• Have you experienced any recent power outages?
• Does this behavior occur daily or sporadically?
• Does this behavior happen every day or just on some random days? 
• Is there a common wire, or 'C' wire, connected to your thermostat?

Additionally, please provide the following:

• A picture of the current wiring configuration at your thermostat.
• A screenshot of the Nest or Google Home app's configuration to rule out setup problems.
• A screenshot of your energy history to check for power fluctuations. Refer to this link for instructions: Thermostat Energy History. 

This information will help to determine the best next troubleshooting steps.

Please keep me updated.

Best regards.

Ana

[GBCheval]

In answer to your questions.

It is the NEST learning thermostat

Heat Pump System (Broan and Carrier)

Switching out my Nest learning devices provided no change to symptoms

The only symptom is that the device show "no Power" error code e298, the wires show no connectivity.

This only seems to occur in the late afternoon and will last until 11;30pm., then everything returns to normal operation.

It is only the AC that is impacted, it has never happened with heat.

The install was from a previous homeowner so I do not have the date and do not know if they also experienced this.

The last power outage occurred in October 2025 ( I was not the homeowner).

This seems to occur whenever the temperature gets above 85 degrees.

Yes there is a c-wire, I have checked the air exchanger and the c-wire is in place and connected.

`Not certain of the configuration (Schedules?? There are none shown)

I have tried to insert/attach the screenshots, and I am informed I do not have permissions or the image upload failed.

Thank you for reaching out. I hope to resolve this soon.

[luciaaa]

 Hi, @GBCheval!

Thank you for your prompt response. I really appreciate the detailed information. I’m happy to help you further.

Since you're unable to share pictures directly in the community, please upload them to a Google Drive folder. For instructions, see the Google Drive Help article: Upload files & folders to Google Drive. Then, share the folder link, selecting 'anyone with the link.' Please do not share personal information or the thermostat's serial number. 

In the meantime, please do the following:

• Check if you have an energy savings box near your electric meter or air conditioner. This box allows the utility company to cycle your air conditioner on and off during peak demand periods. If it's cycling during the day, it might be causing the error code you're seeing. 
• The Rush Hour Rewards works similarly to an energy savings box. This option could also be contributing to the error code during peak hours. Please verify your thermostat's enrollment using the following article for instructions and further information: Learn about Rush Hour Rewards.

Please keep me updated. 

Best regards, 

Ana

[GBCheval]

Hello, Thank you for the follow-up and instructions. 

The photos and screenshots are added. The wiring status in the photo is grayed out (last night around 11:30pm), this morning shows all blue.

There is no box next to the HVAC or Power meter. I also spoke with TECO and there is no energy program tied to my account. I looked at Rush Hour Rewards and there does not seem to be any link.

 

[luciaaa]

Hi, @GBCheval!

Thank you for your response and for all the detailed information. I’m happy to help you further. 

Since you don’t have an energy savings box and you are not enrolled in the Rush Hours Rewards program, please try the following troubleshooting steps: 

• Clean the wires. Before you begin, turn off the power breaker to your HVAC system to avoid any accidents. 
• Remove the display from the base plate.
• Take a clear photo of the wiring configuration. To know how to reinstall the wires. 
• Carefully remove all wires and clean them with a dry towel.
• Reinsert the wires as shown in the photo.
• Restore power to the HVAC system and reattach the display.

If you continue to receive the error code after cleaning the wires, please turn off the breakers and check the following in your HVAC system:

• Check if your system’s drip pan or drain tube is full of water or has a clog.
• Ensure the air filter is clean. Replace it if necessary.
• Verify that the fuses are not burned; if that is the case, replace them. 
• Ensure wires are fully inserted. The wires may not be making a proper connection with the terminals. Make sure at least ¼ to ½ inch of the copper wire is exposed, straightened, and fully inserted into each of the required connectors. If necessary, strip and re-insert the wires.

Please let me know how it goes. 

Best regards, 

Ana