Nest thermostat Gen3

[Scuba28173]

Lately my Nest thermostat changes modes by itself. It only recently started this. I have it set to heat/cool and at some point it goes back to heat. I've erased all the schedules and set a schedule for just the heat/cool mode, but that didn't help. I use home/away assist, but that puts the thermostat into eco mode not heat. I'm at my wits end with this issue. Any help would be appreciated. Also, I did chat with support, but they were no help.

[luciaaa]

Hi, @Scuba28173!

Thank you for posting in the community. It is certainly concerning that your Nest Learning Thermostat (3rd gen) is automatically switching modes, specifically returning to heat mode despite you setting it to cool or heat. I appreciate your troubleshooting efforts and your contact with chat support. I'm truly sorry the inconvenience persists. I'd like to help you find a solution.

To better assist you, please answer the following questions: 

• Is this a new installation?
• When did the inconvenience start?
• What other strange symptoms have you experienced since the inconvenience started?
• Is the thermostat displaying any error messages?
• Do you have a conventional system (furnace and AC unit) or a heat pump system (single unit for heating and cooling)?
• When was the last maintenance check for your HVAC system?
• Do you have any schedule set? 
• Do you have the Nest Renew subscription? You can check this article to learn about Nest Renew. 
• Are you enrolled in the Rush Hour Reward program? Refer to this article for more information: Learn about Rush Hour Rewards.

Additionally, please provide the following information: 

• A picture of the current wiring configuration on your Nest Learning Thermostat (3rd gen).
• A screenshot of the configuration on the Nest or Google Home app.

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

Please keep me updated.

Best regards.

Ana