Nest Gen4 - Fan will not stop running in off mode

rmck — Mon, 02 Mar 2026 00:40:52 GMT

I recently installed a Gen3 Nest. However, the fan will not stop running. The only option to stop the fan is to remove the G (green wire) or turn off the system at the breaker. Any suggestions?

Re: Nest Gen4 - Fan will not stop running in off mode

TEEBE — Wed, 04 Mar 2026 16:16:29 GMT

You don't have a fan schedule set up, correct?

I wish there was more transparency for the internal Nest decision making.

Re: Nest Gen4 - Fan will not stop running in off mode

GabrielaG — Thu, 05 Mar 2026 23:11:43 GMT

Hi @rmck,

Thanks for reaching out to the community. I'm sorry to hear that your Nest Learning Thermostat is not working as expected because the fan will not stop running in off mode and the only option you have to stop it is to remove the G (green) wire. I appreciate your efforts to fix this, and I'm glad to help you.

Thank you for jumping in @TEEBE.

To get a better understanding of the situation, please help me out by answering the following questions:

Just to confirm, is your Nest Learning Thermostat a 3rd gen or 4th gen? If you need help identifying it, check this article: How to tell which Nest thermostat you have.
What type of HVAC system do you have? (e.g., gas, electric, or heat pump)
Do you see any error codes on the thermostat’s screen?
Could you please send me a picture of the thermostat backplate? This will help me see the current wiring configuration.

Keep me posted so I can provide you with further assistance.

Regards,

Gabriela

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Nest Gen4 - Fan will not stop running in off mode

Re: Nest Gen4 - Fan will not stop running in off mode

Re: Nest Gen4 - Fan will not stop running in off mode