Hi WendyM,
Thanks for reaching out here in the community! I'm sorry to hear that you're having an error message that says no power to Y even if it's connected to your Nest Thermostat E. I understand how important it is to get your heating working, especially when the temperature is at 17 degrees outside. I'd be happy to help!
Regarding your question about whether the Y1 wire is necessary in the winter when you're not using the AC, it depends on your current wiring setup. Sometimes, if your thermostat doesn't have a dedicated common wire to stay powered, it can use the Y1 (air conditioner) wire to power itself.
To better assist you, I'd like to ask the following:
- Did you see any specific error code?
- What type of HVAC system do you have (heat pump, conventional system, etc.)?
- Would you mind sharing a picture of your current wiring installation?
- Have you tried any troubleshooting steps so far?
In the meantime, I'd suggest the following:
- To identify if there’s power loss on the Y1 terminal or the whole system, check the power readouts one more time by going to Settings > Technical Info > Power. And share with me the VIN, VOC, and IIN values.
- Check that the wires are fully inserted into the terminal and the connector buttons are securely pushed down. This ensures proper wire connections. For reference, you can check out this article: Troubleshoot Nest thermostat help codes. Important: Before touching any wires, turn off the power to your HVAC system at the breaker box.
Please keep me posted.
Best regards,
Jennifer
