Nest thermostat gen 3 error E77

[zoro07]

Hi all,

I am trying to setup my nest thermostat 3rd gen and getting an error E77 that wire Y1 is not connected.

I do not have any Y wire connected to my old thermostat. Could some one please help me understand the right setup of my nest thermostat.

[AxelD]

Hi zoro07,

Thanks for posting in the Community! Sorry to hear that you’re getting the error E77 while you’re setting up your Nest Learning Thermostat. No worries, help is here! Please provide me with the following information:

1. Could you post a photo of your previous and current wiring?
2. What kind of system do you have? (Conventional or Heat Pump)

In the meantime, you may find helpful information in this article to Troubleshoot Nest thermostat help codes. It offers specific guidance for the E77 error.

Keep me posted.

Regards,

Axel.