topic Re: Wiring a nest thermostat with 5 wires in Nest Thermostats

Wiring a nest thermostat with 5 wires

Andy53 — Mon, 09 Mar 2026 19:42:44 GMT

I have a 5 wire system. Brown White Red Green Blue. How do I wire the nest with these colors?

Re: Wiring a nest thermostat with 5 wires

Andy53 — Mon, 09 Mar 2026 19:51:24 GMT

E103 error Y wire issue

Re: Wiring a nest thermostat with 5 wires

CoolingWizard — Tue, 10 Mar 2026 05:48:45 GMT

@Andy53 ,

In the installation instructions you were advised to take a screenshot of you old thermostat wiring before you removed the old thermostat. Looking at that screenshot, you should see letters next to the terminal connections. just match the colors and let her from the old one to the color wire to the new one.

AC Cooling Wizard

Re: Wiring a nest thermostat with 5 wires

CoolingWizard — Tue, 10 Mar 2026 05:52:49 GMT

@Andy53 ,

If your thermostat is reporting an E103 on Y1, it is seeing excessive voltage coming in the wire. This sometimes happens when put the R wire in Y1.
Double check the wires from your old thermostat screenshot and make sure the color of the wire attached to Y on your old thermostat.

The Cooling Wizard