Google Nest setup with black, green, yellow and red wires?

[LP99]

Greetings,

I have spent hours trying to setup my Google Nest Thermostat to no avail. At first I did successfully set it up using the app, but only the cooling system was recognized. The old thermostat does not currently have a white wire and I am wondering if that effects things?

I had to hook up the old Honeywell thermostat for the time being and the heat is running just fine with only the black, green, yellow and red wires. Is this wire setup not compatible with Google Nest?

[Markjosephp]

Hello LP99,

I understand the frustration you're experiencing with your Google Nest Thermostat setup. It's not uncommon to encounter challenges during installation, but let's work together to find a solution.

First, the absence of a white wire in your old thermostat might be a factor. If you have a heating system, a wire should be available at the W terminal. Also, the Nest Thermostat typically requires a common wire (C-wire) for full functionality. The C-wire provides constant power to the thermostat, and its absence might affect the recognition of your heating system.

If your current setup includes only black, green, yellow, and red wires, it's likely missing the C-wire or heating wire. You may want to check if there's an unused wire tucked behind your thermostat wiring or in your HVAC system. 

Let us know how it goes.

Best regards,
Mark