Car wiring diagrams: First Generation Nest Wiring Diagram, wiring diagram, wire wiring harness, schematic circuit diagram, wiring diagran, wireing diagram, wirring diagram, wiring daigram, wiring diagrams. Here s a step by step guide to help you. Take a picture of your current thermostat s wiring. Confirm that your system is compatible and get a wiring diagram. Install your Nest Thermostat. Switch off the power. Remove the cover of your existing thermostat. Check your system and get a wiring diagram..How to tell which Nest Thermostat you have st Gen, nd Gen or rd st generation Nest Thermostat. Installation Guide pages, .MB ..Install your thermostat on the wall . Set up Your Nest Thermostat will guide you through a series of simple questions about your home, what .