Wiring guide
Amazon Smart Thermostat wiring for aC only, with C wire
Good news: the Amazon Smart Thermostat is a direct swap for this setup. Every wire has a matching terminal.
Cooling-only systems (central AC with an air handler and no heat) are common in the South. With a C wire, most smart thermostats install directly. Read the full aC only, with C wire guide for how to confirm your setup and mistakes to avoid.
Wiring diagram
Detected system: 1-stage cooling, fan, C wire present · 4 wires
Amazon Smart Thermostat
Works: direct swap| Wire | Color | Job | Connect to | Note |
|---|---|---|---|---|
| R | red | 24 V power | R | |
| Y | yellow | Cooling, stage 1 | Y | |
| G | green | Fan | G | |
| C | blue | Common (C wire) | C |
Install steps
- Turn off power to the furnace/air handler (switch or breaker) and the AC condenser. Confirm the old thermostat is dead.
- Photograph the old wiring, then label each wire with the letter it came off. Ignore short jumpers.
- Connect each wire to the Amazon Smart Thermostat terminal shown above. Cap unused wires one at a time.
- Restore power and finish setup in the app.
- Test heat, cool and fan. If a breaker trips or equipment runs nonstop, power off and call a pro.
What you need
- Amazon Smart ThermostatThe thermostat itselfCheck price
As an Amazon Associate we earn from qualifying purchases, at no cost to you.
Confirm against the official Amazon install guide. The app also checks your wiring during setup.
Frequently asked questions
Where does each wire go on the Amazon Smart Thermostat?
R → R; Y → Y; G → G; C → C.
Do I need a C wire for the Amazon Smart Thermostat?
You already have a C wire, so no adapter is needed.