Wire My ThermostatAmazon Smart Thermostat wiring for heat pump + emergency heat
The Amazon Smart Thermostat should work, but one wire needs checking before you connect it.
Separate AUX and E wires are common on older heat pumps. Many smart thermostats have no E terminal, so what happens to that wire decides whether you have a direct swap.
1Snap a photo of your old thermostat’s wires (optional)
AI reads the terminal letters and wire colors, then you double-check them. Photos are not saved.
2Tick every terminal that has a wire
Pull the faceplate off your old thermostat. Use the letter printed next to each wire, not its color. Skip short jumper wires between two terminals.
More labels (W3, X, X2, K, PEK, L, S, T, U, HUM, DEHUM)
3A few quick questions
4Your wiring
Which smart thermostats work with your wires?
Amazon Smart Thermostat
Probably works: verify first| Wire | Color | Job | Connect to | Note |
|---|---|---|---|---|
| R | red | 24 V power | R | |
| C | blue | Common (C wire) | C | |
| Y | yellow | Cooling, stage 1 | Y | |
| G | green | Fan | G | |
| O | orange | Reversing valve (O/B) | O/B | |
| AUX | white | Auxiliary heat | W | |
| E | brown | Emergency heat | Verify first | No E terminal. If E and AUX land on the same terminal at the air handler (common), cap E. Emergency heat then uses the aux wire. |
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 using the settings below.
- Test heat, cool and fan. If a breaker trips or equipment runs nonstop, power off and call a pro.
App settings to choose
- Reversing valve (O/B): set to O.
- Equipment type: heat pump with auxiliary (electric strip) heat.
What you need
- Amazon Smart ThermostatThe thermostat itselfCheck price
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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; C → C; Y → Y; G → G; O → O/B; AUX → W; E → verify first.
Do I need a C wire for the Amazon Smart Thermostat?
You already have a C wire, so no adapter is needed.