Wiring guide
Google Nest Learning Thermostat (4th gen) wiring for heat pump with C wire
Good news: the Google Nest Learning Thermostat (4th gen) is a direct swap for this setup. Every wire has a matching terminal.
The standard modern heat pump: compressor (Y), fan (G), reversing valve (O/B), backup heat (AUX), and power on R and C. Read the full heat pump with C wire guide for how to confirm your setup and mistakes to avoid.
Wiring diagram
Detected system: Heat pump, 1-stage compressor, 1-stage aux heat, fan, C wire present · 6 wires
Google Nest Learning Thermostat (4th gen)
Works: direct swap| Wire | Color | Job | Connect to | Note |
|---|---|---|---|---|
| R | red | 24 V power | Rc or Rh | |
| C | blue | Common (C wire) | C | |
| Y | yellow | Cooling, stage 1 | Y | |
| G | green | Fan | G | |
| O/B | orange | Reversing valve (O/B) | *OB | |
| AUX | white | Auxiliary heat | AUX |
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 Nest Learning (4th gen) 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 or B (O for most brands; B for Rheem, Ruud and some others).
- Equipment type: heat pump with auxiliary (electric strip) heat.
- Single R wire: the Nest app tells you whether to use Rc or Rh.
What you need
- Google Nest Learning Thermostat (4th gen)The thermostat itselfCheck price
As an Amazon Associate we earn from qualifying purchases, at no cost to you.
Confirm against the official Google Nest install guide. The app also checks your wiring during setup.
Frequently asked questions
Where does each wire go on the Nest Learning (4th gen)?
R → Rc or Rh; C → C; Y → Y; G → G; O/B → *OB; AUX → AUX.
Do I need a C wire for the Nest Learning (4th gen)?
You already have a C wire, so no adapter is needed.