I recently installed an Aqara Thermostat Hub W200 to replace a Honeywell thermostat on a conventional heating/cooling system (furnace + AC, no heat pump).
My wiring is as follows:
- Rc: red
- G: green
- C: blue
- Y1: yellow
- W1: orange (stage 1 heat)
- W2: white (stage 2 heat)
The old Honeywell thermostat worked correctly — cooling and heating both functioned as expected on the same wiring and same air handler. Nothing was changed at the air handler during installation.
The old thermostat base plate is physically labeled “CONVENTIONAL” and wires were connected on the conventional terminal row. There is no O/B wire, confirming this is not a heat pump system.
Issue:
The Aqara blows hot air when set to Cool mode. The app shows W1 and W2 as “Aux Heat” rather than “Heat,” suggesting the thermostat is not fully exiting heat pump mode despite being configured as a conventional furnace system.
Diagnostics performed:
- Completed full setup as conventional system (Furnace/Run). Device screen shows Cooling: 1 Cool and Furnace (Run): 2 Heat. However the wiring diagram still shows W1 as Aux Heat. (no color)
- When set to Cool, it blows hot.
- Disconnected W1 and W2 entirely — system still blows hot in Cool mode, ruling out the W terminals as the sole cause.
- Fan-only mode works correctly, producing neutral unconditioned air. The thermostat is controlling the fan properly.
- Wiring at the air handler was verified and is correct.
- Performed multiple full resets and reconfigurations — issue persists.
Not sure if it’s because of the firmware update or not…