Use fan mode when heat/cool is idle in homekit

homeassistant/components/homekit_controller/climate.py

@@ -106,6 +106,8 @@
     FAN_HIGH: ROTATION_SPEED_HIGH,
 }
 
+HOMEKIT_CURRENT_FAN_STATE_ACTIVE = 2
+
 
 async def async_setup_entry(
     hass: HomeAssistant,
@@ -484,6 +486,7 @@ def get_characteristic_types(self) -> list[str]:
             CharacteristicsTypes.TEMPERATURE_TARGET,
             CharacteristicsTypes.RELATIVE_HUMIDITY_CURRENT,
             CharacteristicsTypes.RELATIVE_HUMIDITY_TARGET,
+            CharacteristicsTypes.FAN_STATE_CURRENT,
         ]
 
     async def async_set_temperature(self, **kwargs: Any) -> None:
@@ -666,7 +669,19 @@ def hvac_action(self) -> HVACAction | None:
             return HVACAction.IDLE
 
         value = self.service.value(CharacteristicsTypes.HEATING_COOLING_CURRENT)
-        return CURRENT_MODE_HOMEKIT_TO_HASS.get(value)
+        current_hass_value = CURRENT_MODE_HOMEKIT_TO_HASS.get(value)
+
+        # If a device has a fan state (such as an Ecobee thermostat)
+        # show the Fan state when the device is otherwise idle.
+        if (
+            current_hass_value == HVACAction.IDLE
+            and self.service.has(CharacteristicsTypes.FAN_STATE_CURRENT)
+            and self.service.value(CharacteristicsTypes.FAN_STATE_CURRENT)
+            == HOMEKIT_CURRENT_FAN_STATE_ACTIVE
+        ):
+            return HVACAction.FAN
+
+        return current_hass_value
 
     @property
     def hvac_mode(self) -> HVACMode:

tests/components/homekit_controller/test_climate.py

@@ -66,6 +66,9 @@ def create_thermostat_service(accessory: Accessory) -> None:
     char = service.add_char(CharacteristicsTypes.RELATIVE_HUMIDITY_CURRENT)
     char.value = 0
 
+    char = service.add_char(CharacteristicsTypes.FAN_STATE_CURRENT)
+    char.value = 0
+
 
 def create_thermostat_service_min_max(accessory: Accessory) -> None:
     """Define thermostat characteristics."""
@@ -648,6 +651,18 @@ async def test_hvac_mode_vs_hvac_action(
     assert state.state == "heat"
     assert state.attributes["hvac_action"] == "idle"
 
+    # Simulate the fan running while the heat/cool is idle
+    await helper.async_update(
+        ServicesTypes.THERMOSTAT,
+        {
+            CharacteristicsTypes.FAN_MODE_CURRENT: 2,
+        },
+    )
+
+    state = await helper.poll_and_get_state()
+    assert state.state == "heat"
+    assert state.attributes["hvac_action"] == "fan"
+
     # Simulate that current temperature is below target temp
     # Heating might be on and hvac_action currently 'heat'
     await helper.async_update(