Fix MQTT climate action null warnings (#64658)

homeassistant/components/mqtt/climate.py

@@ -125,6 +125,8 @@ CONF_TEMP_MAX = "max_temp"
 CONF_TEMP_MIN = "min_temp"
 CONF_TEMP_STEP = "temp_step"
 
+PAYLOAD_NONE = "None"
+
 MQTT_CLIMATE_ATTRIBUTES_BLOCKED = frozenset(
     {
         climate.ATTR_AUX_HEAT,
@@ -441,6 +443,12 @@ class MqttClimate(MqttEntity, ClimateEntity):
             if payload in CURRENT_HVAC_ACTIONS:
                 self._action = payload
                 self.async_write_ha_state()
+            elif not payload or payload == PAYLOAD_NONE:
+                _LOGGER.debug(
+                    "Invalid %s action: %s, ignoring",
+                    CURRENT_HVAC_ACTIONS,
+                    payload,
+                )
             else:
                 _LOGGER.warning(
                     "Invalid %s action: %s",

tests/components/mqtt/test_climate.py

@@ -900,6 +900,15 @@ async def test_get_with_templates(hass, mqtt_mock, caplog):
     state = hass.states.get(ENTITY_CLIMATE)
     assert state.attributes.get("hvac_action") == "cooling"
 
+    # Test ignoring null values
+    async_fire_mqtt_message(hass, "action", "null")
+    state = hass.states.get(ENTITY_CLIMATE)
+    assert state.attributes.get("hvac_action") == "cooling"
+    assert (
+        "Invalid ['off', 'heating', 'cooling', 'drying', 'idle', 'fan'] action: None, ignoring"
+        in caplog.text
+    )
+
 
 async def test_set_with_templates(hass, mqtt_mock, caplog):
     """Test setting various attributes with templates."""