diff --git a/pyhilo/device/climate.py b/pyhilo/device/climate.py
index 3a2b09a..c65a32a 100644
--- a/pyhilo/device/climate.py
+++ b/pyhilo/device/climate.py
@@ -102,9 +102,20 @@ def hvac_action(self) -> str:
         """
         Gets the current HVAC action of the device.
 
+        For 24 V thermostats the action comes from currentState ("HEATING",
+        "COOLING", "OFF").  For baseboard thermostats it is derived from the
+        reported heating power.
+
         Returns:
-            str: 'heating' if heating is active, 'idle' otherwise.
+            str: one of 'heating', 'cooling', or 'idle'.
         """
+        if self.is_low_voltage:
+            state = self.current_state
+            if state == "HEATING":
+                return "heating"
+            if state == "COOLING":
+                return "cooling"
+            return "idle"
         attr = self.get_value("heating", 0)
         return "heating" if attr > 0 else "idle"
 
@@ -170,11 +181,7 @@ def allowed_fan_modes(self) -> list[str]:
 
     @property
     def current_state(self) -> str | None:
-        """Raw running state reported by a 24 V thermostat.
-
-        Exposed for consumers, but deliberately not mapped to hvac_action yet:
-        its vocabulary has not been observed in enough operating conditions.
-        """
+        """Raw running state reported by a 24 V thermostat ("HEATING", "COOLING", "OFF")."""
         return self._optional_str("current_state")
 
     @property
diff --git a/tests/test_climate.py b/tests/test_climate.py
index a6854fd..d331f88 100644
--- a/tests/test_climate.py
+++ b/tests/test_climate.py
@@ -41,6 +41,33 @@ def _climate(**readings):
     return device
 
 
+class TestHvacAction:
+    @pytest.mark.parametrize(
+        "current_state, expected",
+        [
+            pytest.param("HEATING", "heating", id="heating"),
+            pytest.param("COOLING", "cooling", id="cooling"),
+            pytest.param("OFF", "idle", id="off-is-idle"),
+            pytest.param(None, "idle", id="unreported-is-idle"),
+        ],
+    )
+    def test_low_voltage_maps_current_state(self, current_state, expected):
+        kwargs = {"Thermostat24VMode": "AUTO"}
+        if current_state is not None:
+            kwargs["CurrentState"] = current_state
+        assert _climate(**kwargs).hvac_action == expected
+
+    @pytest.mark.parametrize(
+        "heating, expected",
+        [
+            pytest.param(1, "heating", id="power-on-is-heating"),
+            pytest.param(0, "idle", id="power-off-is-idle"),
+        ],
+    )
+    def test_baseboard_uses_heating_power(self, heating, expected):
+        assert _climate(Heating=heating).hvac_action == expected
+
+
 class TestAsList:
     def test_none_is_empty(self):
         assert as_list(None) == []