diff --git a/blueprints/danfoss_ally_trv_external_sensor.yaml b/blueprints/danfoss_ally_trv_external_sensor.yaml
index 80842cf..46325b8 100644
--- a/blueprints/danfoss_ally_trv_external_sensor.yaml
+++ b/blueprints/danfoss_ally_trv_external_sensor.yaml
@@ -41,15 +41,23 @@ triggers:
   trigger: state
 
 conditions:
-# We only want to execute the action if the temperature has changed by at least
-# 0.1 degress C, according to the Zigbee2MQTT documentation for the device:
-# https://www.zigbee2mqtt.io/devices/014G2461.html
+# We only want to execute the action if
+#
+# * the temperature sensor is available, or
+#
+# * the temperature has changed by at least 0.1 degress C, according to the
+#   Zigbee2MQTT documentation for the device:
+#   https://www.zigbee2mqtt.io/devices/014G2461.html
 #
 # `external_measured_room_sensor` defaults to `-8000`, so this will work in all
 # cases.
 - condition: template
   value_template: |-
-    {% if state_attr(climate_entity, 'external_measured_room_sensor') == None %}
+    {# if the temperature entity doesn't have a state, e.g. if it's powered off #}
+    {% if states(temperature_entity) is none %}
+    False
+    {# if the radiator has been unavailable #}
+    {% elif state_attr(climate_entity, 'external_measured_room_sensor') is none %}
     True
     {% else %}
     {{
@@ -65,8 +73,8 @@ actions:
     # which case we pull the temperature from the sensor instead of the trigger
     # state.
     external_temperature: |-
-      {% if trigger.id is not defined %}
-      {{ state_attr(temperature_entity, 'temperature') }}
+      {% if (trigger.id is not defined) or (trigger.to_state.state in ['unavailable', 'unknown']) %}
+      {{ states(temperature_entity) }}
       {% else %}
       {{ trigger.to_state.state | float }}
       {% endif %}