diff --git a/frappy_psi/qnw.py b/frappy_psi/qnw.py
index 28725e7..f60d6da 100644
--- a/frappy_psi/qnw.py
+++ b/frappy_psi/qnw.py
@@ -21,7 +21,7 @@
 
 
 from frappy.core import Readable, Parameter, FloatRange, IDLE, ERROR, BoolType,\
-    StringIO, HasIO, Property, Writable, Drivable, BUSY, StringType, Done
+    StringIO, HasIO, Property, WARN, Drivable, BUSY, StringType, Done
 from frappy.errors import InternalError
 
 
@@ -93,10 +93,13 @@ class TemperatureLoopTC1(SensorTC1, Drivable):
         if reply[4] == '+':
             return BUSY, 'ramping'
         if reply[3] == 'C':
-            if self.ramp_used:
-                return BUSY, 'stabilizing'
-            return BUSY, 'changing'
-        return IDLE, ''
+            if self.control:
+                if self.ramp_used:
+                    return BUSY, 'stabilizing'
+                return BUSY, 'changing'
+        if self.control:
+            return IDLE, ''
+        return WARN, 'control off'
 
     def write_target(self, target):
         if self.ramp_used: