diff --git a/custom_components/daikin_residential/daikin_base.py b/custom_components/daikin_residential/daikin_base.py
index e1f107c..db7bc5e 100644
--- a/custom_components/daikin_residential/daikin_base.py
+++ b/custom_components/daikin_residential/daikin_base.py
@@ -101,7 +101,8 @@ def getCommandSet(self, param):
             cmd_set = DAIKIN_CMD_SETS[param].copy()
         if "%operationMode%" in cmd_set[2]:
             operation_mode = self.getValue(ATTR_OPERATION_MODE)
-            cmd_set[2] = cmd_set[2].replace("%operationMode%", operation_mode)
+            if operation_mode:
+                cmd_set[2] = cmd_set[2].replace("%operationMode%", operation_mode)
         return cmd_set
 
     def getData(self, param):