When the air side heat exchanger temperature is higher than 63C for 10 seconds the system will display and the heat pump will stop running until the temperature drops below 52C. 

Possible causes:

  • Temperature Sensor not connected properly or has malfunctioned.
  • Poor heat exchange
  • Fan motor damaged


  • Assure the cooling fins on the heat pump are free from blockage and that the air can move freely. 
  • Check the fan(s) to assure they are spinning freely.
  • Test the sensor at CN24 of the control board for continuity. If it shows full continuity the sensor may have failed.