Communication fault between the main control board and the drive board.  This may also be accompanied by an R10 Error.

Try to unplug both the fan motors and see if it fixes the error. (note: your heat pump may only have one fan motor) 

  • If yes then plug them in one at a time and see if one causes the board to go dead. That would be the bad fan motor. 
  • If they both cause the error, then both the fan motors are bad.
  •  If unplugging the fan motors does nothing then we will need to replace the drive board.