Hitachi Inverter-driven. Multi-split System. Heat Pump Air Conditioners Alarm Codes; Code: 01 Content of Abnormality: Tripping of Protection Device Leading Cause: Failure of Fan Motor, Drain Discharge, PCB, Relay Code: 02 Content of Abnormality: Tripping of Protection Device Leading Cause:  Activation of PSH Code: 03 Content of Abnormality: Abnormality between Indoor (or outdoor) and Outdoor (or Indoor) Leading Cause:  Incorrect Wiring.