Mitsubishi Electric PUHY-P250YNW-A Service Handbook page 198

Chapter 8 Troubleshooting Based on Observed Symptoms
8-1 MA Remote Controller Problems......................................................................................................... 1
8-1-1 The LCD Does Not Light Up. .................................................................................................................. 1
8-1-2 The LCD Momentarily Lights Up and Then Goes Off. ............................................................................ 2
8-1-3 "HO" and "PLEASE WAIT" Do Not Go Off the Screen. .......................................................................... 3
8-1-4 Air Conditioning Units Do Not Operate When the ON Button Is Pressed. .............................................. 4
8-2 Refrigerant Control Problems.............................................................................................................. 5
8-2-1 Units in the Cooling Mode Do Not Operate at Expected Capacity.......................................................... 5
8-2-2 Outdoor Units Stop at Irregular Times. ................................................................................................... 7
8-3 External Input Problems (including operation mode) ....................................................................... 8
8-4 Checking Transmission Waveform and for Electrical Noise Interference ...................................... 9
8-4-1 M-NET..................................................................................................................................................... 9
8-4-2 MA Remote Controller .......................................................................................................................... 11
8-5 Pressure Sensor Circuit Configuration and Troubleshooting Pressure Sensor Problems......... 12
8-5-1 Comparing the High-Pressure Sensor Measurement and Gauge Pressure......................................... 12
8-5-2 High-Pressure Sensor Configuration (63HS1)...................................................................................... 13
8-5-3 Comparing the Low-Pressure Sensor Measurement and Gauge Pressure.......................................... 14
8-5-4 Low-Pressure Sensor Configuration (63LS) ......................................................................................... 15
8-6 Troubleshooting Solenoid Valve Problems...................................................................................... 16
8-7 Troubleshooting Outdoor Unit Fan Problems.................................................................................. 18
8-8 Troubleshooting LEV Problems ........................................................................................................ 19
8-8-1 General Overview on LEV Operation.................................................................................................... 19
8-8-2 Possible Problems and Solutions ......................................................................................................... 22
8-8-3 Coil Removal Instructions ..................................................................................................................... 23
8-9 Troubleshooting Inverter Problems .................................................................................................. 25
8-9-1 Inverter-Related Problems and Solutions ............................................................................................. 25
8-9-2 Checking the Inverter Board Error Detection Circuit............................................................................. 27
8-9-3 Checking the Compressor for Ground Fault and Coil Resistance Problems ........................................ 27
8-9-4 Checking the Inverter for Damage at No-Load ..................................................................................... 28
8-9-5 Checking the Inverter for Damage during Compressor Operation........................................................ 29
8-9-6 Checking the Converter for Damage during Compressor Operation .................................................... 31
8-9-7 Checking the Fan Motor for Ground Fault and Coil Resistance Problems ........................................... 31
8-9-8 Checking the Fan Board Error Detection Circuit at No Load ................................................................ 31
8-9-9 Checking the Fan Board for Damage at No Load................................................................................. 32
8-9-10 Checking the Fan Board for Damage with Load ................................................................................... 32
8-9-11 Checking the Installation Conditions..................................................................................................... 33
8-9-12 Solutions for the Main Breaker Trip ...................................................................................................... 33
8-9-13 Solutions for the Main Earth Leakage Breaker Trip .............................................................................. 34
8-9-14 Simple Check on Inverter Circuit Components ..................................................................................... 35
8-9-15 Troubleshooting Problems with IGBT Module ...................................................................................... 35
8-9-16 Checking the Fan Inverter Heatsink for Clogging ................................................................................. 39
8-10 Control Circuit..................................................................................................................................... 40
8-10-1 Control Power Supply Function Block................................................................................................... 40
8-10-2 Troubleshooting Problems with Outdoor Unit Transmission Power Supply Circuit .............................. 41
8-11 Measures for Refrigerant Leakage .................................................................................................... 43
8-12 Parts Replacement Instructions ........................................................................................................ 45
8-12-1 Ensuring Maintenance Space (Preparation for the Maintenance of Refrigerant Circuit Parts)............. 45
8-12-2 Notes on Wiring Installation .................................................................................................................. 47
GB_BS_08_C