Mitsubishi Electric HP120TNU-A Service Handbook page 241

8-10-13 Simple Check on Inverter Circuit Components ..................................................................................... 52
8-10-14 Troubleshooting Problems with IGBT Module ...................................................................................... 53
8-10-15 Checking the Fan Inverter Heatsink for Clogging ................................................................................. 56
8-11 Control Circuit..................................................................................................................................... 57
8-11-1 Control Power Supply Function Block................................................................................................... 57
8-11-2 Troubleshooting Problems with Outdoor Unit Transmission Power Supply Circuit .............................. 59
8-12 Measures for Refrigerant Leakage .................................................................................................... 63
8-13 Parts Replacement Instructions ........................................................................................................ 65
8-13-1 Ensuring Maintenance Space (Preparation for the Maintenance of Refrigerant Circuit Parts)............. 65
8-13-2 Notes on Wiring Installation .................................................................................................................. 66
8-13-3 Four-way Valve Replacement Procedure (Applicable to four-way valves 21S4a and 21S4b) ............. 67
8-13-4 Replacement Procedure for the Check Valve Block Assembly ............................................................ 73
8-13-5 Compressor Replacement Procedure................................................................................................... 80
8-13-6 Removal Instructions for the Control Box ............................................................................................. 82
8-13-7 Transformer box replacement instructions............................................................................................ 84
8-13-8 Maintenance Procedure for the Drain Pan............................................................................................ 86
8-13-9 Maintenance Procedures for the Heat Exchanger ................................................................................ 88
8-13-10 Accumulator Replacement Procedure .................................................................................................. 95
8-14 BC Controller Maintenance Instructions .......................................................................................... 97
8-15 Troubleshooting Problems Using the LED Status Indicators on the Outdoor Unit ................... 100
HWE18220_GB