Midea VRF Series

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V6R VRF 50/60Hz

111

Part

Diagnosis and Troubleshooting

L5: Zero speed protection

There is abnormal noise of compressor

when startup or running

Replace the compressor

Yes

Replace the inverter module

L5 Fault

Disconnect the

power supply

L5 Protection

Main Page

Contents2
General Information4
Indoor and Outdoor Unit Capacities5
VRF Indoor Units5
Standard Indoor Unit Abbreviation Codes5
Indoor Unit Capacity Range5
Fresh Air Processing Unit6
Heat Recovery Ventilator6
High Temperature Hydro Module6
Outdoor Units6
External Appearance7
Indoor Unit Appearance7
Fresh Air Processing Unit Appearance7
Heat Recovery Ventilator Appearance8
High Temperature Hydro Module Appearance8
Single Units9
Single Outdoor Unit Appearance9
Combination Outdoor Unit Appearance9
Mode Selection Box10
MS Box Appearance10
Outdoor Unit Combinations11
Combination Ratio12
Indoor and Outdoor Unit Combination Ratio Limitations12
Combinations of Indoor and Outdoor Units13
Component Layout and Refrigerant Circuits14
Layout of Functional Components15
8/10/12HP Top View15
8/10/12HP Front View15
14/16/18/20HP Top View16
14/16/18/20HP Front View16
Piping Diagrams17
8HP/10HP/12HP Piping Diagram17
14HP/16HP/18/20HP Piping Diagram18
Key Components19
Oil Separator19
Gas-Liquid Separator19
Electronic Expansion Valve19
Refrigerant Flow Diagrams20
Cooling Operation20
Refrigerant Flow During Cooling Operation20
Main Cooling Operation21
Refrigerant Flow During Main Cooling Operation21
Heating Operation22
Refrigerant Flow During Heating Operation22
Main Heating Operation23
Refrigerant Flow During Main Heating Operation23
Oil Return Operation in Cooling Mode24
Refrigerant Flow During Oil Return Operation in Cooling Mode24
Oil Return Operation in Heating Mode and Defrosting Operation25
Control26
Table of Contents26
General Control Scheme Flowchart27
Stop Operation28
Component Control During Stop Operation28
Standby Control29
Startup Control29
Crankcase Heater Control29
Startup Sequence and Frequency Control in Combination Modules29
Component Control During Startup in Cooling Only/Main Cooling Mode30
Component Control During Startup in Heating Only / Main Heating Mode31
Normal Operation Control32
Outdoor Unit Component Control During Normal Operation32
Indoor Unit Component Control During Normal Operation32
MS04-12 Component Control During Normal Operation33
MS01 Component Control During Normal Operation33
Compressor Control34
Simultaneous Cooling and Heating Operation34
Rotation of Compressors35
Compressor Priority and Rotation – Two Outdoor Units35
Compressor Priority and Rotation – Three Outdoor Units35
Heat Exchanger Control35
Electronic Expansion Valve Control36
EEVA Control36
EEVC Control36
Outdoor Fan Control37
Outdoor Fan Speed Steps37
Upper Limit Fan Step in Static Pressure Mode37
Protection Control38
High Pressure Protection Control38
Low Pressure Protection Control38
Low Pressure Protection Control in Cooling Operation38
Discharge Temperature Protection Control39
Low Pressure Protection Control in Heating Operation39
Over-Current Protection Control39
Current Limitation for Compressor Inverter Modules39
Ambient Temperature out of Range Protection Control40
Disable Cooling Control40
Inverter Module Temperature Protection Control40
Wet Compression Protection Control41
High Pressure Ratio Protection Control41
Special Control42
Oil Return Operation42
Cooling Only/Main Cooling Oil Return Control42
Timing of Oil Return Operation42
Heating Oil Return Control43
Defrosting Operation44
Reverse Cycle Defrosting Operation44
Indoor Unit Component Control During Defrosting Operation45
Rotating Defrosting Operation45
Switching Action of Two-Module Parallel System Heat Exchanger45
Switching Action of Three-Module Parallel System Heat Exchanger46
Other Control47
Overload Control47
Pump-Down Control47
Recover Refrigerant to Outdoor Unit47
Recover Refrigerant to Indoor Units and MS Boxes48
Recover Refrigerant to Indoor Units and MS Units48
Vacuum Control48
Auto Snow-Blowing Control49
Auto Mode and Dual Set Points49
Timing of Auto Snow-Blowing Operation49
Low Noise Mode51
8.6 Power Limitation Mode51
Field Settings52
Outdoor Unit Field Settings53
PCB Switches and Switch Settings53
Outdoor Unit Main PCB Switches53
Modes Set on Main PCB55
Night Silent Mode Setting55
Silent Mode Setting55
Mode Selection Box Field Settings56
MS01 Switches Settings56
MS01 PCB Switches56
MS04-12 Switches Settings57
MS04-12 PCB Switch Settings57
Manually Address Setting57
Electrical Components and Wiring Diagrams58
Outdoor Unit Electric Control Box Layout59
8-12HP Top Layer of Electric Control Box59
8-12HP Bottom Layer of Electric Control Box59
14-20HP Top Layer of Electric Control Box60
14-20HP Bottom Layer of Electric Control Box60
Outdoor Unit Main PCB61
Ports61
Main PCB Port62
Components63
Outdoor Unit Main PCB Components63
Main Control Chip63
Function of Buttons SW3 to SW663
Menu Mode64
Menu Mode Selection Flowchart64
Menu Mode Function65
How to Exit Specified Menu Mode66
Exit Specified Menu Mode Method66
Digital Display Output68
Digital Display Output in Different Operating States68
Data Transfer Module69
Data Transfer Module Layout69
PCB Components69
Data Transfer Module PCB Components69
Sync Information from Main PCB Digital Display70
Auto Snow-Blowing Setting70
Data Acquisition70
Fault Data Storage70
Compressor Inverter Module71
8-12HP Compressor Inverter Module Ports71
14-20HP Compressor Inverter Module Ports73
Fan Module75
Fan Module Ports75
Mode Selection Box Main PCB76
MS01 Main PCB Ports76
MS04-12 Main PCB Ports77
Spot Check78
MS04-12 Spot Check78
Wiring Diagrams79
‐7.1: V6R Outdoor Unit Wiring Diagram79
MS01 Wiring Diagram80
MS04/MS06 Wiring Diagram81
MS08/MS10/MS12 Wiring Diagram82
Diagnosis and Troubleshooting84
Error Code Table85
MS04-12 Error Code Table87
MS01 Error Code Table87
Troubleshooting for Outdoor Unit88
E0: Communication Error between Outdoor Units88
Trigger / Recover Condition88
Possible Causes88
E2: Communication Error between MS Box and Master Unit90
E4: T3/T4 Temperature Sensor Error92
E5: Abnormal Power Supply Voltage93
E7: Discharge Temperature Sensor Error (T7C1)95
E8: Outdoor Unit Address Error96
E9: EEPROM Mismatch of Compressor97
F1: DC Bus Voltage Error98
Zf6: Electronic Expansion Valve Connection Error101
H0: Communication Error between Main Board and Compressor Drive Board103
H2, H3: Qty. of Outdoor Unit Decreases/ Increases Error105
H4: Compressor Inverter Module Protection107
Specific Error Codes for H4 Inverter Module Protection107
8-12HP LED Indicators LED1 and LED2 on Inverter Module108
14-18HP LED Indicators LED1 and LED2 on Inverter Module108
L0: Inverter Module Protection109
L1: DC Bus Low Voltage Protection110
Inverter Module Terminals110
L2: DC Bus High Voltage Protection111
L5: Zero Speed Protection112
L7: Phase Sequence Error113
LA: PED Software Verification Failed114
Compressor Replacement Procedure115
Check Oil in Other Compressors in the System115
Check Filters115
Vacuum Drying and Refrigerant Charging116
Inspecting Compressor Oil116
Effects of Spoiled Compressor Oil117
H7: Qty. of Indoor Units Mismatching118
H8: High Pressure Sensor Error120
Hb: Low Pressure Sensor Error122
Yhd: Slave Unit Malfunction124
P1: High Pressure Protection125
P2, H5: Suction Pipe Low Pressure Protection127
P31: Primary Current Protection129
P32: Secondary Current Protection131
P9, H9: Fan Module Protection136
PL, C7: Inverter Module Temperature Protection138
PP: Compressor Discharge Insufficient Superheat Protection139
A0: Emergency Shutdown141
A1W: Refrigerant Leakage Protection143
CA1, CA2, CA3, CA4, CA5: Connection Combination Error144
CB1, CB2, CB3, CB4: Overmatch Protection145
U0: Force Cooling Operation Not Performed146
U21, U22, U23: Ambient Temperature Is out Range of Test Operation147
U31, U32, U33: Stop Valve Is Not Open149
Troubleshooting for Mode Selection Box151
E2: Communication Error between MS and Master Outdoor Unit151
E3/E4: T1C1/T2C2 Temperature Sensor Error153
E7: EEPROM Error154
FE: MS Has no Address When First Powered on155
LL: S1+S2 Dialing Setting Error (for MS04-12)156
H0: Communication between Master and Slave Control Boards Failed157
F6: Electronic Ball Valve Connection Failure158
F7: Main Power off (for MS01)160
F9: Overload Error (for MS01)161
A1: Refrigerant Leakage Protection (for MS01)162
Temperature Sensor Resistance Characteristics163
Parameters of Excess and Insufficient Refrigerant System166
Outdoor Unit Operating Parameters in Excess Refrigerant System166
Outdoor Unit Operating Parameters in Insufficient Refrigerant System166

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