Midea V4+R Series Service Manual
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Midea V4+R Series Service Manual

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Summary of Contents for Midea V4+R Series

  • Page 1 R410A Commercial Air Conditioners Service Manual...
  • Page 3 V4+R VRF 50/60Hz CONTENTS Part 1 General Information ................3 Part 2 Component Layout and Refrigerant Circuits ........11 Part 3 Control ....................23 Part 4 Field Settings ..................37 Part 5 Diagnosis and Troubleshooting ............41 201608...
  • Page 4 V4+R VRF 50/60Hz 201608...
  • Page 5 V4+R VRF 50/60Hz Part 1 General Information Indoor and Outdoor Unit Capacities ..........4 External Appearance ................6 Outdoor Unit Combinations ..............9 Combination Ratio ................10 201702...

  • Page 6: Indoor And Outdoor Unit Capacities

    V4+R VRF 50/60Hz 1 Indoor and Outdoor Unit Capacities 1.1 Indoor Units Table 1-1.1: Standard indoor unit abbreviation codes Abbreviation Abbreviation Type Type code code One-way Cassette High Static Pressure Duct Two-way Cassette Wall-mounted Q4-C Compact Four-way Cassette Ceiling & Floor Four-way Cassette Floor Standing Low Static Pressure Duct...
  • Page 7 V4+R VRF 50/60Hz 1.3 Outdoor Units Table 1-1.4: Outdoor unit capacity range Capacity 10HP 12HP 14HP 16HP Model 252(8) 280(10) 335(12) 400(14) 450(16) (MDV-*W/D2RN1T(C)) Capacity 18HP 20HP 22HP 24HP 26HP 28HP 30HP 32HP Model 532(18) 560(20) 615(22) 680(24) 730(26) 800(28) 850(30) 900(32) (MDV-*W/D2RN1T(C))

  • Page 8: External Appearance

    V4+R VRF 50/60Hz 2 External Appearance 2.1 Indoor Units Table 1-2.1: Standard indoor unit appearance One-way Cassette Two-way Cassette Compact Four-way Cassette Four-way Cassette Q4-C Low Static Pressure Duct Medium Static Pressure Duct High Static Pressure Duct Wall-mounted Ceiling & Floor Floor Standing Console 201702...
  • Page 9 V4+R VRF 50/60Hz 2.2 Heat Recovery Ventilator Table 1-2.2: Heat recovery ventilator appearance Heat Recovery Ventilator 2.3 Outdoor Units 2.3.1 Single units Table 1-2.3: Single outdoor unit appearance 8/10/12/14/16HP 2.3.2 Combinations of units Table 1-2.4: Combination outdoor unit appearance 18/20/22/24/26/28/30/32HP 34/36/38/40/42/44/46/48HP 50/52/54/56/58/60/62/64HP 201702...
  • Page 10 V4+R VRF 50/60Hz boxes 2.4 MS Table 1-2.5: MS box appearance Max. number of Model name Appearance downstream indoor units MS01/N1-C MS02/N1-C MS04/N1-C MS06/N1-C MS02E/N1-C MS04E/N1-C 201702...

  • Page 11: Outdoor Unit Combinations

    V4+R VRF 50/60Hz 3 Outdoor Unit Combinations Table 1-3.1: Outdoor unit combinations System capacity Modules Number Outdoor branch joint kit of units 25.2 ● 28.0 ● — 33.5 ● 40.0 ● 45.0 ● 53.2 ● ● 56.0 ●● 61.5 ● ●...

  • Page 12: Combination Ratio

    Capacity index of the outdoor units Table 1-4.1: Indoor and outdoor unit combination ratio limitations Type Minimum combination ratio Maximum combination ratio V4+R Series outdoor units 130% Table 1-4.2: Combinations of indoor and outdoor units Outdoor unit capacity Maximum number of...
  • Page 13 V4+R VRF 50/60Hz Part 2 Component Layout and Refrigerant Circuits Layout of Functional Components ............12 Piping Diagrams .................. 14 Refrigerant Flow Diagrams ..............16 201702...
  • Page 14 V4+R VRF 50/60Hz 1 Layout of Functional Components MDV-252(8)W/D2RN1T(C) / MDV-280(10)W/D2RN1T(C) / MDV-335(12)W/D2RN1T(C) Figure 2-1.1: MDV-252(8)W/D2RN1T(C) / MDV-280(10)W/D2RN1T(C) / MDV-335(12)W/D2RN1T(C) top view Solenoid valve Solenoid valve Electronic Solenoid valve expansion valve Electronic expansion valve Figure 2-1.2: MDV-252(8)W/D2RN1T(C) / MDV-280(10)W/D2RN1T(C) / MDV-335(12)W/D2RN1T(C) front view Unloading valve DC fan motor DC fan motor...
  • Page 15 V4+R VRF 50/60Hz MDV-400(14)W/D2RN1T(C) / MDV-450(16)W/D2RN1T(C) Figure 2-1.3: MDV-400(14)W/D2RN1T(C) / MDV-450(16)W/D2RN1T(C) top view High pressure sensor Solenoid valve High pressure switch Solenoid valve Electronic Electronic expansion valve expansion valve Figure 2-1.4: MDV-400(14)W/D2RN1T(C) / MDV-450(16)W/D2RN1T(C) front view DC fan motor DC fan motor Unloading valve Four-way valve High pressure switch...
  • Page 16 V4+R VRF 50/60Hz 2 Piping Diagrams MDV-252(8)W/D2RN1T(C) / MDV-280(10)W/D2RN1T(C) / MDV-335(12)W/D2RN1T(C) Figure 2-2.1: MDV-252(8)W/D2RN1T(C) / MDV-280(10)W/D2RN1T(C) / MDV-335(12)W/D2RN1T(C) piping diagram EXV-A Liquid stop valve EXV-B Heat exchanger 2 Heat exchanger 1 Low pressure gas stop valve High pressure gas stop valve Gas balance stop valve High pressure switch...
  • Page 17 V4+R VRF 50/60Hz Key components: 1. Oil separator: Separates oil from gas refrigerant pumped out of the compressor and quickly returns it to the compressor. Separation efficiency is up to 99%. 2. Accumulator: Stores liquid refrigerant and oil to protect compressor from liquid hammering. 3.
  • Page 18 V4+R VRF 50/60Hz 3 Refrigerant Flow Diagrams Cooling operation Figure 2-3.1: refrigerant flow during cooling operation Cooling Operation High temperature, high pressure gas High temperature, high pressure liquid Low temperature, low pressure gas Indoor unit operation Cooling Cooling Cooling Fan ON Fan OFF Fan OFF To other MS unit...
  • Page 19 V4+R VRF 50/60Hz Mixed cooling operation Mixed Cooling Operation Figure 2-3.2: refrigerant flow during mixed cooling operation High temperature, high pressure gas High temperature, high pressure liquid Low temperature, low pressure gas Indoor unit operation Cooling Cooling Heating Fan ON Fan ON Fan ON To other MS unit...
  • Page 20 V4+R VRF 50/60Hz Heating operation Heating Operation Figure 2-3.3: refrigerant flow during heating operation High temperature, high pressure gas High temperature, high pressure liquid Low temperature, low pressure gas Indoor unit operation Heating Heating Heating Fan ON Fan ON Fan ON To other MS unit heat heat...
  • Page 21 V4+R VRF 50/60Hz Mixed heating operation Figure 2-3.4: refrigerant flow during mixed heating operation Mixed Heating Operation High temperature, high pressure gas High temperature, high pressure liquid Low temperature, low pressure gas Indoor unit operation Heating Heating Cooling Fan ON Fan ON Fan ON To other MS unit...
  • Page 22 V4+R VRF 50/60Hz Oil return operation in cooling mode Figure 2-3.5: refrigerant flow during oil return operation in cooling mode Cooling Oil Return High temperature, high pressure gas High temperature, high pressure liquid Low temperature, low pressure gas Indoor unit operation Cooling Cooling Cooling...
  • Page 23 V4+R VRF 50/60Hz Oil return operation in other mode Figure 2-3.6: refrigerant flow during oil return operation in other mode Other Mode Oil Return High temperature, high pressure gas High temperature, high pressure liquid Low temperature, low pressure gas Indoor unit operation Cooling Cooling Heating...
  • Page 24 V4+R VRF 50/60Hz Defrosting operation Defrost Figure 2-3.7: refrigerant flow during defrosting operation High temperature, high pressure gas High temperature, high pressure liquid Low temperature, low pressure gas Indoor unit operation Cooling Cooling Heating Fan OFF Fan OFF Fan OFF To other MS unit heat heat...

  • Page 25: Table Of Contents

    V4+R VRF 50/60Hz Part 3 Control General Control Scheme Flowchart ............24 Stop Operation ..................25 Standby Control ................... 25 Startup Control ..................26 Normal Operation Control ..............27 Protection Control ................32 Special Control ..................34 201702...

  • Page 26: General Control Scheme Flowchart

    V4+R VRF 50/60Hz 1 General Control Scheme Flowchart Sections 3-2 to 3-7 on the following pages detail when each of the controls in the flowchart below is activated. Stop operation  Abnormal shutdown  System stops  A unit stops when the load demanded decreases Standby control Special control ...

  • Page 27: Stop Operation

    V4+R VRF 50/60Hz 2 Stop Operation The stop operation occurs for one of the three following reasons: 1. Abnormal shutdown: in order to protect the compressors, if an abnormal state occurs the system makes a 'stop with thermo off' operation and an error code is displayed on the digital display. 2.

  • Page 28: Startup Control

    V4+R VRF 50/60Hz 4 Startup Control 4.1 Compressor Startup Delay Control In initial startup control, compressor startup is delayed for 12 minutes in order to let the master unit search for the indoor units’ addresses. In restart control (except in oil return operation and defrosting operation), compressor startup is delayed such that a minimum of 7 minutes has elapsed since the compressor stopped, in order to prevent frequent compressor on/off and to equalize the pressure within the refrigerant system.

  • Page 29: Normal Operation Control

    V4+R VRF 50/60Hz 5 Normal Operation Control 5.1 Component Control During Normal Operation Table 3-5.1: Component control during normal cooling operation Wiring Component 8-12HP 14-16HP Control functions and states diagram label Inverter compressor A ● ● COMP(INV) Controlled according to load requirement Inverter compressor B COMP(INV1) ●...
  • Page 30 V4+R VRF 50/60Hz 5.3 Compressor Step Control The running speed of the compressors in rotations per second (rps) is half the frequency (in Hz) of the electrical input to the compressor motors. The compressor speed can be altered in increments of 1 rps. 5.4 Operating Priority and Rotation of Compressors Figures 3-5.1 to 3-5.4 show the compressor operating priority and rotation in systems with one, two, three and four outdoor units.
  • Page 31 V4+R VRF 50/60Hz Figure 3-5.4: Compressor priority and rotation – four outdoor units No. 1 No. 2 No. 3 No. 4 ① No. 4 No. 1 No. 2 No. 3 ② No. 3 No. 4 No. 1 No. 2 ③ No.
  • Page 32 V4+R VRF 50/60Hz No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 No. 8 ① ② No. 7 No. 8 No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 ③ No. 5 No.
  • Page 33 V4+R VRF 50/60Hz 5.6 Outdoor Fan Control The speed of the outdoor unit fans is adjusted in steps, as shown in Table 3-5.3. Table 3-5.3: Outdoor fan speed steps 8/10HP 12HP 14/16HP Fan speed index FANA FANB FANA FANB FANA FANB 8 (super silent mode) 10 (silent mode)

  • Page 34: Protection Control

    V4+R VRF 50/60Hz 6 Protection Control 6.1 High Pressure Protection Control This control protects the system from abnormally high pressure and protects the compressors from transient spikes in pressure. Figure 3-6.1: High pressure protection control Normal operation > 4.4MPa < 3.2MPa High pressure protection, error code P1 is displayed Notes: : Discharge pressure...
  • Page 35 V4+R VRF 50/60Hz 6.4 Compressor and Inverter Module Protection Control This control protects the compressors from abnormally high currents and protects the inverter modules from abnormally high temperatures. It is performed for each compressor and inverter module. Figure 3-6.4: Compressor current protection control Normal operation Current >...

  • Page 36: Special Control

    V4+R VRF 50/60Hz 7 Special Control 7.1 Outdoor Unit Duty Cycling In systems with multiple outdoor units, outdoor unit duty cycling is used to prevent compressor burn out due to unbalanced oil levels between outdoor units. Timing of outdoor unit duty cycling: ...
  • Page 37 V4+R VRF 50/60Hz Table 3-7.2: Indoor unit component control during oil return operation in cooling mode Component Unit state Control functions and states Thermo on Remote controller setting Standby Thermo off Thermo on Normal control Electronic expansion valve Standby 300 (steps) Thermo off 300 (steps) Tables 3-7.3 and 3-7.4 show component control during oil return operation in heating mode.
  • Page 38 V4+R VRF 50/60Hz 7.3 Defrosting Operation In order to recover heating capacity, the defrosting operation is conducted when the outdoor unit heat exchanger is performing as an evaporator. The defrosting operation is controlled according to outdoor ambient temperature, outdoor heat exchanger temperature, indoor heat exchanger temperature and outdoor units running time. Table 3-7.5: Outdoor unit component control during defrosting operation Component Wiring diagram label...
  • Page 39 V4+R VRF 50/60Hz Part 4 Field Settings Outdoor Unit Field Settings ..............38 201702...
  • Page 40 V4+R VRF 50/60Hz 1 Outdoor Unit Field Settings 1.1 PCB Switches and Switch Settings Figure 4-1.1: Outdoor unit main PCB switches PCB switches ENC1 ENC3 S12 S3 S7 ENC2 S1 ENC4 Table 4-1.1: Outdoor unit main PCB switch settings Switch Setting Switch positions Description...
  • Page 41 V4+R VRF 50/60Hz Table 4-1.1: Outdoor unit main PCB switch settings (continued) Switch Setting Switch positions Description Reserved The number of indoor units is in the range 0-15 ENC3 0-9 on ENC3 indicate 0-9 indoor units; A-F on ENC3 indicate 10-15 indoor units The number of indoor units is in the range 16-31 ENC3 ENC3 S12...
  • Page 42 V4+R VRF 50/60Hz 1.2 Modes Set on Main PCB 1.2.1 Night silent time setting Night silent mode is activated X hours after the peak daytime temperature, and is deactivated after Y hours, where X and Y are as specified in Table 4-1.2. Table 4-1.2: Night silent time setting Switch Switch positions...
  • Page 43 V4+R VRF 50/60Hz Part 5 Diagnosis and Troubleshooting Outdoor Unit Electric Control Box Layout ..........42 Outdoor Unit Main PCB ............... 44 Error Code Table .................. 48 Troubleshooting .................. 50 Appendix to Part 5 ................97 201608...
  • Page 44 V4+R VRF 50/60Hz 1 Outdoor Unit Electric Control Box Layout MDV-252(8)W/D2RN1T(C) / MDV-280(10)W/D2RN1T(C) / MDV-335(12)W/D2RN1T(C) Figure 5-1.1: Bottom layer of electric control box Figure 5-1.2: Top layer of electric control box Table 5-1.1: MDV-252(8)W/D2RN1T(C) / MDV-280(10)W/D2RN1T(C) / MDV-335(12)W/D2RN1T(C) Outdoor Unit Electric Control Box Layout Content Electric control box assembly Three-phase bridge rectifier...
  • Page 45 V4+R VRF 50/60Hz MDV-400(14)W/D2RN1T(C) / MDV-450(16)W/D2RN1T(C) Figure 5-1.3: Bottom layer of electric control box Figure 5-1.4: Top layer of electric control box Table 5-1.1: MDV-400(14)W/D2RN1T(C) / MDV-450(16)W/D2RN1T(C) Outdoor Unit Electric Control Box Layout Content Electric control box assembly Inverter module Three-phase bridge rectifier Temperature sensor Outdoor power supply board...
  • Page 46 V4+R VRF 50/60Hz 2 Outdoor Unit Main PCB 2.1 Ports Figure 5-2.1: Outdoor unit main PCB ports Notes: Label descriptions are given in Table 5-2.1. 201608...
  • Page 47 V4+R VRF 50/60Hz Table 5-2.1: Main PCB ports Label in Port Content Port voltage Figure 5-2.1 code Compressor top temperature sensor (single compressor units) or CN10 compressor A compressor top temperature sensor (dual 0-5V DC (varying) compressor units) connection Discharge pipe temperature sensor (single compressor units) or CN11 compressor B compressor top temperature sensor (dual 0-5V DC (varying)
  • Page 48 V4+R VRF 50/60Hz 2.2 Components 2.2.1 Layout Figure 5-2.2: Outdoor unit main PCB components DSP1 Digital display Current sensors DSP2 Buttons SW1/2/3/4 Inverter drive chips LED indicators LED1/2/3 LED indicators Main control chip LED6/7 Communication chip LED indicators LED4/5 2.2.2 Function of buttons SW1 to SW4 Table 5-2.2: Function of buttons SW1 to SW4 Button...
  • Page 49 V4+R VRF 50/60Hz Table 5-2.3: SW2 system check (continued) DSP1 Parameters displayed on DSP2 Remarks content Outdoor unit output metric (this unit) Fan A speed index Refer to Note 3 Fan B speed index Refer to Note 3 Average indoor heat exchanger mid-point temperature (°C) Actual value = value displayed Average indoor heat exchanger outlet temperature (°C) Actual value = value displayed...
  • Page 50 V4+R VRF 50/60Hz 2.2.4 Digital display output Table 5-2.4: Digital display output in different operating states Outdoor unit state Parameters displayed on DSP1 Parameters displayed on DSP2 DSP1 number indoor units On standby Unit's address communication with the outdoor units For single Running speed of the compressor in Normal...
  • Page 51 V4+R VRF 50/60Hz Table 5-3.1: Error code table (continued) Error code Content Remarks Number of indoor units detected by master unit not same as number set Only displayed on the master unit on main PCB Discharge pipe low pressure protection Displayed on the unit with the error Slave unit malfunction Only displayed on the master unit...
  • Page 52 V4+R VRF 50/60Hz 4 Troubleshooting 4.1 Warning Warning  All electrical work must carried by competent and suitably qualified, certified accredited professionals and in accordance with all applicable legislation (all national, local and other laws, standards, codes, rules, regulations and other legislation that apply in a given situation). ...
  • Page 53 V4+R VRF 50/60Hz 4.2 E0 Troubleshooting 4.2.1 Digital display output 4.2.2 Description  Communication error between outdoor units.  All units stop running.  Error code is only displayed on the slave unit with the error. 4.2.3 Possible causes  Incorrect outdoor unit address setting. ...
  • Page 54 V4+R VRF 50/60Hz 4.2.4 Procedure ODU addresses on switch ENC1 are set Set the ODU addresses correctly incorrectly Ensure the communication wires are Communication wires between ODUs are three-core shielded cable and are not connected properly connected properly Wires between outdoor main PCB and electric control box communication Ensure the wires are connected properly terminals block are loose...
  • Page 55 V4+R VRF 50/60Hz 4.3 E1 Troubleshooting 4.3.1 Digital display output 4.3.2 Description  Phase sequence error.  All units stop running.  Error code is only displayed on the unit with the error. 4.3.3 Possible causes  Power supply phases not connected in correct sequence. ...
  • Page 56 V4+R VRF 50/60Hz 4.3.4 Procedure The phase sequence of the 3-phase Exchange any two of the 3 phase wires power supply is incrorrect Ensure all supply terminals are securely Some power supply terminals are loose fastened The power supply is abnormal Check the power supply equipment Replace outdoor main PCB Notes:...
  • Page 57 V4+R VRF 50/60Hz 4.4 E2 Troubleshooting 4.4.1 Digital display output 4.4.2 Description  Communication error between indoor and master unit.  All units stop running.  Error code is only displayed on the master unit. 4.4.3 Possible causes  Communication wires between indoor and outdoor units not connected properly. ...
  • Page 58 V4+R VRF 50/60Hz 4.4.4 Procedure Communication wires P Q E have short Reconnect the communication wires circuited or disconnected Communication wires P Q E are not Connect the communication wires in a connected in a daisy chain daisy chain IDU power supply is abnormal Ensure normal power supply Wires between outdoor main PCB and electric control box communication...
  • Page 59 V4+R VRF 50/60Hz 4.5 E4, E7 Troubleshooting 4.5.1 Digital display output 4.5.2 Description  E4 indicates an outdoor ambient temperature sensor error and condenser pipe temperature sensor error.  E7 indicates discharge pipe temperature sensor error.  All units stop running. ...
  • Page 60 V4+R VRF 50/60Hz 4.5.4 Procedure E4 / E7 Temperature sensor connection on main Ensure the sensor is connected properly PCB is loose Temperature sensor has short-circuited Replace the sensor or failed Replace outdoor main PCB Notes: Outdoor ambient temperature sensor connection is port CN1 on the main PCB (labeled 32 in Figure 5-2.1 in Part 5, 2.2 “Ports”). Compressor top temperature sensor and discharge pipe temperature sensor connections are ports CN10 and CN11 on the main PCB (labeled 1 and 2, respectively, in Figure 5-2.1 in Part 5, 2.2 “Ports”).
  • Page 61 V4+R VRF 50/60Hz 4.6 E5 Troubleshooting 4.6.1 Digital display output 4.6.2 Description  Abnormal power supply voltage.  All units stop running.  Error code is only displayed on the unit with the error. 4.6.3 Possible causes  Outdoor unit power supply voltage not within ±10% of rated voltage or a phase is missing. ...
  • Page 62 V4+R VRF 50/60Hz 4.6.4 Procedure ODU power supply voltage is not within ±10% of rated voltage or a phase is Provide normal power supply missing Wires between outdoor main PCB, AC filter boards and electric control box Ensure the wires are connected properly power supply terminals are loose High voltage circuit error has occurred, such as the compressor has...
  • Page 63 V4+R VRF 50/60Hz 4.7 E8 Troubleshooting 4.7.1 Digital display output 4.7.2 Description  Outdoor unit address error.  All units stop running.  Error code is only displayed on the unit with the error. 4.7.3 Possible causes  Invalid outdoor unit address. ...
  • Page 64 V4+R VRF 50/60Hz 4.7.4 Procedure The ODU's address is not in the valid Slave units addresses should be set from range 1 to 3 Replace the outdoor main PCB Notes: The master unit address should be set as 0, slave units addresses should be set from 1 to 3, and the addresses should not be repeated within one system. Refer to Part 4, 1.1 “PCB Switches and Switch Settings”.
  • Page 65 V4+R VRF 50/60Hz 4.8 xE9 Troubleshooting 4.8.1 Digital display output In the error code, 'x' is a placeholder for the compressor system (compressor and related electrical components), with 1 representing compressor system A and 2 representing compressor system B. 4.8.2 Description ...
  • Page 66 V4+R VRF 50/60Hz 4.8.4 Procedure Power off the unit and wait for the digital The outdoor unit was powered on display to turn off before restarting the immediately after being powered off unit Replace outdoor main PCB Notes: When performing a manual restart of an outdoor unit, once the unit has been powered off it should not be powered on again until the digital display has turned off.
  • Page 67 V4+R VRF 50/60Hz 4.9 xH0, H1 Troubleshooting 4.9.1 Digital display output In the error code, 'x' is a placeholder for the compressor system (compressor and related electrical components), with 1 representing compressor system A and 2 representing compressor system B. 4.9.2 Description ...
  • Page 68 V4+R VRF 50/60Hz 4.9.4 Procedure xH0 / H1 Power supply for main PCB and Provide normal power supply transformer is abnormal The transformer has malfunctioned Replace the transformer There is a source of electromagnetic radiation near the unit, such as Remove the source of interference high-frequency transmitter or other high strength radiation device...
  • Page 69 V4+R VRF 50/60Hz 4.10 H2, H3 Troubleshooting 4.10.1 Digital display output 4.10.2 Description  H2 indicates that the number of slave units detected by master unit has decreased.  H3 indicates that the number of slave units detected by master unit has increased. ...
  • Page 70 V4+R VRF 50/60Hz 4.10.4 Procedure H2 / H3 Some outdoor units in the system are Power on all the outdoor units powered off The power supply is abnormal Check the power supply equipment Troubleshoot as for an E0 error Notes: Check LED1 on the main PCB.
  • Page 71 V4+R VRF 50/60Hz 4.11 H7 Troubleshooting 4.11.1 Digital display output 4.11.2 Description  Number of indoor units detected by master unit not same as number set on main PCB.  All units stop running.  Error code is only displayed on the master unit. 4.11.3 Possible causes ...
  • Page 72 V4+R VRF 50/60Hz 4.11.4 Procedure Number of indoor units set on main PCB Change the setting on the PCB to be the not same as actual number of indoor same as the actual number of indoor units units Some indoor units are powered off Power on all indoor units After re-starting the ODUs and IDUs and Refer to indoor unit troubleshooting...
  • Page 73 V4+R VRF 50/60Hz 4.12 H8 Troubleshooting 4.12.1 Digital display output 4.12.2 Description  Discharge pipe low pressure protection. When the discharge pressure falls below 0.3MPa, the system displays H8 protection and all units stop running. When the discharge pressure returns to normal, H8 is removed and normal operation resumes.
  • Page 74 V4+R VRF 50/60Hz 4.12.4 Procedure ODU stop valves are closed Open the stop valves High pressure sensor connection on main Ensure the sensor is connected properly PCB is loose High pressure sensor has short-circuited Replace the sensor or failed Insufficient refrigerant caused by Add refrigerant and inspect system for refrigerant leakage leaks...
  • Page 75 V4+R VRF 50/60Hz 4.13 yHd Troubleshooting 4.13.1 Digital display output In the error code, 'x' is a placeholder for the address (1, 2 or 3) of the slave unit with the error. 4.13.2 Description  1Hd indicates an error on the slave unit with address 1. ...
  • Page 76 V4+R VRF 50/60Hz 4.13.4 Procedure Check relevant slave unit 201608...
  • Page 77 V4+R VRF 50/60Hz 4.14 P0, P4, H6 Troubleshooting 4.14.1 Digital display output 4.14.2 Description  P0 indicates compressor temperature protection.  P4 indicates discharge temperature protection. When the discharge temperature rises above 115°C the system displays P4 protection and all units stop running. ...
  • Page 78 V4+R VRF 50/60Hz … flowchart continued from previous page Insufficient refrigerant caused by Add refrigerant and inspect the system refrigerant leakage for leaks Inspect the system and fix the error. If the The system is blocked, caused by crushed filter is blocked by ice, the piping should or bent pipe, blocked EXV or dirty filter be cleaned Make sure the combination ratio is less...
  • Page 79 V4+R VRF 50/60Hz 4.15 P1 Troubleshooting 4.15.1 Digital display output 4.15.2 Description  Discharge pipe high pressure protection. When the discharge pressure rises above 4.4MPa, the system displays P1 protection and all units stop running. When the discharge pressure falls below 3.2MPa, P1 is removed and normal operation resumes.
  • Page 80 V4+R VRF 50/60Hz … flowchart continued from previous page Flush all refrigerant then vacuum the System contains air or nitrogen system and recharge the refrigerant. Add oil to the system if it leaks The high pressure side is blocked, caused Inspect the system and fix the error by crushed or bent pipe or blocked EXV The condenser heat exchange is poor...
  • Page 81 V4+R VRF 50/60Hz 4.16 P2, H5 Troubleshooting 4.16.1 Digital display output 4.16.2 Description  P2 indicates suction pipe low pressure protection. When the suction pressure falls below 0.05MPa, the system displays P2 protection and all units stop running. When the pressure rises above 0.15MPa, P2 is removed and normal operation resumes.
  • Page 82 V4+R VRF 50/60Hz 4.16.4 Procedure P2 / H5 ODU stop valves are closed Open the stop valves Insufficient refrigerant caused by Add refrigerant or inspect the system for refrigerant leakage leaks The low pressure side is blocked, caused Inspect the system and fix the error. If the by crushed or bent pipe, blocked EXV, or filter is blocked by ice, the piping should dirty filter...
  • Page 83 V4+R VRF 50/60Hz 4.17 xP3 Troubleshooting 4.17.1 Digital display output 'x' is a placeholder for the compressor system (compressor and related electrical components), with 1 representing compressor system A and 2 representing compressor system B. 4.17.2 Description  1P3 indicates current protection on compressor A. ...
  • Page 84 V4+R VRF 50/60Hz … flowchart continued from previous page Discharge part of the refrigerant. Add oil Excess refrigerant if it leaks during discharge Flush all refrigerant then vacuum the System contains air or nitrogen system and recharge refrigerant. Add oil to the system if it leaks The condenser heat exchange is poor Inspect the system and fix the error...
  • Page 85 V4+R VRF 50/60Hz 4.18 P5 Troubleshooting 4.18.1 Digital display output 4.18.2 Description  Outdoor heat exchanger temperature protection. When the outdoor heat exchanger temperature rises above 65 the system displays P5 protection and all units stop running. When the temperature returns to the normal range, P5 is removed and normal operation resumes.
  • Page 86 V4+R VRF 50/60Hz 4.18.4 Procedure ODU stop valves are closed Open the stop valves Outdoor heat exchanger temperature Ensure the sensor is connected properly sensor connection on main PCB is loose Outdoor heat exchanger temperature Replace the sensor sensor has short-circuited or failed Make sure the combination ratio is less The indoor load is too large than 130%...
  • Page 87 V4+R VRF 50/60Hz 4.19 xP6, xH4 Troubleshooting 4.19.1 Digital display output In the error code, 'x' is a placeholder for the compressor system (compressor and related electrical components), with 1 representing compressor system A and 2 representing compressor system B. 4.19.2 Description ...
  • Page 88 V4+R VRF 50/60Hz Table 5-4.1: Specific error codes for error xH4 Specific error code Content Inverter module protection DC bus low voltage protection DC bus high voltage protection MCE error Zero speed protection Phase sequence error Compressor frequency variation greater than 15Hz within one second protection Actual compressor frequency differs from target frequency by more than 15Hz protection Notes: 'x' is a placeholder for the compressor system (compressor and related electrical components), with 1 representing compressor system A and...
  • Page 89 V4+R VRF 50/60Hz 4.19.5 First troubleshooting step To troubleshoot xH4 errors, first ensure that the DC bus wire is connected correctly. The DC bus wire should run from the N terminal on the inverter module, through the current sensor (in the direction indicated by the arrow on the current sensor), and end at the N terminal on the DC filter board.
  • Page 90 V4+R VRF 50/60Hz Figure 5-4.8: Inverter module terminals 4.19.7 xL1/xL4 troubleshooting Step 1: Check inverter module  Check the DC voltage between terminals 1 and 2. The normal value is 510-580V. If the voltage is lower than 510V, go to Step 2. Figure 5-4.9: Inverter module terminals Step 2: Check rectifier wiring circuit ...
  • Page 91 V4+R VRF 50/60Hz 4.19.8 xL2 troubleshooting Step 1: Check inverter module  Check the DC voltage between terminals 1 and 2. The normal value is 510-580V, if the voltage is higher than 580V, go to Step 2. Figure 5-4.11: Inverter module terminals Step 2: Check capacitor board ...
  • Page 92 V4+R VRF 50/60Hz and ensure the wiring is correct; if the compressor with the xL8/xL9 error still does not run normally, it needs to be replaced. Refer to Part 5, 4.11.10 “Compressor replacement procedure”. Figure 5-4.13: Connecting compressor to an error-free unit Unit with error Unit operating normally Connect...
  • Page 93 V4+R VRF 50/60Hz Step 5: Check filters(s)  If the oil from a compressor is spoiled (lightly or heavily), check the filter between the gas stop valve and the 4-way valve in that unit. If it is blocked, clean with nitrogen or replace. Figure 5-4.15: Compressor piping Step 6: Replace the faulty compressor and re-fit the other compressors ...
  • Page 94 V4+R VRF 50/60Hz Figure 5-4.17: Effects of spoiled compressor oil Worn crankshaft Worn scroll plate Worn scroll plate Normal compressor bearings Seriously worn and damaged bearings Filter blocked by impurities, which leads to abnormal compressor suction 201608...
  • Page 95 V4+R VRF 50/60Hz 4.20 P9, H9 Troubleshooting 4.20.1 Digital display output 4.20.2 Description  P9 indicates fan module protection. All units stop running.  H9 indicates that P9 protection has occurred 3 times in 60 minutes. When an H9 error occurs, a manual system restart is required before the system can resume operation.
  • Page 96 V4+R VRF 50/60Hz … flowchart continued from previous page The power supply is abnormal Check the power supply equipment Voltage between P and N on fan module Replace AC filter board is abnormal Replacing the fan module resolves the error Replace outdoor main PCB Notes: Refer to Part 4, 1.1 “PCB Switches and Switch Settings”.
  • Page 97 V4+R VRF 50/60Hz 4.21 PL, C7 Troubleshooting 4.21.1 Digital display output 4.21.2 Description  PL indicates inverter module temperature protection. When the main inverter module temperature rises above 80 the system displays PL protection and all units stop running.  C7 indicates PL protection has occurred 3 times in 100 minutes. When a C7 error occurs, a manual system restart is required before the system can resume operation.
  • Page 98 V4+R VRF 50/60Hz 4.21.4 Procedure PL / C7 The inverter module heat sink is blocked Clean or replace the heat sink or dirty The screws connecting the heat sink to Tighten the screws and make sure the the inverter module are loose heat sink is well-connected Inverter module temperature sensor Ensure the sensor is connected properly...
  • Page 99 V4+R VRF 50/60Hz 5 Appendix to Part 5 5.1 Temperature Sensor Resistance Characteristics Table 5-5.1: Outdoor ambient temperature sensor and outdoor heat exchanger temperature sensor resistance characteristics Temperature Resistance Temperature Resistance Temperature Resistance Temperature Resistance (°C) (kΩ) (°C) (kΩ) (°C) (kΩ) (°C) (kΩ)
  • Page 100 V4+R VRF 50/60Hz Table 5-5.2: Compressor top temperature sensor and discharge pipe temperature sensor resistance characteristics Temperature Temperature Temperature Temperature Resistance Resistance Resistance Resistance (kΩ) (kΩ) (kΩ) (kΩ) (°C) (°C) (°C) (°C) 542.7 68.66 13.59 3.702 511.9 65.62 13.11 3.595 483.0 62.73 12.65...
  • Page 101 V4+R VRF 50/60Hz Table 5-5.3: Inverter module temperature sensor resistance characteristics Temperature Temperature Temperature Temperature Resistance Resistance Resistance Resistance (kΩ) (kΩ) (kΩ) (kΩ) (°C) (°C) (°C) (°C) 971.4 109.0 19.70 5.000 912.8 103.9 18.97 4.855 858.2 99.02 18.26 4.705 807.3 94.44 17.59 4.566...
  • Page 102 V4+R VRF 50/60Hz 5.2 Normal Operating Parameters of Refrigerant System Under the following conditions, the operating parameters given in Tables 5-5.4 and 5-5.5 should be observed:  The master outdoor unit can detect all the indoor units.  The number of indoor units displayed on DSP2 is steady and is equal to the actual number of indoor units installed. ...
  • Page 104 Commercial Air Conditioner Division Midea Group Add.: Midea Headquarters Building, 6 Midea Avenue, Shunde, Foshan, Guangdong, China Postal code: 528311 Midea CAC After-service Application Midea CAC News Application Tel: +86-757-26338346 Fax: +86-757-22390205 cac.midea.com global.midea.com Note: Product speci cations change from time to time as product improvements and developments are released and may vary from those in this document.

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