Midea R32 Servise Manual

Aqua thermal Series

Midea Building Technologies Division

R32

Service Manual

All DC Inverter

Aqua thermal

Part 1 - General Information

Part 1

General Information

1 Unit Capacities and External Appearance............................................... 4

2 Water outlet temperature range ............................................................ 4

3

Aqua thermal

Midea Aqua thermal Service Manual

Model

MC-SU75-RN8L-B

MC-SU90-RN8L-B

MC-SU140-RN8L-B

MC-SU180-RN8L-B

Power supply

380-415V/3Ph/50Hz

Appearance

Notes:

① Normal mode

② Low leaving water temperature mode

Low leaving water temperature mode can be set through wired controller, please refer to the Operation Manual for details. If low leaving water

temperature function is effective, the operation range will extend to the red frame above. When the set temperature is less than 5℃, antifreeze

liquid (concentration above 15%) should be added in the water system, otherwise the unit will be damaged.

③ T4: Ambient temperature

Two: Leaving water temperature

Outlet water temperature (℃)

-15

-10

-5

0

5

10

15

20

25

30

35

40

45

50

55

0

5 10

15

20

25

30

outdoor temperature (℃)

COOLING

①

②

1 Unit Capacities and External Appearance

2 Water outlet temperature range

2.1 Cooling operating range

4

Aqua thermal

Part 1 - General Information

MC-SU75-RN8L-B, MC-SU140-RN8L-B

MC-SU90-RN8L-B, MC-SU180-RN8L-B

Outlet water temperature (℃)

-25

-20

-15

-10

-5

0

5

10

15

20

25

30

35

40

45

50

20

25

30

35

40

45

50

55

60

outdoor temperature (℃)

HEATING

-25

-20

-15

-10

-5

0

5

10

15

20

25

30

35

40

45

50

20 25 30 35 40 45 50 55 60

Outlet water temperature (℃)

outdoor temperature (℃)

2.2 Heating operating range

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Midea Aqua thermal Service Manual

6

Aqua thermal

Part 2 - Component Layout and Refrigerant Circuits

Part 2

Component Layout and

Refrigerant Circuits

1 Layout of Functional Components .............................................................. 8

2 Piping Diagrams ....................................................................................... 12

3 Refrigerant Flow Diagrams ....................................................................... 21

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Midea Aqua thermal Service Manual

Component list of MC-SU75-RN8L-B

1

Axial fan

6

Plate heating exchanger

11

Four-way valve

2

Brushless DC Motor

7

Flow switch

12

Plate heating exchanger

3

Condenser

8

Safety valve (Refrigerant side)

13

Oil separator

4

Exhaust valve

9

Gas-liquid separator

14

DC inverter scroll compressor

5

Safety valve (Water side)

10

Electric control box

1 Layout of Functional Components

8

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Part 2 - Component Layout and Refrigerant Circuits

Component list of MC-SU90-RN8L-B

1

Compressor 1

13

Filter

24

Liquid storage tank

2

Compressor 2

14

One-way valve

25

Solenoid valve suit

3

Vapor injection solenoid valve 1

15

Electronic expansion valve

26

Pressure sensor

4

Vapor injection solenoid valve 2

16

Plate heating exchanger

27

Safety valve

5/6

High pressure switch

17

Electionic expansion valve

28

Gas-liquid separator

7/8

Filter

18

Heat sink assembly

29

Meter connector

9

Meter connector

19

Single pass solenoid valve suit

30

Low pressure switch

10

Oil seperator

20/22

One way valve

31/33

Filter

11

4-way valve

21

Electronic expansion valve

32

Solenoid valve suit(Oil balance)

12

Condenser

23

Filter

34

Plate heat exchanger

123

4

5

6

9

10

12

13 25

26

11

29

7/8

30

31

33

32

15 14

16

17

18

19

20

21

22

23

242728

34

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Midea Aqua thermal Service Manual

Component list of MC-SU140-RN8L-B

1

DC inverter compressor 1

5

Condenser

9

Electronic expansion valve

2

DC inverter compressor 2

6

Electronic expansion valve

10

Gas-liquid separator

3

Oil seperator

7

Brazing plates heating exchanger

11

Plate heat exchanger

4

4-way valve

8

Electronic expansion valve

1

2

3

4

5

6

7

8

9

10

11

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Part 2 - Component Layout and Refrigerant Circuits

Component list of MC-SU180-RN8L-B

1

DC inverter compressor 1

13

Filter

25

Single pass solenoid valve suit

2

DC inverter compressor 2

14

One-way valve

26

Pressure sensor

3

Enhanced vapor injection solenoid valve 1

15

Electronic expansion valve

27

Safety valve

4

Enhanced vapor injection solenoid valve 2

16

Brazing plates heating exchanger

28

Gas-liquid separator

5

High pressure switch

17

Electionic expansion valve

29

Meter connector

6

High pressure switch

18

Heat sink assembly

30

Low pressure switch

7

Filter

19

Single pass solenoid valve suit

31

Filter

8

Filter

20

One way valve

32

Single pass solenoid valve suit

9

Meter connector

21

Electronic expansion valve

33

Filter

10

4-way valve

22

One way valve

34

Plate heat exchanger

11

Oil seperator

23

Filter

12

Condenser

24

Liquid storage tank

15 14

16

17

18

19

20

21

22

23

3

9

12

13

25

26

24

27

34

28

7/8

11

29

30

31

33

32

11

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Midea Aqua thermal Service Manual

Legend

1

Crankcase heater

25

Solenoid valve

2

DC inverter compressor

26

Vapor-liquid separator

3

Discharge temperature sensor 1

27

Filter

4

Discharge temperature switch 1

28

Suction temperature sensor

5

High pressure switch

29

Low pressure sensor

6

High pressure sensor

30

Low pressure switch

7

Pin valve (Discharge side)

31

Capillary

8

Oil separator

32

Filter

9

4-way-valve

33

Enhanced vapor injection solenoid valve

10

Condenser

34

Muffler

11

DC fan 1

35

Ambient temperature sensor

12

DC fan 2

36

temperature sensor

13

Filter

37

temperature sensor

14

One-way valve

38

Antifreeze temperature sensor 1

15

Heating Electronic expansion valve

39

Antifreeze temperature sensor 2

16

Plate heat exchanger (Economizer)

40

Entering water temperature sensor

17

EVI Electronic expansion valve

41

Safety valve

18

Coil for cooling electronic control board

42

Air purge valve

19

Liquid side bypass solenoid valve

43

Leaving water temperature sensor

20

One-way valve

44

Water flow switch

21

Cooling Electronic expansion valve

45

Water drain

22

One-way valve

46

Total leaving water temperature sensor

23

Filter

47

Pin valve (Suction side)

24

Plate heat exchanger

48

Safety valve

2 Piping Diagrams

MC-SU75-RN8L-B

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Part 2 - Component Layout and Refrigerant Circuits

Key components:

1. Compressor:

Maintains pressure differential between high and low pressure sides of the refrigerant system.

2. Fan:

Ventilates the air side heat exchanger.

3. Air side heat exchanger:

In the cooling mode, the heat of the refrigerant from the water side heat exchanger can be released into the air.

In the heating mode, the refrigerant can absorb the heat in the air and provide it to the water side heat exchanger.

4. Water side heat exchanger:

In cooling mode, the refrigerant can absorb heat from the water and reduce the temperature of the water.

In heating mode, the refrigerant can release heat into the water and increase the temperature of the water.

5. Four-way valve:

Controls refrigerant flow direction. Closed in cooling mode and open in heating mode. When closed, the air side heat

exchanger functions as a condenser and water side heat exchanger functions as an evaporator; when open, the air side heat

exchanger functions as an evaporator and water side heat exchanger function as a condenser.

6. Vapor-liquid separator:

Stores liquid refrigerant to protect the compressor from liquid hammering.

7. 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%.

8. Plate heat exchanger (Economizer):

In cooling mode, it can improve super-cooling degree and the super-cooled refrigerant can achieve better heat exchange in

indoor side. In heating mode, the refrigerant comes from the plate heat exchanger going to the compressor can enhance the

refrigerant enthalpy and improve the heating capacity in low ambient temperature. Refrigerant volume in plate heat

exchanger is controlled according to temperature different between plate heat exchanger inlet and outlet.

9. Electronic expansion valve:

Controls refrigerant flow and reduces refrigerant pressure.

10. Solenoid valve SV5 (defrost):

Multiple functions for enhancing reliability.

11. Solenoid valve SV6 (by pass):

Increase refrigerant flow.

12. Solenoid valve SV8A, SV8B (injection):

Enhance enthalpy and capacity.

13. High and low pressure switches:

Regulate refrigerant system pressure. When the refrigerant system pressure rises above the upper limit or falls below the

lower limit, the high or low pressure switches turn off, stopping the compressor.

14. Discharge temperature switch:

Protects the compressor from abnormally high temperatures and transient spikes in temperature.

15. High pressure sensor:

Measures compressor discharge side pressure of refrigerant.

16. Low pressure sensor:

Measures compressor suction side pressure of refrigerant.

17. Air purge valve:

Automatically removes air from the water circuit.

18. Safety valve (water side):

Prevents excessive water pressure by opening at 6bar and discharging water from the water circuit.

19. Water flow switch:

Detects water flow rate to protect the compressor and water pump in the event of insufficient water flow.

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Midea Aqua thermal Service Manual

20. Safety valve (refrigerant side):

Prevents excessive refrigerant pressure by opening at 42bar and discharging refrigerant from the refrigerant system.

21. Crankcase heater:

Prevents refrigerant from mixing with compressor oil when the compressors are stopped.

22. Water side heat exchanger electric heater:

Protects the water side heat exchanger from ice formation.

23. Water flow switch electric heater:

Protects the water from ice formation.

24. Pin valve (high and low pressure side):

Charges or discharges refrigerant.

25. Capillary:

Normally return oil to the compressor.

26. Wired Controller:

Control and query the operation status of the unit.

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Part 2 - Component Layout and Refrigerant Circuits

MC-SU90-RN8L-B

Legend

1

Crankcase heater 1

30

System pressure sensor

2

Crankcase heater 2

31

Solenoid valve

3

DC inverter compressor 1

32

Vapor-liquid separator

4

DC inverter compressor 2

33

Pin valve (Suction side)

5

Discharge temperature sensor 1

34

Suction temperature sensor

6

Discharge temperature sensor 2

35

Low pressure switch

7

Discharge temperature switch 1

36

Fast oil return solenoid valve

8

Discharge temperature switch 2

37

Capillary

9

High pressure switch 1

38

Filter

10

High pressure switch 2

39

Capillary

11

Pin valve (Discharge side)

40

Filter

12

Oil separator

41

Capillary

13

4-way-valve

42

Filter

14

Condenser

43

Enhanced vapor injection solenoid valve 1

15

DC fan 1

44

Enhanced vapor injection solenoid valve 2

16

DC fan 2

45

Muffler 1

17

Filter

46

Muffler 2

18

One-way valve

47

Ambient temperature sensor

19

Heating Electronic expansion valve

48

Antifreeze temperature sensor 1

20

Plate heat exchanger (Economizer)

49

Antifreeze temperature sensor 2

21

EVI electronic expansion valve

50

Water side heat exchanger electric heater

22

Coil for cooling electronic control board

51

Entering water temperature sensor

23

Liquid side bypass solenoid valve

52

Safety valve

24

One-way valve

53

Air purge valve

25

Cooling Electronic expansion valve

54

Leaving water temperature sensor

26

One-way valve

55

Total leaving water temperature sensor

27

High pressure tank

56

Water flow switch

28

Filter

57

Manual water drain valve

29

Plate heat exchanger

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Midea Aqua thermal Service Manual

Key components:

1. Compressor

Maintains pressure differential between high and low pressure sides of the refrigerant system.

2. Fan:

Ventilates the air side heat exchanger.

3. 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%.

4. Vapor-liquid separator:

Stores liquid refrigerant to protect the compressor from liquid hammering.

5. Electronic expansion valve:

Controls refrigerant flow and reduces refrigerant pressure.

6. Four-way valve:

Controls refrigerant flow direction. Closed in cooling mode and open in heating mode. When closed, the air side heat

exchanger functions as a condenser and water side heat exchanger functions as an evaporator; when open, the air side heat

exchanger functions as an evaporator and water side heat exchanger function as a condenser.

7. High and low pressure switches:

Regulate refrigerant system pressure. When the refrigerant system pressure rises above the upper limit or falls below the

lower limit, the high or low pressure switches turn off, stopping the compressor.

8. Discharge temperature switch:

Protects the compressor from abnormally high temperatures and transient spikes in temperature.

9. Air purge valve:

Automatically removes air from the water circuit.

10. Safety valve:

Prevents excessive water pressure by opening at 6bar and discharging water from the water circuit.

11. Water flow switch:

Detects water flow rate to protect the compressor and water pump in the event of insufficient water flow.

12. Pressure sensor:

Measures refrigerant system pressure.

13. Crankcase heater:

Prevents refrigerant from mixing with compressor oil when the compressors are stopped.

14. Water side heat exchanger electric heater:

Protects the water side heat exchanger from ice formation.

15. Water flow switch electric heater:

Protects the water from ice formation.

16. Plate heat exchanger(Economizer):

In cooling mode, it can improve super-cooling degree and the super-cooled refrigerant can achieve better heat exchange in

indoor side. In heating mode, the refrigerant comes from the plate heat exchanger going to the compressor can enhance

the refrigerant enthalpy and improve the heating capacity in low ambient temperature. Refrigerant volume in plate heat

exchanger is controlled according to temperature different between plate heat exchanger inlet and outlet.

17. Pin valve (high and low pressure side):

Charges or discharges refrigerant.

18. Capillary:

Normally return oil to the compressor.

19. Solenoid valve SV4(oil balance):

Quickly return oil to the compressor.

20. Solenoid valve SV5(defrost):

Multiple functions for enhancing reliability.

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Part 2 - Component Layout and Refrigerant Circuits

21. Solenoid valve SV6(by pass):

Increase refrigerant flow.

22. Solenoid valve SV8A, SV8B(injection):

Enhance enthalpy and capacity.

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Midea Aqua thermal Service Manual

Legend

1

Crankcase heater 1

31

Filter

2

Crankcase heater 2

32

Plate heat exchanger

3

DC inverter compressor 1

33

Solenoid valve

4

DC inverter compressor 2

34

Pin valve (Suction side)

5

Discharge temperature sensor 1

35

Safety valve

6

Discharge temperature sensor 2

36

Vapor-liquid separator

7

Discharge temperature switch 1

37

Filter

8

Discharge temperature switch 2

38

Suction temperature sensor

9

High pressure switch 1

39

Low pressure sensor

10

High pressure switch 2

40

Low pressure switch

11

One-way valve

41

Capillary

12

Pin valve

42

Filter

13

High pressure sensor

43

Capillary

14

Oil separator

44

Filter

15

4-way-valve

45

Enhanced vapor injection solenoid valve 1

16

Condenser

46

Muffler 1

17

DC fan 1

47

Enhanced vapor injection solenoid valve 2

18

DC fan 2

48

Muffler 2

19

Filter

49

Ambient temperature sensor

20

One-way valve

50

temperature sensor

21

Electronic expansion valve

51

temperature sensor

22

temperature sensor

52

Antifreeze temperature sensor 1

23

Plate heat exchanger (Economizer)

53

Antifreeze temperature sensor 2

24

EVI plate heat exchanger refrigerant temperature sensor

54

Entering water temperature sensor

25

Electronic expansion valve

55

Safety valve

26

Coil for cooling electronic control board

56

Air purge valve

27

Liquid side bypass solenoid valve

57

Leaving water temperature sensor

28

One-way valve

58

Water flow switch

29

Electronic expansion valve

59

Water drain

30

One-way valve

60

Total leaving water temperature sensor

53

Taf2

inlet

outlet

Tz

EXVA

W-Heat

Taf1

T4

Twi

Two

Tw

ST1

E

D

S

C

T3B

Th

Tp1

Tp2

SV6

EXVC

T6B

T6A

SV5

T3A

16mm

SV8A

SV8B

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

23

24

25

26

27

22

28

29

30

31

32

33

36

34

35

37

38

39

40

41

42

43

44

45

46

47

48

49

51

50

52

54

55

56

57

58

59

60

EXVB

MC-SU140-RN8L-B

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Part 2 - Component Layout and Refrigerant Circuits

Key components:

1. Compressor Maintains pressure differential between high and low pressure sides of the refrigerant system.

2. Fan: Ventilates the air side heat exchanger.

3. Air side heat exchanger: In the cooling mode, the heat of the refrigerant from the water side heat exchanger can be released into the air.

In the heating mode, the refrigerant can absorb the heat in the air and provide it to the water side heat exchanger.

4. Water side heat exchanger: In cooling mode, the refrigerant can absorb heat from the water and reduce the temperature of the water.

In heating mode, the refrigerant can release heat into the water and increase the temperature of the water.

5. 4-way valve:

Controls refrigerant flow direction. Closed in cooling mode and open in heating mode. When closed, the air side heat exchanger functions as a condenser and water side heat exchanger functions as an evaporator; when open, the air side heat exchanger functions as an evaporator and water side heat exchanger function as a condenser.

6. Vapor-liquid separator: Stores liquid refrigerant to protect the compressor from liquid hammering.

7. 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%.

8. Plate heat exchanger (Economizer):

In cooling mode, it can improve super-cooling degree and the super-cooled refrigerant can achieve better heat exchange in indoor side. In heating mode, the refrigerant comes from the plate heat exchanger going to the compressor can enhance the refrigerant enthalpy and improve the heating capacity in low ambient temperature. Refrigerant volume in plate heat exchanger is controlled according to temperature different between plate heat exchanger inlet and outlet.

9. Electronic expansion valve: Controls refrigerant flow and reduces refrigerant pressure.

10. Solenoid valve SV5 (defrost):

Multiple functions for enhancing reliability.

11. Solenoid valve SV6 (by pass):

Increase refrigerant flow.

12. Solenoid valve SV8A, SV8B (injection):

Enhance enthalpy and capacity.

13. High and low pressure switches:

Regulate refrigerant system pressure. When the refrigerant system pressure rises above the upper limit or falls below the lower limit, the high or low pressure switches turn off, stopping the compressor.

14. Discharge temperature switch:

Protects the compressor from abnormally high temperatures and transient spikes in temperature.

15. High pressure sensor:

Measures compressor discharge side pressure of refrigerant.

16. Low pressure sensor:

Measures compressor suction side pressure of refrigerant.

17. Air purge valve:

Automatically removes air from the water circuit.

18. Safety valve (water side):

Prevents excessive water pressure by opening at 6bar and discharging water from the water circuit.

19. Water flow switch:

Detects water flow rate to protect the compressor and water pump in the event of insufficient water flow.

20. Safety valve (refrigerant side):

Prevents excessive refrigerant pressure by opening at 42bar and discharging refrigerant from the refrigerant system.

21. Crankcase heater:

Prevents refrigerant from mixing with compressor oil when the compressors are stopped.

22. Water side heat exchanger electric heater:

Protects the water side heat exchanger from ice formation.

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Midea Aqua thermal Service Manual

23. Water flow switch electric heater:

Protects the water from ice formation.

24. Pin valve (high and low pressure side):

Charges or discharges refrigerant.

25. Capillary:

Normally return oil to the compressor.

26. Wired Controller:

Control and query the operation status of the unit.

MC-SU180-RN8L-B

The piping diagrams is the same as MC-SU90-RN8L-B. MC-SU180-RN8L-B system consists of two independent MC-SU90-RN8L-B

systems.

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Part 2 - Component Layout and Refrigerant Circuits

inlet

outlet

E

D

S

C

inlet

outlet

E

D

S

C

High temperature, high press gas

High temperature, high press liquid

Low temperature, low press

3 Refrigerant Flow Diagrams

MC-SU75-RN8L-B

Heating operation

Cooling and defrosting operation

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Midea Aqua thermal Service Manual

Heating operation

High temperature, high press gas

High temperature, high press liquid

Low temperature, low press

MC-SU90-RN8L-B

Cooling and defrosting operation

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Part 2 - Component Layout and Refrigerant Circuits

inlet

outlet

E

D

S

C

inlet

outlet

E

D

S

C

High temperature, high press gas

High temperature, high press liquid

Low temperature, low press

MC-SU140-RN8L-B

Heating operation

Cooling and defrosting operation

MC-SU180-RN8L-B

The refrigerant flow diagrams is same as MC-SU90-RN8L-B. MC-SU180-RN8L-B system consists of two independent

MC-SU90-RN8L-B systems.

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Midea Aqua thermal Service Manual

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Part 3 - Control

Part 3

Control

1 General Control Scheme Flowchart .......................................................... 26

2 Stop Operation ........................................................................................ 27

3 Standby Control ....................................................................................... 27

4 Startup Control ........................................................................................ 28

5 Normal Operation Control ....................................................................... 31

6 Protection Control ................................................................................... 37

7 Special Control ......................................................................................... 41

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Midea Aqua thermal Service Manual

Easy control

Conditions met

for defrosting

On

Special control

 Outdoor unit duty cycling

 TEMP-SWITCH control

 Defrosting operation

7

Stop operation

 System stops

2

Standby control

 Water pump control

3

Startup control

 Startup control for cooling operation

4

Normal operation control

 Outdoor fan control

5

Protection control

 Water side heat exchanger low pressure protection control

6

On

1 General Control Scheme Flowchart

 Abnormal shutdown

 Crankcase heater control

 Compressor startup delay control

 Startup control for heating operation

 Component control during normal operation

 Compressor output control

 Compressor step control

 Water pump select control

 Four-way valve control

 Electronic expansion valve control

 High pressure protection control

 Low pressure protection control

 Discharge temperature protection control

 Compressor and Inverter Module Protection Control

 Voltage protection control

 DC fan motor protection control

 Water side heat exchanger anti-freeze protection control

 Air side heat exchanger high temperature protection control

 Water side heat exchanger temperature difference protection control

 Water side heat exchanger low temperature protection control

Note:

1. Numbers in the top right-hand corners of boxes indicate the relevant section of text on the following pages.

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Part 3 - Control

Notes:

1. Tp1: discharge temperature sensor 1;

2. Tp2: discharge temperature sensor 2.

Ambient temperature < 35 oC

Ambient temperature > 40 oC

Crankcase heater off

Crankcase heater is controlled according to discharge temperature

Min (Tp1, Tp2) < 40 oC

Min (Tp1, Tp2) > 50 oC

Crankcase heater off

Crankcase heater on

2 Stop Operation

The stop operation occurs for one of the 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 outdoor unit’s PCB digital displays and on the user interface.

2. The system stops when the set temperature has been reached.

In order to prevent the compressor from starting and stopping frequently and to balance the pressure in the refrigeration

system, forcibly stop the compressor for 7 minutes before starting. (Except for special controls such as defrosting).

3 Standby Control

3.1 Crankcase Heater Control

The crankcase heater is used to prevent refrigerant from mixing with compressor oil when the compressors are stopped. The

crankcase heater is controlled according to the outdoor ambient temperature and discharge temperature. When the outdoor

ambient temperature is above 40°C, the crankcase heater is off; when the outdoor ambient temperature is below 35°C, the

crankcase heater is controlled according to discharge temperature.

3.2 Water Pump Control

When the outdoor unit is in standby, the circulator pump run continuously.

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Midea Aqua thermal Service Manual

Component

Wiring diagram label

90kW

Control functions and states

DC fan motor A

Fan A

●

Startup after 4-way valve changes refrigerant flow direction.

Controlled according to discharge pressure.

DC fan motor B

Fan B

●

Electronic expansion valve A

EXVA

●

Step from 0 to 480. Controlled according to discharge temperature

superheat.

Electronic expansion valve B

EXVB

●

Step 480

Electronic expansion valve C

EXVC

●

Step from 0 to 480. Controlled according to temperature difference

between economizer plate heat exchanger inlet and outlet.

Four-way valve

ST1

●

On

Solenoid valve (oil balance)

SV4

●

Closed for 200s, open for 600s, then closed.

Solenoid valve (defrost)

SV5

●

Closed

Solenoid valve (by pass)

SV6

●

Closed

Solenoid valve (injection)

SV8A/B

●

Open

Water flow switch

Water-SW

●

After water pump (field supplied) is turned on for 2min, if water flow

switch is open, water pump stops and water flow error code

appears. The compressor can be started after the water flow is

normal.

Electric auxiliary heater (pipe)

-

●

Controlled according to ambient temperature and total water outlet

temperature.

Crankcase heater

CCH

●

Controlled according to ambient temperature and discharge

temperature.

Component

Wiring diagram label

75kW

140kW

Control functions and states

Water pump

PUMP

●

Non-standard component: After the pump is turned on for

2 minutes, detect the water flow switch continuously. The

compressor can be started only after the water flow is

normal.

Inverter compressor 1

BP1

●

Control the outlet water temperature. The operating

increased and decreased frequency is 1Hz/s, and is

executed according to the starting platform.

Inverter compressor 2

BP2

●

Inverter fan1

FAN1

●

Startup after 4-way valve changes refrigerant flow

direction. Controlled according to ambient temperature,

discharge pressure and compressor frequency.

Inverter fan 2

FAN2

●

Electronic expansion valve

EXV-A

●

Step from 0 to 480. Controlled according to discharge

temperature superheat.

Electronic expansion valve

EXV-B

●

Step 480P

Electronic expansion valve

EXV-C

●

Enhanced vapor injection EXV，Step from 0 to 480.

Controlled according to temperature difference between

4 Startup Control

4.1 Compressor Startup Delay Control

In initial startup control and restart control (except in defrosting operation), compressor startup is delayed such that a minimum

7 minutes has elapsed since the compressor stopped, in order to prevent frequency compressor on/off and to equalize the

pressure within the refrigerant system.

4.2 Startup Control for Heating Operation

For MC-SU90-RN8L-B:

For MC-SU75-RN8L-B and MC-SU140-RN8L-B:

28

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Part 3 - Control

economizer plate heat exchanger inlet and outlet.

Four-way valve

ST1

●

Open

Solenoid valve (defrost)

SV5

●

Closed

Solenoid valve (by pass)

SV6

●

Closed

Solenoid valve (injection)

SV8A/B

●

Open

Water flow switch

Water-SW

●

After water pump (field supplied) is turned on for 2min, if

water flow switch is open, water pump stops and water

flow error code appears. The compressor can be started

after the water flow is normal.

Electric auxiliary heater (pipe)

-

●

Controlled according to ambient temperature and total

water outlet temperature.

Crank case heater

CCH

●

Controlled according to ambient temperature and

discharge temperature.

Component

Wiring diagram

label

180kW

Control functions and states

Inverter compressor

BP1/2

●

Compressor startup program selected according to ambient

temperature.

DC fan motor

FAN

●

Fan run at maximum speed1.

Electronic expansion valve

EXV

●

Position (steps) from 0 (fully closed) to 480 (fully open),

controlled according to outdoor ambient temperature,

discharge temperature, suction superheat, compressor speed

and refrigerant system pressure.

Four-way valve

ST1

●

On

Component

Wiring diagram

label

90kW

Control functions and states

DC fan motor A

Fan A

●

According to ambient temperature, compressor frequency and air

side heat exchanger refrigerant total outlet temperature.

DC fan motor B

Fan B

●

Electronic expansion valve A

EXVA

●

Step 480

Electronic expansion valve B

EXVB

●

Step from 0 to 480. Controlled according to suction temperature

superheat.

Electronic expansion valve C

EXVC

●

Step from 0 to 480. Controlled according to temperature difference

between economizer plate heat exchanger inlet and outlet.

Four-way valve

ST1

●

Closed

Solenoid valve (oil balance)

SV4

●

Closed for 200s, open for 600s, then closed.

Solenoid valve (defrost)

SV5

●

Closed

Solenoid valve (by pass)

SV6

●

Open for 600s then closed.

Solenoid valve (injection)

SV8A/B

●

Open

Water side heat exchanger heater

-

●

According to water side heat exchanger anti-freezing temperature.

Water flow switch

Water-SW

●

After water pump (field supplied) is turned on for 2min, if water flow

switch is open, water pump stops and water flow error code appears.

The compressor can be started after the water flow is normal.

Water flow switch heater

●

Controlled according to ambient temperature, water inlet

temperature and water outlet temperature.

Crank case heater

CCH

Controlled according to ambient temperature and discharge

temperature.

For MC-SU180-RN8L-B:

Notes: 1. Refer to Table 3-4.1 in Part 3, 5.8 “Outdoor Fan Control”.

4.3 Startup Control for Cooling Operation

For MC-SU90-RN8L-B:

29

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Midea Aqua thermal Service Manual

Component

Wiring diagram label

75kW

140kW

Control functions and states

Water pump

PUMP

●

Non-standard component: After the pump is turned on for 2

minutes, detect the water flow switch continuously. The

compressor can be started only after the water flow is

normal.

Inverter compressor 1

BP1

●

Control the outlet water temperature. The operating

increased and decreased frequency is 1Hz/s, and is executed

according to the starting platform.

Inverter compressor 2

BP2

●

Inverter fan1

FAN1

●

Control According to the exhaust pressure of the outdoor

unit, the initial target windshield is operated for the first

60s, and then correct every 20-60s.

Inverter fan 2

FAN2

●

Electronic expansion valve

EXV-A

●

Step from 0 to 480. Controlled according to discharge

temperature superheat.

Electronic expansion valve

EXV-B

●

Step 480P

Electronic expansion valve

EXV-C

●

Step from 0 to 480. Controlled according to temperature

difference between economizer plate heat exchanger inlet

and outlet.

Four-way valve

ST1

●

Open

Solenoid valve (defrost)

SV5

●

Closed

Solenoid valve (by pass)

SV6

●

Open for 600s, then closed.

Solenoid valve (injection)

SV8A/B

●

Open

Water flow switch

Water-SW

●

After water pump (field supplied) is turned on for 2min, if

water flow switch is open, water pump stops and water flow

error code appears. The compressor can be started after the

water flow is normal.

Water flow switch heater

●

Controlled according to ambient temperature, water inlet

temperature and water outlet temperature.

Crank case heater

CCH

● Controlled according to ambient temperature and discharge

temperature.

Component

Wiring diagram

label

180kW

Control functions and states

Inverter compressor

BP1/2

●

Compressor startup program selected according to ambient

temperature1.

DC fan motor

FAN

●

Fan run at maximum speed2.

Electronic expansion valve

EXV

●

Position (steps) from 0 (fully closed) to 480 (fully open),

controlled according to outdoor ambient temperature,

discharge temperature, suction superheat, compressor speed

and refrigerant system pressure.

Four-way valve

ST1

●

Off

For MC-SU75-RN8L-B and MC-SU140-RN8L-B:

For MC-SU180-RN8L-B:

30

Aqua thermal

Part 3 - Control

Component

Wiring diagram label

90kW

Control functions and states

Inverter compressor A

BP1

●

Controlled according to load requirement.

Inverter compressor B

BP2

●

DC fan motor A

Fan A

●

Startup after 4-way valve changes refrigerant flow direction.

Controlled according to discharge pressure.

DC fan motor B

Fan B

●

Electronic expansion valve A

EXVA

●

Step from 0 to 480. Controlled according to discharge temperature

superheat.

Electronic expansion valve B

EXVB

●

Step 480

Electronic expansion valve C

EXVC

●

Step from 0 to 480. Controlled according to temperature difference

between economizer plate heat exchanger inlet and outlet.

Four-way valve

ST1

●

On

Solenoid valve (oil balance)

SV4

●

Open for 3min after every 17min.

Solenoid valve (defrost)

SV5

●

Closed

Solenoid valve (by pass)

SV6

●

Closed

Solenoid valve (injection)

SV8A/B

●

Open

Water flow switch

Water-SW

●

After water pump (field supplied) is turned on for 2min, if water

flow switch is open, water pump stops and water flow error code

appears. The compressor can be started after the water flow is

normal.

Electric auxiliary heater

(pipe)

-

●

Controlled according to ambient temperature and total water

outlet temperature.

Crank case heater

c

●

Controlled according to ambient temperature and discharge

temperature.

Component

Wiring

diagram label

75kW

140kW

Control functions and states

Water pump

PUMP

● ● Open

Inverter

compressor 1

BP1

●

Control the outlet water temperature. The operating increased and decreased

frequency is 1Hz/s.

Inverter

compressor 2

BP2

●

Inverter fan1

FAN1

●

Startup after 4-way valve changes refrigerant flow direction. Controlled according

to ambient temperature, discharge pressure and compressor frequency.

Inverter fan 2

FAN2

●

Electronic

expansion valve

EXV-A

●

Step from 0 to 480. Controlled according to discharge temperature superheat.

Electronic

expansion valve

EXV-B

●

Step 480.

Electronic

expansion valve

EXV-C

●

Enhanced vapor injection EXV，Step from 0 to 480. Controlled according to

temperature difference between economizer plate heat exchanger inlet and outlet.

Four-way valve

ST1

●

Open

Solenoid valve

(defrost)

SV5

●

Open during defrost and close at other times.

Solenoid valve (by

pass)

SV6

●

Closed

Solenoid valve

(injection)

SV8A/B

●

Open

5 Normal Operation Control

5.1 Component Control during heating mode

For MC-SU90-RN8L-B:

For MC-SU75-RN8L-B and MC-SU140-RN8L-B:

31

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Midea Aqua thermal Service Manual

Component

Wiring

diagram

label

180kW

Control functions and states

Inverter

compressor

BP1/2

●

Controlled according to load requirement from hydronic system.

DC fan motor

FAN

●

Controlled according to outdoor heat exchanger pipe temperature.

Electronic

expansion valve

EXV

●

Position (steps) from 0 (fully closed) to 480 (fully open), controlled according to outdoor

ambient temperature, discharge temperature, suction superheat, compressor speed and

refrigerant system pressure.

Four-way valve

ST1

●

On

Component

Wiring diagram label

90kW

Control functions and states

Inverter compressor A

BP1

●

Controlled according to load requirement.

Inverter compressor B

BP2

●

DC fan motor A

Fan A

●

Controlled according to ambient temperature and discharge

pressure and air side heat exchanger refrigerant temperature.

DC fan motor B

Fan B

●

Electronic expansion valve A

EXVA

●

Step 480

Electronic expansion valve B

EXVB

●

Step from 0 to 480. Controlled according to suction temperature

superheat.

Electronic expansion valve C

EXVC

●

Step from 0 to 480. Controlled according to temperature

difference between economizer plate heat exchanger inlet and

outlet.

Four-way valve

ST1

●

Closed

Solenoid valve (oil balance)

SV4

●

Open for 3min after every 17min.

Solenoid valve (defrost)

SV5

●

Closed

Solenoid valve (by pass)

SV6

●

Closed

Solenoid valve (injection)

SV8A/B

●

Open

Water side heat exchanger

heater

-

●

According to water side heat exchanger anti-freezing

temperature.

Water flow switch

Water-SW

●

After water pump (field supplied) is turned on for 2min, if water

flow switch is open, water pump stops and water flow error

code appears. The compressor can be started after the water

flow is normal.

Water flow switch heater

-

●

Controlled according to ambient temperature, water inlet

temperature and water outlet temperature.

Crank case heater

CCH

●

Controlled according to ambient temperature and discharge

temperature.

Component

Wiring diagram label

75kW

140kW

Control functions and states

Inverter compressor 1

BP1

●

Control the outlet water temperature. The operating

increased and decreased frequency is 1Hz/s.

Inverter compressor 2

BP2

●

Inverter fan1

FAN1

●

Control according to the exhaust pressure of the

outdoor unit. Correct every 20-60s, and adjust in

0-32 gears.

Inverter fan 2

FAN2

●

Electronic expansion valve

EXV-A

●

Step 480.

For MC-SU180-RN8L-B:

5.2 Component control during cooling mode

For MC-SU90-RN8L-B:

For MC-SU75-RN8L-B and MC-SU140-RN8L-B:

32

Aqua thermal

Part 3 - Control

Electronic expansion valve

EXV-B

●

Step from 0 to 480. Controlled according to discharge

temperature superheat.

Electronic expansion valve

EXV-C

●

Enhanced vapor injection EXV, Step from 0 to 480.

Controlled according to temperature difference

between economizer plate heat exchanger inlet and

outlet.

Four-way valve

ST1

●

Closed

Solenoid valve (defrost)

SV5

●

Closed

Solenoid valve (by pass)

SV6

●

Closed

Solenoid valve (injection)

SV8A/B

●

Open

Water side heat exchanger

heater

-

●

According to water side heat exchanger anti-freezing

temperature

Water flow switch

Water-SW

●

After water pump (field supplied) is turned on for

2min, if water flow switch is open, water pump stops

and water flow error code appears. The compressor

can be started after the water flow is normal.

Water flow switch heater

-

●

Controlled according to ambient temperature, water

inlet temperature and water outlet temperature

Crank case heater

CCH

●

Controlled according to ambient temperature and

discharge temperature

Component

Wiring diagram label

180kW

Control functions and states

Inverter compressor

BP1/2

●

Controlled according to load requirement from hydronic system.

DC fan motor

FAN

●

Controlled according to outdoor heat exchanger pipe temperature.

Electronic expansion valve

EXV

●

Position (steps) from 0 (fully closed) to 480 (fully open), controlled

according to outdoor ambient temperature, discharge

temperature, suction superheat, compressor speed and refrigerant

system pressure.

Four-way valve

ST1

●

Off

For MC-SU180-RN8L-B:

5.3 Compressor Output Control

The compressor rotation speed is controlled according to the load requirement. Before compressor startup, the outdoor unit

determines the compressor target speed according to outdoor ambient temperature, discharge temperature and then runs the

appropriate compressor startup program. Once the startup program is complete, the compressor runs at the target rotation

speed.

The compressor speed is controlled according to two parts in normal operation:

In cooling mode: In a single system, the compressor speed is controlled according to the water outlet temperature and water

outlet setting temperature. In a combination system, the compressor of master unit is controlled according total water outlet

temperature and water outlet setting temperature, the compressor of the slave unit is controlled according to water inlet and

water outlet temperature. Both in a single system and combination system, the compressor speed is limited by the inverter

module temperature (calculated value), ambient temperature, discharge temperature, discharge pressure and air side heat

exchanger refrigerant total outlet temperature.

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Midea Aqua thermal Service Manual

Fan speed index

Fan speed (rpm)

FAN A

FAN B 0 0

0

1

150

0

2

190 0 3

230

0

4

270 0 5

330 0 6

150

7

170

8

190

190 9 210

210

10

230

11

250

12

270

13

290

14

310

15

330

16

350

17

370

18

400

19

430

20

450

21

470

22

510

23

550

5.4 Compressor Step Control

The running speed of six-pole compressors in rotations per second (rps) is one third of the frequency (in Hz) of the electrical

input to the compressor motor. The frequency of the electrical input to the compressor motors can be altered at a rate of 1Hz in

two seconds.

5.5 Four-way Valve Control

The four-way valve is used to change the direction of refrigerant flow through the water side heat exchanger in order to switch

between cooling and heating operations. During heating operation, the four-way valve is on; during cooling and defrosting

operation, the four-way valve is off.

5.6 Electronic Expansion Valve Control

 Power-on self-test:

When the power is first turned on, the EXV is closed for 700 steps, proofreading the 0-step position, and re-opening at a

maximum of 480.

 Startup:

Adjust from 480 to the initial position, (the initial opening is determined by the ambient temperature), maintain for a

period of time. EXV is controlled according to suction superheat, exhaust, and compressor speed.

 When the outdoor unit is in standby:

The EXV is at position 480 (steps).

 When the outdoor unit stops:

After the compressor shuts down for 1 minute, the EXV is fully closed first, and then opened to the initial position.

5.7 Outdoor Fan Control

For MC-SU75-RN8L-B:

34

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Part 3 - Control

24

580

25

610

26

640

27

680

28

710

29

750

30

780

31

800

32

830

Fan speed index

Fan speed (rpm)

FAN A

FAN B

0 0 0

1

150

0

2

190 0 3

230 0 4

270

0

5

330 0 6

150

150 7 170

150 8 170

150 9 190

170

10

210

190

11

230

210

12

250

230

13

270

250

14

290

270

15

310

290

16

330

310

17

350

330

18

370

350

19

400

370

20

430

400

21

450

430

22

480

460

23

500

480

24

520

500

25

540

520

26

560

540

27

560

540

28

580

560

29

580

560

30

600

580

31

600

580

32

620

600

For MC-SU90-RN8L-B and MC-SU180-RN8L-B:

35

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Midea Aqua thermal Service Manual

Fan speed index

Fan speed (rpm)

FAN A

FAN B 0 0

0

1

150 0 2

190 0 3

230

0

4

270

0

5

330

0

6

150

7

170

8

170

170 9 190

190

10

210

11

230

12

250

13

270

14

290

15

310

16

330

17

350

18

370

19

400

20

430

21

470

22

510

23

550

24

600

25

650

26

680

27

700

28

720

29

750

30

780

31

800

32

830

For MC-SU140-RN8L-B:

36

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Part 3 - Control

Notes:

1. P

c

: Discharge pressure

Notes:

1. P

e

: Suction pressure

Pc > 4.2MPa

Pc < 3.2MPa

Normal operation

High pressure protection, error code P0 is displayed

When P0 protection occurs 3 times in

60 minutes, a manual system restart is

required before the system can

resume operation.

Pe < 0.05MPa

Pe > 0.15MPa

Normal operation

Low pressure protection, error code P1 is displayed

When P1 protection occurs 3 times in

60 minutes, a manual system restart is

required before the system can

resume operation.

Discharge temperature > 115°C

Discharge temperature < 90°C

Normal operation

High discharge temperature protection, error code P0 is displayed

When P0 protection occurs 3 times in

60 minutes, a manual system restart is

required before the system can

resume operation.

6 Protection Control

6.1 High Pressure Protection Control

This control protects the refrigerant system from abnormally high pressure and protects the compressor from transient spikes in

pressure.

When the discharge pressure rises above 4.2MPa the system displays P0 protection and the faulty unit stops running. When the

discharge pressure drops below 3.2MPa, the compressor enters re-start control.

6.2 Low Pressure Protection Control

This control protects the refrigerant system from abnormally low pressure and protects the compressor from transient drops in

pressure.

6.3 Discharge Temperature Protection Control

This control protects the compressor from abnormally high temperatures and transient spikes in temperature.

When the discharge temperature rises above 115°C the system displays P0 protection and the faulty unit stops running. When

the discharge temperature drops below 90°C, the compressor enters re-start control.

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Midea Aqua thermal Service Manual

Notes:

1. P4 is the protection for System A, P5 is the protection for System B.

Notes:

1. P4 is the protection for System A, P5 is the protection for System B.

Notes:

1. The module temperature is calculated by inverter module.

Current > protection current

Current < protection current

Normal operation

Compressor current protection, error code P4/P5 is displayed

Current > protection current

Current < protection current

Normal operation

Compressor current protection, error code P4/P5 is displayed

Module temperature1> 100°C

Module temperature1< 70°C

Normal operation

Inverter module temperature protection, error code PL is

displayed

When P4 or P5 protection occurs 3

times in 60 minutes, a manual system

restart is required before the system

can resume operation.

CL is displayed when PL error occurs 3

times in 100 minutes, a manual

system restart is required before the

system can resume operation.

When P4 or P5 protection occurs 3

times in 60 minutes, a manual system

restart is required before the system

can resume operation.

6.4 Compressor and Inverter Module Protection Control

For MC-SU75-RN8L-B and MC-SU140-RN8L-B:

The inverter module board protection current of a single compressor: AC is 53A, bus DC current is 232A.

For MC-SU90-RN8L-B and MC-SU180-RN8L-B:

The inverter module board protection current of a single compressor: AC is 60A, bus DC current is 140A.

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.

When the compressor current rises above protection current, the system displays P4 or P5 protection and the faulty unit stops

running. When the compressor current drops below protection current, the compressor enters re-start control.

When the module temperature rises above 100°C, the system displays PL protection and all the units stop running. When the module temperature drops below

70°C, the compressor enters re-start control.

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Part 3 - Control

Note:

1. T3: Air side heat exchanger refrigerant outlet temperature

Voltage ≥ 265V

or Voltage ≤ 170V

Voltage < 250V

or Voltage ≥ 180V

Normal operation

Compressor voltage protection, error code H5 is displayed

For normal cooling mode:

Min (Tw/Two/Twi/Taf2) ≤ 4°C for 5s

For low leaving water temperature

Min (Tw/Two/Twi/Taf2) ≤ -1°C for 5s

Any of the following satisfies then recover

°C before compressor runs(judged by

°C and compressor running time

Min(T5/Taf1) ≤ 4°C and compressor running time

≥30min(judged by master unit for single pump control; judged

Normal operation

Anti-freeze protection, error code Pb is displayed; unit runs heating mode

T3 > 62°C

T3 < 55°C

Normal operation

High temperature protection, error code P7 is displayed

6.5 Voltage Protection Control

This control protects the units from abnormally high or abnormally low voltages.

When the phase voltage of AC power supply is at or above 265V for more than 30 seconds, the system displays H5 protection

and the faulty unit stops running. When the phase voltage drops below 250V for more than 30 seconds, the unit restart once the

compressor re-start delay has elapsed. When the phase voltage is below 170V for more than 30 seconds, the system displays H5

protection and all the units stop running. When the AC voltage rises to at or above 180V for more than 30 seconds, the

refrigerant system restarts once the compressor re-start delay has elapsed.

6.6 DC Fan Motor Protection Control

This control protects the DC fan motors from abnormal power supply. DC fan motor protection occurs when the fan module does

not receive any feedback from the fan motor.

When DC fan motor protection control occurs the system displays the PU error code and the faulty unit stops running. When PU

protection occurs 10 times in 120 minutes, the FF error is displayed. When an FF error occurs, a manual system restart is

required before the system can resume operation.

6.7 Water Side Heat Exchanger Anti-freeze Protection Control

When water side heat exchanger anti-freeze protection occurs the system displays error code Pb and the unit enters

anti-freezing mode.

1. Min(Tw/Two/Twi/Taf2) ≥8

master unit)

cooling mode:

2. Min(Tw/Two/Twi/Taf2) ≥15

≥5min (judged by master unit)

3.

by each unit for multiple pumps control)

6.8 Air Side Heat Exchanger High Temperature Protection Control

This control protects the air side heat exchanger from high temperature.

When the air side heat exchanger refrigerant outlet temperature (T3) rises above 62°C, the system displays P7 protection and the

faulty unit stops running. When the air side heat exchanger refrigerant outlet temperature (T3) drops below 55°C, the

compressor enters re-start control.

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Midea Aqua thermal Service Manual

Notes:

1. Twi: Water side heat exchanger inlet temperature;

2. Two: Water side heat exchanger outlet temperature.

Notes:

1. Taf2: Water side heat exchanger anti-freezing temperature 2

∣Twi-Two∣≥ 10°C

∣Twi-Two∣≤ 6°C

Normal operation

Temperature difference protection, error code P9 is displayed

For normal cooling mode:

Normal operation

Low temperature protection, error code PE is displayed

0.5Mpa≤ Pe < 0.6Mpa for 30s

Or Pe < 0.5Mpa for 5s

Unit stops

Normal operation

Low pressure protection, error code PC is displayed

Pe < 0.4Mpa for 30s

Unit stops

Normal operation

Low pressure protection, error code PC is

6.9 Water Side Heat Exchanger Temperature Difference Protection Control

When the temperature difference rises at or above 10°C, the system displays P9 protection and the faulty unit stops running.

When the temperature difference drops below 6°C, the compressor enters re-start control.

6.10 Water Side Heat Exchanger Low Temperature Protection Control

This control protects the water side heat exchanger from ice formation.

Taf2 ≤ 3°C for 3s

For low leaving water temperature mode:

Taf2 ≤ -2°C for 3s

Taf2 > 10°C and unit stops time >3min

For low water outlet cooling mode:

Taf2 > 5°C and unit stops time >7min

6.11 Water Side Heat Exchanger Low Pressure Protection Control

This control protects the water side heat exchanger from ice formation.

 Normal cooling mode

In normal cooling mode, when 0.5Mpa≤ Pe < 0.6Mpa for 30s or Pe < 0.5Mpa for 5s, the system displays PC protection and the

faulty unit stops running. When the unit stop, the compressor enters re-start control.

 Low leaving water temperature mode

In low water temperature cooling mode, when the suction pressure drops below 0.4Mpa for 30s, the system displays PC

protection and the faulty unit stops running. When the unit stop, the compressor enters re-start control.

40

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Part 3 - Control

… …

1 2 8 9 16

Startup Startup Startup

Startup

… …

Running Running Running

Loading

… …

Offloading

Loading in sequence (from 9 to 16)

Offloading in sequence (from 16 to 1)

1 2 8 9 16

… …

16 15 9 8 1

Startup Startup Startup

Startup

… …

Running Running Running

Loading

… …

Offloading

Loading in sequence (from 8 to 1)

Offloading in sequence (from 1 to 16)

16 15 9 8 1

7 Special Control

7.1 Outdoor Unit Duty Cycling

In systems with multiple outdoor units, outdoor unit duty cycling is used to balance the compressor running time. Outdoor unit

duty cycling occurs whenever all the outdoor units stop running (either because the leaving water set temperature has been

reached or because a master unit error has occurred):

Take 16 units in parallel as an example:

 First cycle:

When the outdoor units are powered on for the first time, if there is a load requirement, 50% of the units turn on starting

with the 0# master unit to higher address slave units. As the leaving water temperature approaches its set temperature, units

shut down in succession, starting with the unit with the highest address.

 Second cycle:

The next time a load requirement exists (or following a master unit error), the units turn on starting with the highest

address unit to lower address units. As the leaving water temperature approaches its set temperature, units shut down in

succession, starting with the unit with the lowest address.

 Subsequent cycles will repeat the actions of the first and second cycles

Notes:

1. The address settings on the outdoor unit main PCBs for master unit and slave unit do not change.

41

Aqua thermal

Midea Aqua thermal Service Manual

Component

Wiring diagram

label

4-10kW

Control functions and states

Inverter compressor

COMP

●

Runs at defrosting operation rotation speed

DC fan motor

FAN

●

Off

Electronic expansion valve

EXV

●

Fully open

Four-way valve

4-WAY

●

Off

0# electric control box

“TEMP-SWITCH” port

Power (DC 12V)

Main control board is provided

0# electric control box

“TEMP-SWITCH” port

Power (DC 12V)

Main control board is provided

7.2 Defrosting Operation

In order to recover heating capacity, the defrosting operation is conducted when the outdoor unit air side heat exchanger is

performing as a condenser. The defrosting operation is controlled according to outdoor ambient temperature, air side heat

exchanger refrigerant temperature, water inlet temperature, compressor running time and defrosting time.

7.3 TEMP-SWITCH control

The function of “TEMP-SWITCH” must be set by wired controller for two target water temperature. For cooling and heating mode,

different water temperatures can be switched just by one-touch. The operation method is as follows:

 Setting: “USER MENU”——“DOUBLE SETPOINT”

 Wire connection: Shorting the terminal block CN110 at slave board (Refer to the Part 4, 3.1 Single unit) for

MC-SU75-RN8L-B and MC-SU140-RN8L-B.Connect a switch between 20 and 25 terminals of block XT2 (Refer to the Part 4,

3.1 Single unit) for MC-SU90-RN8L-B and MC-SU180-RN8L-B.If the switch is off, unit operates at first target water

temperature. If the switch is on unit operates at second target water temperature.

42

Aqua thermal

Part 4 - Diagnosis and Troubleshooting

Part 4

Diagnosis and

Troubleshooting

1 Electric Control Box Layout ....................................................................... 44

2 PCB Introduction ...................................................................................... 46

3 Wiring diagram ........................................................................................ 61

4 Error Code Table ....................................................................................... 68

5 Troubleshooting ....................................................................................... 70

6 Drive Module Failure .............................................................................. 141

7 Appendix ................................................................................................ 154

43

Aqua thermal

Midea Aqua thermal Service Manual

Compressor inverter module

PED board

Main power supply

wiring set

Expanding board

Main control board

AC filter board

Inductor

Fan module A

PED board A

Fan module B

PED board B

Main power supply

wiring set

Expanding board

Mian control board

AC Filter board A

Inductor A

Inductor B

AC Filter board B

Fan module board (Fan B)

Module components (Compressor + Fan A)

1 Electric Control Box Layout

For MC-SU75-RN8L-B

For MC-SU140-RN8L-B

44

Aqua thermal

Part 4 - Diagnosis and Troubleshooting

 Electric control box side view-upper layer

Main control board

AC filter board

Fan module A

Fan module B

Connection terminal

Power supply

 Electric control box side view-bottom layer

Compressor Inverter module A

Compressor Inverter module B

Reactor

PED board PED board

 Midea electric control side view

Power supply

For MC-SU90-RN8L-B and MC-SU180-RN8L-B

For MC-SU180-RN8L-B only

45

Aqua thermal

Midea Aqua thermal Service Manual

Label

Code

Port

Explanation

Voltage

1

CN32

POWER

Power supply port

220-240V

2

CN99

Expanding board power connector

220-240V

3

CN68

PUMP

Pump contactor control port (connected in factory)

220-240V

4

CN74/CN67

CCH

compressor heating belt

220-240V

1

2

3

4

5

6

7

8

9

10

11

1213

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

2 PCB Introduction

2.1 Types

Aqua thermal 75kW, 90kW and 140kW unit have one main control board, two compressor inverter module board, two DC fan

inverter module board and one filter board.

Aqua thermal 180kw unit have two main control board, four compressor inverter module board, four DC fan inverter module

board and two filter board.

2.2 Main PCB

Main PCB component

For MC-SU75-RN8L-B and MC-SU140-RN8L-B

46

Aqua thermal

Part 4 - Diagnosis and Troubleshooting

5

CN75/CN66

EVA-HEAT

Plate heat exchanger electric heating belt

220-240V

6

CN48

ST1

Four-way valve

220-240V

7

CN47

SV6

One-way solenoid valve

220-240V

8

CN49

SV5

One-way solenoid valve

220-240V

9

CN84

SV8A

One-way solenoid valve

220-240V

10

CN83

SV8B

One-way solenoid valve

220-240V

11

CN93

ALARM

Fault alarm port

/

12

CN65

USB

USB program burning port

DC5V

13

CN28

PH-PRO

Three-phase protector signal detection port

DC12V

14

CN22

XYE

External unit parallel connection communication port &

external unit and wired controller communication port

DC5V

15

CN46

Wired controller power supply port

DC12V

16

CN26

O-Motor

Module board PTC relay control port/Module board

communication port

DC12V/DC5V

17

CN300

DEBUG

Main control program burn port(WizPro200RS

programmer)

DC3.3V

18

CN33

MS

Expanding board communication port

DC12V/DC5V

19

CN41

Low pressure sensor

DC3.3V

20

CN40

High pressure sensor

DC3.3V

21

CN45

Taf2

Water side antifreeze temperature sensor

DC3.3V

22

CN37

T3A

Pipe temperature sensor of the condenser

DC3.3V

23

CN30

T4

Outdoor ambient temperature sensor

DC3.3V

24

CN16

T3B

Pipe temperature sensor of the condenser

DC3.3V

25

CN38

TP2

DC inverter compressor B discharge temperature sensor

DC3.3V

26

CN27

TP-PRO

Discharge temperature controller

DC3.3V

27

CN42

L-PRO

Low pressure switch

DC3.3V

28

CN8

T6A

Refrigerant inlet temperature of EVI plate heat exchanger

DC3.3V

T6B

Refrigerant outlet temperature of EVI plate heat

exchanger

DC3.3V

29

CN4

Twi

Unit water inlet temperature sensor

DC3.3V

Th

System suction temperature sensor

DC3.3V

Two

Unit water outlet temperature sensor

DC3.3V

Tz/7

Coil final outlet temperature sensor

DC3.3V

Tp1

DC inverter compressor A discharge temperature sensor

DC3.3V

30

CN72

EXVC

Electronic expansion valve A

DC12V

31

CN70

EXVA

Electronic expansion valve B

DC12V

32

CN71

EXVB

Electronic expansion valve C

DC12V

33

SW3

UP

Up button

DC3.3V

SW4

DOWM

Down button

DC3.3V

SW5

MENU

Menu button

DC3.3V

SW6

OK

Confirm button

DC3.3V

34

DSP1/DSP2

Digital tube

DC3.3V

35

ENC1

ADDRESS DIP switch

DC3.3V

36

S1

S1-1

O: normal control mode; 1: remote control mode

DC3.3V

S1-3

0: Single water pump control mode;

1: Multiple water pumps control mode

DC3.3V

47

Aqua thermal

Midea Aqua thermal Service Manual

37

S2

/

Reserve

DC3.3V

38

S3

S3-1

1 (Default)

DC3.3V

39

S4

Ability dial

MC-SU75-RN8L-B：0011；

MC-SU140-RN8L-B：0111

DC3.3V

45 46 47 1

44

43

42 41 40

39 38 37

36

35

34 33

2 3 4 5 6 7

8 9 10 11 12

13

14

15

16

17

32 31 30 29 28 27 26 25 24 23 22 21 20 19 18

Label

Code

Port

Voltage

1

CN30

Power supply port/ sequence detection port

400VAC

2

CN12

Quick oil return solenoid valve

230VAC

3

CN80

Injection solenoid valve of compressor system B

230VAC

4

CN47

Injection solenoid valve of compressor system A

230VAC

5

CN5

Water side heat exchanger heater

230VAC

6

CN40

Multi-function solenoid valve

230VAC

7

CN13

Electric of water side heat exchanger heater

230VAC

8

CN41

Liquid bypass solenoid valve

230VAC

9

CN42

Crankcase heater

230VAC

10

CN6

Four-way valve

230VAC

11

CN43

Crankcase heater

230VAC

12

CN4/CN11

Electric heater of water flow switch

230VAC

13

CN87

Three-way valve(For domestic hot water)

230VAC

14

CN86

Spray cooling valve

230VAC

15

CN25

Pump relay

230VAC

16

CN33

COMP-STATE

230VAC

17

CN26

Pipeline auxiliary Heater

230VAC

18

CN24

Alarm signal output

230VAC

For MC-SU90-RN8L-B and MC-SU180-RN8L-B

48

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Part 4 - Diagnosis and Troubleshooting

19

CN20

Discharge temperature switch

DC12V

20

CN71

System electronic expansion valve(For cooling)

DC12V

21

CN72

Electronic expansion valve(For EVI)

DC12V

22

CN70

System electronic expansion valve1

DC12V

23

CN60

Outdoor units communication or HMI communication port

DC5V

24

CN61

Outdoor units communication or HMI communication port

DC5V

25

CN64

Fan inverter module communication port

DC5V

26

CN65

Compressor inverter module communication port

DC5V

27

CN300

Program burn import (WizPro200RS programming device)

DC5V

28

IC10

EEPROM chip

DC5V

29

CN1

Temperature sensors input port.

T4: Outdoor ambient temperature sensor

T3A/T3B: Pipe temperature sensor of the condenser

T6A: Refrigerant inlet temperature of EVI plate heat exchanger

T6B: Refrigerant inlet temperature of EVI plate heat exchanger

DC5V

30

CN16

System pressure sensor

DC5V

31

CN31

Temperature sensors input port

Th: System suction temperature sensor

Taf2: Water side antifreeze temperature sensor

Two: Unit water outlet temperature sensor

Twi: Unit water inlet temperature sensor

Tw: Total water outlet temperature sensor when several units are connected in

parallel

DC5V

32

CN69

Temperature sensors input port

Tp1 :DC inverter compressor 1 discharge temperature sensor

Tp2:DC inverter compressor 2 discharge temperature sensor

Tz: Coil final outlet temperature sensor

DC5V

33

CN19

Low voltage protection switch

DC5V

34

CN91

Three-phase protector output switch

DC5V

35

CN58

Compressor driver ON/OFF port

DC12V

36

CN8

Remote function of cool/heat port

DC12V

37

CN8

Remote function of on/off port

DC12V

38

CN8

Water flow switch port

DC12V

39

SW3-SW6

SW3: Up button

a) Select different menus when enter menu selection.

b) For spot inspection in conditions.

SW4: Down button

a) Select different menus when enter menu selection.

b) For spot inspection in conditions.

SW5: Menu button

Press to enter menu selection, short press to return to the previous menu.

SW6: OK button

Enter the submenu or confirm the function selected by short pressing.

DC5V

40

USB

Program burn import (USB)

DC5V

41

DSP1/DSP2

Digital tube

1) In case of stand-by, the address of the module is displayed;

2) In case of normal operation, 10. is displayed (10 is followed by dot).

3) In case of fault or protection, fault code or protection code is displayed.

DC5V

42

S5

S5: Dip switch

DC5V

49

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Midea Aqua thermal Service Manual

S5-3: Normal control, valid for S5-3 OFF (factory default)

Remote control, valid for S5-3 ON.

43

CN7

Target water temperature switching port

DC12V

44

ENC2

Power DIP switch for capacity selection.

(MC-SU90-RN8L-B defaults 2; MC-SU180-RN8L-B defaults 6 )

DC5V

45

CN74

Power supply port of the HMI

DC9V

46

ENC4

NET_ADDRESS DIP switch (0~15)

DC5V

47

S12

S12: Dip switch

S12-1: Valid for S12-1 ON (factory default)

S12-2: Single water pump control, valid for S12-2 OFF (factory default)

Multiple water pumps control, valid for S12-2 ON。

DC5V

Switch

Description

ON

OFF

Default factory

setting

S1-1

Control mode

Remote control

Normal

control

OFF

S1-3

Water pump

Multiple water pumps

control

Single water

pump

control

OFF

S3-1

-

- - ON

S4

DIP switch for capacity selection

-

MC-SU75-RN8L-B:

0011

DIP switch for capacity selection

MC-SU140-RN8L-B:

0111

ENC1

0-F valid for unit address setting

on the DIP switches

0 indicates the master unit and 1-F

the auxiliary units

(parallel connection)

- - 0

0# electric control box “HEAT/COOL” port

COOL

Power (DC 12V)

Main control board is provided

0# electric control box “HEAT/COOL” port

HEAT

Power (DC 12V)

Main control board is provided

0# electric

control box

“TEMP-SWITCH” port

Power (DC 12V)

Main control board is provided

0# electric

control box

“TEMP-SWITCH” port

Power (DC 12V)

Main control board is provided

Main PCB field setting

Multiple pumps control: output pump signal on all units.

Single pump control: only the master unit output pump signal, no pump signal output on the slave units.

For MC-SU75-RN8L-B and MC-SU140-RN8L-B

Note:

1. Wiring of “HEAT/COOL” weak electric port

The remote function of “HEAT/COOL” must be set by DIP switch. The remote function “HEAT/COOL” is effective when S1-1or S5-3 is chosen ON, at the same time,

the wire controller is out of control.

Corresponding parallel connect the “HEAT/COOL” port of the main unit’s electric control box, then, connect the “ON/OFF” signal (provide by user) to the

“HEAT/COOL” port of main unit as follows.

Wiring method: Shorting the terminal block CN138 at slave board inside the electric control box to enable the remote function of “HEAT/COOL”.

2. Wiring of “TEMP-SWITCH” weak electric port

The function of “TEMP-SWITCH” must be set by wired controller for two setting water temperature. For cooling and heating mode.

Wiring method: Shorting the terminal block CN110 at slave board inside the electric control box to choose the target water temperature.

50

Aqua thermal

Part 4 - Diagnosis and Troubleshooting

0# electric

control box

“ON/OFF” port

ON

Power (DC 12V)

Main control board is provided

0# electric

control box

“ON/OFF” port

OFF

Power (DC 12V)

Main control board is provided

0# electric

control box “HEAT/COOL” port

COOL

Power (DC 12V)

Main control board is provided

0# electric

control box “HEAT/COOL” port

HEAT

Power (DC 12V)

Main control board is provided

Switch

Description

ON

OFF

Default factory setting

S5

S5-3

Control mode

Remote control

Normal

control

OFF

S12

S12-1

Default setting

-

ON

S12-2

Water pump

Multiple pumps

control

Single pump

control

OFF

ENC2

DIP switch for capacity selection

-

MC-SU90-RN8L-B ：2 MC-SU180-RN8L-B：

6

ENC4

Address setting

0: master unit

1,2,3…F: slave units

-

MC-SU90-RN8L-B: 0

MC-SU180-RN8L-B: 0

and 1

Outdoor unit state

Parameters displayed on DSP1

Parameters displayed on DSP2

Standby 0 1

Normal operation

Running speed of compressor A in

rotations per second

Running speed of compressor B in

rotations per second

Error or protection

-- or placeholder

Error or protection code

Outdoor unit state

Master parameters displayed

Slave parameters displayed

DSP1

DSP2

DSP1

DSP2

Standby

Address

Online number

Address

No display

Normal operation

Running speed

of compressor

A in rotations

per second

Running speed of

compressor B in

rotations

per second

Running speed of

compressor A in

rotations

per second

Running speed of

compressor B in

rotations

per second

Error or protection

-- or placeholder

Error or protection code

DSP1

DSP2

For MC-SU90-RN8L-B and MC-SU180-RN8L-B

Note: When using remote control function, first is to dial the S5-3 switch to ON. The operation method is as below:

1. Remote ON/OFF: Connect a switch between 15 and 24 terminals of block XT2 (Refer to the Part 4, 3.1 Single unit) which can be turned on/off at any time. If the switch is closed, unit turns on. If the switch is open, unit turns off.

2. Remote cool/heat: Connect a switch between 14 and 23 terminals of block XT2 (Refer to the Part 4, 3.1 Single unit) which can change operation mode at any time. If the switch is closed, unit runs in heating mode. If the switch is open, unit runs in cooling mode.

Digital display output

For MC-SU75-RN8L-B, MC-SU90-RN8L-B and MC-SU140-RN8L-B:

For MC-SU180-RN8L-B:

51

Aqua thermal

Midea Aqua thermal Service Manual

Serial

number

Contents of spot check

0

Standby: host address (left 88) + number of online units (right 88),

Power-on: display frequency

Defrosting: dFdF

1

0.xx

Host address

2

1.xx

Number of external units (e.g. 75/140kW respectively display 75/140.)

3

2.xx

Number of online units (Host valid)

4

3.xx

T4 capacity correction (reserved display "1")

5

4.xx

Operation mode (8 shutdown, 1 cooling, 2 heating, 4 hot water)

6

5.xx

Fan gear (0 – 35)

7

6.xx

Fan gear (reserved display "0")

8

7.xx

T3 (min)

9

8.xx

T4

10

9.xx

Outlet water temperature of T5 water tank

11

10.xx

Taf1

12

11.xx

Taf2

13

12.xx

Tw total outlet water temperature of the unit

14

13.xx

Twi inlet water temperature of the unit

15

14.xx

Two outlet water temperature of the unit

16

15.xx

Tz Temperature of refrigerant liquid pipe at plate changing side

17

16.xx

THeatR heat recovery sensor temperature (reserved display "--")

18

17.xx

Discharge temperature 1

19

18.xx

Discharge temperature 2

20

19.xx

Radiation fin temperature 1

21

20.xx

Radiation fin temperature 2

22

21.xx

Discharge superheat temperature Tdsh

23

22.xx

Compressor A current

24

23.xx

Compressor B current

25

24.xx

--

26

25.xx

Electronic expansion valve A open degree (percent, maximum 100%)

27

26.xx

Electronic expansion valve B open degree (percent, maximum 100%)

28

27.xx

Electronic expansion valve C open degree (percent, maximum 100%)

29

28.xx

High pressure (heating mode)

30

L.xx

Low pressure (with decimal display-display during cooling or standby)

31

30.xx

Refrigeration suction superheat temperature Tssh

32

31.xx

Th suction temperature

33

32.xx

First nixie tube on the right: silent mode selection (0: night silent mode; 1: silent mode; 2:

super silent mode; 3: no silent mode (default))

The second nixie tube on the right: the value of silent mode time selection (0-3) depends on

the parameters of the wired controller

34

33.xx

Static pressure selection (0 static pressure is reserved by default)

35

34.xx

DC voltage A (reserved)

36

35.xx

DC voltage B (reserved)

37

36.xx

Frequency limiting serial number (reserved) (0: infinite frequency; 1: T4 frequency limiting; 2:

Spot Check Description

The spot check sequence is shown as follows:

52

Aqua thermal

Part 4 - Diagnosis and Troubleshooting

Tp exhaust frequency limiting; 3: Tz total cooling output frequency limiting; 4: Tf module

temperature frequency limiting; 5: Two water output frequency limiting 6: Pressure

frequency limiting, 7: Current frequency limiting, 8: Voltage frequency limiting

38

37.xx

Defrosting process status (the first digit: T4 selection scheme; the second digit: interval in the

scheme; the third and fourth digits together represent defrosting timing time)

39

38.xx

Fault of Party E: 1 indicates fault, 0 indicates no fault (reserved 90kw is valid)

40

39.xx

Defrosting scheme

41

40.xx

Initial frequency

42

41.xx

Tc (saturation temperature corresponding to high pressure) spot check value + 30

43

42.xx

Te (saturation temperature corresponding to low pressure) spot check value + 30

44

43.xx

T6a

45

44.xx

T6b

46

45.xx

Version number of main control software

47

46.xx

The last

failure

48

47.xx

----

Note: Need to perform spot check operation on the online controller.

53

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Midea Aqua thermal Service Manual

Label

Code

Port

Explanation

Voltage

1

CN1

P-in

Reactor output port

2

CN5

P-out

Reactor input port

3

CN16

L1

Power supply for module board

380-415V

4

CN7

L2 5 CN15

L3 6 CN17

U

Compressor output

7

CN18

V

8

CN19 W 9

CN21

H-SW

High pressure switch

10

S7

module address setting

system A: 00; system B: 01

11

CN27-1

PED board connection port

DC12V/DC5V

12

CN27-2

PED board connection port

DC12V/DC5V

13

CN25

DEBUG

Driver burn port (WizPro200RS programmer)

DC5V

14

CN8

O-Motor

Module Board PTC Relay Control Port/Module Board

Communication Port

DC12V/DC5V

15

CN9

O-Motor

Module Board PTC Relay Control Port/Module Board

Communication Port

DC12V/DC5V

16

CN3

UVW

Fan output port

17

CN26

Fan control power supply output port

DC19V

18

CN39

P N

Fan power supply output port

DC565V

1

2

3

4

16

14

15

5

17

7

6

8

9

10

11 12

13

18

2.3 Compressor Inverter Module Board

Compressor Inverter Module PCB component

For MC-SU75-RN8L-B and MC-SU140-RN8L-B

54

Aqua thermal

Part 4 - Diagnosis and Troubleshooting

1

2

3

4

5

18

17

16

15

14

13

12

11

10

6 7 8 9

Label

Code

Port

Voltage

1

CN1

Reactor output port

DC565V

2

CN6

Three-phase power supply in (L1)

400VAC

3

CN5

Reactor input port

DC565V

4

CN7

Three-phase power supply in (L2)

400VAC

5

CN11

Three-phase power supply in (L3)

400VAC

6

CN12

Compressor connection port U

VUV=VUW=VVW

0-380V AC

7

CN13

Compressor connection port V

8

CN14

Compressor connection port W

9

CN20

Power supply for fan module

DC20V

10

S7

Address DIP switch

DC5V

11

CN3

Power supply for compressor board

AC230

12

CN2

Power supply for compressor board

13

CN23

High pressure switch connection port

DC12V

14

CN22

PED board

DC12V

15

CN9

Compressor board communication port

DC5V

For MC-SU90-RN8L-B and MC-SU180-RN8L-B:

55

Aqua thermal

Midea Aqua thermal Service Manual

16

CN8

Compressor board communication port

DC5V

17

CN38

Power supply for fan module board

DC565V

18

IC25

EEPROM

DC5V

Switch

Description

S7-1

S7-2

S7

Compressor A inverter module address setting

OFF

Compressor B inverter module address setting

OFF

ON

Compressor Inverter Module PCB field setting

56

Aqua thermal

Part 4 - Diagnosis and Troubleshooting

Label

Code

Port

Explanation

Voltage

1

CN6

Fan module control power supply input port

DC19V

2

CN12

Reserve

3

SW1

Fan module address setting

4

CN1/CN4

Fan module communication port

DC5V 5 CN9

DEBUG

Program burn port (WizPro200RS programmer)

DC5V

6

CN7

P N

Fan module power supply port

DC565V

7

CN3

UVW

Fan output port

1

2

4

3

4

7

6

5

1

2

3

4

5

6

7

8

9

2.4 Fan Module Board

Fan Module Board component

For MC-SU75-RN8L-B and MC-SU140-RN8L-B

For MC-SU90-RN8L-B and MC-SU180-RN8L-B

57

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Midea Aqua thermal Service Manual

Label

Code

Port

Voltage

1

CN6

Power supply port

DC20V

2

CN5

Power supply port

DC20V

3

SW1

Address DIP switch

DC5V

4

CN2

Program input port

DC5V

5

CN1

Fan module board communication port

DC5V

6

CN4

Fan module board communication port

DC5V

7

CN7

DC bus voltage N

DC565V

8

CN8

DC bus voltage P

DC565V

9

CN3

Fan output port U/V/W

AC 0~380V

Switch

Description

S1-1

S1-2

S1

Fan A inverter module address setting

OFF

Fan B inverter module address setting

OFF

ON

Label

Code

Port

Explanation

Voltage

1

CN1

L1

Input port L1

380-415V

2

CN2

L2

Input port L2

3

CN3

L3

Input port L3

4

CN4

N

Input port N

5

CN11

Power supply port for main PCB

6

CN12

Port for three phase protector (reserve)

380-415V

7

CN7

L3’

Output port L3

380-415V

8

CN6

L2'

Output port L2

9

CN5

L1'

Output port L1

10

CN16

Three phase water pump power supply

port (reserve)

380-415V

1

2

3

4 5

6

7

8

9

10

Fan Module PCB field setting

2.5 AC Filter Board

For MC-SU75-RN8L-B and MC-SU140-RN8L-B

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Part 4 - Diagnosis and Troubleshooting

Label

Code

Port

Voltage

1

CN4

Input port N

400VAC

2

CN3

Input port L3

400VAC

3

CN2

Input port L2

400VAC

4

CN1

Input port L1

400VAC

5

CN30

Relay driver signal for compressor from main PCB

DC12V

6

CN36

Power supply for compressor inverter module

230VAC

7

CN13

Power supply port for main PCB/Three phase sequence

detection port

230VAC

8

CN34

Power supply for three phase water pump

400VAC

9

CN32

Port for three phase protector

400VAC

10

CN9

Output port L1’

400VAC

11

CN10

Output port L2’

400VAC

12

CN11

Output port L3’

400VAC

13

CN13

Output port N

400VAC

14

CN51

Ground screw hole

/

15

CN50

Ground screw hole

/

4

3

2

1

5

6

7

8

9

10

11

12

13

2

1

2

1

For MC-SU90-RN8L-B and MC-SU180-RN8L-B

2.6 PED Board

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Label

Code

Port

Explanation

Voltage

1

CN26

/

For connecting compressor module board

/ 2 CN27

/

For connecting compressor module board

/

Label

Code

Port

Explanation

Voltage

1

CN140

POWER

Slave PCB board strong power supply

220-240V

2

CN115

W-HEAT

Water pipe electric heating belt

220-240V

3

CN125

3-way valve

Three-way valve for making hot water (used for customized hot

water models)

220-240V

4

CN123

PUMP

Port for water pump contactor control (for market installation)

220-240V

5

CN121

COMP-STATE

Compressor Status Indication

/

6

CN119

HEAT1

Pipe auxiliary motor heating belt

/

7

CN108

PUMP-V

Frequency conversion pump 0-10V control signal

DC 0-10V

8

CN110

W.P-SW

Water pressure difference switch

DC12V

TEMP-SW

Target water temperature switch

DC12V

9

CN138

COOl/HEAT

Remote mode control

DC12V

ON/OFF

Remote switch control

DC12V

10

CN114

WATER-SWITCH

Water flow switch

DC12V

11

CN105

Taf1

Water tank anti-freeze sensor

DC3.3V

12

CN101

TW

Total water sensor

DC3.3V

13

CN103

T5

Water tank sensor

DC3.3V

14

CN300

DEBUG

Main control program burn port (WizPro200RS programmer)

DC3.3V

15

CN109

MS

Communication port of slave PCB board and main PCB board

DC12V/DC3.3V

1

3

4

5

6

7

89

10

12

13

14

15

2.7 Slave PCB Board

For MC-SU75-RN8L-B and MC-SU140-RN8L-B only:

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Part 4 - Diagnosis and Troubleshooting

3 Wiring diagram

3.1 Single unit

For MC-SU75-RN8L-B and MC-SU140-RN8L-B

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For MC-SU90-RN8L-B:

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For MC-SU180-RN8L-B:

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3.2 Multiple units

For MC-SU75-RN8L-B:

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Part 4 - Diagnosis and Troubleshooting

For MC-SU90-RN8L-B:

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For MC-SU140-RN8L-B:

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Part 4 - Diagnosis and Troubleshooting

7

MONITOR

WIRECONTROLLER

MONITOR

WIRECONTROLLER

7

MAIN CONTROL

WIRECONTROLLER

MAIN CONTROL

WIRECONTROLLER

For MC-SU180-RN8L-B:

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Code

Content

Remarks

E0

Main control EPROM error

Displayed on main PCB and user interface

E1

Phase sequence failure of main control board check

Displayed on main PCB and user interface

E2

Main control and wired control transmission error

Displayed on main PCB and user interface Communication failure between master and slave

E3

Total water outlet temperature sensor error (valid for the main unit)

Displayed on main PCB and user interface

E4

Unit water outlet temperature sensor error

Displayed on main PCB and user interface

E5

1E5 Condenser tube temperature sensor T3A error

Displayed on main PCB and user interface 2E5 Condenser tube temperature sensor T3B error

E6

Water tank temperature sensor T5 error

Displayed on main PCB and user interface

E7

Ambient temperature sensor error

Displayed on main PCB and user interface

E8

Power supply phase sequence protector output error

Displayed on main PCB and user interface

E9

Water flow detection error

Displayed on main PCB and user interface

Eb

1Eb: Taf1 the pipe of hot water side antifreeze protection sensor error

Displayed on main PCB and user interface

2Eb: Taf2 cooling evaporator low-temperature antifreeze protection sensor error

Displayed on main PCB and user interface

EC

Slave unit module reduction

Displayed on main PCB and user interface

Ed

System discharge temperature sensor error

Displayed on main PCB and user interface

EE

1EE EVI plate heat exchanger refrigerant temperature T6A sensor error

Displayed on main PCB and user interface

2EE EVI plate heat exchanger refrigerant temperature T6B sensor error

Displayed on main PCB and user interface

EF

Unit water return temperature sensor error

Displayed on main PCB and user interface

EH

System self-check error alarm (for MC-SU90-RN8L-B and MC-SU180-RN8L-B)

Displayed on main PCB and user interface

EP

Discharge sensor error alarm

Displayed on main PCB and user interface

EU

Tz sensor error

Displayed on main PCB and user interface

P0

P0 System high-pressure protection or discharge temperature protection

Displayed on main PCB and user interface

1P0 Compressor module 1 high pressure protection

Displayed on main PCB and user interface

2P0 Compressor module 2 high pressure protection

Displayed on main PCB and user interface

P1

System low pressure protection

Displayed on main PCB and user interface

P2

Tz total cold outlet temperature too high (for MC-SU90-RN8L-B and

MC-SU180-RN8L-B)

Displayed on main PCB and user interface

P3

T4 ambient temperature too high in cooling mode

Displayed on main PCB and user interface

P4

1P4 System A current protection

Displayed on main PCB and user interface

2P4 System A DC bus current protection

Displayed on main PCB and user interface

P5

1P5 System B current protection

Displayed on main PCB and user interface

2P5 System B DC bus current protection

Displayed on main PCB and user interface

P6

Inverter module failure (for MC-SU90-RN8L-B and MC-SU180-RN8L-B)

Displayed on main PCB and user interface

P7

High temperature protection of system condenser

Displayed on main PCB and user interface

P9

Water inlet and outlet temperature difference protection

Displayed on main PCB and user interface

PA

Abnormal water inlet and outlet temperature difference protection

Displayed on main PCB and user interface

Pb

Winter antifreeze protection

Displayed on main PCB and user interface

PC

Cooling evaporator pressure too low

Displayed on main PCB and user interface

PE

Cooling evaporator low temperature antifreeze protection

Displayed on main PCB and user interface

PH

Heating T4 too high temperature protection

Displayed on main PCB and user interface

PL

Tfin module too high temperature protection

Displayed on main PCB and user interface

4 Error Code Table

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Code

Content

Remarks

PU

1PU DC fan A module protection

Displayed on main PCB and user interface

2PU DC fan B module protection

Displayed on main PCB and user interface

H9

1H9 Compressor A inverter module is not matched

Displayed on main PCB and user interface

2H9 Compressor A inverter module is not matched

Displayed on main PCB and user interface

HC

High pressure sensor error

Displayed on main PCB and user interface

HE

1HE No inset A valve error

Displayed on main PCB and user interface

2HE No inset B valve error

Displayed on main PCB and user interface

3HE No inset C valve error

Displayed on main PCB and user interface

F0

1FO IPM module A transmission error

Displayed on main PCB and user interface

2FO IPM module B transmission error

Displayed on main PCB and user interface

F2

Superheat insufficient

Displayed on main PCB and user interface

F4

1F4 module A L0 or L1 protection occurs for 3 times in 60 minutes

Displayed on main PCB and user interface

2F4 module B L0 or L1 protection occurs for 3 times in 60 minutes

Displayed on main PCB and user interface

F6

1F6 A system buss voltage error (PTC)

Displayed on main PCB and user interface

2F6 B system buss voltage error (PTC)

Displayed on main PCB and user interface

Fb

Pressure sensor error

Displayed on main PCB and user interface

Fd

Suction temperature sensor error

Displayed on main PCB and user interface

FF

1FF DC fan A error

Displayed on main PCB and user interface

2FF DC fan B error

Displayed on main PCB and user interface

FP

DIP switch inconsistency of multiple water pumps

Displayed on main PCB and user interface

C7

If PL occurs 3 times, the system reports the C7 failure

Displayed on main PCB and user interface

L0

Compressor inverter module protection (x=1or2) (for MC-SU90-RN8L-B and

MC-SU180-RN8L-B)

Displayed on main PCB

L1

Low-voltage protection (x=1or2) (for MC-SU90-RN8L-B and MC-SU180-RN8L-B)

Displayed on main PCB

L2

High-voltage protection (x=1or2) (for MC-SU90-RN8L-B and MC-SU180-RN8L-B)

Displayed on main PCB

L4

MCE error (x=1or2) (for MC-SU90-RN8L-B and MC-SU180-RN8L-B)

Displayed on main PCB

L5

Zero speed protection (x=1or2) (for MC-SU90-RN8L-B and MC-SU180-RN8L-B)

Displayed on main PCB

L7

Phase sequence error (x=1or2) (for MC-SU90-RN8L-B and MC-SU180-RN8L-B)

Displayed on main PCB

L8

Compressor frequency variation greater than 15Hz within one second protection

(for MC-SU90-RN8L-B and MC-SU180-RN8L-B)

Displayed on main PCB

L9

Actual compressor frequency differs from target frequency by more than 15Hz

protection (for MC-SU90-RN8L-B and MC-SU180-RN8L-B)

Displayed on main PCB

dF

Defrosting prompt (for MC-SU90-RN8L-B and MC-SU180-RN8L-B)

Displayed on main PCB and user interface

bH

1bH Module 1 relay blocking or 908 chip self-check failed

Displayed on main PCB and user interface

2bH Module 2 relay blocking or 908 chip self-check failed

Displayed on main PCB and user interface

Continued:

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 All electrical work must be carried out by competent and suitably qualified, certified and accredited professionals and

in accordance with all applicable legislation (all national, local and other laws, standards, codes, rules, regulations and

Power-off the outdoor units before connecting or disconnecting any connections or wiring, otherwise electric shock

Warning

5 Troubleshooting

5.1 Warning

other legislation that apply in a given situation).



(which can cause physical injury or death) may occur or damage to components may occur.

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Part 4 - Diagnosis and Troubleshooting

5.2 E0/H9 Troubleshooting

Digital display output

Description

For MC-SU75-RN8L-B and MC-SU140-RN8L-B

 E0 indicates that the capability dialing code of the main PCB is inconsistent with the actual model.

 1H9 indicates that the driving model of IPM inverter module (compressor A) does not match.

 2H9 indicates that the driving model of IPM inverter module (compressor B) does not match.

 The faulty unit stops running.

 Error code is displayed on main PCB and user interface...d user interface.

For MC-SU90-RN8L-B and MC-SU180-RN8L-B

 E0 indicates main PCB EEPROM error.

 1H9 indicates IPM inverter module (compressor A) EEPROM error.

 2H9 indicates IPM inverter module (compressor B) EEPROM error.

 The faulty unit stops running.

 Error code is displayed on main PCB and user interface...d user interface.

Possible causes

For MC-SU75-RN8L-B and MC-SU140-RN8L-B

 The dialing code of main PCB capability is error.

 The address dialing code of the IPM inverter module PCB is error.

 Main PCB or IPM inverter module damaged.

For MC-SU90-RN8L-B and MC-SU180-RN8L-B

 Main PCB or IPM inverter module EEPROM is not connected properly.

 Main PCB or IPM inverter module damaged.

 EEPROM damaged.

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No

E0/H9

Main PCB or IPM inverter module PCB

dialing code 1 is not correct

Yes

Ensure the dialing code is correct

E0/H9

Main PCB or IPM inverter module EEPROM1

is not connected properly

Yes

Ensure the EEPROM is connected properly

No

EEPROM damaged

Yes

Replace the EEPROM

No

Replace Main PCB or IPM inverter module

PCB

Replace Main PCB or IPM inverter module

PCB

Procedure

For MC-SU75-RN8L-B and MC-SU140-RN8L-B

Notes:

1. Main PCB capability dialing code is designated S4 on the main PCBs (labeled 39 in Part 4, 2.2.1 Main PCB component);

2. Compressor inverter module PCB address dialing code is designated S7 on compressor inverter module PCB.

For MC-SU90-RN8L-B and MC-SU180-RN8L-B

Notes:

1. Main PCB EEPROM is designated IC10 on the main PCBs (labeled 28 in Part 4, 2.2.1 Main PCB component);

2. Compressor inverter module PCB EEPROM is designated IC25 on compressor inverter module PCB (labeled 18 in Part 4, 2.3.1 Compressor Inverter Module PCB component).

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5.3 E1 Troubleshooting

Digital display output

Description

 Phase sequence error.

 The faulty unit stops running.

 Error code is displayed on main PCB and user interface.

Possible causes

 Power supply phases not connected in correct sequence.

 Power supply terminals loose.

 Power supply abnormal.

 Main PCB damaged.

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E1

The phase sequence of the 3-phase power

supply is incrorrect1

Yes

Exchange any two of the 3 phase wires

No

Some power supply terminals are loose2

Yes

Ensure all supply terminals are securely

fastened

No

The power supply is abnormal

Yes

Check the power supply equipment

No

Replace refrigerant system main PCB

Procedure

Notes:

1. The A, B, C terminals of 3-phase power supply should match compressor phase sequence requirements. If the phase sequence is inverted, the compressor will operate inversely. If the wiring connection of each outdoor unit is in A, B, C phase sequence, and multiple units are connected, the current difference between C phase and A, B phases will be very large as the power supply load of each outdoor unit will be on C phase. This can easily lead to tripped circuits and terminal wiring burnout. Therefore if multiple units are to be used, the phase sequence should be staggered, so that the current is distributed among the three phases equally.

2. Loose power supply terminals can cause the compressor to operate abnormally and compressor current to be very large.

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Part 4 - Diagnosis and Troubleshooting

5.4 E2 Troubleshooting

Digital display output

Description

 Communication error between outdoor unit and user interface.

 Communication failure between master and slave units

 When this error occurs in the main unit, all units stop running. When this error occurs in the slave unit, the slave unit

stops running.

 Error code is displayed on main PCB and user interface.

Possible causes

 Communication wires between outdoor unit and user interface not connected properly.

 For MC-SU90-RN8L-B, Communication wiring P Q E terminals misconnected. For MC-SU75-RN8L-B, MC-SU140-RN8L-B

MC-SU180-RN8L-B, Communication wiring X Y E terminals misconnected

 Wiring connection is loosen

 Interference from high voltage wires or other sources of electromagnetic radiation.

 Communication wire too long.

 Damaged main PCB, user interface or electric control box communication terminals block.

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E2

Communication wires P Q E have short

circuited, disconnected or are

misconnected1

Yes

Reconnect the communication wires

No

Communication wires P Q E are not

connected in a daisy chain

Yes

Connect the communication wires in a

daisy chain

No

Wires between outdoor main PCB and

electric control box communication

terminals block are loose

Yes

Ensure the wires are connected properly

No

Interference from high voltage (220V or

higher) wires

Yes

Ensure the communication wires and high

voltage wires are separated

No

Communication wires are close to a source

of electromagnetic radiation such as

transformer or strong fluorescent lamp

Yes

Remove the source of interference, or add

additional shielding to the communication

wires

No

Damaged control box communication

terminals block

Yes

Replacing electric control box

communication terminals block resolves

the error

No

The length of communication wire is over

1200m

Yes

Reduce the wire length to less than

1200mm or strengthen the signal

No

Replace main PCB or user interface

Procedure

For MC-SU90-RN8L-B:

Notes:

1. Measure the resistance among P, Q and E. The normal resistance between P and Q is 120Ω, between P and E is infinite, between Q and E is infinite. Communication wiring has polarity. Ensure that the P wire is connected to P terminals and the Q wire is connected to Q terminals.

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E2

Communication wires X Y E have short

circuited, disconnected or are

misconnected1

Yes

Reconnect the communication wires

No

Communication wires X Y E are not

connected in a daisy chain

Yes

Connect the communication wires in a

daisy chain

No

Wires between outdoor main PCB and

electric control box communication

terminals block are loose

Yes

Ensure the wires are connected properly

No

Interference from high voltage (220V or

higher) wires

Yes

Ensure the communication wires and high

voltage wires are separated

No

Communication wires are close to a source

of electromagnetic radiation such as

transformer or strong fluorescent lamp

Yes

Remove the source of interference, or add

additional shielding to the communication

wires

No

Damaged control box communication

terminals block

Yes

Replacing electric control box

communication terminals block resolves

the error

No

The length of communication wire is over

1200m

Yes

Reduce the wire length to less than

1200mm or strengthen the signal

No

Replace main PCB or user interface

For MC-SU75-RN8L-B, MC-SU140-RN8L-B and MC-SU180-RN8L-B:

Notes:

1. Measure the resistance among X, Y and E. The normal resistance between X and Y is 120Ω, between X and E is infinite, between Y and E is infinite. Communication wiring has polarity. Ensure that the P wire is connected to P terminals and the Q wire is connected to Q terminals.

2. Check whether the communication wires X, Y and E between units have disconnected or are misconnected.

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5.5 E3, E4, E5, E7, Eb, Ed, EE, EF, EP, EU, Fb, Fd Troubleshooting

Digital display output

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Part 4 - Diagnosis and Troubleshooting

Description

For MC-SU75-RN8L-B and MC-SU140-RN8L-B

 E3 indicates total water outlet temperature sensor error (valid for the main unit)

 E4 unit water outlet temperature sensor error

 1E5 indicates condenser tube temperature sensor T3A error

 2E5 indicates condenser tube temperature sensor T3B error

 E6 Water tank temperature sensor T5 failure

 E7 indicates ambient temperature sensor error

 1Eb indicates pipe of the tank antifreeze protection sensor Taf1 error

 2Eb indicates cooling evaporator low-temperature antifreeze protection sensor Taf2 error

 Ed indicates discharge pipe temperature sensors Tp1 and Tp2 error at the same time

 1EE indicates EVI plate heat exchanger refrigerant temperature sensor T6A error

 2EE indicates EVI plate heat exchanger refrigerant temperature sensor T6B error

 EF indicates unit water return temperature sensor error

 EP indicates discharge temperature sensor failure error

 EU indicates water side heat exchanger refrigerant total outlet temperature sensor Tz error in heating mode.

 Fb indicates Low pressure sensor error.

 Fd indicates suction temperature sensor Th error.

 All stop running.

 Error code is displayed on main PCB and user interface.

For MC-SU90-RN8L-B and MC-SU180-RN8L-B

 E3 indicates total water outlet temperature sensor error (valid for the main unit)

 E4 unit water outlet temperature sensor error

 1E5 indicates condenser tube temperature sensor T3A error

 2E5 indicates condenser tube temperature sensor T3B error

 E7 indicates ambient temperature sensor error

 1Eb indicates pipe of the tank antifreeze protection sensor Taf1 error

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No

Yes

E3 / E4 / E5 / E6 /E7 / Eb / Ed /EE/ EF / EP

/ EU / Fb / Fd

Sensor connection on main PCB or slave

PCB is loose

Yes

Ensure the sensor is connected properly

No

Sensor has short-circuited or failed2

Yes

Replace the sensor

No

Replace main PCB or expansion PCB

If the fault is EP, it is also necessary to

confirm whether the exhaust sensor on

the top of the compressor has fallen

Confirm whether the exhaust sensor on

the top of the compressor has fallen

 2Eb indicates cooling evaporator low-temperature antifreeze protection sensor Taf2 error

 Ed indicates discharge pipe temperature sensors Tp1 and Tp2A error at the same time

 1EE indicates EVI plate heat exchanger refrigerant temperature sensor T6A error

 2EE indicates EVI plate heat exchanger refrigerant temperature sensor T6B error

 EF indicates unit water return temperature sensor error

 EP indicates discharge temperature sensor failure error

 EU indicates air side heat exchanger refrigerant total outlet temperature sensor Tz error.

 Fb indicates pressure sensor error.

 Fd indicates suction temperature sensor Th error.

 All stop running.

 Error code is displayed on main PCB and user interface.

Possible causes

 Sensor not connected properly or has malfunctioned.

 Damaged main PCB.

Procedure

For MC-SU75-RN8L-B and MC-SU140-RN8L-B

Notes:

1. Most sensors are connected to ports CN4 (E4), CN37 (1E5), CN16 (2E5), CN30 (E7), CN45 (2Eb), CN4 and CN38 (Ed), CN8 (EE), CN4 (EF), CN4 and CN38 (EP), CN4 (EU), CN41 (Fb), CN4 (Fd) on the main PCB (labeled 29, 22, 24, 23, 21, 25, 28, 19 in Part 4, 2.2.1 Main PCB component), A few sensors are connected to ports CN101 (E3), CN103 (E6), CN105 (1Eb) on the slave PCB (labeled 14,15,13 in Part 4, 2.7 Slave PCB component).

2. Measure sensor resistance. If the resistance is too low, the sensor has short-circuited. If the resistance is not consistent with the sensor’s resistance characteristics table, the sensor has failed. Refer to Part 4, 6.1 “Temperature Sensor Resistance Characteristics”.

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E3 / E4 / E5 / E7 / Eb / Ed /EE/ EF / EP / EU

/ Fb / Fd

Sensor connection on main PCB is loose

Yes

Ensure the sensor is connected properly

No

Sensor has short-circuited or failed2

Yes

Replace the sensor

No

Replace main PCB

For MC-SU90-RN8L-B and MC-SU180-RN8L-B

Notes:

1. All the sensors are connected to port CN1, CN16, CN31, CN3, CN10 and CN69 on the main PCB (labeled 29, 30, 31, 32 in Part 4, 2.2.1 Main PCB component).

2. Measure sensor resistance. If the resistance is too low, the sensor has short-circuited. If the resistance is not consistent with the sensor’s resistance characteristics table, the sensor has failed. Refer to Part 4, 6.1 “Temperature Sensor Resistance Characteristics”.

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5.6 E8 Troubleshooting

Digital display output

Description

 Power supply phase sequence protector output error

 When this error occurs in the main unit, all units stop running. When this error occurs in the slave unit, the slave unit stops

running.

 Error code is displayed on main PCB and user interface.

Possible causes

 Power supply phases not connected in correct sequence or lose.

 Power supply terminals or Power phase protector wire connection loose.

 Power supply abnormal.

 Damaged main PCB.

 Damaged power phase protector.

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E8

The phase sequence of the 3-phase power

supply is incrorrect1

Yes

Exchange any two of the 3 phase wires

No

Power supply phases lose2

Yes

Ensure all power supply phases is complete

No

Some power supply terminals are loose3

Yes

Ensure all supply terminals are securely

fastened

No

The power supply is abnormal4

Yes

Check the power supply equipment

No

Power phase protector wire connection

loose5

Yes

Check the wire connection of Power phase

protector

No

Replace power phase protector

Yes

Error code disappear

No

Replace Main PCB

Procedure

Notes:

1. The red LED on the power phase protector will on.

2. The red LED on the power phase protector will flash with 1HZ.

3. The A, B, C terminals of 3-phase power supply should match compressor phase sequence requirements. If the phase sequence is inverted, the compressor

will operate inversely. If the wiring connection of each outdoor unit is in A, B, C phase sequence, and multiple units are connected, the current difference between C phase and A, B phases will be very large as the power supply load of each outdoor unit will be on C phase. This can easily lead to tripped circuits and terminal wiring burnout. Therefore if multiple units are to be used, the phase sequence should be staggered, so that the current is distributed among the three phases equally.

4. The red LED on the power phase protector will flash with 3HZ. Loose power supply terminals can cause the compressor to operate abnormally and

compressor current to be very large.

5. For MC-SU75-RN8L-B and MC-SU140-RN8L-B, wire connected to port CN28 on the main PCB. For MC-SU90-RN8L-B and MC-SU180-RN8L-B, wire connected

to port CN91 on the main PCB. (labeled 34 in Part 4, 2.2.1 Main PCB component)

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E9

Water flow switch connection on main PCB

is loose1

Yes

Ensure the switch is connected properly

No

Water flow is insufficient

Yes

Check the water piping and valves. Make

sure the water piping is clean, there is no

air in the water piping and all valves are

open. Make sure the water pump capacity

is enough.

No

Water flow switch is damaged

Yes

Replace the water flow switch

No

Replace main PCB

5.7 E9 Troubleshooting

Digital display output

Description

 Water flow failure.

 E9 indicates water flow switch error. When E9 error occurs 3 times in 60 minutes, manual system restart is required before

the system can resume operation.

 The faulty unit stops running.

 Error code is displayed on main PCB and user interface.

Possible causes

 The wire circuit is short connected or open.

 Water flow rate is too low.

 Water flow switch damaged.

 Damaged main PCB.

Procedure

Notes:

1. For MC-SU75-RN8L-B and MC-SU140-RN8L-B, Water flow switch connection is port CN114 on the slave PCB (labeled 12 in Part 4, 2.7 Slave PCB

component).

2. For MC-SU90-RN8L-B and MC-SU180-RN8L-B, Water flow switch connection is port CN8 on the main PCB (labeled 38 in Part 4, 2.2.1 Main PCB

component).

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EC

Some outdoor units in the system are

powered off1

Yes

Power on all the outdoor units

No

The power supply is abnormal

Yes

Check the power supply equipment

No

Troubleshoot as for an E2 error2

5.8 EC Troubleshooting

Digital display output

Description

 EC indicates that the number of slave units detected by master unit has decreased.

 The slave unit that has lost contact with the main unit stops running.

 Error code is only displayed on the user interface.

Possible causes

 Some outdoor units power off.

 Power supply abnormal.

 Incorrect outdoor unit address setting.

 Communication wires between outdoor units not connected properly.

 Wiring connection is loosen.

 Damaged main PCB or electric control box communication terminals block.

Procedure

Notes:

1. For MC-SU75-RN8L-B and MC-SU140-RN8L-B, check digital display on the main PCB. If digital display is on, the main PCB is powered on, if digital display is

off, the main PCB is powered off. Please refer to labeled 11 in Part 4, 2.7 Slave PCB component.

2. For MC-SU90-RN8L-B and MC-SU180-RN8L-B, check digital display on the main PCB. If digital display is on, the main PCB is powered on, if digital display is

off, the main PCB is powered off. Please refer to labeled 37 in Part 4, 2.2.1 Main PCB component.

3. See Part 4, 4.4 “E2 Troubleshooting”.

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5.9 EH Troubleshooting (for MC-SU90-RN8L-B and MC-SU180-RN8L-B only)

Digital display output

Description

 EH indicates system self-check in the factory, it will not display in the normal operating.

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5.10 P0 Troubleshooting

Digital display output

Description

 Discharge pipe high pressure or discharge temperature switch protection. When the discharge pressure rises above 4.2MPa

or discharge temperature rises above 115°C, the system displays P0 protection and all units stop running. When the

discharge pressure falls below 3.2MPa or discharge temperature fall below 90°C, P0 is removed and normal operation

resumes. When P0 error occurs 3 times in 60 minutes, a manual system restart is required before the system can resume

operation.

 Error code is displayed on main PCB and user interface.

Possible causes

 High pressure switch or discharge temperature switch not connected properly or has malfunctioned.

 Excess refrigerant.

 System contains air or nitrogen.

 High pressure side blockage.

 Poor condenser heat exchange.

 Main PCB damaged.

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P0

High pressure switch or discharge

temperature switch connection on main

PCB is loose1

Yes

Ensure High pressure switch or discharge

temperature switch are connected properly

No

High pressure switch or discharge

temperature switch have short-circuited or

failed2

Yes

Replace the high pressure switch or

discharge temperature switch

No

The high pressure side is blocked, caused

by crushed or bent pipe or blocked EXV3

Yes

Inspect the system and fix the error

No

The heat exchange is poor4

Yes

Inspect the system and fix the error

No

The water flow rate is not sufficient in

cooling mode

Yes

Inspect the water system and fix the error

Excess refrigerant or System contains air or

nitrogen

Drain the refrigerant in the system,

vacuum with a vacuum pump, and refill

the nominal weight of refrigerant after

ensuring that the vacuum degree meets

the requirements

Replace outdoor main PCB

Yes

Replace Inverter Module PCB

Procedure

For MC-SU75-RN8L-B and MC-SU140-RN8L-B

No

Notes:

1. Discharge temperature switch connection is port CN27 on the main PCB(labeled 26 in Part 4, 2.2.1 Main PCB component) .High pressure switch connection

is port CN21 on the IPM inverter module PCB;

2. Measure the resistance among the three terminals of the pressure sensor. If the resistance is of the order of mega Ohms or infinite, the pressure sensor

has failed;

3. High pressure side blockage causes discharge temperature to be higher than normal, discharge pressure to be higher than normal and suction pressure to

be lower than normal;

4. In heating mode check water side heat exchanger, water piping, circulator pumps and water flow switch for dirt/blockages. In cooling mode check air side

heat exchanger, fan(s) and air outlets for dirt/blockages.

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P0

High pressure switch or discharge

temperature switch connection on main

PCB is loose1

Yes

Ensure High pressure switch or discharge

temperature switch are connected properly

No

High pressure switch or discharge

temperature switch have short-circuited or

failed2

Yes

Replace the high pressure switch or

discharge temperature switch

No

The high pressure side is blocked, caused

by crushed or bent pipe or blocked EXV3

Yes

Inspect the system and fix the error

No

The heat exchange is poor4

Yes

Inspect the system and fix the error

No

The water flow rate is not sufficient in

cooling mode

Yes

Inspect the water system and fix the error

No

Replace outdoor main PCB

For MC-SU90-RN8L-B and MC-SU180-RN8L-B

Notes:

1. High pressure switch connection is port CN20 on the main PCB (labeled 19 in Part 4, 2.2.1 Main PCB component).

2. Measure the resistance among the three terminals of the pressure sensor. If the resistance is of the order of mega Ohms or infinite, the pressure sensor has

failed.

3. High pressure side blockage causes discharge temperature to be higher than normal, discharge pressure to be higher than normal and suction pressure to

be lower than normal.

4. In heating mode check water side heat exchanger, water piping, circulator pumps and water flow switch for dirt/blockages. In cooling mode check air side

heat exchanger, fan(s) and air outlets for dirt/blockages.

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5.11 P1 Troubleshooting

Digital display output

Description

For MC-SU75-RN8L-B and MC-SU140-RN8L-B

 P1 indicates suction pipe low pressure protection. When the suction pressure falls below 0.05MPa, the system displays P1

protection and all units stop running. When the pressure rises above 0.15MPa, P1 is removed and normal operation

resumes. When P1 error occurs 3 times in 60 minutes, a manual system restart is required before the system can resume

operation.

 P1 another indicates in the standby state or shutdown state, after the compressor stops for 3min, it is determined that the

refrigerant quantity of the refrigerant system of the unit is insufficient through the saturation temperature corresponding to

the high-pressure pressure, the system displays P1 protection, the unit does not start and the protection is not locked;

When the detection pressure returns to above the judgment value, the protection is released and the unit can resume

startup.

 P1 the last one indicates during the operation of the compressor of the unit, if the exhaust superheat is too high and lasts

for 30min, report P1 protection first, and then judge the low refrigerant. If the low refrigerant protection is not triggered, P1

protection is removed and the operation is restarted according to the demand.

 Error code is displayed on main PCB and user interface.

For MC-SU90-RN8L-B and MC-SU180-RN8L-B

 P1 indicates suction pipe low pressure protection. When the suction pressure falls below 0.05MPa, the system displays P1

protection and all units stop running. When the pressure rises above 0.15MPa, P1 is removed and normal operation

resumes. When P1 error occurs 3 times in 60 minutes, a manual system restart is required before the system can resume

operation.

 Error code is displayed on main PCB and user interface.

Possible causes

 Low pressure switch not connected properly or has malfunctioned.

 Insufficient refrigerant.

 Low pressure side blockage.

 Poor evaporator heat exchange in heating mode.

 Insufficient water flow in cooling mode.

 Main PCB damaged.

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P1

Insufficient refrigerant caused by

refrigerant leakage1

Yes

Add refrigerant or inspect the system for

leaks

No

The low pressure side is blocked, caused by

crushed or bent pipe, blocked EXV, or dirty

filter2

Yes

Inspect the system and fix the error. If the

filter is blocked by ice, the piping should be

cleaned

No

The air side heat exchanger heat exchange

is poor in heating mode3

Yes

Inspect the refrigerant system and fix the

error

No

The water flow rate is not sufficient in

cooling mode4

Yes

Inspect the water system and fix the error

No

Replace main PCB

Procedure

Notes:

1. To check for insufficient refrigerant: An insufficiency of refrigerant causes compressor discharge temperature to be higher than normal, discharge and

suction pressures to be lower than normal and compressor current to be lower than normal, and may cause frosting to occur on the suction pipe. These issues disappear once sufficient refrigerant has been charged into the system.

2. A low pressure side blockage causes compressor discharge temperature to be higher than normal, suction pressure to be lower than normal and

compressor current to be lower than normal, and may cause frosting to occur on the suction pipe. For normal system parameters.

3. Check air side heat exchanger, fan(s) and air outlets for dirt/blockages.

4. Check water side heat exchanger, water piping, circulator pumps and water flow switch for dirt/blockages.

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5.12 P4, P5 Troubleshooting

Digital display output

Description

 1 P4 indicates system A current protection

 2 P4 indicates system A DC bus current protection

 1 P5 indicates system B current protection

 2 P5 indicates system B DC bus current protection

 When the compressor current rises above the protection value 53A/60A (53A for 75/140 model, 60A for90/180 model), or

DC bus current rises above the protection value232A/140A (232A for 75/140 model, 140A for90/180 model), the system

displays P4 or P5 protection and the faulty unit stops running. When the current returns to the normal range, P4 or P5 is

removed and normal operation resumes. When P4 or P5 error occurs 3 times in 60 minutes, a manual system restart is

required before the system can resume operation.

 Error code is displayed on main PCB and user interface.

Possible causes

 Power supply abnormal.

 Poor condenser heat exchange.

 High pressure side blockage.

 Excess refrigerant.

 System contains air or nitrogen.

 Inverter module damaged.

 Compressor damaged.

 Main PCB damaged.

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P4/P5

The power supply is abnormal

Yes

Check the power supply equipment

No

Excess refrigerant

Yes

Discharge part of the refrigerant. Add oil if

it leaks during discharge refrigerant process

No

System contains air or nitrogen

Yes

Flush all refrigerant then vacuum the

system and recharge refrigerant. Add oil to

the system if it leaks

No

The condenser heat exchange is poor1

Yes

Inspect the system and fix the error

No

The high pressure side is blocked, caused

by crushed or bent pipe or blocked EXV2

Yes

Inspect the system and fix the error

No

Inverter module has short-circuited3

Yes

Replace the inverter module

No

Compressor has malfunctioned4

Yes

Replace the compressor

No

Replace outdoor main PCB

Procedure

Notes:

1. In heating mode check water side heat exchanger, water piping, circulator pumps and water flow switch for dirt/blockages. In cooling mode check air side

heat exchanger, fan(s) and air outlets for dirt/blockages.

2. High pressure side blockage causes discharge temperature to be higher than normal, discharge pressure to be higher than normal and suction pressure to

be lower than normal.

3. Set a multi-meter to buzzer mode and test any two terminals of P N and U V W of the inverter module. If the buzzer sounds, the inverter module has

short-circuited.

4. The normal resistances of the inverter compressor is 0.124Ω(at 20℃ ambient temperature) among U V W and infinite between each of U V W and ground.

If any of the resistances differ from these specifications, the compressor has malfunctioned.

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Specific error code1

Content

xL0

Inverter module protection

xL1

DC bus low voltage protection

xL2

DC bus high voltage protection

xL4

MCE error

xL5

Zero speed protection

xL7

Phase sequence error

xL8

Compressor frequency variation greater than 15Hz within one second protection

xL9

Actual compressor frequency differs from target frequency by more than 15Hz protection

Notes:

1. '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.

5.13 P6 Troubleshooting (for MC-SU90-RN8L-B and MC-SU180-RN8L-B)

Digital display output

Description

 Indicates inverter module failure

 When a P6 error occurs, a manual system restart is required before the system can resume operation. The cause of a

P6 error should be addressed promptly in order to avoid system damage.

 The faulty unit stops running.

 Error code is displayed on the main PCB and user interface.

Possible causes

 Inverter module protection

 DC bus low or high voltage protection

 MCE error

 Zero speed protection

 Phase sequence error

 Excessive compressor frequency variation

 Actual compressor frequency differs from target frequency

Specific error codes for XP6 inverter module protection

If P6 error code is displayed, please spot check the specific error code through the wired controller.

The specific error codes xL0, xL1, xL2 and xL4 can also be obtained from the inverter module LED indicators. If an inverter module

error has occurred, LED2 is continuously on and LED1 flashes.

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LED indicators LED1 and LED2 on inverter module

Errors indicated on LED1

LED1 flashing pattern

Corresponding error

Flashes 8 times and stops for 1 second, then repeats

xL0 - Inverter module protection

Flashes 9 times and stops for 1 second, then repeats

xL1 - DC bus low voltage protection

Flashes 10 times and stops for 1 second, then repeats

xL2 - DC bus high voltage protection

Flashes 12 times and stops for 1 second, then repeats

xL4 - MCE error

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IPM internal rectifier circuit

IPMM internal inverter circuit

L0 protection

The DC bus wire connected incorrectly

1

Ensure the wire is

connected properly

The compressor wiring is connected

incorrectly

Reconnect the cables

based on wiring diagram

Replace the compressor

The inverter module is not well heat

dissipation

The IPM screws is loosen

Fasten IPM

screws again

The silica gel is coated not

well for heat radiation

Coat with silica

gel

The compressor has less than 12 hours

preheating before initial operating

Switch on power again to detect

whether the compressor can start

Refer to “P3 over current protection”

Replace the inverter

module

Ensure enough

preheating time

No

Yes

No

Yes

No

Disconnect the power supply

The resistance between 3 phases of

compressor is over 5Ω

The insulation resistance of

compressor is less than 100kΩ

Refer to P4/P5 troubleshooting

L0: Inverter module protection

Note:

1. Make sure wire connection of CN38 port of compressor inverter module board is firm. Plug or pull out the wire under live working is not allowed.

 How to determine whether the compressor module is damaged?

 Three phase rectifier measure

Set the multimeter to diode position. After unit power off for 10min, put the black pin on CN5(P_OUT) and put the red pin on CN6(L1)、CN7(L2)、CN11(L3) respectively. If the voltage value is 0V, it means the three phase rectifier bridge reactor is damaged. Similarly, put the red pin on CN38 (N) and put the black pin on CN6 (L1), CN7 (L2) and CN11 (L3) respectively. If the voltage value is 0V, it means the three phase rectifier bridge reactor is damaged.

 Inverter circuit measure Set the multimeter to diode position. After unit power off for 10min, put the black pin on CN1(P_in) and put the red pin on CN12(U)、CN13(V)、CN14(W) respectively. If the voltage value is 0V, it means the IGBT or freewheel diode is damaged. Similarly, put the red pin on CN38 (N) and put the black pin on CN12 (U), CN13 (V) and CN14 (W) respectively. If the voltage value is 0V, it means the IGBT or freewheel diode is damaged.

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L1

The power supply is abnormal

Yes

Check the power supply equipment

No

DC bus voltage(P, N) is abnormal1

No

Change compressor module board

Yes

Power supply for compressor module

board is abnormal

Yes

Check the wire connection between power

supply terminals and filter board; Check the

wire connection between filter board to

compressor module board

No

Wire connection between reactor and

compressor module board is abnormal

Yes

Rewiring according to the wiring diagram

No

Pressure switch is open

Yes

Check whether P0 error appears or high

pressure switch broken

No

Change compressor module board

L1: Low-voltage protection

Note:

1. The normal DC voltage between terminals P and N of CN38 of compressor inverter module board should be 450-650V. When the voltage is lower than 350V.

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L2

The power supply is abnormal

Yes

Check the power supply equipment

No

DC bus voltage(P, N) is abnormal

No

Change compressor module board

Yes

Power supply for compressor module

board is abnormal

Yes

Check the wire connection between power

supply terminals and filter board; Check the

wire connection between filter board to

compressor module board

No

Change compressor module board

L2: High-voltage protection

Note:

1. The normal DC voltage between terminals P and N on inverter module should be 450-650V. When the voltage is higher than 800V, L2 protection will be

appeared.

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Switch

Description

S7-1

S7-2

S7

Compressor A inverter module address setting

OFF

Compressor B inverter module address setting

OFF

ON

L4 protection

ODU ventilation is not good

Remove barriers from heat

exchanger and air outlet of ODU

ODU stop valves are closed Open the ODU stop valves

Reconnect the cables based on

wiring diagram

The resistance between 3 phases of

compressor is over 5Ω

Replace the compressor

The insulation resistance of

compressor is less than 100Ω

Replace the compressor inverter

board, restart the unit and the error is

solved

Refer to P1 or P3 troubleshooting

No

Yes

Disconnect the power supply

Compressor wiring is not properly

Inverter module address setting1 and

discharge temperature sensor wiring is

not properly

Reset the inverter module address

and reconnect the discharge

temperature sensor cables

Yes

Normal

Yes

No

Refer to P4/P5 troubleshooting

L4: MCE error

Notes:

1. Compressor inverter module address is set through dial switch S7 on the inverter module. The compressor inverter module A/B location refers to the wiring diagram

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L7 protection

Compressor wiring is loose

Reconnect cables based on

wiring diagram

An open circuit in the 3-phase U/V/W

of compressor terminals

Replace the compressor

Replace the inverter module

No

Yes

Disconnect the power supply

L7: Phase sequence error

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L8 protection

ODU stop valves are closed Open the ODU stop valves

Reconnect the cables based on

wiring diagram

The resistance between 3 phases of

compressor is over 5Ω

Replace the compressor

The insulation resistance of

compressor is less than 100Ω

Replace the compressor inverter

board, restart the unit and the error is

solved

Refer to P1 or P3 troubleshooting

No

Yes

Disconnect the power supply

Compressor wiring is not properly

Yes

Normal

Yes

No

L9 protection

The compressor has less than 12 hours

preheating before initial operating

Ensure enough preheating time

Yes

Refer to P4/P5 troubleshooting

L8: Compressor frequency variation greater than 15Hz within one second protection

L9: Actual compressor frequency differs from target frequency by more than 15Hz protection

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