Midea M thermal A Mono Series User manual

M thermal A Series Mono(18~30kW)
Commercial Air Conditioners
R32
Service
Manual
Midea CAC
Confidential

M thermal Mono
202008 1
CONTENTS
CONTENTS
Part 1 General Information ............................................................................ 3
Part 2 Component Layout and Refrigerant Circuits ..................................... 5
Part 3 Control ............................................................................................... 11
Part 4 Diagnosis and Troubleshooting ......................................................... 25
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M thermal Mono
2 202008
Midea M thermal Mono
Service Manual
Midea CAC
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M thermal Mono
202008 3
Part 1
-
General Information
Part 1
General Information
1 Unit Capacities and External Appearance .............................................. 4
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M thermal Mono
4 202008
Midea M thermal Mono
Service Manual
1 Unit Capacities and External Appearance
1.1 Unit Capacities
Table 1-1.1: Capacity range
Capacity 18kW 22kW 26kW 30kW
Model MHC-V18W/D2RN8 MHC-V22W/D2RN8 MHC-V26W/D2RN8 MHC-V30W/D2RN8
1.2 External Appearance
Table 1-1.2: Appearance
18/22/26/30kW
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M thermal Mono
202008 5
Part 2
-
Component Layout
and
Refrigerant Circuits
Part 2
Components Layout and
Refrigerant Circuits
1 Layout of Functional Components .............................................................. 6
2 Piping Diagrams ......................................................................................... 7
3 Refrigerant Flow Diagrams ......................................................................... 9
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M thermal Mono
6 202008
Midea M thermal Mono
Service Manual
1 Layout of Functional Components
Figure 2-1.1: MHC-V18(22,26,30)W/D2RN8 front view
Air side heat exchanger
Fan motor
Gas-liquid separator
DC inverter compressor
Electric control box
4-way valve
Pressure sensor
Electronic expansion valve
High pressure switch
Low pressure switch
Water pump
Safety valve
Manometer
Figure 2-1.2: MHC-V18(22,26,30)W/D2RN8 side view
Expansion vessel
Accumulator
One-way valve
Air purge valve
Water flow switch
Water side heat exchanger
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M thermal Mono
202008 7
Part 2
-
Component Layout
and
Refrigerant Circuits
LW
EW
1
4
14
6
9
26
19
8
8
20
25
2
5
7
11
12
17 18
21 22 23 24
3
15
13
27
16
F
10
2 Piping Diagrams
Figure 2-2.1: MHC-V18(22,26,30)W/D2RN8 piping diagram
Legend
1 Compressor 15 Low pressure switch
2 Discharge temperature sensor 16 Suction temperature sensor
3 High Pressure Switch 17 Single-way electromagnetic valve
4 4-Way Valve 18 Capillary
5 Outdoor temperature sensor 19 Water Inlet temp. sensor
6 Air side heat exchanger 20 Y-shape filter (Accessories)
7 Air side heat exchanger refrigerant outlet temperature sensor(cooling) 21 Water outlet temp. sensor
8 Filter 22 Manometer
9 Electronic expansion valve 23 Safety valve
10 Accumulator 24 Circulating pump
11 Refrigerant temperature sensor (liquid line) 25 Expansion vessel
12 Refrigerant temperature sensor (gas line) 26 Air purge valve
13 Pressure sensor 27 Flow switch
14 Gas-liquid separator
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8 202008
Midea M thermal Mono
Service Manual
Key components:
1. Accumulator:
Stores liquid refrigerant and oil to protect compressor from liquid hammering.
2. Electronic expansion valve (EXV):
Controls refrigerant flow and reduces refrigerant pressure.
3. 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.
4. High and low pressure switches:
Regulate refrigerant system pressure. When 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.
5. Air purge valve:
Automatically removes air from the water circuit.
6. Safety valve:
Prevents excessive water pressure by opening at 43.5 psi (3 bar) and discharging water from the water circuit.
7. Expansion vessel:
Balances water system pressure. (Expansion vessel volume: 8L in 18/22/26/30kW units)
8. Water flow switch:
Detects water flow rate to protect compressor and water pump in the event of insufficient water flow.
9. Manometer:
Provides water circuit pressure readout.
10. Water pump:
Circulates water in the water circuit.
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M thermal Mono
202008 9
Part 2
-
Component Layout
and
Refrigerant Circuits
Pressure sensor
Filter
Electronic
expansion valve
Filter
High pressure
switch
Low pressure
switch
Air side heat exchanger
4-way
valve
High tempera
tu
re, high pressure g
as
High temperature, high pressure liquid
Low temperature, low pressure
Single-way electromagnetic valve Capillary
Accumulator
Pressure sensor
Filter
Electronic
expansion valve
Filter
High pressure
switch
Low pressure
switch
Air side heat exchanger Accumulator
4-way
valve
High tempera
tu
re, high pressure g
as
High temperature, high pressure liquid
Low temperature, low pressure
Single-way electromagnetic valve Capillary
3 Refrigerant Flow Diagrams
Heating and domestic hot water operation
Figure 2-3.1: Refrigerant flow during heating or domestic hot water operation
Cooling and defrosting operation
Figure 2-3.2: Refrigerant flow during cooling and defrosting operations
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