Mitsubishi Electric Mr.Slim MU-A18ND-S1 User manual

CONTENTS
1. TECHNICAL CHANGES ····································2
2. PART NAMES AND FUNCTIONS······················3
3. SPECIFICATION·················································3
4. OUTLINES AND DIMENSIONS ·························4
5. WIRING DIAGRAM ············································6
6. REFRIGERANT SYSTEM DIAGRAM ················8
7. PERFORMANCE CURVES······························10
8. TROUBLESHOOTING······································12
9. DISASSEMBLY INSTRUCTIONS ····················21
10. PARTS LIST······················································27
11. RoHS PARTS LIST···········································30
SPLIT-TYPE AIR CONDITIONERS
TM
MU-A18ND
MU-A18ND-
MU-A18ND-
MU-A24ND-
MU-A24ND-
MU-A30ND-
MU-A30ND- S2
S1
S2
S1
S2
S1
Indoor unit service manual
MS-A• ND Series (OB404)
No. OB405
REVISED EDITION-E
SERVICE MANUAL
Models
OUTDOOR UNIT
NOTE:
• This service manual describes technical data of the outdoor units.
• RoHS compliant products have <G> mark on the spec name plate.
For servicing of RoHS compliant products, refer to the RoHS Parts List.
Please void OB405 REVISED EDITION-D.
Revision E:
•SPECIFICATION has been modified.
OB405E.qxp 09.10.14 9:16 AM Page 1

2
TECHNICAL CHANGES1
2
Compressor: NH30VCD ➞ RH247NRAT
Compressor: RH277NHD
➞ RH247NRAT
Electricity receiving unit: Indoor unit ➞ Outdoor unit
Gas pipe diameter: [15.88
➞ [12.7
Rated voltage: 220V ➞ 220-230V
Frequency
New Model
Old Model
MU-18TN -
S1
w : change
MU-A18ND -
S1
60Hz
MU-18SN -
C1
w
w
w
w
w
w
w
w
Outdoor unit:Unit size:W850mmoH605mmoD290mm ➞ W840mmoH850mmoD330mm
Outdoor unit:Unit size:W870mmoH850mmoD295mm ➞ W840mmoH850mmoD330mm
Compressor: NH38NBD ➞ PH33NPBT
Electricity receiving unit: Indoor unit ➞ Outdoor unit
Liquid refrigerant pipe diameter: [9.52
➞ [6.35
Rated voltage: 220V ➞ 220-230V
Frequency
New Model
Old Model
MU-24TN -
S1
MU-A24ND -
S1
60Hz
MU-24SN -
C2
w
w
w
w
w
w
w
w
w
w
MU-A30ND -
New model
S1
MU-A18ND -➔MU-A18ND -
• Valve cover has been added.
S2S1
MU-A24ND -➔MU-A24ND -
• Compressor contactor has been added.
S2S1
MU-A30ND -➔MU-A30ND -
• Solenoid valve and solenoid valve coil have been changed.
S2S1
Revision A:
• Check of solenoid valve coil has been partially modified.
Revision B:
• MU-A24ND -has been added.
S2
Revision C:
• MU-A18ND -has been added.
S2
Revision D:
• MU-A30ND -has been added.
S2
Revision E:
• SPECIFICATION has been modified.
OB405E.qxp 09.10.14 9:16 AM Page 2

3
PART NAMES AND FUNCTIONS
2
SPECIFICATION
3
Outdoor model
Function
Power supply
Capacity
Dehumidification
Air flow (High/Low)
Power outlet
Running current (Total)
Power input (Total)
Power factor (Total)
Starting current (Total)
Compressor motor current
Fan motor current
Model
Output
Winding
resistance (at 20:)
Model
Winding
resistance (at 20:)
Dimensions WOHOD
Weight
Sound level (High/Low)
Fan speed (High/Low)
Fan speed regulator
Refrigerant filling
capacity (R22)
Refrigeration oil (Model)
kW
R/h
K/h
A
A
W
%
A
A
A
W
"
"
mm
kg
dB
rpm
kg
cc
Cooling
Single phase
220-230V, 60Hz
2,880
58
0.66
PH33NPBT
1,500
C-R 0.84
C-S 2.09
RA6N75-BA
WHT-BLK 65.0
BLK-RED 65.4
67
54
790
1
2.20
900 (MS32N1)
Electrical data
Compressor
Fan motor
Special remarks
Coefficient of performance (C.O.P) (Total)
Capacity
2,480
15
40
0.55
RH247NRAT
1,200
C-R 1.43
C-S 2.06
RA6V60-MA
WHT-BLK 71.2
BLK-RED 89.3
850o605o290
44
54
945
1
1.40
520 (MS56)
ISO 5151
5.10
2.3
8.52
1,800
96-92
7.60
2.83
SSA 385
5.9
2.7
20( )
12.42
2,650
97
11.39
2.23
ISO 5151
6.6
3.2
15( )
10.54
2,250
97-93
9.50
2.93
SSA 385
6.6
3.2
17.52
3,700
96
16.49
1.78
ISO 5151
8.1
4.3
14.25
3,010
96-92
13.22
2.69
SSA 385
4.40
1.8
9.94
2,100
96
9.02
2.10
MU-A24ND MU-A30ND
2,880/1,380
25
78
0.66
NH44NAVT
2,000
C-R 0.62
C-S 1.40
RA6N75-AA
WHT-BLK 64.2 BLK-YLW 32.9
YLW-RED 32.7
76
55/51
790/490
2
2.40
1,300 (MS32N1)
840o850o330
S2
S1
MU-A18ND
NOTE: Test conditions are based on ISO 5151 / SSA 385
Cooling : Indoor DB27°C WB19°C / DB29°C WB19°C
Outdoor DB35°C WB24°C / DB46°C WB24°C
Indoor-Outdoor piping length: 5 / 7.5 m
OUTDOOR UNIT
Air inlet
Air outlet
Drain outlet
Piping
Drain hose
Air inlet
Air outlet
(back and side)
MU-A18ND MU-A24ND MU-A30ND
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4
OUTLINES AND DIMENSIONS4
Unit: mm
100mm or more
350mm or more
100mm or more
100mm or more
REQUIRED SPACE
500mm or more
100
157
161
Liquid refrigerant
pipe joint
Refrigerant pipe
(Flared) [6.35
Service panel
183
500
850
30
50
20350
35
248
605
292
20
310 290
345
Air in
Air out
Drainage
3holes [33
50
90
Air in
Drainage
hole [16.2
355
74
30-
35-
Gas refrigerant
pipe joint
Refrigerant pipe
(flared) [12.7
MU-A18ND - S1
OUTDOOR UNIT
100
157
161
Liquid refrigerant
pipe joint
Refrigerant pipe
(Flared) [6.35
Service panel
183
500
850
30
50
20350
35
248
605
292
20
310 290
345
Air in
Air out
Drainage
3holes [33
50
90
Air in
Drainage
hole [16.2
355
81
74
30-
35-
Gas refrigerant
pipe joint
Refrigerant pipe
(flared) [12.7
100mm or more
350mm or more
100mm or more
100mm or more
REQUIRED SPACE
500mm or more
MU-A18ND - S2
OB405E.qxp 09.10.14 9:16 AM Page 4

5
30-
35-
155
90
198
40
515
299
66
34
51
330
360
850
430
500
80
121
840
REQUIRED SPACE Open as a rule
500mm or more if
the front and both
sides are open
100mm or more
200mm or more if
there are obstacles
to both sides
Open as a rule
500mm or more if the back,
both sides and top are open
Service panel
Gas refrigerant
pipe joint
Refrigerant pipe
(flared) [15.88
Liquid refrigerant
pipe joint
Refrigerant pipe
(flared) [6.35(MU-A24ND)
[9.52(MU-A30ND)
350mm or more
100mm or more
MU-A24ND MU-A30ND
OUTDOOR UNIT
OB405E.qxp 09.10.14 9:16 AM Page 5

6
WIRING DIAGRAM
5
MU-A18ND
R
S
2
N
L
TB2
RED
ORN
BLU
BRN
WHT
GRN/YLW
C2
RED
MF
BLACK
4
WHITE
ORANGE
321
BLK
L
N
TB1
BRN
BLU C1 RED
C
MC
BLU
220-230V~
CONNECTING
TO INDOOR UNIT
POWER SUPPLY
220-230V ~/N 60Hz
F
BLU
DSAR
220-230V~
WHT
1.About the indoor side electric wiring refer to the indoor unit electric wiring diagram for servicing.
2.Use copper conductors only (For field wiring).
3.Symbols below indicate.
: Connector
: Terminal block,
NOTES:
SYMBOL
C1
C2
DSAR
SYMBOL
F
MC
MF
SYMBOL
TB1
TB2
NAME NAME NAME
COMPRESSOR CAPACITOR
OUTDOOR FAN CAPACITOR
SURGE ABSORBER
FUSE (3.15A)
COMPRESSOR(INNER PROTECTOR)
OUTDOOR FAN MOTOR(INNER PROTECTOR)
TERMINAL BLOCK
TERMINAL BLOCK
MU-A24ND- S1
L
N
2
BRN
RED
BLK
WHT
BLU
TB2
BLU
WHT
RED
C2
ORN
DSAR
TB1
GRN/YLW
BRN
F
MF
2
1
ORN
RED
3
4
N
L
PE
BLU
MC
WHT
BLU SC
R
C1
BLK
SYMBOL
C1
C2
DSAR
SYMBOL
F
MC
MF
SYMBOL
TB1
TB2
NAME NAME NAME
COMPRESSOR CAPACITOR
OUTDOOR FAN CAPACITOR
SURGE ABSORBER
FUSE(3.15A)
COMPRESSOR(INNER PROTECTOR)
OUTDOOR FAN MOTOR(INNER PROTECTOR)
TERMINAL BLOCK
TERMINAL BLOCK
NOTES: 1.Use copper conductors only (For field wiring).
2.Since the indoor and outdoor unit connecting wires have polarity, connect them according to the numbers (2,N,L).
3.Symbols below indicate.
: Terminal block, : Connector
TO INDOOR UNIT CONNECTING
220-230V~
220-230V~
POWER SUPPLY
~/N 220-230V 60Hz
OUTDOOR UNIT
OUTDOOR UNIT
OB405E.qxp 09.10.14 9:16 AM Page 6

7
MU-A30ND
SYMBOL
C1
C2
DSAR
F61
LEV
MC
MF
SYMBOL
NR61
RT62
RT63
SR61
SR62
TB1
TB2
SYMBOL
T61
X52
X63
21S2
52C
NAME
DEICER
P.C. BOARD
2
N
3
N
L
12V
WHT
BLU
RED
BLU
WHT
WHT
T61
YLW
BLK WHT
RED
BLU
TB2
5
CN730
YLW
BLK WHT
1
52C
2
RED
C2
ORN
A1 A2BLU 52C
DSAR
WHT
C1
BLK
S
C
R
MC
BLU
NR61
3
1
TB1
GRN/YLW
BRN
SR62
SR61
F61
TAB52
COM NO
X52
CN711
CN724
CN662
6
MF
RT62 RT63
123
21
ORN RED
3456
LEV
COM NO
X63 3
2
1
CN722
X52
PE
220-230V~
TO INDOOR UNIT CONNECTING
POWER SUPPLY
~/N 220-230V 60Hz
X63
21S2
NAME NAME
COMPRESSOR CAPACITOR
OUTDOOR FAN CAPACITOR
SURGE ABSORBER
FUSE(3.15A)
EXPANSION VALVE COIL
COMPRESSOR(INNER PROTECTOR)
OUTDOOR FAN MOTOR(INNER PROTECTOR)
VARISTOR
DISCHARGE TEMPERATURE THERMISTOR
AMBIENT TEMPERATURE THERMISTOR
SOLID STATE RELAY
SOLID STATE RELAY
TERMINAL BLOCK
TERMINAL BLOCK
TRANSFORMER
CONTACTOR
SOLENOID VALVE COIL RELAY
SOLENOID VALVE COIL
COMPRESSOR CONTACTOR
NOTES: 1.Use copper conductors only (For field wiring).
2.Since the indoor and outdoor unit connecting wires have polarity, connect them according to the numbers (3,N,2).
3.Symbols below indicate.
: Terminal block, : Connector
MU-A24ND- S2
OUTDOOR UNIT
OUTDOOR UNIT
SYMBOL
C1
C2
DSAR
SYMBOL
F
MC
MF
SYMBOL
TB1
TB2
52C
NAME NAME NAME
COMPRESSOR CAPACITOR
OUTDOOR FAN CAPACITOR
SURGE ABSORBER
FUSE(3.15A)
COMPRESSOR(INNER PROTECTOR)
OUTDOOR FAN MOTOR(INNER PROTECTOR)
TERMINAL BLOCK
TERMINAL BLOCK
COMPRESSOR CONTACTOR
NOTES: 1.Use copper conductors only (For field wiring).
2.Since the indoor and outdoor unit connecting wires have polarity, connect them according to the numbers (2,N,L).
3.Symbols below indicate.
: Terminal block, : Connector
BLK
WHT
ORN
BLU
WHT
ORN
RED
BLK
WHT
BLU
BLU BLU
WHT
BRN
52C
GRN/YLW
BLU
BRN
BRN
C2
C1
TO INDOOR UNIT CONNECTING
220-230V~
220-230V~
POWER SUPPLY
~/N 220-230V 60Hz
56
DSAR
L
N
2
N
L
TB2
TB1
MF
MC
4
52C
1
R
S
C
RED RED
F
4
3
2
1
PE
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8
REFRIGERANT SYSTEM DIAGRAM6
MU-A24ND
OUTDOOR UNIT
Outdoor
heat
exchanger
Flared connection
Flared connection
Stop valve
Stop valve
(with service port)
Capillary tube
[3.0 x [2.0 x 550
Refrigerant flow in cooling
Compressor
Refrigerant pipe
[15.88
(with heat insulator)
Refrigerant pipe
[6.35
(with heat insulator)
Strainer
#100
Accumulator
MU-A18ND
OUTDOOR UNIT
Unit : mm
Refrigerant pipe
{6.35
(with heat insulator)
Refrigerant pipe
{12.7
(with heat insulator)
Compressor
Outdoor heat
exchanger
Flared
connection
Strainer
#100
Stop Valve
(with service port)
Stop Valve Capillary tube
[3.0 x [1.8 x 400
OB405E.qxp 09.10.14 9:16 AM Page 8

9
Outdoor
heat
exchanger
Flared connection Discharge
temperature
thermistor
RT62
Flared connection
Stop valve
Stop valve
(with service port)
Capillary tube
[3.6 x [2.4 x 50
Refrigerant flow in cooling
Compressor
Refrigerant pipe
[15.88
(with heat insulator)
Refrigerant pipe
[9.52
(with heat insulator)
Strainer
#100
Strainer
#100
Accumulator
Ambient
temperature
thermistor
RT63
Capillary tube
[4.0 x [2.4 x 200
Capillary tube
[4.0 x [2.4 x 100
LEV
(Expansion valve)
Solenoid valve
[4.2 x [3.0 x 50
MU-A30ND
OUTDOOR UNIT
MAX.REFRIGERANT PIPING LENGTH and MAX.HEIGHT DIFFERENCE
Model
Piping size O.D : mm
Refrigerant piping : m
Max. length
A
Max. Height
difference
B
Gas Liquid
30
MU-A18ND
MU-A24ND
MU-A30ND
{15.88
{6.35
{9.52
15
{12.7
Indoor
unit
Outdoor unit
Max. length
A
Max. Height
difference
B
ADDITIONAL REFRIGERANT CHARGE(R22 : g)
NOTE : Calculation : Xg=15g/m ✕ (Refrigerant piping length (m)-7)
Model Outdoor unit precharged Refrigerant piping length (one way)
15m
120
20m
195
30m
345
7m
0
10m
45
2,200
1,400
2,400
MU-A18ND
MU-A30ND
MU-A24ND
Unit : mm
OB405E.qxp 09.10.15 1:32 PM Page 9

10
PERFORMANCE CURVES7
The standard data contained in these specifications apply only to the operation of the air conditioner under normal conditions.
Since operating conditions vary according to the areas where these units are installed. The following information has been
provided to clarify the operating characteristics of the air conditioner under the conditions indicated by the performance curve.
(1) GUARANTEED VOLTAGE
198 ~ 253V, 60Hz
(2) AIR FLOW
Air flow should be set at MAX.
(3) MAIN READINGS
(1) Indoor intake air wet-bulb temperature : °CWB
(2) Indoor outlet air wet-bulb temperature : °CWB
(3) Outdoor intake air dry-bulb temperature : °CDB
(4) Total input: W
Indoor air wet/dry-bulb temperature difference on the left side of the following chart shows the difference between the
indoor intake air wet/dry-bulb temperature and the indoor outlet air wet/dry-bulb temperature for your reference at service.
MU-A18ND MU-A24ND MU-A30ND
Indoor intake air WB temperature (:)
Outdoor intake air DB temperature (:)
Indoor intake air WB temperature (:)
Outdoor intake air DB temperature (:)
MS-A30ND MU-A30ND MS-A24ND MU-A24ND MS-A18ND MU-A18ND
9.9
9.1
8.3
7.5
6.7
5.9
12.5
11.4
10.3
9.3
8.3
7.3
18.6
16.8
15.1
13.5
12.0
10.5
Wet and dry-bulb
thermometers
Wet-and dry-bulb
thermometers
How to measure the indoor air wet/dry-bulb temperature difference
1. Attach at least 2 sets of wet and-dry-bulb thermometers to the indoor air intake as shown in the figure, and at least 2 sets
of wet-and-dry-bulb thermometers to the indoor air outlet. The thermometers must be attached to the position where air
speed is high.
2. Attach at least 2 sets of wet and dry-bulb thermometers to the outdoor air intake.
Cover the thermometers to prevent direct rays of the sun.
3. Check that the air filter is cleaned.
4. Open windows and doors of the room.
5. Press the EMERGENCY OPERATION switch once to start the EMERGENCY COOL MODE.
6. When system stabilizes after more than 15 minutes, measure temperature and take an average temperature.
7. 10 minutes later, measure temperature again and check that the temperature does not change.
INDOOR UNIT OUTDOOR UNIT
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11
10.0
9.0
8.0
7.0
6.0
5.0
15 18 20
50 60 70
25 30 32
35(:)
(%)
MU-A24ND MU-A24ND
Outdoor low pressure
Outdoor unit current (A)
Ambient temperature (˚C)/Ambient humidity (%) Ambient temperature (˚C)/Ambient humidity (%)
0.8
0.7
0.6
0.5
0.4
0.3
15 18 20
50 60 70
25 30 32
8.0
7.0
6.0
5.0
4.0
3.0 35(:)
(%)
(kgf/F[Gauge])(MPa [Gauge])
① Both indoor and outdoor units are under the same temperature/humidity condition.
OUTDOOR LOW PRESSURE AND OUTDOOR UNIT CURRENT
COOL operation
➁ Air flow should be set at MAX.
Dry-bulb temperature (:)Relative humidity (%)
20 50
25 60
30 70
3The unit of pressure has been changed to MPa on the international system of units(SI unit system).
The conversion factor is : 1(MPa [Gauge]) =10.2(kgf/ff[Gauge])
18
50 60 70
32 35(:)
(%)
15 20 25 30
4.0
5.0
6.0
7.0
8.0
MU-A18ND MU-A18ND
Outdoor low pressure
Outdoor unit current (A)
Ambient temperature (˚C)/Ambient humidity (%) Ambient temperature (˚C)/Ambient humidity (%)
8.0
7.0
6.0
5.0
4.0
3.0 18
50 70
32 (:)
(%)
15 20 25 30 35
0.3
0.4
0.5
0.6
0.7
0.8
(kgf/F[Gauge])(MPa [Gauge])
OB405E.qxp 09.10.14 9:16 AM Page 11

12
MU-A30ND
15 18 20
50
25
60
30 32
70
35(:)
(%)
0.2
0.3
0.4
0.5
0.6
2.0
3.0
4.0
5.0
6.0
15 18 20
50
25
60
30 32
70
35(:)
(%)
9.0
10.0
11.0
12.0
13.0
14.0
15.0
Outdoor low pressure
Outdoor unit current(A)
(kgf/F[Gauge])(MPa[Gauge]) MU-A30ND
Ambient temperature (˚C)/Ambient humidity (%) Ambient temperature (˚C)/Ambient humidity (%)
3. Troubleshooting procedure
1) First, check if the OPERATION INDICATOR lamp on the indoor unit is flashing on and off to indicate an abnormality.
To make sure, check how many times the abnormality indication is flashing on and off before starting service work.
2) Before servicing that the connector and terminal are connected properly.
3) If the electronic control P.C. board is supposed to be defective, check the copper foil pattern for disconnection and the
components for bursting and discolouration.
4) When troubleshooting, refer to 8-2.
TROUBLESHOOTING8
8-1. Cautions on troubleshooting
1. Before troubleshooting, check the following:
1) Check the power supply voltage.
2) Check the indoor/outdoor connecting wire for mis-wiring.
2. Take care the following during servicing.
1) Before servicing the air conditioner, be sure to turn off the main unit first with the remote controller, and then after
confirming the horizontal vane is closed, turn off the breaker and / or
disconnect the power plug.
2) Be sure to turn OFF the power supply before removing the front panel,
the cabinet, the top panel and the electronic control P.C. board.
3) When removing the electronic control P.C. board, hold the edge of the
board with care NOT to apply stress on the components.
4) When connecting or disconnecting the connectors, hold the housing of
the connector. DO NOT pull the lead wires.
Lead wiring
Housing point
MU-A18ND MU-A24ND MU-A30ND
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13
Start
Indoor unit
operates.
Outdoor unit
dose not
operate.
Indoor unit
dose not receive
the signal from
remote controller.
OPERATION INDICATOR
lamp on the indoor unit is
flashing on and off.
Outdoor unit
operates in
only Test Run
operation.
MU-A30ND
Outdoor unit
dose not
operate
even in
Test Run
operation.
Indoor unit
operates, when
EMERGENCY
OPERATION
switch is pressed.
Indoor unit
dose not operate,
when
EMERGENCY
OPERATION
switch is pressed.
Check room
temperature
thermistor.
Refer to
"Test point
diagram and
voltage".
Refer to
8-4. A
"Check of
outdoor unit".
Refer to
"Check of
remote controller
and receiver
P.C. board".
MS-A30ND
Flash on and
off at 0.5-second
intervals
Cause:
Indoor/
Outdoor unit
•Mis-wiring
2-time flash
Cause:
Indoor unit
•Trouble of
room temp-
erature/
indoor coil
thermistor
3-time flash
Cause:
Indoor unit
•Trouble of
indoor fan
motor
MU-A30ND
6-time flash
Cause:
Outdoor unit
•Trouble of
thermistor
in outdoor
unit
MU-A30ND
7-time flash
Cause:
Outdoor unit
•Trouble of
outdoor
control
system
Refer to
8-4. C
"How to
check
mis-wiring
(When
outdoor unit
dose not
work)" .
Check room
temperature
thermistor
and indoor
coil thermis-
tor.
Refer to
"Test point
diagram and
voltage".
Refer to
"Check of
indoor fan
motor".
Refer to
8-4. E
"Check of
outdoor
thermistor".
Replace the
deicer
P.C. board.
MU-A30ND
10-time flash
Cause:
Outdoor unit
•Trouble of
low discharge
temperature
protection
Refer to
8-4. D
"Check of
LEV".
4-time flash
Cause:
Indoor unit
•Trouble of
indoor
control
system
Replace the
indoor
electronic
control
P.C. board.
1. Check indoor /
outdoor
connecting wire.
2. Check of
outdoor fuse.
(MU-A18/A24ND)
3. Refer to
"Check of indoor
electronic control
P.C. board".
MU-A24ND - S2
MU-A30ND
Outdoor unit
dose not
stop even
if indoor unit
stop.
Refer to
8-4. B
"Check of
outdoor unit".
Indoor unit
operates.
Outdoor unit
dose not operate
normally.
MU-A30ND
Outdoor unit
repeats start
and stop.
Refer to
8-4. F
"Check of
solenoid
valve coil".
w
w
Refer to indoor unit service manual.
"Test Run operation" means the operation within 30 minutes after EMERGENCY OPERATION switch is pressed.
w
8-2. Instruction of troubleshooting
OB405E.qxp 09.10.14 9:16 AM Page 13

14
8-3. Trouble criterion of main parts
MU-A18ND MU-A24ND MU-A30ND
Part name FigureCheck method and criterion
Measure the resistance between the terminals with a tester.
(Coil wiring temperature -10°C ~ 40°C)
Compressor
(MC)
INNER
PROTECTOR
155i5:OPEN
90i10:CLOSE
Normal
MU-A18ND
Color of
lead wire
C –R
C –S
1.26 "~ 1.55 "
1.81 "~ 2.23 "
MU-A24ND
0.74 "~ 0.91 "
1.84 "~ 2.26 "
MU-A30ND
0.54 "~ 0.67 "
1.23 "~ 1.52 "
LEV(Expansion valve)
MU-A30ND
Color of lead wire
WHT –RED
RED –ORN
YLW –BRN
BRN –BLU
Normal
37.4 "~ 53.9 "
Measure the resistance with a tester.
(Part temperature : 0˚C ~ 40˚C)
Measure the resistance with a tester.
(Part temperature –10˚C ~ 40˚C)
Discharge temperature
thermistor(RT62)
MU-A30ND
Ambient temperature
thermistor(RT63)
MU-A30ND
Measure the resistance with a tester.
Before measurement, hold the thermistor with your hands to warm it up.
(Part temperature 0˚C ~ 40˚C)
Refer to 8-5. "Test point diagram and voltage", "Outdoor deicer P.C. board",
the chart of thermistor.
Refer to 8-5. "Test point diagram and voltage", "Outdoor deicer P.C. board",
the chart of thermistor.
MU-A18ND MU-A24ND MU-A30ND
Measure the resistance between the terminals with a tester.
(Coil wiring temperature -10°C ~ 40°C)
Color of
lead wire
WHT –BLK
BLK –RED
BLK –YLW
YLW –RED
63 "~ 77 "
79 "~ 96 "
–
–
57 "~ 70 "
58 "~ 71 "
–
–
57 "~ 69 "
–
29 "~ 35 "
29 "~ 35 "
Normal
Outdoor fan motor
(MF)
INNER
PROTECTOR
135i5:OPEN
87i15:CLOSE
Measure the resistance with a tester.
(Part temperature : –10˚C ~ 40˚C)
Solenoid valve coil
(21S2)
MU-A30ND
Normal
MU-A30ND - S1
1,738 "~ 2,125 "
MU-A30ND - S2
1,230 "~ 1,330 "
WHT BLK YLW RED ORN
MAIN
AUX.
MAIN
AUX.
WHTBLK RED ORN
MU-A18/A24ND
MU-A30ND
RED
WHT
BLK
P
C
SR
:INNER PROTECTOR
P
LEV
WHT6
RED1
ORN4
YLW5
BRN2
BLU3
OB405E.qxp 09.10.14 9:16 AM Page 14

15
Is there 220-230V AC to
between L-Non the
outdoor terminal block?
No Check the outdoor power supply
and connection of wiring.
Yes
Check the deicer P.C.
board. Refer to 8-5.
Is there 5V DC?
Compressor
dose not operate.
Yes
Press the EMERGENCY
OPERATION switch.
3-minute time delay works.
Test run operation
operates for 30 minutes.
Outdoor fan motor
dose not operate.
No Make the connection
of wiring correct.
Check the compressor.
Replace the compressor
contactor(52C).
Turn ON the power supply.
Yes
Is there 220-230V AC between
2on the compressor
contactor(52C) and Non
the outdoor terminal block?
Yes
Is there 220-230V AC CN730
on the deicer P.C. board?
Replace the
deicer P.C. board.
Replace the
deicer P.C. board.
No
No
No
Yes
Yes
Check the deicer P.C.
board. Refer to 8-5.
Is there 5V DC?
Yes
Is there 220-230V AC
CN711 1-3or 2-3on
the deicer P.C. board?
No Make the connection
of wiring correct.
Check the outdoor fan
motor. Refer to 8-3.
Yes
Is there 220V AC CN730
on the deicer P.C. board?
Replace the
deicer P.C. board.
Replace the
deicer P.C. board.
No
No
Press the EMERGENCY
OPERATION switch.
3-minute time delay works.
Test run operation
operates for 30 minutes.
Is there 220-230V AC
between A1 and A2 on the
compressor contactor (52C)?
Check of outdoor unit
A
8-4. Troubleshooting flow
Compressor and / or outdoor fan motor dose not operate.
MU-A30ND
OB405E.qxp 09.10.14 9:16 AM Page 15

16
Compressor and / or outdoor fan motor dose not stop.
After 30 seconds,
did compressor stop?
No
Yes
Replace the
deicer P.C. board.
Yes
1Turn OFF the power supply.
2After 30 seconds, turn ON the power supply again.
3Operate the unit in COOL mode by pressing the
EMERGENCY OPERATION switch.
4Operate the unit for 1 minute or more and stop it by
pressing the EMERGENCY OPERATION switch again.
Ok
No
After 30 seconds,
did outdoor fan stop? Replace the
deicer P.C. board.
Yes
Ok
No
Is there 220-230V AC between
2on the compressor
contactor(52C) and N
on the outdoor terminal
block?
Yes
Replace the compressor
contactor(52C).
No Make the connection
of wiring correct.
Is there 220-230V AC
between A1 and A2 on the
compressor contactor (52C)?
MU-A30ND
1Turn OFF the power supply.
2After 30 seconds, turn ON the power supply again.
3Operate the unit in COOL mode by pressing the
EMERGENCY OPERATION switch.
4Operate the unit for 1 minute or more and stop it by
pressing the EMERGENCY OPERATION switch again.
After 30 seconds, does
compressor stop ?
Yes
No
Is there 220-230V AC
between 3-Non the outdoor
terminal block?
Replace the indoor
electronic control P.C.
board.
No Make the connection
of wiring correct.
Is there 220-230V AC
between 3-Non the indoor
terminal block?
Yes
Reconnect the continuity
of indoor and outdoor
unit connection.
Is there 220-230V AC
between 1on the compressor
contactor(52C) and Non the
outdoor terminal block?
No
Yes
Reconnect the continuity
of indoor and outdoor
unit connection.
Yes
Replace the compressor
contactor(52C).
OK
No
After 30 seconds, does
outdoor fan motor stop ?
Yes
Is there 220-230V AC
between 3-Non the indoor
terminal block?
No
OK
Replace the indoor
electronic control P.C.
board.
Yes
No
Is there 220-230V AC
between 3-Non the outdoor
terminal block?
Make the connection
of wiring correct.
Is there 220-230V AC
between 3on the compressor
contactor(52C) and Non the
outdoor terminal block?
Yes
Replace the compressor
contactor(52C).
No
Yes
No
MU-A24ND - S2
Check of outdoor unit
B
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17
How to check mis-wiring
C
1. Turn OFF the power supply and disconnect only terminal
block 3of indoor/ outdoor connecting wire on indoor side.
2. Short-circuit terminal block N-3by lead wire.
3. Turn ON the power supply and press EMERGENCY OPERATION switch once.
When EMERGENCY OPERATION
is operated, is there 10V DC between both
ends of R601 on the deicer P.C. board?
(Refer to 8-5.)
However the stylus of a tester would be
between 5 ~10V.
Start
No
No
Is there 1V DC detected between both ends
of PS132 on the indoor electronic control P.C.
board ?
However, the stylus of a tester would be
between 0 and 20V.
•Turn ON the power supply.
•Press EMERGENCY OPERATION switch once.
Is this mis-wiring, poor contact,
or wire disconnection?
Make them sure.
Replace the indoor electronic
control P.C. board.
Is there 220-230V AC between L-N
on the outdoor terminal block?
No Check the outdoor power supply
and connection of wiring.
Is there 5V DC between J101 + -J401 - ?
(Refer to 8-5.)
Yes
No Replace the deicer P.C. board.
Yes
No Make the wiring between CN730
on the deicer P.C. board and
outdoor terminal block correct.
(Refer to 8-5.)
Replace the deicer P.C. board.
Yes
Yes
Yes
When the unit has mis-wiring, in 3 minutes,
OPERATION INDICATOR lamp on indoor unit
flash on and off at 0.5 second intervals. w
wShort circuit of JPG and JPS on the indoor electronic control
P.C. board enables self -check to be displayed in 3 seconds.
•Turn OFF the power supply.
•Disconnect the lead wire that terminal
block N-3is short-circuited.
•
Connect ON indoor/outdoor connecting wire.
Turn ON the power supply.
Refer to indoor unit
service manual.
When OPERATION INDICATOR lamp flashes ON and OFF in every 0.5-second.
Outdoor unit dose not operate.
MU-A30ND
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18
Check of outdoor thermistor
Measure
resistance
between CN 662
3and 4.
No
Yes
Replace the
thermistor.
Measure
resistance
between CN 662
1and 2.
Connect CN662.
Turn ON the power
supply and press
the EMERGENCY
OPERATION
switch.
Does the
resistances of
thermistor have
the characteristics
on 8-5.?
No
Yes
Does the unit operate
10 minutes or more?
Replace the deicer P.C.
board.
Ok W
Turn OFF the
power supply.
Discharge temperature
thermistor(RT62)
Ambient temperature
thermistor(RT63)
WDefective contact of the connector is considered.
wDisconnect the connectors CN662 from the deicer P.C. board. (Check the characteristics of each thermistor.)
E
When OPERATION INDICATOR lamp flashes 6-time.
Thermistors in the outdoor unit are abnormal.
Check of LEV (Expansion valve)
D
With remote controller set toward the indoor unit, press
OPERATE/ STOP(ON/ OFF) button and confirm one beep tone.
LEV operates in full-opening
direction.
Is LEV properly fixed to
the expansion valve?
Ok
Do you hear the expansion valve
"click, click·······"?
Do you feel the expansion valve
vibrate on touching it?
Does the resistance of LEV
have the characteristics
on 8-3?
No
Yes
Yes
Yes
No
No Properly fix LEV coil to
the expansion valve.
Replace the
deicer P.C. board.
NOTE : After check of LEV, do the undermentioned operation.
1. Turn OFF the power supply and turn ON again.
2. Press the RESET button on the remote controller.
Replace the LEV.
Remote controller model : KP0B
Turn ON the power supply.
1While pressing OPERATION
SELECT button on the remote
controller, press RESET button.
2Release RESET button to confirm
if all LCD in operation display
section of the remote controller is
displayed.
3Release OPERATION SELECT
button.
Remote controller model : KM04B
Turn ON the power supply.
1While pressing both OPERATION
SELECT button and TOO COOL
button on the remote controller at the
same time, press RESET button.
2First, release RESET button.
And release the other two buttons
after all LCD in operation display
section of the remote controller is
displayed after 3 seconds.
KP0B KM04B
AMPM
CLOCK
˚C
AMPM
AMPM
CLOCK
˚C
AMPM
When OPERATION INDICATOR lamp flashes 10-time.
Cooling mode dose not operate.
MU-A30ND
MU-A30ND
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19
Ok
Do you hear "click" from the
solenoid valve coil?
No
Yes
After 1minute or more has passed since the
compressor started, operate the solenoid valve coil
by heating or cooling the ambient temperature
thermistor.
(Refer to Solenoid valve control.)
Turn ON the power supply.
Operate the unit in COOL mode by pressing
the EMERGENCY OPERATION switch.
Yes
Check of the
solenoid valve coil.
(Refer to 8-3.)
Is there 220-230V AC
CN722 on the deicer
P.C. board?
Replace the
deicer P.C. board.
No
Turn ON the
solenoid valve coil.
(Refer to Solenoid
valve control.)
Check of solenoid valve coil
F
Outdoor unit repeats start and stop.
Solenoid valve control
The solenoid valve opens when the ambient temperature thermistor RT63 temperature reaches 49.2:or more after 1
minute has passed since the compressor turned on. Then, the solenoid valve maintains to open until the ambient tem-
perature thermistor RT63 temperature falls 46.2:or less.
NOTE: The solenoid valve remains to close when the ambient temperature thermistor RT63 temperature is 49.2:or
less after 1 minute has passed since the compressor turned on.
ON
OFF 46.2:49.2:
Ambient temperature thermistor
RT63 temperature
Solenoid valve
MU-A30ND
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20
8-5. Test point diagram and voltage
MU-A30ND
Outdoor deicer P.C. board
Varistor
(NR62)
Fuse
3.15A / 250V
}12V DC
}
5V
DC
+
+
Temperature(:)
Discharge temperature thermistor(RT62)
Resistance(k")
0 102030405060708090100110120
0
100
200
300
400
500
600
700
800
900
Ambient temperature thermistor (RT63)
-20 -10 0 10 20 30 40
0
10
20
30
40
50
60
70
80
90
100
Temperature(:)
Resistance(k")
CN662 1-2
Discharge temperature
thermistor (RT62)
(Refer to 8-4.E.)
CN662 3-4
Ambient tempera-
ture thermistor
(RT63)
(Refer to 8-4.E.)
LEV
connector
(CN724)
Fan motor
connector
(CN711)
Varistor (NR61)
CN7301-3
220-230-240V
AC
}
(Refer to
8-4. C.)
}
R601
10V DC
(Refer to
8-4. C.)
(Refer to
8-4. A or C.)
J101
J401
+
Solenoid
valve coil
(CN722)
OB405E.qxp 09.10.14 9:16 AM Page 20