Mitsubishi Electric MSH-18NV User manual

SERVICE MANUAL
SPLIT-TYPE, HEAT PUMP AIR CONDITIONERS
CONTENTS
1. TECHNICAL CHANGES ····································2
2. PART NAMES AND FUNCTIONS······················2
3. SPECIFICATION·················································4
4. OUTLINES AND DIMENSIONS ························ 5
5. WIRING DIAGRAM ············································6
6. REFRIGERANT SYSTEM DIAGRAM················7
7. PERFORMANCE CURVES································8
8. MICROPROCESSOR CONTROL ····················10
9. SERVICE FUNCTIONS ····································19
10. TROUBLESHOOTING······································21
11. DISASSEMBLY INSTRUCTIONS·····················30
12. PARTS LIST······················································34
13. OPTIONAL PARTS···········································37
Wireless type
Model
MSH-18NV - (WH) · MUH-18NV - E4E4
No. OB229
REVISED EDITION-A
MSH-18NV - E4
•Refer to the Service Manual OB185 REVISED EDITION C when MSH-18NV- is connected with
MXZ-32NV- or MXZ-32NV- as multi system units.
•Refer to the Service Manual OB227 REVISED EDITION-B when MSH-18NV- is connected with
MXZ-32RV- as multi system units.
E1
E4
E2E1
E4
Revision:
●Information for connecting MSH-18NV- with
MXZ-32RV- was described.
●TROUBLESHOOTING has been modified.
E1
E4

2
PART NAMES AND FUNCTIONS
2
INDOOR UNIT


,

(When the grille is open)
Front panel
MSH-18NV - E4
TECHNICAL CHANGES
MSH-18NV- became possible the connection to MXZ-32RV- as multi system units.
E1E4
1

3
Drainage hose
Piping
Air inlet
Air outlet
Drain outlet
(back and side)
OUTDOOR UNIT
MUH-18NV - E4
TEMPERATURE buttons
VANE CONTROL button
SWING button
OFF-TIMER button
RESET button
Signal transmitting section
Operation display section
OPERATE/STOP
(ON/OFF)button
OPERATION SELECT button
FAN SPEED CONTROL button
SLEEP button
ON-TIMER button
CLOCK SET button
HR. button
MIN. button
(TIMER SET button)
MSH-18NV - E4
REMOTE CONTROLLER

4
Capacity
Electrical data
Compressor
Indoor
fan motor
Outdoor
fan motor
Dimensions
Weight
Special remarks
Model
Function
Power supply
Coefficient of performance(C.O.P)
Capacity
Dehumidification
Air flow(Hi)
Power outlet
Running current
Power input
Auxiliary heater
Power factor
Starting current
Compressor motor current
Fan motor current
Model
Output
Winding resistance(at20:)
Model
Winding resistance(at20:)
Model
Winding resistance(at20:)
Indoor unit
Outdoor unit
Indoor unit
Outdoor unit
Air direction
Sound level
(Hi)
Fan speed
(Hi)
Fan speed
regulator
Refrigerant filling capacity(R-22)
Refrigerating oil (Model)
Thermistor
Width
Height
Depth
Width
Height
Depth
Indoor unit
Outdoor unit
Indoor unit
Outdoor unit
Indoor unit
Outdoor unit
RT11(at25:)
RT12(at25:)
RT61(at0:)
kW
R/h
K /h
A
A
W
A(kW)
%
A
A
A
W
"
"

"
mm
mm
mm
mm
mm
mm
kg
kg
dB
dB
rpm
rpm
kg
cc
k"
k"
k"
MSH-18NV - E4
Single phase,220-240V,50Hz
INDOOR 756 OUTDOOR 2142-2244
15
52-58
INDOOR 0.25 OUTDOOR 0.39
PH-36VPET
1600
C-R1.03 C-S2.04
RA4V27-EA or EF
WHT-BLK183.8 BLK-RED250.5
RA6V50-OF or OG
WHT-BLK116.4 BLK-RED111.0
1,015
320
190
850
605
290
14
54
5
42
52
1,180
810-845
4
1
1.65
900 (MS32N1)
10
10
33.18
Cooling
5.1
2.5
9.4-9.2
2,030-2,120
—
98-96
8.76-8.56
2.51-2.41
Heating
5.4
—
9.2-9.0
1,980-2,070
—
98-96
8.56-8.36
2.73-2.61
WMSH-18NV-
E4
(INDOOR UNIT)
Cooling Heating
Single phase,220-240V,50Hz
— —
—
756
10
0.28
60
—
97-89
—
—
0.25
—
—
—
—
RA4V27-EA or EF
WHT-BLK183.8 BLK-RED250.5
—
—
1,015
320
190
—
—
—
14
—
5
42
—
1,180
—
4
—
—
—
10
10
—
wRefer to the Service Manual OB185 REVISED EDITION C when MSH-18NV- is connected with
MXZ-32NV- or MXZ-32NV- as multi system units.
wRefer to the Service Manual OB227 REVISED EDITION-B when MSH-18NV- is connected with
MXZ-32RV- as multi system units.
E1
E4
E2E1
E4
SPECIFICATION
3
NOTE:Test conditions
Cooling : Indoor DB27°C / WB19°C Heating : Indoor DB20°C /WB15.5°C
Outdoor DB35°C / WB24°C Outdoor DB7°C / WB6°C

5
OUTLINES AND DIMENSIONS
4
Unit: mm
OUTDOOR UNIT
MSH-18NV - E4
MUH-18NV - E4
INDOOR UNIT
3 297
450
450
352438
254
20
60
40
150 648 217
5190
995
19077550
320
1015
17.5
160
56
4holes 11✕20 Indoor unit
Installation plate
Power supply cord
Lead to right 2m
Lead to left 1m
Wall hole [75
Installation plate
Liquid line [8-0.5m
Gas line [12-0.43m
Insulation [50 O.D
[28 I.D
Insulation [28
Drain hose [16
Air out
{
Air in
If the right/left sides or
back side is vacant, the
front has only to be 50cm
unobstructed.
If the front or right/left sides
are vacant, the top has only
to be 10cm unobstructed.
Drainage
3holes [33 Air out
Air in
Air in
Service panel
Liquid refrigerant
pipe joint
Refregerant pipe
(flared) [6.35
Gas refregerant
pipe joint
Refregerant pipe
(flared) [15.88
35-
30-
30
100
161
157
74
850
500
183
20 292
605 248
35
350
50
290
310 345
20
355
90
Drainage
hole [16.2

6
MSH-18NV - E4
MUH-18NV - E4
MODEL WIRING DIAGRAM
MODEL WIRING DIAGRAM
INDOOR UNIT
OUTDOOR UNIT
CIRCUIT BREAKER
N
2
12VDC L
50Hz
CORD
POWER
SUPPLY
~/N 220-240V
F11
NR11
TRANS
HIC1
12VDC
220-240V~
DSAR
BRN
GRN/YLW
LD1
DISPLAY
P.C.BOARD
RECEIVER
P.C.BOARD
33
101 102
CN CN
1
TO OUTDOOR
UNIT
CONNECTING
NBLU
GRN/YLW MV
151
CN
5
BLU 3
BLU
ELECTRONIC CONTROL P.C BOARD
REMOTE
CONTROLLER
3
BLU
BLU
RED 2
1
F12
2WHT
BRN
BRN
L
3
TB
CN201 CN211
121
CN
112
CN
3
4
RT11
BRN
YLW
RED
GRY
WHT
BLK
RT12
52C
IC141
C11
1
2
4MF
FOR MULTI SYSTEM
TO OUTDOOR
UNIT
CONNECTING
3
111
CN
❈
❈
❈❈
❈
❈
SYMBOL
RT12
TB
52C
SYMBOL
HIC1
MF
MV
NR11
RT11
SYMBOL
C11
DSAR
F11
F12
IC141
NAME NAME NAME
INDOOR FAN CAPACITOR
SURGE ABSORBER
FUSE(3.15A)
THERMAL FUSE(93:)
HYBRID IC
DC/DC CONVERTER
INDOOR FAN MOTOR(INNER FUSE)
VANE MOTOR
VARISTOR
ROOM TEMPERATURE THERMISTOR
INDOOR COIL THERMISTOR
TERMINAL BLOCK
CONTACTOR
CN720
52C
1
X62
21S4
CN721 MF
SR61
MC
WHT
WHT
WHT
VLT
VLT
COM
52C
TAB21
DSAR
ORN
WHT
WHT RED
RED
RED
WHT
BLU
BLU
RED
BLK
CN730
C65
DEICER P.C.BOARD
RT61
F61
IC881
X62
CN711
BLK
TRANS
TAB20
BLK
R
C
C1
FROM
INDOOR UNIT CONNECTING
GRN/YLW
12VDC TB
220-240V~
N
2
3
4
1
4
3
2
1
BLK
BLK
CN661
NO
NR61
S
3
2
❈
❈❈
❈
❈
NAME NAME NAME
SYMBOL
C1
C65
DSAR
F61
IC881
SYMBOL
TB
X62
21S4
52C
SYMBOL
MC
MF
NR61
RT61
SR61
COMPRESSOR CAPACITOR
OUTDOOR FAN CAPACITOR
SURGE ABSORBER
FUSE(2A)
DC/DC CONVERTER
COMPRESSOR(INNER THERMOSTAT)
OUTDOOR FAN MOTOR(INNER THERMOSTAT)
VARISTOR
DEFROST THERMISTOR
SOLID STATE RELAY
TERMINAL BLOCK
REVERSING VALVE COIL RELAY
REVERSING VALVE COIL
CONTACTOR
NOTE:1. For the outdoor electric wiring refer to the outdoor unit electric wiring diagram for servicing.
2. Use copper conductors only.(For field wiring)
3. Symbols below indicate.
: Terminal block, : Connector
WIRING DIAGRAM
5
Sleeve
Locking lever
NOTE:1. Use copper conductors only (For field wiring).
2. Symbols below indicate.
: Terminal block, : Connector
3. “❈”show the terminals with a lock mechanism, so they cannot be removed when you pull
the lead wire.
Be sure to pull the wire by pushing the locking lever (projected part) of the terminal with a finger.
1.Slide the sleeve.
2.Pull the wire while
pushing the locking
lever.

7
REFRIGERANT SYSTEM DIAGRAM
6
MSH-18NV - E4 MUH-18NV - E4
INDOOR UNIT OUTDOOR UNIT
Indoor
heat
exchanger
Room temperature
thermistor
RT11
Refrigerant pipe [15.88
(Option)
Flared connection
Flared connection
Indoor coil
thermistor
RT12
Refrigerant pipe[ 6.35
(Option)
Stop valve
Strainer
Check
valve
Capillary tube
[3.0o[2.0o500
Capillary tube
[3.0o[1.6o750
(2 pcs)
Compressor
Accumulator
Stop valve
(with service port)
Muffler
Outdoor
heat
exchanger
Defrost
thermistor
RT61
Reversing valve coil
(4-way valve coil)
Heating ON
Cooling OFF
Refrigerant flow in cooling
Refrigerant flow in heating
(with heat insulator)
Strainer
Distributor
Reversing valve
(4- way valve)
Model Piping size O.D : mm Length of connecting pipe : m
Refrigerant piping
Max. length : m
A
15
Indoor unit
Gas 0.43
Liquid 0.5
Gas
15.88
Liquid
6.35
Outdoor unit
Gas 0
Liquid 0
MSH-18NV - E4
Indoor
unit
wMax. Height
difference: 5m
A
Refrigerant Piping
Max. Length
wHeight difference should be within 5m
regardless of which unit, indoor or outdoor position is high.
Outdoor unit
Model
MSH-18NV - E4
Refrigerant piping length (one way)
Outdoor unit precharged
(up to 7m)
1650
15m
400
7m
010m
150
MAX. HEIGHT DIFFERENCE
ADDITIONAL REFRIGERANT CHARGE(R-22 : g)
MAX. REFRIGERANT PIPING LENGTH
Calculation : Xg=50g/m ✕ (A-7)m
(with heat insulator)

8
11.2
7.2
8.2
9.1
10.1
12.2
MSH-18NV - E4
7
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
Rated voltage : ±10% (198 ~ 264V), 50Hz
(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
(5) Indoor intake air dry-bulb temperature : °CDB
(6) Outdoor intake air wet-bulb temperature : °CWB
(7) Total input : W
Indoor air wet/dry-bulb temperature difference on the left side of the chart on this page and next page 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.
How to measure the indoor air wet-bulb/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 room.
5. Press the EMERGENCY OPERATION switch once(twice) to start the EMERGENCY COOL(HEAT) 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
}
}
Cooling
Heating
PERFORMANCE CURVES
Wet-and dry-bulb
thermometers Wet-and dry-bulb
thermometers
MSH-18NV - E4

9
28.0
25.9
23.7
21.6
19.4
17.2
15.1
12.9
MSH-18NV - E4
NOTE:The above curves are for the heating operation without any frost.
OUTDOOR LOW PRESSURE AND OUTDOOR UNIT CURRENT
COOL operation
11Both indoor and outdoor unit are under the same temperature/humidity condition.
22Air flow should be set at MAX.
Dry-bulb temperature Relative humidity(%)
20 50
25 60
30 70
33The unit of pressure has been changed to MPa on the international system of units(SI unit system).
The conversion factor is : 1(MPa • G) =10.2(kgf/ff• G)
15 20
50 25 60 30 70(%) 35(:)
0.3
0.4
0.5
0.6
0.7
18 32
220V/240V
7
6
5
4
3
15 20
50 25 60 30 70(%) 35(:)
6
7
8
9
10
11
18 32
220V/240V
MUH-18NV - E4
MUH-18NV - E4
Outdoor low pressure
Ambient temperature(˚C)
Ambient humidity(%) Ambient temperature(˚C)
Ambient humidity(%)
Outdoor unit current (A)
(kgf/F•G)(MPa•G)
HEAT operation
Condition indoor:Dry bulb temperature 20.0°C
Wet bulb temperature 14.5°C
Outdoor:Dry bulb temperature 7,15,20°C
Wet bulb temperature 6,12,14.5°C
MUH-18NV - E4
5 10152025
7
8
9
10
11
721
220V/240V
(:)
Outdoor unit current (A)
Ambient temperature(˚C)

10
MICROPROCESSOR CONTROL
8
Once the operation mode are set, the same operation mode
can be repeated by simply turning the OPERATE/STOP
(ON/OFF) button ON.
Indoor unit receives the signal with a beep tone.
When the system turns off, 3-minute time delay will operate to
protect system from overload and compressor will not restart
for 3 minutes.
8-1. “I FEEL CONTROL” ( ) OPERATION
(1) Press OPERATE/STOP (ON/OFF) button on the remote
controller. Operation Indicator lamp of the indoor unit
turns on with a beep tone.
(2) Press OPERATION SELECT button to set “I FEEL
CONTROL”( ). Then a beep tone is heard.
(3) The operation mode is determined by the room
temperature at start-up of the operation.
lighting
not lighting
Approx. 2 : 
or more
Difference
betweeen set
temperature
and room
temperature
Approx. 2 : 
or less
This shows that the
air conditioner is
operating to reach
the target temperature.
Please wait unit the
target temperature is
obtained.
This shows that the
room temperature is
approaching the
target temperature.
Operation state
Indication
Operation Indicator
Operation Indicator lamp
The operation indicator at the right side of the indoor
unit indicates the operation state.
INDOOR UNIT DISPLAY SECTION
WIRELESS REMOTE CONTROLLER
Example
Previous operation
COOL mode of
“I FEEL CONTROL”
or COOL mode
• Once the mode is fixed, the mode does not change by
room temperature afterwards.
• Under the ON-TIMER ( ) operation, mode is
determined according to the room temperature as the
operation starts.
• When the system is stopped with the OPERATE/STOP
(ON/OFF) button on the remote controller, and restarted
within 2 hours in “I FEEL CONTROL” ( ) mode, the
system operates in previous mode automatically
regardless of the room temperature.
Mode
COOL mode of
"I FEEL CONTROL"
DRY mode of
"I FEEL CONTROL"
HEAT mode of
"I FEEL CONTROL"
Initial room temperature
25:or more
23:to 25:
less than 23:
Example
Previous operation
COOL mode of
“I FEEL CONTROL”
or COOL mode
When the system is restarted after 2 hours and more, the
operation mode is determined by the room temperature
at start-up of the operation.
Restart
COOL mode of
“I FEEL CONTROL”
Restart
COOL or DRY or
HEAT mode of “I FEEL
CONTROL” that
determined by room
temperature at start-up
of the operation.
MSH-18NV - E4

11
Model
COOL mode of
"I FEEL CONTROL"
DRY mode of
"I FEEL CONTROL"
HEAT mode of
"I FEEL CONTROL"
Initial room temperature Initial set temperature
26:
26:or more
25:to 26:
less than 23:
23:to 25:
24:
Initial room temperature
minus 2:
Initial room temperature
minus 2:
❈1
❈1 When the system is restarted with the remote controller, the system operates with the previous set temperature
regardless of room temperature at restart.
The set temperature is calculated by the previous set temperature.
(5) TEMPERATURES buttons
In “I FEEL CONTROL” ( ) mode, set temperature is decided by the microprocessor based on the room temperature.
In addition, set temperature can be controlled by TOO WARM or TOO COOL buttons when you feel too cool or too warm.
Each time the TOO WARM or TOO COOL button is pressed,the indoor unit receives the signal and emits a beep tone.
• Fuzzy control
When the TOO COOL or TOO WARM button is pressed, the microprocessor changes the set temperature, considering
the room temperature, the frequency of pressing TOO COOL or TOO WARM button and the user’s preference to heat or
cool. So this is called “Fuzzy control”, and works only in “I FEEL CONTROL” mode.
In DRY mode of “I FEEL CONTROL”, the set temperature doesn’t change.
▲ TOO
COOL … To raise the set temperature 1~2 degrees(°C)
▼ TOO
WARM … To lower the set temperature 1~2 degrees(°C)
(4) The initial set temperature is decided by the initial room temperature.
1. Indoor fan speed control
Indoor fan operates at the set speed by FAN SPEED CONTROL button.
In AUTO the fan speed is as follows. Initial temperature difference Fan Speed
Room temperature minus set temperature : 2 degrees or more ····························Hi
Room temperature minus set temperature : Between 1 and 2 degrees ·················Me
Room temperature minus set temperature : less than 1 degree ···························· Lo
— COOL mode of “I FEEL CONTROL” —
Difference between room
temperature and set temperature
during operation.
1deg. 1.7deg.
2deg. 4deg.
2. Coil frost prevention
① Temperature control
When the indoor coil thermistor RT12 reads 3°C or below, the coil frost prevention mode starts immediately.
However, the coil frost prevention doesn’t work for 5 minutes since the compressor has started.
The indoor fan operates at the set speed and the compressor stops for 5 minutes.
After that, if RT12 still reads below 3°C this mode prolonged until the RT12 reads over 3°C.

Operation time chart
Example
3. Coil frost prevention
• The operation is as same as coil frost prevention during COOL mode of “I FEEL CONTROL”.
• Indoor fan operates at the set speed and the compressor stops for 5 minutes, because protection(Coil frost
prevention) has the priority.
However, when coil frost prevention works while the compressor is not operating, it’s speed becomes Lo.
Thermostat
Indoor fan
Outdoor fan
Compressor
ON
8 min. 1 min.
4 min.
3 min.
ON
OFF
OFF
OFF
OFF
OFF
ON
ON
ON
ON
ON
ON
12
Compressor
Outdoor fan OFF
ON
(continuously at set speed)
Indoor fan ON
ON
OFF
Operation chart
Example
—DRY mode of “I FEEL CONTROL”—
The system for dry operation uses the same refrigerant circuit as the cooling circuit.
The compressor and the indoor fan are controlled by the room temperature.
By such controls, indoor flow amounts will be reduced in order to lower humidity without much room temperature
decrease.
1. Indoor fan speed control
Indoor fan operates at the set speed by FAN SPEED CONTROL button.
However, in AUTO fan operation, fan speed becomes Lo.
2. The operation of the compressor and indoor/ outdoor fan
Compressor operates by room temperature control and time control.
Set temperature is controlled to fall 2°C from initial room temperature.
Indoor fan and outdoor fan operate in the same cycle as the compressor.
•When the room temperature is 23°C or over:
When the thermostat is ON, the compressor repeats 8 minutes ON and 3 minutes OFF.
When the thermostat is OFF, the compressor repeats 4 minutes OFF and 1 minute ON.
•When the room temperature is under 23°C.
When the thermostat is ON, the compressor repeats 2 minutes ON and 3 minutes OFF.
When the thermostat is OFF, the compressor repeats 4 minutes OFF and 1 minute ON.
OFF
OFF
OFF
② Time control
When the three conditions as follows have been satisfied for 1 hour and 45 minutes, compressor stops for 3 minutes.
a. Compressor has been continuously operating.
b. Indoor fan speed is Lo or Me.
c. Room temperature is below 26°C.
When compressor stops, the accumulated time is cancelled and when compressor restarts, time counting starts from the
beginning.
Time counting also stops temporarily when the indoor fan speed becomes Hi or the room temperature exceeds
26°C.However, when two of the above conditions (b.and c.) are satisfied again.Time accumulation is resumed.

Difference between room
temperature and set temperature
during operation.
1deg. 1.7deg.
2deg. 4deg.
13
— HEAT mode of “I FEEL CONTROL” —
1. Indoor fan speed control
(1) In AUTO the fan speed is as follows.
Set temperature minus room temperature: 2 degrees or more················································· Hi
Set temperature minus room temperature: Between 1 and 2 degrees····································· Me
Set temperature minus room temperature: less than 1 degree················································· Lo
(2) Cold air prevention control
The fan runs at set speed when the indoor coil thermistor RT12 temperature exceeds 22°C. The fan operates at VLo
when the temperature of indoor coil thermistor RT12 is below 18°C. But the fan stops when the indoor fan operates at
VLo and the room temperature is 15°C or less.
NOTE : At initial in hysteresis this control works.
(3) Warm air control.
When compressor starts in heating operation or after defrosting, the fan changes the speed due to the indoor coil
thermistor RT12 temperature to blow out warm air.
After releasing of cold air prevention, when the indoor coil temperature is 37°C or above, the fan speed shifts to the set
speed, and when the fan speed is changed by the remote controller, the fan speed is the set speed.
When the indoor coil temperature is less than 37°C, the fan speed is controlled by time as below.
<Time condition> <Indoor fan speed>
less than 2 minutes························Lo
2 minutes to 4 minutes···················Me
4 minutes or more··························Hi
The upper limit of the fan speed is the set speed.
If the thermostat turns off, this operation changes to flow soft control.
(4) Flow soft control
After the thermostat turns off, the indoor fan operates at VLo.
NOTE : When the thermostat turns on, the fan operates at the set speed. Due to the cold air prevention control, the fan
does not start at set speed until the indoor coil thermistor RT12 reads 22°C or more.
Initial temperature difference Fan speed
Released
Cold Air Prevention 18:22:
Fan speed
Set speed
VLo or stop
High pressure protection
Released 56:60:ON
Outdoor fan
OFF
2. High pressure protection
During heating operation, the outdoor fan motor is controlled by the temperature of indoor coil thermistor RT12 for excess
rise protection of compressor discharge pressure.
Outdoor fan OFF: 60°C
Outdoor fan ON : 56°C
High pressure protection chart
Example
Indoor coil thermistor
RT12 temperature
60˚C
56˚C
Outdoor fan motor
Outdoor fan motor
turn OFF
Outdoor fan motor
turn ON
ON ON
OFF OFF
NOTE 1 During high pressure protection and for 4 minutes and 15 seconds after high pressure protection, defrosting of
outdoor heat exchanger is not detected by the defrost thermistor RT61.
NOTE 2 When connected to MXZ-32NV- or MXZ-32NV- or MXZ-32RV- outdoor unit, the indoor unit send the data
for the temperature to the outdoor unit according to the indoor coil temperature.
For the further information, refer to the service manual No.OB185 REVISED EDITION C(Outdoor unit: MXZ-32NV-
or MXZ-32NV- ) or the service manual No.OB227 REVISED EDITION-B(Outdoor unit: MXZ-32RV- ).
E1E2
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14
NOTE1 • When the indoor coil thermistor reads above 18°C, indoor fan operates at VLo for 30 seconds.
• When the indoor coil thermistor reads 18°C or less, the indoor fan stops.
NOTE2 • Refer to the Service Manual OB185 REVISED EDITION C when MSH-18NV- is connected with
MXZ-32NV- or MXZ-32NV- as multi system units.
• Refer to the Service Manual OB227 REVISED EDITION-B when MSH-18NV- is connected with
MXZ-32RV- as multi system units.
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(3) Defrosting time chart
Defrost thermistor RT61
3: or more
-3:or less
Outdoor 52C
contactor(Compressor)
X62
(Reversing valve coil)
SR61
Outdoor fan
Defrost
counter
Indoor fan
Indoor vane
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
Horizontal
Set position
Max 10 min.
30 sec.
15 sec. 30 sec.
5~15 sec.
NOTE1
3. Defrosting
Defrosting of outdoor heat exchanger is controlled by DEICER P.C. board, with detection by the defrost thermistor RT61.
(1) Starting conditions of defrost
When all conditions of a) ~ c) are satisfied, the defrosting operation starts.
a) Under the heat operation, the compressor cumulative operation time exceeds 40 minutes without the defrosting
operation working.
b) The defrost thermistor RT61 reads - 3°C or less.
c) After releasing the high pressure protection 4 minutes and 15 seconds have elapsed.
(2) Releasing conditions of defrost
When the condition d) or e) is satisfied, the defrosting operation stops.
d) The defrost thermistor RT61 reads 3°C or more.
e) The defrosting time exceeds 10 minutes.
VLo

15
8-2. COOL ( ) OPERATION
(1) Press OPERATE/STOP (ON/OFF) button.
Operation Indicator lamp of the indoor unit turns on with a beep tone.
(2) Select COOL mode with the OPERATION
SELECT button.
(3) Press the TEMPERATURES button.
(TOO WARM or TOO COOL button) to select
the desired temperature.
The setting range is 16 ~ 31°C.
✻ Indoor fan continues to operate regardless of
thermostat’s OFF-ON at set speed.
✻ Coil frost prevention is as same as COOL
mode of “I FEEL CONTROL”.
8-3. DRY ( ) OPERATION
(1) Press OPERATE/STOP (ON/OFF) button.
Operation Indicator lamp of the indoor unit turns
on with a beep tone.
(2) Select DRY mode with the OPERATION
SELECT button.
(3) The microprocessor reads the room
temperature and determines the set
temperature. Set temperature is as shown on
the right chart.
Thermostat (SET TEMP.)does not work.
The other operations are same as DRY mode of
“I FEEL CONTROL”.
(4) DRY operation will not function when the room
temperature is 13°C or below.
(5) When DRY operation functions, the fan speed
is lower than cool operation.
8-4. HEAT ( ) OPERATION
(1) Press OPERATE/STOP (ON/OFF) button.
Operation Indicator lamp of the indoor unit turns on with a beep tone.
(2) Select HEAT mode with the OPERATION SELECT button.
(3) Press TEMPERATURES button (TOO WARM or TOO COOL button) to select the desired temperature.
The setting range is 16 ~ 31°C.
(4) Indoor fan speed control, high pressure protection, defrosting, reversing valve control are the same as HEAT mode of “I
4. Reversing valve control
Heating · · · · · ON
Cooling · · · · · OFF
Dry · · · · · · · · OFF
NOTE1 The Reversing valve reverses for 5 seconds right before start-up of the compressor.
NOTE2 • Refer to the Service Manual OB185 REVISED EDITION C when MSH-18NV- is connected with MXZ-32NV-
or MXZ-32NV- as multi system units.
• Refer to the Service Manual OB227 REVISED EDITION-B when MSH-18NV- is connected with MXZ-32RV-
as multi system units. E1E4
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ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
Compressor
Reversing valve
Outdoor fan
(COOL / DRY) (HEAT)
5 sec. 5 sec.

SLEEP
8-6. AUTO VANE OPERATION
(1) Vane motor drive
This model is equipped with a stepping motor for the horizontal vane. The rotating direction, speed, and angle of the
motor are controlled by pulse signals (approx. 12V) transmitted from indoor microprocessor.
(2) The horizontal vane angle and mode changes as follows by pressing the VANE CONTROL ( ) button.
8-5. FAN MOTOR CONTROL
(1) Rotational frequency feedback control
The indoor fan motor is equipped with a rotational frequency sensor, and outputs signal to the microprocessor to feed
back the rotational frequency. Comparing the current rotational frequency with the target rotational frequency
(Hi,Me,Lo,SLEEP), the microprocessor controls IC141 and adjusts fan motor electric current to make the current
rotational frequency close to the target rotational frequency. With this control, when the fan speed is switched, the
rotational frequency changes smoothly.
(2) Fan motor lock-up protection
When the rotational frequency feedback signal has not output for 12 seconds, (or when the microprocessor cannot
detect the signal for 12 seconds) the fan motor is regarded locked-up. Then the electric current to the fan motor is shut
off. 3 minutes later, the electric current is applied to the fan motor again. During the fan motor lock-up, the Operation
Indicator lamp flashes on and off to show the fan motor abnormality. (See page 23.)
16
① In COOL and DRY operation
➁ In HEAT operation
Vane angle is fixed to Angle 1.
Vane angle is fixed to Angle 4.
(3) Positioning
The vane is once pressed to the vane stopper below to confirm the standard position and then set to the desired angle.
Confirming of standard position is performed in case of follows.
(a) When the OPERATE/STOP (ON/OFF) button is pressed.
(b) When the vane control is changed from AUTO to MANUAL.
(c) When the SWING is finished.
(d) When the test run starts.
(e) When the power supply turns ON.
(4) VANE AUTO ( ) mode
In VANE AUTO mode, the microprocessor automatically determines the vane angle and operation to make the optimum
room-temperature distribution.

17
(5) Dew prevention
During COOL or DRY operation at vane Angle 4 or 5 when the compressor cumulative operation time exceeds 1 hour,
the vane angle automatically changes to Angle 1 for dew prevention.
(6) SWING MODE ( )
By pressing the SWING button ( ) the horizontal vane swings vertically. The remote controller displays “ ”. SWING
mode is cancelled when the SWING button or VANE CONTROL button ( ) is pressed or the mode is changed to other
mode.
(7) Cold air prevention in HEAT operation
When any of the following conditions occurs in HEAT operation, the horizontal vane angle changes to Angle 1
automatically to prevent cold air blowing on users.
① Compressor is not operating.
➁ Defrosting is performed.
➂ Indoor coil thermistor RT12 reads 24:or below.
➃ Indoor coil thermistor RT12 temperature is raising from 24°C or below, but it does not exceed 28:.
8-7. SLEEP MODE ()
• When the SLEEP button ( ) is pressed, the indoor fan speed drops and the air flow sound from the indoor
unit is decreased.
• The indications of the remote controller are “ ” and “ ”.
• When the FAN SPEED CONTROL button ( ) or the SLEEP button ( ) or mode change button is pressed during
the SLEEP mode, the SLEEP mode is released.
Released
Cold Air Prevention 24:28:Angle 1
Horizontal vane
Set position
Indoor coil thermistor RT12 temperature
NOTE:At initial in hysteresis this control works.
8-8. TIMER OPERATION
1. How to set the timer
(1) Press OPERATE/STOP (ON/OFF) button to start the air conditioner.
(2) Check that the current time is set correctly.
NOTE : Timer operation will not work without setting the current time. Initially “AM0:00” blinks at the current time display of
TIME MONITOR, so set the current time correctly with CLOCK SET button.
(3) Press TIMER CONTROL button to select the operation.
“ ” button... AUTO START operation (ON timer)
“ ” button... AUTO STOP operation (OFF timer)
(4) Press HR. and MIN. button to set the timer. Time setting is 10-minute units.
HR. and MIN. button will work when “ ” or “ ” mark is flashing.
These marks disappear in 1 minute.
After setting the ON timer, check that OPERATION INDICATOR lamp of the indoor unit lights.
NOTE1 : Be sure to place the remote controller at the position where its signal can reach the air conditioner even during
TIMER operation, or the set time may deviate within the range of about 10 minutes.
NOTE2 : Reset the timer in the following cases, or the set time may deviate and other malfunctions may occur.
• A power failure occurs.
•The circuit breaker functions.
2. Cancel
TIME setting can be cancelled with the TIMER CONTROL buttons. (“ ” or “ ”)
To cancel the ON timer, press the “ ” button.
To cancel the OFF timer, press the “ ” button.
TIME is cancelled and the display of set time disappears.

PROGRAM TIMER
(Example 1) The current time is 8:00 PM.
The unit turns off at 11:00 PM, and on at 6:00 AM.
• The OFF timer and ON timer can be used in combination.
• “ ” and “ ” display shows the order of the OFF timer and ON timer operation.
(Example 2) The current time is 11:00 AM.
The unit turns on at 5:00 PM, and off at 9:00 PM.
NOTE : TIMER setting will be cancelled by power failure or breaker functioning.
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8-9. EMERGENCY-TEST OPERATION
When the remote controller is missing, has failed or the batteries run down, press the EMERGENCY OPERATION switch
on the front of the indoor unit. The unit will start and the Operation Indicator lamp will light.
The first 30 minutes of operation is the test run operation. This operation is for servicing. The indoor fan runs at high notch
and the system is in continuous operation. (The thermostat is ON.)
After 30 minutes of test run operation the system shifts to EMERGENCY COOL/HEAT MODE with a set temperature of 24°C.
The fan shifts to Me notch.
This operation continues until the EMERGENCY OPERATION switch is pressed again or the unit receives any signal from
the remote controller. In case of latter normal operation will start.
The coil frost prevention works even in this operation, and defrosting too.
In the test run or emergency operation, the horizontal vane operates in VANE AUTO mode.
NOTE : Do not press the EMERGENCY OPERATION switch during normal operation.
EMERGENCY OPERATION switch
Press once <Cool>
Press again <Heat>
Press once again <Stop>
Operation Indicator lamp

19
9SERVICE FUNCTIONS
9-1. COMPULSORY DEFROSTING MODE FOR SERVICE
By short circuit of the connector JP607 and R853 on the outdoor deicer P.C. board, defrosting mode can be accomplished
regardless of the defrost interval restriction. See page 29.
Defrost thermistor RT61 must read below -3°C.
9-2. CHANGE IN DEFROST SETTING
<JPC> when the JPC wire of the deicer P.C. board is cut, the defrost interval time will be changed. (See page 29.)
<JPE> when the JPE wire of the deicer P.C. board is cut, the defrost temperature will be changed. (See page 29.)
9-4. P.C. BOARD MODIFICATION FOR INDIVIDUAL OPERATION
A maximum of 4 indoor units with wireless remote controllers can be used in a room.
In this case, to operate each indoor unit individually by each remote controller, P.C. boards of remote controller must be
modified according to the number of the indoor unit.
How to modify the remote controller P.C. board
Remove batteries before modification.
The board has a print as shown below :
Jumper wire
JPC
JPE
Change point
Defrost interval time changes from 40 minutes to 15 minutes
Deforst start temperature changes from -3:to 0:
Deforst finish temperature changes from 3:to 10:.
9-3. TIMER SHORT MODE
For service, set time can be shortened by short circuit of JPG and JPS the electronic control P.C. board.
The time will be shortened as follows.
3-minutes delay : 3-minutes ➔ 3-seconds.
AUTO START : 1 hour ➔ 1-minute
AUTO STOP : 1 hour ➔ 1-minute Short the connector during the timer mode.
}
The P.C.board has the print “J1” and “J2”.Jumper wires are mounted to each “J1” and “J2”.Cut J1 and J2 according to the
number of indoor unit as shown in Table. 1.
After modification, push the reset button.
No. 1 unit
No. 2 unit
No. 3 unit
No. 4 unit
1 unit operation
No modification
–
–
–
2 units operation
Same as at left
Cut J1
–
–
3 units operation
Same as at left
Same as at left
Cut J2
–
4 units operation
Same as at left
Same as at left
Same as at left
Cut both J1 and J2
Table.1
NOTE : At power supply failure or installation, indoor unit deletes the memory about remote controller. When
the power supply is turned on and indoor unit receives the first signals from the remote controller, the
remote controller number is designated as the indoor unit number. Therefore at and after the second
time indoor unit accepts the remote controller of the initial setting number.
At setting - error, turn the power supply off to cancel the individual operation and then turn the power
supply on to restart the setting.
NOTE : For remodelling, take out
the batteries at first.
After finish remodelling, put
back the batteries then
push the RESET button.
MSH-18NV -
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20
When the indoor unit is controlled with the remote controller, the operation mode, set temperature, and the fan speed are
memorized by the indoor electronic control P.C.board. The “AUTO RESTART FUNCTION” sets to work the moment power
has restored after power failure.Then, the unit will restart automatically. However if the unit is operated in “I FEEL
CONTROL” mode before power failure, the operation is not memorized. In “I FEEL CONTROL” mode, the operation is
decided by the initial room temperature.
How to set “AUTO RESTART FUNCTION”
1Turn off the main power for the unit.
2Remove the electronic control P.C. board and the display P.C.board. (See page 30.)
3Cut the RESISTOR JR06 on the indoor electronic control P.C.board.
JR06
CN102
CN151
CN112 CN111 CN121
CN101
BZ
SW
52C
IC101 RA102
IC141
CN211
C11CN201
Operation
1If the main power (220/240V AC) has been cut, the operation settings remain.
2After the power is restored, the unit restarts automatically according to the memory.(However, it takes at least 3 minutes
for the compressor to start running.)
NOTE
•The operation settings are memorized when 10 seconds have passed after the remote controller was operated.
•If main power is turned off or a power failure occurs while AUTO START/STOP timer is active ,the timer setting is
cancelled.
•If the unit has been off with the remote controller before power failure, the auto restart function does not work as the
power button of the remote controller is off.
•To prevent breaker off due to the rush of starting current, systematize other home appliances not to turn on at the same
time.
•When some air conditioners are connected to the same supply system, if they are operated before power failure, the
starting current of all the compressors may flow simultaneously at restart.
Therefore, the special counter-measures are required to prevent the main voltage-drop or the rush of the starting current
by adding to the system that allows the units to start one by one.
9-5. AUTO RESTART FUNCTION