Mitsubishi MSH-18NV- E4, MUH-18NV- E4 Service Manual

SPLIT-TYPE, HEAT PUMP AIR CONDITIONERS

SERVICE MANUAL

Wireless type
Model

Revision:

●Information for connecting MSH-18NV- with
MXZ-32RV- was described.

●TROUBLESHOOTING has been modified.

E1

E4

No. OB229

REVISED EDITION-A

MSH-18NV -

MSH-18NV -

E4

(WH)

· MUH-18NV -

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

E4E4

•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

E2E1

E4

E4

1

TECHNICAL CHANGES

MSH-18NV- became possible the connection to MXZ-32RV- as multi system units.

2

INDOOR UNIT

MSH-18NV -

PART NAMES AND FUNCTIONS

E4

E1E4

Front panel

(When the grille is open)

2

OUTDOOR UNIT

MUH-18NV -

E4

Air inlet

(back and side)

Piping

Drainage hose

Air outlet

Drain outlet

REMOTE CONTROLLER

MSH-18NV -

E4

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)

TEMPERATURE buttons

VANE CONTROL button

SWING button

OFF-TIMER button

RESET button

3

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
—

3

SPECIFICATION

E4

E4

wRefer to the Service Manual OB185 REVISED EDITION C when MSH-18NV- is connected with

MXZ-32NV- or MXZ-32NV- as multi system units.

E2E1

wRefer to the Service Manual OB227 REVISED EDITION-B when MSH-18NV- is connected with

MXZ-32RV- as multi system units.

NOTE:Test conditions

Cooling : Indoor DB27°C / WB19°C Heating : Indoor DB20°C /WB15.5°C

E1

Outdoor DB35°C / WB24°C Outdoor DB7°C / WB6°C

4

4

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

OUTLINES AND DIMENSIONS

MSH-18NV -

INDOOR UNIT

Unit: mm

E4

MUH-18NV -

OUTDOOR UNIT

E4

5

5

Sleeve

Locking lever

WIRING DIAGRAM

MSH-18NV -

INDOOR UNIT

SYMBOL

C11

DSAR

F11
F12

IC141

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

E4

MODEL WIRING DIAGRAM

TO OUTDOOR
UNIT
CONNECTING

12VDC

L
3

220-240V~

POWER
SUPPLY
CORD
~/N 220-240V
50Hz

CIRCUIT BREAKER

FOR MULTI SYSTEM

12VDC

TO OUTDOOR
UNIT
CONNECTING

NAME
INDOOR FAN CAPACITOR
SURGE ABSORBER
FUSE(3.15A)
THERMAL FUSE(93:)
HYBRID IC

TB

2

N

❈

BRN

❈
❈

❈

BLU

L
3
2
N

BRN

F12

WHT

BLU

BRN

DSAR

GRN/YLW

SYMBOL

HIC1

MF

MV
NR11
RT11

RED

BLU

2

BLU

GRN/YLW

RECEIVER
P.C.BOARD

REMOTE
CONTROLLER

1

LD1

CN CN
101

102

CN201

BLU

3
1

CN
151

ELECTRONIC CONTROL P.C BOARD

5

33

MV

DISPLAY
P.C.BOARD

NAME NAME
DC/DC CONVERTER
INDOOR FAN MOTOR(INNER FUSE)
VANE MOTOR
VARISTOR
ROOM TEMPERATURE THERMIST OR

❈

4

❈

3

HIC1

52C

TRANS

F11

SYMBOL

RT12

TB

52C

IC141

NR11

CN
112

CN
121

CN211

4

C11

2
1

CN
111

RT12

3

BRN
YLW
GRY

MF

WHT
RED
BLK

RT11

INDOOR COIL THERMISTOR
TERMINAL BLOCK
CONTACTOR

E4

MUH-18NV -

MODEL WIRING DIAGRAM

OUTDOOR UNIT

RT61

TB

12VDC

220-240V~

3

❈

RED

❈

2

WHT

N

❈

BLU

INDOOR UNIT

CONNECTING

FROM

GRN/YLW

SYMBOL

C1

C65

DSAR

F61

IC881

NOTE:1. Use copper conductors only (For field wiring).

COMPRESSOR CAPACITOR
OUTDOOR FAN CAPACITOR
SURGE ABSORBER
FUSE(2A)
DC/DC CONVERTER

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.

NAME

SYMBOL

MC

MF
NR61
RT61
SR61

CN730

1

WHT

❈

TAB21

❈

TAB20

DSAR

WHT

BLU

COMPRESSOR(INNER THERMOSTAT)
OUTDOOR FAN MOTOR(INNER THERMOSTAT)
VARISTOR
DEFROST THERMISTOR
SOLID STATE RELAY

CN661

F61

IC881

TRANS

X62

21S4

BLK

BLK

CN721

NR61

SR61

52C

CN720

X62

VLT

CN711

VLT

C65

RED
WHT

BLK

1
2
3
4

RED

ORN

WHT
BLK

1
2
3
4

DEICER P.C.BOARD

52C

NO

COM

C1

NAME NAME

WHT

RED

BLK

SYMBOL

TB

X62

21S4

52C

C

MC

S

R

TERMINAL BLOCK
REVERSING VALVE COIL RELAY
REVERSING VALVE COIL
CONTACTOR

1.Slide the sleeve.

2.Pull the wire while
pushing the locking
lever.

MF

6

6

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

w Height 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

0

10m

150

REFRIGERANT SYSTEM DIAGRAM

MSH-18NV -

INDOOR UNIT

Indoor
heat
exchanger

Room temperature
thermistor
RT11

E4

Indoor coil
thermistor
RT12

Distributor

Refrigerant pipe [15.88
(Option)

(with heat insulator)

Flared connection

Flared connection

Refrigerant pipe[ 6.35
(Option)

(with heat insulator)

Muffler

Stop valve
(with service port)

Accumulator

Strainer

Stop valve

Reversing valve
(4- way valve)

Capillary tube

[3.0o[2.0o500

Check
valve

Strainer

Compressor

Refrigerant flow in cooling
Refrigerant flow in heating

MUH-18NV -

OUTDOOR UNIT

Outdoor

Defrost
thermistor
RT61

heat
exchanger

Capillary tube

[3.0o[1.6o750

(2 pcs)

Reversing valve coil
(4-way valve coil)
Heating ON
Cooling OFF

E4

MAX. REFRIGERANT PIPING LENGTH

MAX. HEIGHT DIFFERENCE

ADDITIONAL REFRIGERANT CHARGE(R-22 : g)

7

Calculation : Xg=50g/m ✕ (A-7)m

7

Wet-and dry-bulb
thermometers

Wet-and dry-bulb
thermometers

PERFORMANCE CURVES

MSH-18NV -

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

(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.

E4

), 50Hz

Cooling

}

Heating

}

INDOOR UNIT

12.2

11.2

10.1

9.1

8.2

7.2

OUTDOOR UNIT

MSH-18NV - E4

8

28.0

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

25.9

23.7

21.6

19.4

17.2

15.1

12.9

NOTE:The above curves are for the heating operation without any frost.

MSH-18NV - E4

OUTDOOR LOW PRESSURE AND OUTDOOR UNIT CURRENT
COOL operation

11

Both indoor and outdoor unit are under the same temperature/humidity condition.

Dry-bulb temperature

20
25

Relative humidity(%)

50
60

30 70

22

Air flow should be set at MAX.

33

The 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)

(kgf/F•G)(MPa•G)

MUH-18NV -

Outdoor low pressure

Ambient temperature(˚C)
Ambient humidity(%)

E4

MUH-18NV -

Outdoor unit current (A)

Ambient temperature(˚C)
Ambient humidity(%)

E4

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

E4

220V/240V

10

11

MUH-18NV -

9

8

Outdoor unit current (A)

7

5 10152025

7

21

(:)

Ambient temperature(˚C)

9

8

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

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:

MICROPROCESSOR CONTROL

WIRELESS REMOTE CONTROLLER

MSH-18NV -

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.

E4

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.

• 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.

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.

Example

Previous operation

COOL mode of

“I FEEL CONTROL”

or COOL mode

10

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.

(4) The initial set temperature is decided by the initial room temperature.

Difference between room
temperature and set temperature
during operation.

1deg. 1.7deg.

2deg. 4deg.

Model

COOL mode of

"I FEEL CONTROL"

Initial room temperature Initial set temperature

26: or more

25: to 26:

Initial room temperature

24:

minus 2:

DRY mode of

"I FEEL CONTROL"

HEAT mode of

"I FEEL CONTROL"

23: to 25:

less than 23:

Initial room temperature
minus 2:

26:

❈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.

❈1

▲ TOO

COOL… To raise the set temperature 1~2 degrees(°C)

▼ TOO
WARM … To lower the set temperature 1~2 degrees(°C)

— COOL mode of “I FEEL CONTROL” —

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
Room temperature minus set temperature : Between 1 and 2 degrees
Room temperature minus set temperature : less than 1 degree

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.

····························Hi

·················Me

····························

Lo

11

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.

Operation chart

Example

Compressor
Outdoor fan

Indoor fan

—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

(continuously at set speed)

ON

ON

OFF

ON

Operation time chart

Example

Thermostat

Indoor fan

Outdoor fan
Compressor

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.

OFF

ON

OFF

OFF

8 min.

ON

ON

OFF

OFF

ON

ON

3 min.

OFF

OFF

4 min.

OFF

ON

ON

1 min.

ON

12

Difference between room
temperature and set temperature
during operation.

1deg. 1.7deg.

2deg. 4deg.

— HEAT mode of “I FEEL CONTROL” —

Released

Cold Air Prevention

18: 22:

Fan speed
Set speed
VLo or stop

High pressure protection

Released

56: 60:

ON

Outdoor fan

OFF

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

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

NOTE 1 During high pressure protection and for 4 minutes and 15 seconds after high pressure protection, defrosting of

NOTE 2 When connected to MXZ-32NV- or MXZ-32NV- or MXZ-32RV- outdoor unit, the indoor unit send the data

High pressure protection chart
Example

Indoor coil thermistor

RT12 temperature

60˚C

Outdoor fan motor
turn OFF

56˚C

Outdoor fan motor
turn ON

Outdoor fan motor

ON

OFF

ON

OFF

outdoor heat exchanger is not detected by the defrost thermistor RT61.

E1E2E1

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-32NV­or MXZ-32NV- ) or the service manual No.OB227 REVISED EDITION-B(Outdoor unit: MXZ-32RV- ).

13

E1E2

E1

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.

(3) Defrosting time chart

Defrost thermistor RT61
3: or more

-3: or less

Outdoor 52C
contactor(Compressor)

ON
OFF

X62
(Reversing valve coil)

ON
OFF

SR61
Outdoor fan

Defrost
counter

Indoor fan

ON
OFF

ON
OFF

ON
VLo
OFF

Indoor vane

Horizontal

Set position

30 sec.

NOTE1

15 sec.

30 sec.

5~15 sec.

Max 10 min.

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.

E2E1

• Refer to the Service Manual OB227 REVISED EDITION-B when MSH-18NV- is connected with
MXZ-32RV- as multi system units.

E1

E4

E4

14

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.

E2

• Refer to the Service Manual OB227 REVISED EDITION-B when MSH-18NV- is connected with MXZ-32RV­as multi system units.

E1E4

E1E4

(COOL / DRY)

5 sec.

Compressor

ON
OFF

ON

Reversing valve

OFF

ON

Outdoor fan

OFF

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.

(HEAT)
5 sec.

ON
OFF

ON
OFF

ON
OFF

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

15

SLEEP

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.)

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.

(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.

① In COOL and DRY operation

Vane angle is fixed to Angle 1.

➁ In HEAT operation

Vane angle is fixed to Angle 4.

16

(5) Dew prevention

Released

Cold Air Prevention

24: 28:

Angle 1

Horizontal vane

Set position

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 CONTROLbutton ( ) 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:.

Indoor coil thermistor RT12 temperature

NOTE:At initial in hysteresis this control works.

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.

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.

• Apower 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.

17

PROGRAM TIMER

EMERGENCY OPERATION switch

Press once <Cool>

Press again <Heat>

Press once again <Stop>

Operation Indicator lamp

• 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 1) The current time is 8:00 PM.

The unit turns off at 11:00 PM, and on at 6:00 AM.

(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.

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
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.

EMERGENCY COOL/HEAT MODE

with a set temperature of 24°C.

NOTE : Do not press the EMERGENCY OPERATION switch during normal operation.

18

9

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:.

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

SERVICE FUNCTIONS

MSH-18NV -

E4

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.)

9-3. 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.

}

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 :

NOTE : For remodelling, take out

the batteries at first.
After finish remodelling, put
back the batteries then
push the RESET button.

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.

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.

19

JR06

CN102

CN151

CN112 CN111CN121

CN101

BZ

SW

52C

IC101 RA102

IC141

CN211

C11CN201

9-5. AUTO RESTART FUNCTION

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.

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.

20

10 TROUBLESHOOTING

Lead wiring

Housing point

RESET button

MSH-18NV -

E4

10-1. 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 first turn off the remote controller to stop the main unit, and then after

confirming the horizontal vane is closed, turn off the breaker and / or disconnect the power plug.

(2) When removing the electronic control P.C. board, hold the edge of the board with care NOT to apply stress on the

components.

(3) When connecting or disconnecting the connectors, hold the housing of the connector. DO NOT pull the lead wires.

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) 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.

(3) When troubleshooting, refer to the flow chart on page 22 and the check table on page 23.

4. How to replace batteries

Weak batteries may cause the remote controller malfunction.
In this case, the remote controller can not be repaired only by the battery replacement. To operate the remote controller
normally, discharge the remote controller in the following order.
This remote controller has the RESET button. After refilling new batteries, press the RESET button with tip end of ball
point pen or the like, and then use the remote controller.

NOTE: INFORMATION FOR MULTI SYSTEM AIR CONDITIONER

(OUTDOOR UNIT : MXZ-32NV- , MXZ-32NV-

Multi system air conditioner (Outdoor unit: MXZ-32NV- , MXZ-32NV- , MXZ-32RV- ) can connect two or more
indoor units with one outdoor unit.

According to the capacity, two or more units can operate simultaneously.

•When you try to operate two or more indoor units with one outdoor unit simultaneously, one for the cooling and the
other for heating, the operation mode of the indoor unit that operates earlier is selected. The other indoor units that
will start the operation later cannot operate, indicating as shown in the figure below. In this case, please set all the
indoor units to the same operation mode.

•When indoor units starts the operation while the defrosting of outdoor unit is being done, it takes a few minutes
(max. 10 minutes) to blow out the warm air.

•In the heating operation, though indoor unit that does not operate may get warm or the sound of refrigerant flowing
may be heard, they are not malfunction. The reason is that the refrigerant continuously flows into it.

, MXZ-32RV- )

E1E2E1

Operation Indicator

21

E1E2E1

lighting

flashing

10-2. Instruction of troubleshooting

Start

Indoor unit
operates. Outdoor
unit doesn’t

Outdoor unit
operates in
only Test
Run
operation.

Check room
temperature
thermistor.

Outdoor unit
doesn’t
operate even
in Test Run
operation.

Refer to
“Check of
outdoor unit”
on page 26.

Refer to
“How to check
mis-wiring and
signal error
(when outdoor unit
doesn’t work)”
on page 27.❈1

D

E

Indoor unit
doesn’t receive
the signal from
remote
controller.

Refer to “Check
of remote controller
and receiver P.C.
board” on page 25.

1-time flash

Cause:indoor/outdoor unit

connecting

Trouble of mis-wiring

(

Trouble of the serial signal

B

Check indoor coil
thermistor. Refer
to“Test point
diagram and
voltage” on page

28.

Operation Indicator lamp
on the indoor unit is
flashing on and off.

2-time flash

2.5-second OFF

3-time flash

2.5-second OFF

Cause:Indoor unit
2-time-Room

temperature/Indoo
r coil thermistor
trouble

3-time-Indoor fan motor

trouble

Refer to
“Check of indoor
fan motor” on
page 25.

Indoor unit doesn’t
receive the signal from
remote controller.
Also, Operation Indicator
lamp doesn’t flash, when
the EMERGENCY
OPERATION switch is
pressed.

Refer to “Check of
indoor electronic control
P.C. board” on page 26.

6-time flash

Cause:outdoor unit
6-time-check the defrost

A

Check room temperature
thermistor. Refer to“Test
point diagram and
voltage” on page 28.

C

2.5-second OFF

thermistor

❈1<The case of the trouble of the serial signal>

When the power is turned off and then turned on again, the
indication shows “the trouble of mis-wiring.”

22

1. troubleshooting check table

Operation Indicator

Operation Indicator

❈ Before taking measures, make sure that the symptom reappears, for accurate troubleshooting.
Self check table

NO.

Abnormal

point

Indication

Symptom

Detect method

Check point

Mis-wiring

1

Serial

signal

Indoor coil

thermistor

2

Room
temperatur
e
thermistor

Indoor fan

3

motor

Defrost

4

thermistor

❈

Outdoor
power

5

system

❈

Outdoor
control

6

P.C. board

❈

Outdoor
control

7

P.C. board

❈

Outdoor
control

8

P.C. board

❈

The indication is shown only when the indoor unit connects with the outdoor unit MXZ-32NV- or MXZ-32NV- or
MXZ-32RV- .

0.5-second ON

0.5-second OFF

1-time flash

2.5-second OFF

2-time flash

2.5-second OFF

3-time flash

2.5-second OFF

6-time flash

2.5-second OFF

5-time flash

2.5-second OFF

7-time flash

10-time flash

lighting 2.5-second OFF
flashing

E1

2.5-second OFF

2.5-second OFF

Outdoor unit
does not run.

Outdoor unit
does not run.

Indoor fan motor
repeats 12
seconds ON and
3 minutes OFF.
When the indoor
fan breaks, the
fan motor keeps
stopping.

Outdoor unit
does not run

Outdoor unit
does not run

Outdoor unit
does not run

Outdoor unit
does not run

Outdoor unit
runs but the
indoor unit does
not run.

23

When serial signal stops for 4
to 5 seconds after 1st on of
52C relay by POWER turning
on.

When serial signal from
outdoor unit stops for 4 to 5
seconds.

Detect Indoor coil/room
temperature thermistor short
or open circuit every 8
seconds during operation.

When rotational frequency
feedback signal is not emit
during 12-second indoor fan
operation.

When the defrost thermistor
shorts or opens after the
compressor start-up.

When the compressor
operation is continuously three
times interrupted by over
current protection within 1
minute after start-up , it stops
operation.

The outdoor unit stops
operation when it cannot
properly read data in the
nonvolatile memory of the
outdoor control P.C.board.

When the indoor unit detects
drain abnormality and the
indoor coil temperature is too
low.

When the operation mode of
each rooms is set
COOL(includes DRY) and
HEAT at same time, it take
precedence the operation
mode runs first.

● Check wiring (visual check and
conductivity check).

● Check indoor electronic control
P.C.board.

● Check outdoor DEICER P.C. board.

● Check electrical parts.

● Check resistance of thermistor.

● Reconnect connector.

● Check indoor electronic control P.C.board.

● Disconnect connector CN211 and then

check connector CN121 - to make
sure rotational frequency feedback signal
of 1.5V or over exists.

● Check indoor electronic control P.C.
board.

● Check indoor fan motor.

● Reconnect connector.

● Check outdoor DEICER P.C. board.

● Check resistance of thermistor.

● Reconnect connector.

● Check the inverter output.

● Check the compressor.

● Check the outdoor control P.C.board.

● Check the drain pump.

● Check the drain sensor.

● Check LEV.

● Adjust the operation mode.

2

3

E2E1

2. Trouble criterion of main parts

P

~

BLK

R

MAIN

AUX

RED

S

C

WHT

MAIN

AUX

BLK

RED

WHTORN

P

MSH-18NV -

E4

Part name

Room
temperature
thermistor

Indoor coil
thermistor

Defrost
thermistor

Compressor

Indoor fan
motor

Check method and criterion

Measure the resistance with a tester.
(Part temperature 10°C ~ 30°C)

Normal

8k½ ~ 20k½

Opened or short-circuited

Abnormal

Measure the resistance with a tester.
(Part temperature –10°C ~ 40°C)

Normal

5k½ ~ 60k½

Opened or short-circuited

Abnormal

Measure the resistance between the terminals with a tester.
(Coil wiring temperature –10°C ~ 40°C)

Normal
C-R
C-S

0.90½ ~ 1.11½

1.79½ ~ 2.20½

Measure the resistance between the terminals with a tester.
(Coil wiring temperature10°C ~ 30°C)

Normal

Motor part

WHT-BLK

BLK-RED

176 ~ 192½
240 ~ 261½

Measure the voltage Power ON.

Normal

Sensor part

BRN-YLW

YLW-GRY

4.5 ~ 5.5V

(When fan revolved one time)

0V➔5V➔0V

(Approx.)

Abnormal

Opened or

short-circuited

Abnormal

Opened or

short-circuited

Abnormal

Remain 0V or 5V

FUSE

Figure

MAIN

AUX

BLK

YLW

BRN

GRY

RED

WHT

Outdoor fan
motor

Vane motor

Measure the resistance between the terminals with a tester.
(Coil wiring temperature –10°C ~ 40°C)

Normal
WHT-BLK
BLK-RED

102 ~ 126½

97.9 ~ 120½

Measure the resistance between the terminals with a tester.
(Part temperature10°C ~ 30°C)

Normal

358 ~ 388½

Opened or short-circuited

Abnormal

Abnormal

Opened or

short-circuited

PNK

ORN
RED

YLW

P

INNER PROTECTOR

ROTOR

BLU

24

A

Check of indoor fan motor

Indoor fan does not operate.

No

Reconnect the lead wires.

Check of remote controller and receiver P.C. board

B

Are lead wires connected?

Disconnect lead wires from connector CN211 on the indoor electronic control P.C. board.
Measure resistance between lead wires No.1 and No.4 and then No.1 and No.2.

Turn OFF the power supply.
Check connector CN211 visually.

Yes

Is resistance 0 (short circuit) or ° (open circuit)?

Yes ( 0 or ° )

Repair the indoor fan motor.

Is soldered point normal?

No

Yes

Insert screwdriver into air outlet to rotate indoor fan
motor slowly for 1 revolution or over, and measure
voltage No.2(+) and No.3(-) on CN121.

No

(others)

No

Does voltage repeat 0V DC and 5V DC?

Yes

Replace the indoor electronic control P.C. board.

Resolder it.

Indoor unit operates by pressing the EMERGENCY OPERATION switch, but does not operate with the remote
controller.

w Check if the remote controller is exclusive for this air conditioner.

Switch on the remote controller.

Is LCD display on the the remote
controller visible?

Yes

Remove the batteries and then set them
back. Check if the unit operates with the
remote controller.

Does the unit operate with the
remote controller?

Yes

OK

No
(not clear)

No

Measure the voltage between receiver P.C. board connector No.2
pressed.

Replace the batteries.(See page 21.)

Turn on a radio to AM and press switch on
the remote controller.

Is noise heard from radio?

Yes

Are there any fluorescent lights of

inverter or rapid-start type within
the range of 1m?

No

No

Yes

Replace the remote controller.

● Re-install the unit away from lights.

● Attach a filter on receiving part.

(+)

and No.1 when the remote controller button is

Is the voltage approx. 4V DC?

No(5V or 0V DC)

Replace the receiver P.C. board.

25

Yes

Replace the indoor electronic control P.C.
board.

Check of indoor electronic control P.C. board

Check the both “parts side” and “pattern
side” of indoor electronic control P.C.
board visually.

Replace the fuse.

Is fuse(F11) blown?

Be sure to check both fuse
and varistor in any case.

Replace the fan
motor.

Replace the indoor
electronic control
P.C. board.

Is winding
resistance of
fan motor 0 "?

Is winding
resistance of
vane motor 0 "?

No

Yes

Replace the vane
motor.

No

Yes

Yes

Is varistor(NR11) burnt?

Replace the varistor.

Yes

Turn OFF the power supply.
Remove indoor fan motor connector CN211 and
vane motor connector CN151 from the indoor electronic
control P.C. board and turn ON the power supply.

No

No

The unit doesn’t operate with the remote controller.
Also, the Operation Indicator lamp doesn’t light up
by pressing the EMERGENCY OPERATION switch.

No

Yes

Measure the
resistance between
CN201

1 on the

indoor electronic
control P.C. board
and

N on the terminal

block with the tester.

Is resistance approx. 0"?

Replace the fuse (F12).

CN201

1
2

L
N

F12

1

3

Terminal
block

Be sure to check both resistance.

No(°)

Yes

Turn OFF the
power supply.

Turn OFF the
power supply.

C

The unit doesn’t operate with the remote controller. Also, the OPERATION INDICATOR lamp doesn’t light up by
pressing the EMERGENCY OPERATION switch.

D

Check of outdoor unit

Compressor and outdoor fan do not operate.(Only indoor fan operates.)

Start

Press the EMERGENCY OPERATION switch.
3-minute time delay works.
Test run operation operates for 30 minutes.

Check the voltage to the terminal block of outdoor

unit. Is there 220-240V AC to the terminal block
between - ?

Check the voltage to the terminal block of indoor unit.

Is there 220-240V AC to the terminal block between

N

2

- ?

2

N

Replace the indoor

electronic control P.C.

No

No

Yes

Yes

Check the outdoor DEICER P.C.board at first, then check
the outdoor fan motor and the compressor.

Check the continuity of indoor and outdoor unit connection.

26

How to check mis-wiring and serial signal error (when outdoor unit does not work)

E

Start

3 min. later, when 52C contactor turns ON, what self-check result
is displayed on Operation Indicator lamp on the indoor unit? ❈1

Repair wiring.

Yes

1. Turn OFF the power supply and disconnect in-out connecting wire on the indoor side.

2. Short-circuit between indoor terminal block and .

3. Turn ON the power supply and press the EMERGENCY OPERATION switch.

Is there 20V DC between both ends of R132 when
52C contactor turns ON?
( By tester, the stylus is between 0 ~ 20V. )

Yes

1. Turn OFF the power supply.

2. Reconnect in-out connecting wire.

3. Turn ON the power supply.

1. Turn OFF the power supply.

2. Turn ON the power supply.

3. Press the

EMERGENCY OPERATION

switch.

Mis-wiring is indicated.(0.5-sec.ON, 0.5-sec.OFF)

Is there mis-wiring, poor contact, or wire disconnection?

No

3

N

No

❈1 Short circuit of JPG and JPS on the

indoor electronic control P.C. board
enables self-check to be displayed in 3
seconds.

Serial signal error is indicated.
(0.5-sec.ON, 2.5-sec.OFF)

Replace the indoor electronic control
P.C. board.

3 minutes later, when the EMERGENCY OPERATION switch is
pressed and 52C contactor turns ON, is there 220-240V AC between

N

the outdoor terminal block - ? ❈2

2

Yes

Is there 5V DC between

+

–

J8 -J9 on the outdoor DEICER P.C. board? ❈2

No

Yes

Is there 10V DC between both ends of R601? ❈2

No

(By tester, the stylus is between 5 ~10V)

Yes

Replace the outdoor DEICER P.C. board.

No

Rectify in-out connecting wire.

Check and rectify the fuse and the varistor
on the outdoor DEICER P.C. board.

Rectify in-out connecting wire.

❈2 While the serial signal error is indicated,

52C contactor alternates ON for about 10
seconds and OFF for 3 minutes.
Measure the voltage when 52C contactor
is ON.

27

TEST POINT DIAGRAM AND VOLTAGE
MSH-18NV -

E4

Fan motor power supply

Fuse 250V AC 3.15A

Power supply input

220-240V AC

}

R132

0~20V DC

C144

+

5V DC

}

C144

Room temperature
thermistor(RT11)

Indoor coil thermistor(RT12)
JPS

Time short mode point
JPG

Emergency operation switch

JPG

12V DC

}

+

JP41

P.C.board

28

MUH-18NV ­Outdoor deicer P.C. board

E4

Outdoor fan motor

220-240V AC

}

Reversing valve
coil
220-240V AC

}

R601
5~10V DC

}

+

INPUT

220-240V AC

}

Defrost thermistor(RT61)

}

Fuse 2A/250V

Defrost interval
time short pin

+

J9

}

J8

5V DC

}

12V DC

+

+

}

52C

12V DC

29

Jumper wire for change in
defrost setting (JPC, JPE)
(See page 19.)

11

(1)

(2)

1Slide the sleeve.
2Pull the terminal while

pushing the locking
lever.

1Hold the sleeve, and
pull out the terminal
slowly.

In the case of terminal with lock mechanism, detach the terminal as shown below.

<"Terminal with lock mechanism" Detaching points>

NOTE:

DISASSEMBLY INSTRUCTIONS

11-1. MSH-18NV -

E4

INDOOR UNIT

OPERATING PROCEDURE

1. Removing the front panel

(1) Remove the screw caps at the down of the front panel.

Remove the screws.

(2) Pull the panel down to your side slightly and unhook the

catches at the top.

PHOTOS

Photo 1

Front panel

Screws

2. Removing the electronic control P.C. board

(1) Remove the front panel. (Refer to 1)
(2) Remove the electrical cover.
(3) Remove the screw, remove the terminal cover.
(4) Remove the screw of terminal block.
(5) Unhook the catch of the lamp holder.
(6) Remove the receiver holder.
(7) Disconnect the connectors and the lead wire from 52C

contactor on the electronic control P.C. board and remove
the ground and the indoor coil thermistor.

(8) Remove the electronic control P.C. board.

Photo 2

30

Ground

Indoor coil thermistor

Screw

Terminal
block
screw

Indoor
electronic
control
P.C. board

OPERATING PROCEDURE

PHOTOS

3. Removing the electrical box

(1) Remove the front panel. (Refer to 1)
(2) Remove the electrical cover.
(3) Disconnect the connector of the indoor coil thermistor.
(4) Disconnect the motor connector (CN211 and CN121) and

the vane motor connector (CN151) on the electronic
control P.C. board.

(5) Remove the screw of the electrical box, remove the

electrical box.

4. Removing the indoor fan motor and the line flow fan

(1) Remove the front panel.
(2) Remove the electrical box.
(3) Unhook the catch on the both sides of the nozzle

assembly.
(4) Remove the nozzle assembly.
(5) Remove the screws of the bearing support.
(6) Remove the screw of the heat exchanger unhook the

catch.
(7) Lifting the heat exchanger, remove the bearing support.
(8) Remove the motor support.
(9) Loose the screw fixing the line flow fan, remove the line

flow fan.

)

(

Remove the screws of the motor band, remove the fan

10

motor.

Photo 3

Photo 4

Catch

Heat exchanger

screw

Bearing support
screws

screw

screw

Heat exchanger

31

Photo 5

Indoor fan motor

Fan
motor
screws

Line flow fan Motor band

11-2. MUH-18NV -

E4

OUTDOOR UNIT

OPERATING PROCEDURE PHOTOS

1. Removing the cabinet

(1) Remove the screws of the cabinet.
(2) Hold the down of the cabinet on the both side to remove

the cabinet.

Photo 1

Photo 2

Screws

2. Removing the deicer P.C. board

(1) Remove the service panel and the cabinet.
(2) Disconnect all the connectors and the terminals on the

deicer P.C. board.

(3) Remove the deicer P.C. board.

Service
panel

Photo 3

Screws

Screws

Deicer
P.C. board

32

Compressor
capacitor

Red lead wire

White lead wire

Black lead wire

Terminal
block

OPERATING PROCEDURE PHOTOS

3. Removing the outdoor fan motor

(1) Remove the cabinet. (Refer to 1)
(2) Disconnect the connector remove the clamp of fan motor

lead wire.
(3) Remove the propeller nut and remove the propeller fan.
(4) Remove screws securing the fan motor.

4. Removing the compressor

(1) Remove the cabinet. (Refer to 1)
(2) Remove the soundproof felt.
(3) Remove the terminal cover on the compressor.
(4) Remove the electrical assembly.

(Refer to 2)
(5) Release gas from the refrigerant circuit.
(6) Disconnect the welded part of the discharge pipe.
(7) Disconnect the welded part of the suction pipe.
(8) Remove nuts fixing the compressor.
(9) Remove the compressor.

Photo 4

propeller fan

Outdoor
fan motor

Propeller
fan nut

Photo 5

Set screws for
outdoor fan motor

Discharge
pipe

Lead clamps

Set screws for
outdoor fan motor

Terminal cover

Suction
pipe

33

Compressor

Compressor nuts

12 PARTS LIST

Symbol

in Wiring

Diagram

Q'ty/unit

3PCS/SET

RemarksPart No.

NO.

Part Name

MSH-18NV-

1
2
3
4
5
6
7

FRONT PANEL(WH)
GRILLE(WH)
BOX(WH)
AIR FILTER
INSTALLATION PLATE
SCREW CAP(WH)
LAMP PANEL(WH)

(WH)

E4

1
1
1
2
1
3
1

E02 138 000
E02 138 010
E02 143 234
E02 141 100
E02 141 970
E02 143 067
E02 168 007

E02 141 620
E02 138 667
E02 138 666

8
9

10

INDOOR HEAT EXCHANGER
UNION(LIQUID)
UNION(GAS)

{6.35
{15.88

1
1
1

MSH-18NV - (WH)

E4

12-1. INDOOR UNIT

STRUCTURAL PARTS

1

2

6

12-2. INDOOR UNIT

HEAT EXCHANGER

5

3

Optional parts
(See page 37.)

9

4

8

10

12-1. INDOOR UNIT STRUCTURAL PARTS

Part number that is circled is not shown in the illustration.

12-2. INDOOR UNIT HEAT EXCHANGER

34

MSH-18NV - (WH)

E02 139 426
E02 141 083

21
22

REMOTE CONTROLLER
REMOTE CONTROLLER HOLDER

1
1

E4

12-3. INDOOR UNIT

FUNCTIONAL PARTS
AND ELECTRICAL PARTS

SLEEVE
BEARING

11

810

15

12-4. ACCESSORY PARTS

AND REMOTE CONTROLLER

21 22

7

5

3

4

1

16

14

2

INDOOR COIL
THERMISTOR

9

12

6

17

ROOM TEMPERATURE
THERMISTOR

12-3. INDOOR UNIT FUNCTIONAL PARTS AND ELECTRICAL PARTS

Part number that are circled are not shown in the illustration.

Q'ty/unit

MSH-18NV-

(WH)

1
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1

NO.

Part No.

1

E02 143 235

2

E02 143 040

3

E02 141 702

4

E02 141 300

5

E02 001 505

6

E02 138 395

7

E02 444 452

8

E02 141 302

9

E02 141 303

10

E02 138 329

11

E02 141 509

12

E02 198 375

13

E02 336 385

14

E02 141 468

15

E02 001 504

16

E02 138 307

17

E02 138 308

18

E02 127 382

19

E02 205 381

20

E02 138 383

Part Name

NOZZLE(WH)
VANE(WH)
DRAIN HOSE
INDOOR FAN MOTOR
FAN MOTOR RUBBER MOUNT
POWER SUPPLY CORD
ELECTRONIC CONTROL P.C. BOARD
LINE FLOW FAN
VANE MOTOR
DISPLAY P.C. BOARD
BEARING MOUNT
TERMINAL BLOCK
VARISTOR
RECEIVER P. C. BOARD
SLEEVE BEARING
INDOOR COIL THERMISTOR
ROOM TEMPERATURE THERMISTOR
FUSE
THERMAL FUSE
SURGE ABSORBER

Symbol
in Wiring
Diagram

MF

MV

TB

NR11

RT12
RT11

F11
F12

DSAR

E4

Remarks

RA4V27 ­2PCS/SET

AUTO RESTART

3.15A
93:

12-4. ACCESSORY PARTS AND REMOTE CONTROLLER

35

Symbol

in Wiring

Diagram

Q'ty/unit

MUH-18NV-

Remarks

Part No. Part Name

E4

E02 141 232
E02 141 521
E02 141 245
E02 139 630
E02 139 515
E02 277 900
E02 277 290
E02 144 301
E02 141 501
E02 277 353
E02 004 340
E02 198 374
E02 139 936
E02 064 936
E02 138 506
E02 139 662
E02 150 661
E02 140 233
E02 095 382
E02 444 451
E02 440 310
E02 139 490
E02 444 961
E02 128 383
E02 214 642

1
2
3
4
5
6
7
8
9

10

11

12

13
14

15
16
17
18
19
20
21
22
23
24

CABINET
GRILLE
SERVICE PANEL
OUTDOOR HEAT EXCHANGER
MOTOR SUPPORT
COMPRESSOR
BASE
OUTDOOR FAN MOTOR
PROPELLER FAN
COMPRESSOR CAPACITOR
CONTACTOR
TERMINAL BLOCK
CAPILLARY TUBE
CAPILLARY TUBE
COMPRESSOR RUBBER SET
STOP VALVE(LIQUID)
STOP VALVE(GAS)
BACK PANEL
FUSE
DEICER P.C. BOARD
DEFROST THERMISTOR
REVERSING VALVE COIL
REVERSING VALVE
SURGE ABSORBER
CHECK VALVE

1
1
1
1
1
1
1
1
1
1
1
1
2
1
4
1
1
1
1
1
1
1
1
1
1

MC

MF

C1

52C

TB

F61

RT61

21S4

DSAR

PH-36VPET

RA6V50 -

55+/420V


{3.0✕{1.6✕750
{3.0✕{2.0✕500

4RUBBERS/SET

{ 6.35
{15.88

250V / 2A

NO.

MUH-18NV -

E4

12-5. OUTDOOR UNIT

STRUCTURAL PARTS

17

DEFROST
THERMISTOR

20

8

19

12

1

4

Part number that are circled are not shown in the illustration.

592

36

14

10

22

3

15
16

6

7

Deodorizing filter (Gray sponge type)

,

Air cleanig filter (White bellows type)

Model

Part No.

MAC-1100FT

MSH-18NV-

E4

Model

Part No.

MAC-1600DF

MSH-18NV-

E4

MUH-18NV -

E4

12-6. ACCESSORY PARTS

1

2

Q'ty/unit

MUH-18NV-

1
2
1

E4

[33
[16.2

NO.

Part No.

1

E02 444 704

2

E02 444 705

3

E02 444 706

Part Name

DRAIN SOCKET
DRAIN CAP
DRAIN CAP

Symbol

in Wiring

Diagram

13 OPTIONAL PARTS

13-1. AIR CLEANING FILTER

● AIR CLEANING FILTER removes fine dust of 0.01 micron from air by means of static electricity.

● Normal life of AIR CLEANING FILTER is 3 months. However, when it becomes dirty, replace it as soon as possible.

● Clogged AIR CLEANING FILTER may reduce the air conditioner capacity or cause frost on the air outlet.

● DO NOT reuse AIR CLEANING FILTER even if it is washed.

● DO NOT remove or attach AIR CLEANING FILTER during unit operation.

Remarks

13-2. DEODORIZING FILTER

● DEODORIZING FILTER removes ammonia and hydrogen sulphide emitted from tobacco, and odor of pets.

● Clean DEODORIZING FILTER every two weeks. If the filter is particularly dirty, clean the filter more often.

● For cleaning, soak the filter in warm water for a while, and then wash and rinse it. Dry the filter in the shade thoroughly.

● When the filter color is still dark even after cleaning, replace the filter with a new one.

Replace the filter at least once a year.

● DEODORIZING FILTER and AIR CLEANING FILTER can be attached on either side.

37

HEAD OFFICE MITSUBISHI DENKI BLDG.MARUNOUCHI TOKYO100-8310 TELEX J24532 CABLE MELCO TOKYO

CC

Copyright 1999 MITSUBISHI ELECTRIC ENGINEERING CO.,LTD
Issued in Apr. 1999. No.OB229 REVISED EDITION-A 294
Issued in Jan. 1999. No.OB229 305
Printed in Japan

New publication, effective Apr. 1999
Specifications subject to change without notice.