Mitsubishi Electric MSH-A24ND, MSH-A18ND-S1, MSH-A24ND-S1 Service Manual

SPLIT-TYPE, HEAT PUMP AIR CONDITIONERS

INDOOR UNIT

SERVICE MANUAL

Wireless type
Models

Revision B:

•Remote controller model has been changed.

•RoHS PARTS LIST has been added.
Please void OB427 REVISED EDITION-A.

No. OB427

REVISED EDITION-B

MSH-A18ND ­MSH-A24ND -

MSH-A18ND
MSH-A24ND

S1

S1

Outdoor unit service manual

MUH-A·ND Series (OB428)

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. SERVICE FUNCTIONS ······································8

8. TROUBLESHOOTING······································10

9. DISASSEMBLY INSTRUCTIONS ····················18

10. PARTS LIST······················································20

11. RoHS PARTS LIST···········································23

NOTE:

This service manual describes technical data of the indoor units.
RoHS compliant products have <G> mark on the spec name plate.
For servicing of RoHS compliant products, refer to the RoHS PARTS LIST (RoHS compliant).

TM

Grille

Air inlet

Remote controller

Remote control

receiving section

Air cleaning filter
(White bellows type)

Horizontal vane

Vertical vanes

Catechin air filter

(When the grille is opened)

Operation section

Display section

Emergency operation switch

Operation indicator lamp

Remote control

receiving section

Front panel

1
2
3
4
5
6
7
8

Installation plate
Installation plate fixing screw 4 o 25 mm
Remote controller holder
Fixing screw for 3 o 3.5 o 1.6 mm (Black)
Battery (AAA) for remote controller
Wireless remote controller
Air cleaning filter
Felt tape (Used for left or left-rear piping)

1
7
1
2
2
1
2
1

MSH-A18ND
MSH-A24ND

Revision A:

• Parts No. of 10.PARTS LIST has been revised.

Revision B:

•Remote controller model has been changed. (KP0A ➔ KM04A)
Both remote controllers can be used as alternative.

•RoHS PARTS LIST has been added.

1

MSH-18TN - ➔ MSH-A18ND ­MSH-24TN - ➔ MSH-A24ND -

1. Model name has been changed.

2. Grille design has been changed.

3. Unit size has been changed.(W 1,015a o H 320a o D 190a ➔ W 1,100a o H 325a o D 258a)

4. Electricity receiving unit has been changed from indoor unit to outdoor unit.

2

TECHNICAL CHANGES

S1S1

S1S1

PART NAMES AND FUNCTIONS

INDOOR UNIT

MSH-A18ND
MSH-A24ND

ACCESSORIES

2

REMOTE CONTROLLER

ON/OFF

TOO

COOL

PM

AM

TOO

WARM

ON/OFF

FAN

TOO

WARM

TOO

COOL

VANE

MODE

ECONO COOL

STOP

START

HR.

MIN.

WIDE VANE

LONG

I FEEL

COOL

HEAT

DRY

PM

CLOCK

AM

RESET CLOCK

Open the front lid.

Signal transmitting section

Operation display section

OPERATE /STOP
(ON /OFF) button

TEMPERATURE buttons

OPERATION SELECT button

FAN SPEED CONTROL button

OFF-TIMER button

HR. button

MIN. button

(TIME SET button)

ON-TIMER button

RESET button

ECONO COOL button

VANE button

(Horizontal vane button)

CLOCK SET button

LONG button

WIDE VANE button

(Vertical vane button)

Indication of remote controller
model is on back.

MSH-A18ND
MSH-A24ND

3

3

Indoor model

Function

Power supply

Air flow

(High/Med./Low)
Running current
Power input
Power factor
Model
Current
Winding
resistance (at 20:)
Dimensions WOHOD
Weight
Air direction
Sound level (High/Med./Low)
Fan speed (High/Med./Low)
Fan speed regulator
Remote controller model

K /h

A
W
%

A

"

mm

kg

dB

rpm

Single phase

220V, 60Hz

768/642/516

0.28
60
97

RC4N32-AA

0.28

WHT-BLK 205.5
BLK-RED 217.6
1,100O325O258

16

5

42/37/32

1,070/920/780

3

KP0A, KM04A

Cooling

Heating Cooling

954/822/684

1,280/1,130/970

Heating

954/834/726

1,280/1,150/1,020

Single phase

220V, 60Hz

0.37
81
99

RC4V40-AA

0.37

WHT-BLK 138.2
BLK-RED 159.0
1,100O325O258

16

5

47/42/37

3

KP0A, KM04A

Electrical

data

Fan

motor

Special

remarks

Capacity

MSH-A18ND MSH-A24ND

NOTE: Test conditions are based on ISO 5151.

SPECIFICATION

Cooling : Indoor DB27°C WB19°C Heating : Indoor DB20°C WB 15.5°C

Outdoor DB35°C WB(24°C) Outdoor DB 7°C WB 6°C

Indoor-Outdoor piping length : 5m

Test conditions are based on SSA 356/366.
Cooling : Indoor DB29°C WB19°C Heating : Indoor DB21°C

Outdoor DB46°C WB24°C Outdoor DB 7°C WB 6°C

Indoor-Outdoor piping length : 7.5m

4

4

258

162

19

58

47

7.5

315

255.547

2.5

98

173

98 173414.5 414.5

5

253

791

56

1068

1100

325

Air out

Air in

Insulation [28

Drain hose [16
(Connected part O.D)

Installation plate

Wall hole [75

Wireless remote controller

Installation plate

Indoor unit

{

Liquid line [ 6.35-0.5m
Gas line [ 12-0.43m
Insulation [ 50 O.D

[ 32 I.D

{

Liquid line [ 9.52-0.5m
Gas line [ 12-0.43m
Insulation [ 50 O.D

[ 32 I.D

for MSH-A18ND

for MSH-A24ND

OUTLINES AND DIMENSIONS

MSH-A18ND
MSH-A24ND

INDOOR UNIT

Unit: mm

5

5

WIRING DIAGRAM

MSH-A18ND

INDOOR UNIT

TO OUTDOOR
UNIT
CONNECTING

12V

220V~

SYMBOL

C11

HIC1

NOTES:

INDOOR FAN CAPACITOR

F11

FUSE (3.15A)
DC/DC CONVERTER

MF

FAN MOTOR (INNER PROTECTOR)

1.About the outdoor side 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

3
N
2

TB

NAME

RED
BLU
BRN

CN
151

GRN/YLW

MV2 MV2 MV1

: Connector

15

SYMBOL

NR11

RT11

CN201

3
2
1

TAB12

CN

102

CN

ELECTRONIC CONTROL P.C. BOARD

101

33

DISPLAY
P.C.BOARD

RECEIVER
P.C.BOARD

NAME
MV1
MV2

VANE MOTOR (HORIZONTAL)
VANE MOTOR (VERTICAL)
VARISTOR
ROOM TEMPERATURE THERMISTOR

HIC1

F11

REMOTE
CONTROLLER

NR11

SR141

SYMBOL

C11

RT12

SR141

TB

CN
112

CN
111

CN
121

1
3
4

CN211

3

RT12
RT11

BLK
GRY
YLW
BRN
WHT
RED

MF

NAME
INDOOR COIL THERMISTOR
SOLID STATE RELAY
TERMINAL BLOCK

MSH-A24ND

INDOOR UNIT

TO OUTDOOR
UNIT
CONNECTING

12V

220V~

SYMBOL

C11
F11

HIC1

MF

MV1

NOTES:

1.About the outdoor side 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

TB

3

RED

N

BLU

2

BRN

CN

151

MV2

15

MV1

GRN/YLW

MV2

NAME
INDOOR FAN CAPACITOR
FUSE (3.15A)
DC/DC CONVERTER
INDOOR FAN MOTOR (INNER PROTECTOR)
VANE MOTOR (HORIZONTAL)

: Connector

CN201

3
2
1

TAB12

CN
102

CN

ELECTRONIC CONTROL P.C. BOARD

101

33

DISPLAY
P.C.BOARD

SYMBOL

MV2
NR11
RT11
RT12
RT13

VANE MOTOR (VERTICAL)
VARISTOR
ROOM TEMPERATURE THERMIST OR
INDOOR COIL THERMISTOR (MAIN)
INDOOR COIL THERMISTOR (SUB)

RECEIVER
P.C.BOARD

NAME NAME

6

HIC1

F11

REMOTE
CONTROLLER

NR11

SR141

4
3
2
1

CN112

CN
121

1

C11

3
4

CN211

CN
111

SYMBOL

SR141

TB

RT13

RT12

BLK

3

GRY
YLW

MF

BRN
WHT
RED

RT11

SOLID STATE RELAY
TERMINAL BLOCK

6

Strainer

#50

Strainer

#50

REFRIGERANT SYSTEM DIAGRAM

MSH-A18ND

INDOOR UNIT

Indoor
heat
exchanger

Room temperature
thermistor
RT11

Indoor coil
thermistor
RT12

Distributor

Refrigerant pipe [12.7
(with heat insulator)

Flared connection

Flared connection

MSH-A24ND

INDOOR UNIT

Indoor
heat
exchanger

Indoor coil
thermistor
RT13(sub)

Room temperature
thermistor
RT11

Indoor coil
thermistor
RT12(main)

Distributor

Unit:mm

Refrigerant pipe [15.88
(with heat insulator)

Flared connection

Flared connection

Refrigerant pipe [6.35
(with heat insulator)

Refrigerant pipe [6.35
(with heat insulator)

Refrigerant flow in cooling
Refrigerant flow in heating

7

7

No. 1 unit
No. 2 unit
No. 3 unit
No. 4 unit

1 unit operation
No modification

–
–
–

2 units operation

Same as at left

Solder J1

–
–

3 units operation

Same as at left
Same as at left

Solder J2

–

4 units operation

Same as at left
Same as at left
Same as at left

Solder both J1 and J2

SERVICE FUNCTIONS

MSH-A18ND
MSH-A24ND

7-1. TIMER SHORT MODE

For service, set time can be shortened by short circuit of JPG and JPS on the electronic control P.C. board.
The time will be shortened as follows.

Set time : 1 minute ➔ 1-second
Set time : 3 minute ➔ 3-second (It takes 3 minutes for the compressor to start operation. However, the starting time is

shortened by short circuit of JPG and JPS.)

7-2. 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 modification, take out the batteries and press the OPERATE/STOP(ON/OFF) button 2 or 3 times at first.

After modification, put back the batteries then press the RESET button.

Remote controller model : KM04A

J2

J1

The P.C. board has the print “J1” and “J2”. Solder “J1” and “J2” according to the number of indoor unit as shown in Table 1.
After modification, press the RESET button.

Remote controller model : KP0A

J2

Table 1

How to set the remote controller exclusively for particular indoor unit

After you turn the breaker ON, the first remote controller that sends the signal to the indoor unit will be regarded as the
remote controller for the indoor unit.
The indoor unit only accepts the signal from the remote controller that has been assigned to the indoor unit once they are
set. The setting will be cancelled if the breaker has turned off, or the power supply has shut down.
Please conduct the above setting once again after the power has restored.

J1

7-3. 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. “Auto restart function” automatically starts operation in the same
mode just before the shutoff of the main power. However if the unit is operated in “I FEELCONTROL” mode before power

failure, the operation is not memorized. In “I FEEL CONTROL” mode, the operation is decided by the initial room tempera­ture.

8

How to release “AUTO RESTART FUNCTION”

JR07

IC152

CN151

CN112

CN111

CN121

SW1

IC101

RA102

C11

CN201

CN211

TAB12

1Turn off the main power for the unit.
2Pull out the electronic control P.C. board, the receiver P.C.

board and the display P.C.board. (Refer to 9-2.)

3Solder jumper wire to JR07 on the indoor

electronic control P.C. board. (Refer to 8-6.)

Operation

If the main power has been cut, the operation settings remain.

1
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 with the

remote controller.

•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

8

Lead wiring

Housing point

RESET button

Insert the negative pole
of the batteries first.
Check if the polarity of
the batteries is correct.

TROUBLESHOOTING

MSH-A18ND
MSH-A24ND

8-1. Cautions on troubleshooting

1. Before troubleshooting, check the following:

(1) Check the power supply voltage.
(2) Check the indoor/outdoor connecting wire for mis-wiring.

2. Take care of 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) Be sure to turn OFF the power supply before removing the front panel, the cabinet, the top panel, and the electronic

control P.C. board.

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

components.

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

3. Troubleshooting procedure

(1) First, check if the OPERATION INDICATOR lamp on the indoor unit is flashing on and off to indicate an abnormality.

To make sure, check how many times the abnormality indication is flashing on and off before starting service work.
(2) Before servicing, check that the connector and terminal are connected properly.
(3) When the electronic control P.C. board seems to be defective, check the copper foil pattern for disconnection and the

components for bursting and discolouration.
(4) When troubleshooting, refer to 8-2. and 8-3.

4. How to replace batteries

Weak batteries may cause the remote controller malfunction.
In this case, replace the batteries to operate the remote controller normally.
1 Remove the front lid and insert batteries.

Then reattach the front lid.

2 Press the RESET button with tip end of ball point

pen or the like, and then use the remote controller.

NOTE : If the RESET button is not pressed, the remote controller may not operate correctly.

10

8-2. Instruction of troubleshooting

Start

Indoor unit
operates.
Outdoor unit
doesn't
operate.

Outdoor unit
operates when
the EMERGENCY
OPERATION
switch is pressed.

Check room
temperature
thermistor.
Refer to 8-6.
"Test point
diagram and
voltage".

Outdoor unit
doesn't
operate
when the
EMERGENCY
OPERATION
switch is pressed.

Refer to
"Check of
outdoor unit".

Indoor unit
operates.
Outdoor unit
doesn't operate
normally.

Outdoor unit
doesn't
stop even
if indoor unit
stops.

Refer to
"Check of
outdoor unit".

Unit doesn't
operate
normal
operation in
COOL or
HEAT mode.

Refer to
"Check of
R.V. coil".

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

Indoor unit
operates when
the EMERGENCY
OPERATION
switch is pressed.

Refer to 8-5.B
"Check of
remote controller
and receiver
P.C. board".

OPERATION INDICATOR
lamp on the indoor unit is
flashing on and off.

Indoor unit
doesn't operate
when the
EMERGENCY
OPERATION
switch is pressed.

1. Check indoor /
outdoor
connecting wire.

2. Refer to 8-5.C
"Check of indoor
electronic control
P.C. board".

Flash on and
off at 0.5
second
intervals
Cause:
Indoor/
Outdoor unit

• Mis-wiring

Refer to
8-5. D
"How to
check
mis-wiring
(When
outdoor unit
doesn't
work)".

Refer to outdoor unit service manual.

-

2-time flash
Cause:
Indoor unit

• Trouble of
room temp­ erature/
indoor coil
thermistor

Check room
temperature
thermistor
and indoor
coil thermis­tor.
Refer to 8-6.
"Test point
diagram and
voltage".

3-time flash
Cause:
Indoor unit

• Trouble of
indoor fan
motor

Refer to
8-5. A
"Check of
indoor fan
motor".

4-time flash
Cause:
Indoor unit

• Trouble of
indoor unit
control
system

Replace the
indoor
electronic
control
P.C. board.

11

6-time flash
Cause:
Outdoor unit

• Trouble of
thermistor
in outdoor
unit

Refer to
"Check of
outdoor
thermistor".

7-time flash
Cause:
Outdoor unit

• Trouble of
outdoor
control
system

Replace the
deicer
P.C. board.

8-3. Troubleshooting check table

Operation Indicator

Lighted
Not lighted

No.

1

2

4

6

SymptomOperation indicator lamp

Condition

Correspondence

Mis-Wiring

Outdoor
thermistor

Outdoor
control
system

Indoor coil
thermistor

3 minutes after power supply turns ON, when
serial signal is not received.

<Thermistor short>
Thermistors are abnormal when they short
after compressor start-up.
<Thermistor open>
Thermistors are abnormal when they open
after compressor start-up.
However, discharge temperature thermistor is
abnormal when open circuit is detected more
than 10 minutes after compressor start-up.

When it cannot properly read data in the
nonvolatile memory of the deicer P.C. board,
outdoor unit stops.

• Shortage of refrigerant

• Check the deicer P.C.

board.
Refer to "Check of outdoor

thermistor".
Refer to outdoor unit service
manual.

• Check the deicer P.C. board.
Refer to outdoor unit service
manual.

• Refer to 8-5. D "How to check
mis-wiring ".

3

Indoor fan
motor

Abnormal

point

Outdoor unit
does not
operate.

Room
temperature
thermistor

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

• Refer to the characteristics of
main indoor coil thermistor,
sub indoor coil thermistor,
and room temperature
thermistor in 8-6.

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

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

• Refer to 8-5. A "Check of

indoor fan motor".

Indoor
control
system

When it cannot properly read data in the
nonvolatile memory of the indoor electronic
control P.C. board.

Outdoor unit
does not
operate.

Outdoor unit
does not
operate.

• Check the indoor electronic
control P.C. board.

Outdoor unit
does not
operate.

Outdoor unit
does not
operate.

5

0.5-second ON

0.5-second OFF

2-time flash

2.5-second OFF

3-time flash

2.5-second OFF

4-time flash

2.5-second OFF

6-time flash

2.5-second OFF

7-time flash

2.5-second OFF

• The following indication applies regardless of shape of the indicator.

• Before taking measures, make sure that the symptom reappears for accurate troubleshooting.

When the indoor unit has started operation and the following detection method has detected an abnormality
(the first detection after the power ON), the indoor electronic control P.C. board turns OFF the indoor fan motor with the
OPERATION INDICATOR lamp flashing.

· Flashing of the OPERATION INDICATOR lamp (on the left-hand side)
indicates possible abnormalities.

· The OPERATION INDICATOR lamp (on the left-hand side) is lighting
during normal operation.

12

Part name FigureCheck method and criterion

Indoor fan motor(MF)

MSH-A18ND

INNER FUSE
145: CUT OFF

MSH-A24ND

INNER
PROTECTOR
135i 5: OPEN

Color of

lead wire
WHT – BLK
BLK – RED

MSH-A18ND
198 " ~ 214 "
209 " ~ 227 "

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

Normal

8 k" ~ 20 k"

Room temperature
thermistor (RT11)

Indoor coil thermistor
(RT12(main), RT13(sub))

Horizontal vane
motor(MV1)
Vertical vane
motor(MV2)

Motor part

Sensor part

Measure the resistance between the terminals with a tester.
(Part temperature 10˚C ~ 30˚C)

Color of lead wire

BRN – YLW

YLW – GRY

Normal

4.5 ~ 5.5V

Measure the voltage power ON.

(When fan revolved one time)

0V➔5V➔0V

(Approx.)

Normal

282" ~ 306 "

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

BLK

RED

WHT

GRY

YLW

BRN

MAIN

AUX

FUSE

BLK

RED

WHT

GRY

YLW

BRN

MSH-A24ND
132 " ~ 144 "
152 " ~ 166 "

Normal

MSH-A18ND

MSH-A24ND

YLW

GRNORN

BRN

RED

ROTOR

MAIN

AUX.

P

:INNER PROTECTOR

P

8-4. Trouble criterion of main parts

MSH-A18ND
MSH-A24ND

13

8-5. Troubleshooting flow

When OPERATION INDICATOR lamp flashes 3-time.
Indoor fan motor doesn’t operate.

A

Check of indoor fan motor

Turn OFF the power supply.
Check connector CN211 visually.

No

Reconnect the lead wires.

Disconnect lead wires from connector CN211 on the indoor electronic control P.C. board.
Measure resistance between lead wires No.3 and No.4 and then No.1 and No.4.

Are lead wires connected?

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

Repair or replace the indoor fan motor.

Yes

Yes ( 0 or ∞ )

Is soldered point of the connector
correctly soldered?

Yes

Turn ON the power supply. Stop it if the unit operate.
Insert screwdriver into air outlet to rotate indoor fan
motor slowly for 1 revolution or over, and measure

No

(others)

voltage between No.2(+) and No.3(-) on CN121.

No

Does voltage repeat 0V DC and 5V DC?

Replace the indoor electronic control P.C. board.

No

Resolder it.

Yes

Indoor unit operates by pressing the EMERGENCY OPERATION switch, but doesn’t operate with the remote controller.

Check of remote controller and receiver P.C. board

B

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

Press OPERATE/STOP(ON/OFF)

button on the remote controller.

Is LCD display on the the remote
controller visible?

Yes

No
(not clear)

Replace the batteries.(Refer to 8-1.4.)

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

Does the unit operate with the
remote controller?

Yes

OK

No

Turn on a radio to AM and press
OPERATE/STOP(ON/OFF) button 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

Measure the voltage between receiver P.C. board connector CN301 No.1(+) and No.3(-) when the remote
controller button is pressed.

Is the voltage approx. 4V DC?

No(5V or 0V DC)

Replace the receiver P.C. board.

No

Yes

Yes

Replace the remote controller.

● Reinstall the unit away from lights.

● Attach a filter on receiving part.

Replace the indoor electronic control P.C.
board.

14

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

Check of indoor electronic control P.C. board

C

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

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.

Does the unit operate with the remote controller?
Does the OPERATION INDICATOR lamp light up
by pressing the EMERGENCY OPERATION switch?

Yes

Turn OFF the
power supply.

Replace the vane
motor.

Yes

Is winding
resistance of
vane motor 0 "?

No

Is winding
resistance of
fan motor 0 "?

Yes

Replace the fan
motor.

Turn OFF the
power supply.

No

No

Replace the fuse.

Yes

Is fuse(F11) blown?

No

Is varistor(NR11) burnt?

Yes

Replace the varistor.

Fuse (F11)

Indoor electronic
control P.C. board

No

Varistor (NR11)

Replace the indoor
electronic control
P.C. board.

15

1. Turn OFF the power supply (outdoor unit) and disconnect indoor and outdoor connecting
wire 3 on indoor side.

2. Short-circuit terminal block N-3 by lead wire.

3. Turn ON the power supply (outdoor unit) and press EMERGENCY OPERATION switch once.

During EMERGENCY OPERATION, is there
10V DC between both ends of R601 on the
deicer P.C. board?
(By tester, the stylus is between 5 ~10V.)

Refer to outdoor unit service manual.

Start

No

No

Is there 20V DC between both ends of
PS132 on the indoor electronic control P.C.
board ?
( By tester, the stylus is between 0 ~ 20V. )

• Turn ON the power supply. (outdoor unit)

• Press EMERGENCY OPERATION switch once.

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

Correct them.

Replace the indoor electronic
control P.C. board.

No

Replace the deicer P.C. board.

Yes

No

Make the wiring between CN730
on the deicer P.C. board and
outdoor terminal block correct.

Replace the deicer P.C. board.

Yes

Is there 5V DC between J205 + -J101 -
/ J101 + -J401 - on the deicer P.C. board?

Yes

Yes

After 3 minutes, mis-wiring is indicated
(0.5-second ON, 0.5-second OFF)
on OPERATION INDICATOR
lamp on indoor unit.w

w Short circuit of JPG and JPS on the indoor electronic control
P.C. board enables self -check to be displayed in 3 seconds.

• Turn OFF the power supply.

(outdoor unit)

• Connect ON indoor/ outdoor connecting
wire.

Turn ON the power supply. (outdoor unit)

When OPERATION INDICATOR lamp flashes ON and OFF in every 0.5-second.
Outdoor unit doesn’t operate.

How to check mis-wiring

D

16

8-6. Test point diagram and voltage

Indoor coil thermistor(RT12(main), RT13(sub))

Room temperature thermistor (RT11)

Resistance(k")

MSH-A18ND MSH-A24ND

Indoor electronic control P.C. board

Fuse (F11)
250V AC 3.15A

PS132

Fan motor power supply

Power supply input

}

220V AC

5V DC

}

+

Room temperature ther­mistor(RT11)

Indoor coil
thermistor(RT12(main))

MSH-A24ND

Indoor coil
thermistor(RT13(sub))

Receiver P.C. board

Release of “Auto restart function”
Solder jumper wire to JR07.
(Refer to 7-3.)

+

}

12V DC

Emergency operation
switch

Timer short mode point
(JPS, JPG)
(Refer to 7-1.)

17

9

(1) Slide the sleeve and check if there is a locking lever or not.

(2) The terminal with this connector has the
locking mechanism.

1Slide the sleeve.
2Pull the terminal while

pushing the locking
lever.

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

The terminal which has the locking mechanism can be detached as shown below.
There are two types ( Refer to (1) and (2)) of the terminal with locking mechanism.
The terminal without locking mechanism can be detached by pulling it out.
Check the shape of the terminal before detaching.

<"Terminal with locking mechanism" Detaching points>

Connector

Sleeve

Locking lever

DISASSEMBLY INSTRUCTIONS

MSH-A18ND MSH-A24ND
INDOOR UNIT

OPERATING PROCEDURE PHOTOS

1. Removing the front panel

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

Remove the screws.

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

catches at the top.

2. Removing the electronic control P.C. board, the receiver
P.C. board and the display P.C. board

(1) Remove the front panel. (Refer to 1.)
(2) Remove the screw of the electrical cover.

Remove the electrical cover.

(3) Remove the screws of the V.A. clamp.

Remove the V.A. clamp.
(4) Remove the screw of the terminal block.
(5) Remove the screws of the ground wire.
(6) Disconnect all the connectors and all the lead wires on the

electronic control P.C. board.
(7) Remove the R.L holder.
(8) Remove the electronic control P.C. board.
(9) Open the R.L holder, remove the receiver P.C. board and

the display P.C. board.

Screw of
the terminal
block

Photo 1

Photo 2

Front panel

Screws

Screws of the ground wire

R.L
holder

Receiver
P.C.
board

Fan motor
connectors

Vane motor
connector

Indoor
electronic
control
P.C.board

Screw of
the electrical

cover

Screw of the
V.A. clamp

18

OPERATING PROCEDURE

PHOTOS

3. Removing the electrical box

(1) Remove the front panel. (Refer to 1.)
(2) Remove the electrical cover. (Refer to 2.)
(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 screws of ground wire.
(6) Remove the fan motor lead wire and indoor coil thermistor

from the electrical box.
(7) Remove the lead wire of vane motor from the bottom of

electrical box.
(8) Remove the screw fixing the electrical box and remove the

electrical box.

4. Removing the vane motor

(1) Remove the front panel. (Refer to 1.)
(2) Remove the electrical cover. (Refer to 2.)
(3) Remove the lead wire of vane motor. (Refer to 3.)
(4) Remove the R.L. holder.
(5) Pull out the drain hose from the nozzle assembly and

remove the nozzle assembly.

(6) Remove the screws of the vane motor and disconnect the

connector.

(7) Remove the vane motor.

Photo 5

Screws of the
vane motor

Photo 3

Photo 4

Screws of the ground wire

Vane motors

Screw of the
electrical cover

Screw of the
electrical box

Screws
of the
vane
motor

Vane motor

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

(1) Remove the front panel. (Refer to 1.)
(2) Remove the electrical box. (Refer to 3.)
(3) Pull out the drain hose from the nozzle assembly and

remove the nozzle assembly.
(4) Remove the water cut.
(5) Slide the hole cover and remove the hole cover.
(6) Remove the hexagon socket set screw from the line flow

fan.
(7) Remove the screws fixing the fan motor and remove the

fan motor. (Be careful not to drop the fan motor because it

is heavy.)
(8) Remove the screws fixing the left side of the heat

exchanger.
(9) Lift the left side of the heat exchanger.
(

10

) Remove the line flow fan.

Photo 8

Hole
cover

Photo 6

Screws fixing
the left side
of the heat
exchanger

Photo 7

Indoor
coil
thermistor

Water cut

Screws fixing the fan motor

19

10

MSH-A24ND -

S1

MSH-A18ND -

S1

E02 527 970
E02 685 234
E02 888 000
E02 408 142
E02 685 067
E02 888 010
E02 534 100

E02 685 975
E02 888 007

INSTALLATION PLATE
BOX
FRONT PANEL ASSEMBLY
CATCH
SCREW CAP
GRILLE
CATECHIN AIR FIL TER
AIR CLEANING FILTER
CORNER BOX RIGHT
LAMP PANEL

Symbol

in Wiring

Diagram

Q'ty/unit

Including No.4,5,6

4PCS/ SET
3PCS/ SET

MAC-1700FT

RemarksPart No.

NO.

Part Name

1
2
3
4
5
6
7
8
9

10

1
1
1
4
3
1
2
2
1
1

1
1
1
4
3
1
2
2
1
1

E02 891 620
E02 893 620
E02 179 667
E02 527 666
E02 151 667

INDOOR HEAT EXCHANGER
INDOOR HEAT EXCHANGER
UNION (GAS)
UNION (GAS)
UNION (LIQUID)

{12.7
{15.88
{6.35

11

12
13

1

1
1

1

1

1

PARTS LIST (non-RoHS compliant)

MSH-A18ND
MSH-A24ND
10-1. INDOOR UNIT STRUCTURAL PARTS

1
2

3

10-2. INDOOR UNIT HEAT EXCHANGER

11

4
5

8 (See 10-5.)

6

7

10-1. INDOOR UNIT STRUCTURAL PARTS

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

9

12

13

10-2. INDOOR UNIT HEAT EXCHANGER

20

23
24

E02 529 426
E02 527 083

REMOTE CONTROLLER
REMOTE CONTROLLER HOLDER

1
1

1
1

KP0A,

KM04A

PARTS LIST (non-RoHS compliant)

MSH-A18ND
MSH-A24ND

10-3. INDOOR UNIT FUNCTIONAL PARTS AND

ELECTRICAL PARTS

1

20

19

10-4. ACCESSORY AND

REMOTE CONTROLLER

23

2

3

4

12

11

18

5
6

14

13

10

7

8

9

15

16

17

10-3. INDOOR UNIT FUNCTIONAL PARTS AND ELECTRICAL PARTS

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

1
1
1
1
1
1
1
1
1
1
1

2
1
1

1
1
1

1
1
1

1
1

Q'ty/unit

S1

MSH-A24ND -

NO.

E02 527 302

1

E02 408 509

2

E02 001 504

3

E02 408 702

4

E02 996 235

5

E02 685 040

6

E02 685 041

7

E02 A49 382

8

E02 817 385

9

E02 527 034

10

E02 A17 300

11

E02 527 300
E02 448 303

12

E02 408 303

13

E02 817 333

14

E02 527 333
E02 528 329

15

E02 527 468

16

E02 A17 452

17

E02 A18 452
E02 527 308

18

E02 814 375

19

E02 408 307

20

E02 527 307

21

E02 528 034

22

E02 529 034

Part Name

LINE FLOW FAN
BEARING MOUNT
SLEEVE BEARING
DRAIN HOSE
NOZZLE
VANE UPPER
VANE LOWER
FUSE
VARISTOR
VANE CRANK SET
INDOOR FAN MOTOR ASSEMBLY
INDOOR FAN MOTOR ASSEMBLY
VANE MOTOR (VERTICAL)
VANE MOTOR (HORIZONTAL)
MOTOR BAND
MOTOR BAND
DISPLAY P.C. BOARD
RECEIVER P.C. BOARD
ELECTRONIC CONTROL P.C. BOARD
ELECTRONIC CONTROL P.C. BOARD
ROOM TEMPERATURE THERMISTOR
TERMINAL BLOCK
INDOOR COIL THERMISTOR
INDOOR COIL THERMISTOR
VANE MOTOR SUPPORT SET (RIGHT)
VANE MOTOR SUPPORT SET (LEFT)

Symbol

in Wiring

Diagram

F11

NR11

MF

MF
MV2
MV1

RT11

TB

RT12

RT12, RT13

MSH-A18ND -

24

S1

1
1
1
1
1
1
1
1
1
1

1
2
1

1
1
1

1
1
1

1
1
1

RemarksPart No.

3.15A

RC4V32 ­Including RUBBER MOUNT

RC4V40 ­Including RUBBER MOUNT

RIGHT & LEFT
UP & DOWN

AUTO RESTART
Including No.16
AUTO RESTART
Including No.16

10-4. ACCESSORY AND REMOTE CONTROLLER

21

Air cleaning filter (White bellows type)

Model Part No.

MAC-1700FT

MSH-A18ND
MSH-A24ND

PARTS LIST (non-RoHS compliant)

10-5. 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 4 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.

22

11

MSH-A24ND -

S1

MSH-A18ND -

S1

E12 527 970
E12 685 234
E12 888 000
E12 408 142
E12 685 067
E12 888 010
E12 534 100

E12 685 975
E12 888 007

INSTALLATION PLATE
BOX
FRONT PANEL ASSEMBLY
CATCH
SCREW CAP
GRILLE
CATECHIN AIR FIL TER
AIR CLEANING FILTER
CORNER BOX RIGHT
LAMP PANEL

Symbol

in Wiring

Diagram

Q'ty/unit

Including No.4,5,6

4PCS/ SET
3PCS/ SET

MAC-1700FT

RemarksPart No.

NO.

Part Name

1
2
3
4
5
6
7
8
9

10

1
1
1
4
3
1
2
2
1
1

1
1
1
4
3
1
2
2
1
1

RoHS

G
G
G
G
G
G
G
G
G
G

E12 891 620
E12 893 620
E12 179 667
E12 527 666
E12 151 667

INDOOR HEAT EXCHANGER
INDOOR HEAT EXCHANGER
UNION (GAS)
UNION (GAS)
UNION (LIQUID)

{12.7
{15.88
{6.35

11

12
13

1

1
1

1

1

1

G
G
G
G
G

RoHS PARTS LIST (RoHS compliant)

MSH-A18ND
MSH-A24ND
11-1. INDOOR UNIT STRUCTURAL PARTS

1
2

3

11-2. INDOOR UNIT HEAT EXCHANGER

11

4
5

8 (See 11-5.)

6

7

11-1. INDOOR UNIT STRUCTURAL PARTS

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

9

12

13

11-2. INDOOR UNIT HEAT EXCHANGER

23

E12 527 302
E12 408 509
E12 001 504
E12 408 702
E12 996 235
E12 685 040
E12 685 041
E12 A49 382
E12 817 385
E12 527 034
E12 A17 300
E12 527 300
E12 448 303
E12 408 303
E12 817 333
E12 527 333
E12 528 329
E12 527 468
E12 A17 452
E12 A18 452
E12 527 308
E12 814 375
E12 408 307
E12 527 307
E12 528 034
E12 529 034

1
2
3
4
5
6
7
8
9

10
11
12

13
14

15
16

17
18

19
20

21
22

LINE FLOW FAN
BEARING MOUNT
SLEEVE BEARING
DRAIN HOSE
NOZZLE
VANE UPPER
VANE LOWER
FUSE
VARISTOR
VANE CRANK SET
INDOOR FAN MOTOR ASSEMBLY
INDOOR FAN MOTOR ASSEMBLY
VANE MOTOR (VERTICAL)
VANE MOTOR (HORIZONTAL)
MOTOR BAND
MOTOR BAND
DISPLAY P.C. BOARD
RECEIVER P.C. BOARD
ELECTRONIC CONTROL P.C. BOARD
ELECTRONIC CONTROL P.C. BOARD
ROOM TEMPERATURE THERMISTOR
TERMINAL BLOCK
INDOOR COIL THERMISTOR
INDOOR COIL THERMISTOR
VANE MOTOR SUPPORT SET (RIGHT)
VANE MOTOR SUPPORT SET (LEFT)

Symbol

in Wiring

Diagram

Q'ty/unit

3.15A

RIGHT & LEFT
UP & DOWN

RemarksPart No.

NO.

Part Name

F11

NR11

MF

MF
MV2
MV1

RT11

TB

RT12

RT12, RT13

1
1
1
1
1
1
1
1
1
1

1
2
1

1
1
1

1
1
1

1
1
1

1
1
1
1
1
1
1
1
1
1
1

2
1
1

1
1
1

1
1
1

1
1

RC4V32 ­Including RUBBER MOUNT

AUTO RESTART
Including No.16
AUTO RESTART
Including No.16

RC4V40 ­Including RUBBER MOUNT

MSH-A18ND -

S1

MSH-A24ND -

S1

RoHS

G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G

23
24

E12 529 426
E12 527 083

REMOTE CONTROLLER
REMOTE CONTROLLER HOLDER

1
1

1
1

KP0A, KM04AG

G

RoHS PARTS LIST (RoHS compliant)

MSH-A18ND
MSH-A24ND

11-3. INDOOR UNIT FUNCTIONAL PARTS AND

ELECTRICAL PARTS

1

20

19

11-4. ACCESSORY AND

REMOTE CONTROLLER

23

2

3

4

12

11

18

5
6

14

13

10

7

8

9

15

16

17

11-3. INDOOR UNIT FUNCTIONAL PARTS AND ELECTRICAL PARTS

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

24

11-4. ACCESSORY AND REMOTE CONTROLLER

24

Model Part No.

MAC-1700FT

MSH-A18ND
MSH-A24ND

RoHS PARTS LIST (RoHS compliant)

11-5. 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 4 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.

Air cleaning filter (White bellows type)

25

26

27

TM

HEAD OFFICE: TOKYO BLDG., 2-7-3, MARUNOUCHI, CHIYODA-KU, TOKYO 100-8310, JAPAN

CC

Copyright 2005 MITSUBISHI ELECTRIC ENGINEERING CO.,LTD
Distributed in May 2007. No.OB427 REVISED EDITION-B 6
Distributed in Feb. 2006. No.OB427 REVISED EDITION-A 106
Distributed in Nov. 2005. No.OB427 106
Made in Japan

New publication, effective May 2007
Specifications subject to change without notice.