Mitsubishi MCFZ-A12WV-E1, MCFZ-A18WV-E1, MCFZ-A24WV-E1 Service Manual

SERVICE MANUAL

(When installed on the ceiling)

(When installed on the floor)

FLOOR AND CEILING TYPE AIR CONDITIONERS

Wireless type
Models

E1

E1

(WH)
(WH)

MCFZ-A12WV ­MCFZ-A18WV -

Revision A:

● MCFZ-A18WV- and MCFZ-A24WV­have been added.

Please void OB344.

No. OB344

REVISED EDITION-A

E1E1

MCFZ-A24WV -

E1

Indication of
model name

MCFZ-A12WV ­MCFZ-A18WV ­MCFZ-A24WV -

(WH)

CONTENTS

1. PART NAMES AND FUNCTIONS······················2

2. SPECIFICATION·················································4

3. NOISE CRITERIA CURVES·······························5

E1
E1
E1

4. OUTLINES AND DIMENSIONS·························6

5. WIRING DIAGRAM ············································6

6. REFRIGERANT SYSTEM DIAGRAM················8

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

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

9. DISASSEMBLY INSTRUCTIONS ····················19

10. PARTS LIST······················································21

11. OPTIONAL PARTS···········································23

NOTE:

• This service manual describes technical data of indoor units.

• As for outdoor units MUZ-A12YV - and MUZ-A12YVH - ,
refer to the service manual OB328 REVISED EDITION-A.

• As for outdoor units MUZ-A18YV - and MUZ-A24YV - ,
refer to the service manual OB346 REVISED EDITION-A.

E1E1

E1E1

1

(When installed on the floor)

(When the air inlet grille is opened.)

Deodorizing filter
(Gray sponge type)(option)

Air filter

Air inlet

Operation section

Air cleaning filter
(White bellows type)(option)

Front panel

Remote control receiving section

Operation indicator lamp

Horizontal vane

Vertical vanes

Emergency
operation switch

(When installed on the ceiling)

Item

Installation plate
Unit fixing screw
5 o 12mm
Wireless remote
controller
Remote controller
holder
Fixing screw for

3.5 o 16mm (Black)
Battery (AAA) for
remote controller

Drain hose
Drain pipe cover

Knockout cover
Screw for 4 o 10mm

2
2

1
1
2
2

1
1
1
2

Q'ty

Remote controller

ON/OFF

FAN

TOO

WARM

TOO

COOL

VANE

MODE

ECONO COOL

STOP

START

HR.

MIN.

AMPM

CLOCK

˚C

AM

RESET CLOCK

I FEEL

COOL

DRY

AUTO

HEAT

ON/OFF

TOO

COOL

PM

AM

TOO

WARM

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 CONTROL button

CLOCK SET button

Indication of remote controller model
is on back.

PART NAMES AND FUNCTIONS

MCFZ-A12WV - MCFZ-A18WV - MCFZ-A24WV -

INDOOR UNIT

MCFZ-A12WV -

E1

ACCESSORIES

E1E1E1

REMOTE CONTROLLER

2

MCFZ-A18WV - MCFZ-A24WV -

REMOTE CONTROLLER

Signal transmitting section

E1E1

Operation display section

OPERATE/ STOP

(ON/ OFF)button

Open the front lid.

VANE CONTROL button

OPERATION SELECT button

ECONO COOL button

RESET button

ON/OFF

ON/OFF

I FEEL

COOL

VANE

HEAT

DRY

MODE

ECONO COOL

RESET CLOCK

TOO

WARM

CLOCK

TOO

WARM

FAN

PM

AM

TOO

COOL

PM

AM

TOO

COOL

STOP

START

HR.

MIN.

TEMPERATURE buttons

Indication of remote controller model
is on back.

FAN SPEED CONTROL button

OFF-TIMER button

ON-TIMER button

HR. button

MIN. button

(TIME SET button)

CLOCK SET button

3

2

Indoor model

Function

Power supply

Air flow(High/Med.W/LowW)
Power outlet
Running current

✽1

Power input ✽1
Auxiliary heater
Power factor

✽1

Fan motor current

✽1

Model
Winding

resistance(at 20:)
Dimensions WOHOD

Weight
Air direction
Sound level

(High/Med.W/LowW)

Fan speed

(High/Med.W/LowW)
Fan speed regulator
Thermistor RT11(at 25:)
Thermistor RT12(at 25:)
Remote controller model

K /h

A
A

W

A(kW)

%

A

"

mm

kg

dB

rpm

k"
k"

Electrical

data

Fan

motor

Special

remarks

Capacity

MCFZ-A18WV -

E1

Cooling

—

Heating

—

Cooling

—

Heating

—

Cooling

—

Heating

—

Single phase

230V, 50Hz

840/696W/570W

10

0.36
80

97

0.36

RB4V36-AC
WHT-BLK 82.9 BLK-YLW 65.6
YLW-BLU 36.0 BLU-BRN 27.0

BRN-RED 13.7

1,100 O 650 O 180

25

5

48/44W/39

W

1,320/1,145/960

3
10
10

KG04C

MCFZ-A24WV -

E1

Single phase

230V, 50Hz

840/744W/642W

10

0.36
80

97

0.36

RB4V36-DB
WHT-BLK 84.0 BLK-YLW 46.2
YLW-BLU 37.2 BLU-BRN 45.2

BRN-RED 13.6

1,100 O 650 O 180

25

5

48/45W/42

W

1,320/1,190/1,060

3
10
10

KG04C

MCFZ-A12WV -

E1

Single phase

230V, 50Hz

780/636W/492W

10

0.30
66

96

0.30

RB4V25-AC

WHT-BLK 182.2 BLK-YLW 68.9

YLW-BLU 47.5 BLU-BRN 31.5

BRN-RED 22.9

1,100 O 650 O 180

25

5

46/41W/35

W

1,240/1,060W/845

W

3
10
10

KG04B

1.8+ 440V
250V 3.15A

MP20 12V 250"

ERZV10D471/ TNR10V471K410

AQG12212/ G3MC-201PL

3P/ 4P

G5NB-1A-DC12V/ G5N-1A-DC12V

145 i 2:

INDOOR UNIT

Item

Model

Indoor fan capacitor
Fuse
Vane motor
Varistor
Solid state relay
Terminal block
Relay
Compressor contactor
Indoor fan motor thermal fuse

MCFZ-A18WV -

E1

MCFZ-A12WV -

E1

MCFZ-A24WV -

E1

(C11)

(F11)

(MV)

(NR11)

(SR141~SR143)

(TB1/TB2)

(X144)

(52C)

ALF1T12

–

SPECIFICATION

NOTE: Test conditions are based on ISO 5151

Cooling : Indoor Dry-bulb temperature 27°C Wet-bulb temperature 19°C

Outdoor Dry-bulb temperature 35°C Wet-bulb temperature (24°C)

Heating : Indoor Dry-bulb temperature 20°C Wet-bulb temperature 15°C

Outdoor Dry-bulb temperature 7°C Wet-bulb temperature 6°C

Indoor-Outdoor piping length (one way) : 5 m
w Reference value
✽1 Measured under rated operating frequency.

Specifications and rating conditions of main electric parts

4

3

NOISE CRITERIA CURVES

MCFZ-A12WV -

E1

SPEED

High

SPL(dB

46

(A)) LINE

Test conditions,
Cooling : Dry-bulb temperature 27: Wet-bulb temperature 19:

Heating : Dry-bulb temperature 20: Wet-bulb temperature 15:

90

80

70

60

50

40

30

APPROXIMATE

20

THRESHOLD OF
HEARING FOR
CONTINUOUS
NOISE

OCTAVE BAND SOUND PRESSURE LEVEL, dB re 0.0002 MICRO BAR

10

63 125 250 500 1000 2000 4000 8000

BAND CENTER FREQUENCIES, Hz

NC-70

NC-60

NC-50

NC-40

NC-30

NC-20

MCFZ-A18WV -

E1

(A)) LINE

SPEED

High

SPL(dB

48

Test conditions,
Cooling : Dry-bulb temperature 27: Wet-bulb temperature 19:\ 
Heating : Dry-bulb temperature 20: Wet-bulb temperature 15:

90

80

70

60

50

40

30

APPROXIMATE

20

THRESHOLD OF
HEARING FOR
CONTINUOUS
NOISE

OCTAVE BAND SOUND PRESSURE LEVEL, dB re 0.0002 MICRO BAR

10

63 125 250 500 1000 2000 4000 8000

BAND CENTER FREQUENCIES, Hz

NC-70

NC-60

NC-50

NC-40

NC-30

NC-20

MCFZ-A24WV -

E1

(A)) LINE

SPEED

High

SPL(dB

48

Test conditions,

Cooling : Dry-bulb temperature 27: Wet-bulb temperature 19:\ 

Heating : Dry-bulb temperature 20: Wet-bulb temperature 15:

90

80

70

60

50

40

30

APPROXIMATE

20

THRESHOLD OF
HEARING FOR
CONTINUOUS
NOISE

OCTAVE BAND SOUND PRESSURE LEVEL, dB re 0.0002 MICRO BAR

10

63 125 250 500 1000 2000 4000 8000

BAND CENTER FREQUENCIES, Hz

NC-70

NC-60

NC-50

NC-40

NC-30

NC-20

INDOOR UNIT

MICROPHONE

1m

1m

WALL

5

4

(When installed on the floor)

(When installed on the ceiling)

500mm or more

500mm or more

500mm or more

500mm or more

1000mm or more

650

616.5

80.8 906 112.8

114

16

1100

93

77

113

143

180

17042.5

9.52(MCFZ-A12WV)

12.7(MCFZ-A18WV)

15.88(MCFZ-A24WV)

Gas line

6.35

Liquid line

Wireless remote controller

162

19

58

OUTLINES AND DIMENSIONS

MCFZ-A12WV - MCFZ-A18WV - MCFZ-A24WV -

INDOOR UNIT

E1E1E1

Unit: mm

MCFZ-A12WV -

INDOOR UNIT

POWER
SUPPLY
~/N 230V
50Hz

TO OUTDOOR
UNIT
CONNECTING

SYMBOL

C11
F11

HIC1

MF

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

WIRING DIAGRAM5

E1

TB1

PE

CIRCUIT BREAKER

230V~

12V

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

GRN/YLW

L

BLU

N

TB2

2

WHT

N

BLU

3

RED
GRN/YLW

REMOTE
CONTROLLER

: Connector

MODEL WIRING DIAGRAM

BRN

1
2
3

CN201

CN

CN CN

101

113 151

5

4

5

DISP/
RECEIVER
P.C.BOARD

SW/THERMO
P.C.BOARD

SYMBOL

MV

NR11

RT11

RT12

VANE MOTOR
VARISTOR
ROOM TEMPERATURE THERMIST OR
INDOOR COIL THERMISTOR

4

52C

3

ELECTRONIC CONTROL P.C BOARD

6
5

MV

NAME NAME

6

RT11

HIC1

F11

C11

NR11

X144
SR143
SR142
SR141

SYMBOL

SR141~SR143

TB1, TB2

X144

52C

2

2

WHT
ORN
RED
BLK
YLW
BLU
BRN

RT12

WHT

1

ORN

2

RED

3

BLK

4

YLW

5

BLU

6

BRN

7
8

GRN/YLW

CN

112

LDCOM
LDC11
LDC12
LDFH

LDFM
LDFL
LDFVL

SOLID STATE RELAY
TERMINAL BLOCK
RELAY
COMPRESSOR CONTACTOR

MF

SYMBOL

SR141~SR143

TB1, TB2

X144

SYMBOL

MV
NR11
RT11
RT12

NAME

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

VANE MOTOR
VARISTOR
ROOM TEMPERATURE THERMIST OR
INDOOR COIL THERMISTOR

SOLID STATE RELAY
TERMINAL BLOCK
RELAY

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.
: Connector

: Terminal block

NOTES:

SYMBOL

C11

F11

HIC1

MF

MCFZ-A18WV ­MCFZ-A24WV -

E1

MODELS WIRING DIAGRAM

E1

INDOOR UNIT

POWER
SUPPLY

~/N 230V

50Hz

CIRCUIT BREAKER

TO OUTDOOR
UNIT
CONNECTING
12V

PE

TB1

GRN/YLW

N

L

TB2

N

3

REMOTE
CONTROLLER

BLU

BLU
RED

BRN

DISP/
RECEIVER
P.C.BOARD

1
2
3

CN201

CN CN CN

113 151101

5

4

MV

5

SW/THERMO
P.C.BOARD

HIC1

TAB12

F11

ELECTRONIC CONTROL P.C BOARD

6
5

RT11

C11

NR11

X144
SR143

SR142
SR141

CN

112

LDCOM

LDC11
LDC12
LDFH
LDFM
LDFL
LDFVL

2

2

WHT
ORN
RED
BLK
YLW
BLU
BRN

WHT

1

ORN

2

RED

3

BLK

4

YLW

5

BLU

6

BRN

7
8

GRN/YLW

RT12

MF

7

REFRIGERANT SYSTEM DIAGRAM6

Indoor
heat
exchanger

Flared connection

Room temperature
thermistor
RT11

Indoor coil
thermistor
RT12

Flared connection

Refrigerant pipe [9.52
(with heat insulator)

Refrigerant pipe
[6.35
(with heat insulator)

Muffler

Indoor
heat
exchanger

Distributor

Flared connection

Room temperature
thermistor
RT11

Indoor coil
thermistor
RT12

Flared connection

Refrigerant pipe [12.7(MCFZ-A18MV)
Refrigerant pipe [15.88(MCFZ-A24MV)
(with heat insulator)

Refrigerant pipe
[6.35
(with heat insulator)

MCFZ-A12WV-

INDOOR UNIT

E1

MCFZ-A18WV­MCFZ-A24WV-

E1

E1

Unit : mm

INDOOR UNIT

Refrigerant flow in cooling
Refrigerant flow in heating

SERVICE FUNCTIONS7

MCFZ-A12WV - MCFZ-A18WV - MCFZ-A24WV -

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. (Refer to page 17 or 18.)

3-minutes time delay : 3-minutes → 3-seconds
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;

Remote controller model : KG04B(MCFZ-A12WV),KG04C(MCFZ-A18/A24WV)

J2

E1E1E1

NOTE : For remodelling, take out the batteries and

press the OPERATE/STOP(ON/OFF) button
twice or 3 times at first.
After finish remodelling, put back the
batteries then press the RESET button.

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.

J1

8

Table1.

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

JR07

CN151CN113CN112

CN101

CN105

SW2

CN102

CN201

SW1

IC101

C11

52C

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 will 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.

7-3. AUTO RESTART FUNCTION

When the indoor unit is controlled with the remote controller, the operation mode, the 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” or “AUTO” 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 release “AUTO RESTART FUNCTION”

1Turn off the main power for the unit.
2Pull out the electronic control P.C. board. (Refer to page 19.)
3Solder jumper wire to the JR07 on the indoor electronic

control P.C. board. (Refer to page 17 or 18.)

Operation

1If the main power 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 indoor unit 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

TROUBLESHOOTING

MCFZ-A12WV - MCFZ-A18WV - MCFZ-A24WV -

E1E1E1

8-1. Cautions on troubleshooting

1. Before troubleshooting, check the following:

(1) Check the power supply voltage.

(2) Check the indoor/outdoor connecting wire for mis-wiring.

2. Take care the following during service.

(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 has completely closed, turn off the breaker.

(2) Be sure to unplug the power cord before removing the air inlet grille, the front panel, the cabinet, the top panel and

the electronic control P.C. boards.

(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) 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 discoloration.

(3) When troubleshooting, refer to the flow chart and the check table on page 11 and 12.

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.

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

NOTE : 1.These figures show about MCFZ-A18WV or MCFZ-A24WV.

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

3. Remote controller of MCFZ-A12WV has a circuit to automatically reset the microcomputer when batteries are
replaced.

This function is equipped to prevent the microcomputer from malfunctioning due to the voltage drop caused by
the battery replacement.

2 Press the RESET button with tip end of ball point

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

RESET button

10

8-2. Instruction of troubleshooting

Start

Indoor unit
operates.
Outdoor unit
doesn't
operate.

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

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

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

Outdoor unit
operates in
only Test Run
operation.

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

Indoor unit
operates, when
the EMERGENCY
OPERATION
switch is pressed.

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

Check room
temperature
thermistor.
Refer to
"Test point
diagram and
voltage" on
page 17 or 18.

Refer to
"Check of
inverter/
compressor".

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

Refer to B
"Check of
remote controller
and receiver
P.C. board"
on page 14.

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

• Mis-wiring
or trouble of
serial signal

2-time flash
Cause:
Indoor unit

• Trouble of
room
temperature/
indoor coil
thermistor

Check room
temperature
thermistor
and indoor
coil
thermistor.
Refer to
"Test point
diagram and
voltage"
on page 17
or 18.

4-time flash
Cause:
Indoor unit

• Trouble of
indoor unit
control
system

Replace the
indoor
electronic
control P.C.
board.

Refer to D
"How to
check mis­wiring and
serial signal
error (When
outdoor unit
doesn't
work)" on
page 15 or

16.

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

6-time flash
Cause:
Outdoor unit

• Trouble of
thermistor
in outdoor
unit

7-time flash
Cause:
Outdoor unit

• Trouble of
outdoor
control
system

Refer to
"Check of
outdoor
thermistors".

Check the
inverter P.C.
board or
outdoor
electronic
control P.C.
board.

5-time flash
Cause:
Outdoor unit

• Outdoor
power
system
abnormality

Refer to
"Check of
inverter/
compressor".

As for outdoor units MUZ-A12YV and MUZ-A12YVH, refer to service manual OB328 REVISED EDITION-A.
As for outdoor units MUZ-A18YV and MUZ-A24YV, refer to service manual OB346 REVISED EDITION-A.

1. Check indoor / outdoor
connecting wire.
(Check if the power
is supplied to the
indoor unit.)

2. Refer to C
"Check of indoor
electronic control
P.C. board"
on page 14.

11

No.

1

2

3

4

5

SymptomOperation indicator lamp Detection method

Check point

Mis-Wiring
or Serial
signal

Outdoor
power
system

Outdoor
thermistor

Outdoor
control
system

Indoor coil
thermistor

When it consecutively occurs 3 times that
compressor stops for overcurrent protection
within 1 minute after start-up.

<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 inverter P.C. board or
outdoor electronic control P.C. board.

• Shortage of refrigerant.
Refer to "Check of outdoor

thermistor".
Refer to service manual
OB328 REVISED EDITION-A
or OB346 REVISED EDITION-A.

• Refer to "Check of inverter/

compressor".
Refer to service manual
OB328 REVISED EDITION-A

or OB346 REVISED EDITION-A.

• Check the inverter P.C.
board or outdoor electronic
control P.C. board.
Refer to service manual
OB328 REVISED EDITION-A

or OB346 REVISED EDITION-A.

• Refer to D "How to check

mis-wiring and serial signal
error." on page 15 or 16.

6

Abnormal

point

Outdoor unit
does not
operate.

Room
tempera­ture
thermistor

2-time flash

2.5-second OFF

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

• Refer to the characteristics of
indoor coil thermistor, and

room temperature thermistor
on page 17 or 18.

4-time flash

2.5-second OFF

Indoor
control
system

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

Outdoor unit
does not
operate.

Outdoor unit
does not
operate.

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

5-time flash

2.5-second OFF

6-time flash

2.5-second OFF

Outdoor unit
does not
operate.

Outdoor unit
does not
operate.

Outdoor unit
does not
operate.

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

0.5-second ON

0.5-second OFF

7-time flash

2.5-second OFF

1. Troubleshooting check table

Operation Indicator

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

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

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

Lighted
Not lighted

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

Self check table

12

2. Trouble criterion of main parts

BLK RED ORNYLWBLU BRN

WHT

GRN

YLW

FUSE

YLW

GRNORN

BRN

RED

ROTOR

MCFZ-A12WV - MCFZ-A18WV - MCFZ-A24WV -

Part name

Room
temperature
thermistor (RT11)

Indoor coil
thermistor

(RT12)

Indoor fan
motor
(MF)

INNER FUSE
145 i 2: CUT OFF

Vane
motor
(MV)

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

Normal

8kΩ ~ 20kΩ

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

Color of lead

wire

MCFZ-A12WV
WHT-BLK
BLK-YLW 63~69Ω66~72Ω
YLW-BLU 34~38Ω45~50Ω
BLU-BRN 25~29Ω30~33Ω

BRN-RED 13~15Ω22~24Ω

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

Color of lead

wire

BRN-other

one

Check method and criterion

Abnormal

Open or short-circuit

Normal

MCFZ-A18WV

79~87Ω175~190Ω

Normal

~ 356Ω

328

MCFZ-A24WV

short-circuit

E1E1E1

80~88Ω
44~49Ω
35~39Ω
43~47Ω
13~15Ω

Abnormal

Open or

Figure

Abnormal

Open or

short-circuit

Indoor fan does not operate.

A

Check of indoor fan motor

No

Are lead wires connected?

Reconnect the lead wires.

Disconnect lead wires from connector (Indoor fan motor).
Measure resistance between lead wires No.1 and No.4 and then No.3 and No.4 of the indoor fan
motor.

Turn OFF power supply.
Check connector (Fan motor) visually.

Yes

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

Yes ( 0 or ∞ )

Replace the indoor fan motor.

Is soldered point of the connector
correctly soldered?

Yes

Replace the indoor electronic control
P.C. board.

No

(others)

No

Resolder it.

13

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

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

Replace the fuse.

Is fuse (F11) blown?

No

Yes

No

Is varistor (NR11) burnt?

Replace the varistor.

Yes

Replace the indoor
electronic control
P.C. board.

troller.

Check of remote controller and receiver P.C. board

B

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

Switch on the remote controller.

Is LCD display on remote
controller visible?

Yes

Remove the batteries, then set them back and
press the RESET button. (Refer to 10.) Check
if the unit operates with the remote controller.

Does the unit operate with remote

controller?

Yes

OK

No
(not clear)

No

Replace the batteries.(Refer to page 10.)

Turn on a radio to AM and press switch
on 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 CN101 No.2(+) and No.1 (-)
when 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

● Reinstall the unit away from lights.

● Attach a filter on receiving section of

the indoor unit.

Replace the indoor electronic control

P.C. board.

Replace the remote controller.

The unit does not 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

14

When OPERATION INDICATOR lamp flashes ON and OFF in every 0.5-second.

No

Replace the
indoor/ outdoor
connecting wire.

Is there voltage approximate 280V DC between
LD61A (+) and LD66A (–) on the inverter P.C.
board arter 3 minutes?

Turn OFF the power supply and then turn ON
again.
Press EMERGENCY OPERATION switch.
After 3 minutes, is there approximate 230V AC
between outdoor terminal block 2 and N?

w4 Replace the inverter P.C.

board.

Does the right side of OPERATION INDICATOR
lamp blink quickly?

w2 Mis-wiring may damage indoor electronic

control P.C. board during the operation.
Be sure to confirm the wiring is correct
before the operation starts.

Replace the indoor
electronic control
P.C. board.

No

Replace the indoor/ outdoor connecting wire.

Release the failure mode. w3

Yes

Yes

A

B

Turn OFF the power supply(Indoor unit).
Disconnect the indoor/ outdoor connecting wire.
Short-circuit indoor terminal block N and 3.
Turn ON the power supply(Indoor unit).
During pressing both the OPERATION SELECT button
and TOO COOL button on the remote controller at the
same time, press the RESET button.
At first, release the RESET button.
And release the other two buttons since all LCD in
operation display section of the remote controller is
displayed after 3 seconds.
Transmit the signal of remote controller, pressing
OPERATE/STOP (ON/OFF) button on the remote
controller.
(The above procedure allows OPERATION INDICATOR
lamp to indicate the failure-mode.)

Remove the short-circuit between indoor terminal block N
and 3.
Reconnect the indoor/ outdoor connecting wire.
Turn ON the power supply(Indoor unit).
Press the EMERGENCY OPERATION switch.
Is there amplitude of 5 to 10V DC between outdoor
terminal block N and 3 after 3 minutes (for confirmation of
serial signal)?

1. Turn OFF the power supply.

2. Disconnect the connector (CN61) between the
compressor and the power transistor module.

3. Turn ON the power supply.

4. Press the EMERGENCY OPERATION switch.

No

Yes

No

Yes

(light up or OFF)

Is mis-wiring
indicated when
the contactor
(52C) on the
indoor electronic
control P.C.
board turns ON
3 minutes later?

Yes

No

· Turn OFF inverter-controlled lighting
equipment.

· Turn OFF the power supply and then
turn ON again(Indoor unit).

· Press the EMERGENCY
OPERATION switch.

B

· Reinstall
either the
unit or the
light each
other away.

· Attach a filter
on receiving
section of
the indoor
unit.

w3 Be sure to release the failure-mode

recall function after checking.

w4 Be careful to the residual voltage of smoothing capacitor.

Procedure of release of failure-mode.
1 Press the EMERGENCY

OPERATION switch.

2 Turn OFF the power supply.
3 Press the RESET button on the

remote controller.

Start

No

• Turn ON the power supply(Indoor unit).

•

Press once EMERGENCY OPERATION switch.

Is there any mis-wiring, poor contact,
or wire disconnection? w2

Make them sure.

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.

Yes

Is there 230V AC between outdoor terminal
block 2 and N?

No

Replace the
indoor/ outdoor
connecting wire.

A

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

Blinking

Operation Indicator

As for outdoor units MUZ-A12YV and MUZ-A12YVH,
refer to service manual OB328 REVISED EDITION-A.

AMPM

CLOCK

:

AMPM

12345

Outdoor unit does not operate.

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

D

MCFZ-A12WV

15

As for outdoor units MUZ-A18YV and MUZ-A24YV,
refer to service manual OB346 REVISED EDITION-A.

Reconnect the
power supply
cable.

Is there 325V DC between CN801 1 and 3 on the
outdoor electronic control P.C. board?

Replace the outdoor
electronic control P.C.
board.

Does the right side of OPERATION INDICATOR
lamp blink quickly?

w2 Mis-wiring may damage indoor electronic

control P.C. board during the operation.
Be sure to confirm the wiring is correct
before the operation starts.

Replace the indoor
electronic control
P.C. board.

No

Release the failure mode. w3

Yes

Yes

A

B

Remove the short-circuit between indoor terminal block N
and 3.
Reconnect the indoor/ outdoor connecting wire.
Turn ON the power supply (Indoor/ outdoor unit).
Press the EMERGENCY OPERATION switch.
Is there amplitude of 5 to 10V DC between outdoor
terminal block N and 3 after 3 minutes (for confirmation of
serial signal)?

Yes

(light up or OFF)

After 3 minutes,
is mis-wiring
indicated on
OPERATION
INDICATOR
lamp on the
indoor unit?

Yes

No

· Turn OFF inverter-controlled lighting
equipment.

· Turn OFF the power supply and then
turn ON again (Indoor/ outdoor unit).

· Press the EMERGENCY
OPERATION switch.

B

· Reinstall
either the
unit or the
light each
other away.

· Attach a filter
on receiving
section of
the indoor
unit.

w3 Be sure to release the failure-mode

recall function after checking.
Procedure of release of failure-mode.
1 Press the EMERGENCY

OPERATION switch.

2 Turn OFF the power supply

(Indoor/ outdoor unit).

3 Press the RESET button on the

remote controller.

Start

No

• Turn ON the power supply (Indoor/ outdoor unit).

•

Press once EMERGENCY OPERATION switch.

Is there any mis-wiring, poor contact,
or wire disconnection? w2

Make them sure.

Yes

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

Yes

Is there 230V AC between outdoor terminal
block L and N?

No

Replace the
indoor/ outdoor
connecting wire.

A

No

Check of power
supply.

No

Turn OFF the power supply (Indoor/ outdoor unit).
Disconnect the indoor/ outdoor connecting wire.
Short-circuit indoor terminal block N and 3.
Turn ON the power supply (Indoor/ outdoor unit).
During pressing both the OPERATION SELECT button
and TOO COOL button on the remote controller at the
same time, press the RESET button.
At first, release the RESET button.
And release the other two buttons since all LCD in
operation display section of the remote controller is
displayed after 3 seconds.
Transmit the signal of remote controller, pressing
OPERATE/STOP (ON/OFF) button on the remote
controller.
(The above procedure allows OPERATION INDICATOR
lamp to indicate the failure-mode.)

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

AMPM

CLOCK

:

AMPM

12345

Blinking

Operation Indicator

MCFZ-A18WV
MCFZ-A24WV

16

TEST POINT DIAGRAM AND VOLTAGE
MCFZ-A12WV -

E1

Indoor electronic control P.C. board

Fan motor power supply 230V AC

Very
Low

Low

Med.

High

7654321

Fuse (F11)
250V AC

3.15A
Varistor (NR11)

Power supply
input 230V AC

+

5V DC

}

–

–

12V DC

}

+

No.2 No.1

– +

Receiver P.C.
board connector
(CN101)

Room temperature
thermistor(RT11)

Release of “Auto restart function”

Solder jumper wire to the JR07.
(Refer to page 9.)

Room temperature thermistor
(RT11)

Time short point JPG and JPS
(Refer to page 8.)

Indoor coil thermistor (RT12)

EMERGENCY OPERATION switch

GILMS

RT11

TH113

DE00R697B

CH313

12

To the indoor
electronic control
P.C.board CN113

Indoor coil thermistor (RT12)
Room temperature thermistor (RT11)

40

30

20

Resistance (K')

10

0

0

10 20 30 40 50 60

Temperature ( C)

17

DE00R697B

To the indoor
electronic control
P.C.board CN113

Indoor coil thermistor (RT12)
Room temperature thermistor (RT11)

RT11

EMERGENCY OPERATION switch

TH113

CH313

GILMS

12

0

0

10

20

30

40

10 20 30 40 50 60

Temperature ( C)

Resistance (K')

TEST POINT DIAGRAM AND VOLTAGE
MCFZ-A18WV ­MCFZ-A24WV -

E1

E1

Indoor electronic control P.C. board

Fan motor power supply 230V AC

Very
Low

Low

Med.

High

7654321

Fuse (F11)
250V AC

3.15A
Varistor (NR11)

Power supply
input 230V AC

+

5V DC

}

–

–

12V DC

}

+

No.2 No.1
Receiver P.C.
board connector
(CN101)

– +

Room temperature
thermistor(RT11)

Release of “Auto restart function”
Solder jumper wire to the
JR07.
(Refer to page 9.)

Room temperature thermistor (RT11)

Time short point JPG and JPS
(Refer to page 8.)

Indoor coil thermistor (RT12)

18

DISASSEMBLY INSTRUCTIONS9

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

1Slide the sleeve.
2Pull the terminal while

pushing the locking
lever.

In case of terminal with lock mechanism, detach the terminal as shown below.
There are two types ( Refer to (1) and (2)) of the terminal with lock mechanism.
The terminal with no lock mechanism can be removed by pulling it out.
Check the shape of the terminal and work.

<"Terminal with lock mechanism" Detaching points>

Sleeve

Locking lever

MCFZ-A12WV - MCFZ-A18WV - MCFZ-A24WV ­INDOOR UNIT

OPERATING PROCEDURE PHOTOS

1. Removing the electronic control P.C. board.

(1) Pull out the upper part of the grille. (Photo 1)
(2) Remove the screws of the grille.
(3) Remove screws of terminal block cover.

Remove the terminal block cover and remove the terminal

block.
(4) Remove the screws of the electronic box cover.
(5) Pull out the electronic control P.C. board.

Photo 3

MCFZ-A12WV

Photo 1

Photo 2

E1E1E1

Screws

Electronic control P.C. board

MCFZ-A18WV
MCFZ-A24WV

Electronic control P.C. board

19

Electronic box Terminal block

OPERATING PROCEDURE

PHOTOS

2. Removing the indoor fan motor

(1) Remove the grille. (Refer to 1(1) (2).)
(2) Remove the fan casing.(upper)
(3) Disconnect the connector of the indoor fan motor.
(4) Disconnect the ground wire of the fan motor.
(5) Remove the screws of the motor band and remove the

catch.

(6) Take out the sirocco fan and the indoor fan motor.

3. Removing the indoor heat exchanger.

(1) Remove the grille. (Refer to 1(1) (2).)
(2) Remove the screws on both side and in front of the front

panel. (Photo 5)
(3) Remove the screws of the nozzle assembly. (Photo 6)
(4) Remove the electronic box. (Refer to 1.)
(5) Remove the indoor fan motor. (Refer to 2.)
(6) Remove the screws of the motor support.
(7) Remove the fan casing. (Iower)
(8) Remove the insulation of the drain pan and remove the

screws. (Photo 7)
(9) Remove the screws under the drain pan. (Photo 8)
(10) Remove the drain pan.
(11) Remove the indoor heat exchanger.

Photo 4

Fan casing

(upper)

Indoor fan motor

Photo 5

Screws

Motor band

Screws

Fan
casing(upper)

Photo 6

Photo 7

Insulation and screws

Photo 8

Screws

Screws

20

PARTS LIST10

-

E1

(WH)

Q'ty/unit

1
2
3
4
5
6
7
8

9

10
11
12
13

14
15

16

VANE MOTOR
INSTALLATION METAL (L)
AIR FILTER
GRILLE (WH)
FRONT PANEL (WH)
DRAIN PAN
FAN CASING (U)
FAN CASING (L)
UNION (GAS)
UNION (GAS)
UNION (GAS)
INSTALLATION METAL (R)
UNION (LIQUID)
BACK PANEL (IN)
NOZZLE (WH)
INDOOR HEAT EXCHANGER
INDOOR HEAT EXCHANGER
VANE (WH)
GRILLE CATCH (WH)

{9.52
{12.7
{15.88

{6.35

3PCS/SET

1
1
2
1
1
1
2
2
1

1
1
1
1
1

1
3

1
1
2
1
1
1
2
2

1
1

1
1
1

1
1
3

1
1
2
1
1
1
2
2

1
1
1
1
1

1
1
3

MV

MCFZ-A12WV

E02 227 303
E02 179 971
E02 179 100
E02 179 010
E02 179 000
E02 215 700
E02 179 237
E02 179 238
E02 151 666
E02 179 667
E02 138 666
E02 179 972
E02 138 667
E02 179 231
E02 227 235
E02 823 620
E02 824 620
E02 227 040
E02 179 142

No.

Part No. RemarksPart name

Symbol

in Wiring

Diagram

-

E1

(WH)

MCFZ-A18WV

-

E1

(WH)

MCFZ-A24WV

MCFZ-A12WV - (WH)
MCFZ-A18WV - (WH)
MCFZ-A24WV - (WH)

E1

E1

E1

10-1. INDOOR UNIT

STRUCTURAL PARTS

1

2

3

4

15

1314

12

11

10

9

8

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

65

21

7

1
2

3

4
5

6
7

8

9
10
11

SIROCCO FAN
FAN MOTOR RUBBER MOUNT
INDOOR FAN MOTOR
INDOOR FAN MOTOR
INDOOR FAN MOTOR
TERMINAL BLOCK
TERMINAL BLOCK
TERMINAL BLOCK
RECEIVER P.C. BOARD
INDOOR COIL THERMISTOR
ELECTRONIC CONTROL P.C. BOARD
ELECTRONIC CONTROL P.C. BOARD
ELECTRONIC CONTROL P.C. BOARD
SWITCH & ROOM TEMPERATURE THERMISTOR P.C. BOARD
VARISTOR
FUSE

2
2
1

1
1

1
1
1

1
1
1

2
2

1

1
1
1
1

1
1

1
1

2
2

1
1

1
1
1

1
1
1
1

MF
MF

MF
TB2
TB2
TB1

RT12

NR11

F11

REMOTE CONTROLLER
REMOTE CONTROLLER
REMOTE CONTROLLER HOLDER

SW/THERMO

P.C. BOARD

-

E1

(WH)

Q'ty/unit

MCFZ-A12WV

E02 179 500
E02 179 505
E02 228 300
E02 229 300
E02 684 300
E02 842 375
E02 826 375
E02 823 375
E02 227 468
E02 327 307
E02 842 452
E02 875 452
E02 876 452
E02 215 328
E02 820 385
E02 127 382

No. Part No.

RemarksPart name

Symbol

in Wiring

Diagram

-

E1

(WH)

MCFZ-A18WV

-

E1

(WH)

MCFZ-A24WV

2PCS/SET
RB4V25­RB4V36­RB4V36­4P
3P
3P

3.15A

12
13

1
1

1
1

1
1

E02 842 426
E02 826 426
E02 527 083

DISP/RECEIVER

P.C. BOARD

KG04B
KG04C

MCFZ-A12WV - (WH)
MCFZ-A18WV - (WH)
MCFZ-A24WV - (WH)

E1
E1
E1

10-2. INDOOR UNIT

ELECTRICAL PARTS

9 8

1
2

3

2
1

6

7

10-2. INDOOR UNIT ELECTRICAL PARTS

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

10-3. ACCESSORY AND

REMOTE CONTROLLER

5

4

1312

10-3. ACCESSORY AND REMOTE CONTROLLER

22

11

Remove the air
filter and the
deodorizing
filter together.

Separate the deodorizing
filter (gray sponge type)
from the air filter.

Remove the air
filter and the
air cleaning filter
together.

Separate the air
cleaning filter
(white bellows type)
from the air filter.

OPTIONAL PARTS

MCFZ-A12WV - MCFZ-A18WV - MCFZ-A24WV -

E1E1E1

11-1. AIR CLEANING FILTER

● If the air cleaning filter is clogged, it may lower the unit’s capacity or cause condensation at the air outlet.

● The air cleaning filter is disposable. The standard usable term is about 4 months. However, if the color of the filter

turns to dark brown, replace soon.

Models

MCFZ-A12WV ­MCFZ-A18WV ­MCFZ-A24WV -

E1

E1
E1

Part No.

MAC - 1200 FT

11-2. DEODORIZING FILTER

● Clean the filter every two weeks. When it becomes too dirt, clean it more often.

● Replace the filter with a new one when its color can not be restored even after washing or when the filter becomes dark.

● Standard interval for the filter replacement is about 1 year.

Models

MCFZ-A12WV ­MCFZ-A18WV ­MCFZ-A24WV -

Part No.

E1

E1
E1

MAC - 1700 DF

23

HEAD OFFICE: MITSUBISHI DENKI BLDG.,2-2-3, MARUNOUCHI, CHIYODA-KU, TOKYO100-8310, JAPAN

CC

Copyright 2004 MITSUBISHI ELECTRIC ENGINEERING CO.,LTD
Distributed in Jun. 2004. No.OB344 REVISED EDITION-A 6
Distributed in Apr. 2004. No.OB344 6
Made in Japan

New publication, effective Jun. 2004
Specifications subject to change without notice.