SERVICE MANUAL
SPLIT-TYPE, HEAT PUMP AIR CONDITIONERS
Wireless type
Models
No. OB345
MSZ-A18YV MSZ-A24YV MSZ-A26YV -
Indication of model name
MSZ-A18YV MSZ-A24YV MSZ-A26YV -
E1
E1
E1
E1
E1
E1
CONTENTS
1. PART NAMES AND FUNCTIONS······················2
2. SPECIFICATION·················································4
3. NOISE CRITERIA CURVES·······························5
4. OUTLINES AND DIMENSIONS·························6
5. WIRING DIAGRAM ············································7
6. REFRIGERANT SYSTEM DIAGRAM················8
7. SERVICE FUNCTIONS ······································9
8. TROUBLESHOOTING ······································11
9. DISASSEMBLY INSTRUCTIONS ····················19
10. PARTS LIST······················································21
11. OPTIONAL PARTS···········································23
NOTE:
This service manual describes technical data of the indoor unit.
•Refer to the service manual OB346 when MSZ-A18YV - , MSZ-A24YV - or MSZ-A26YV is connected with MUZ-A18YV - , MUZ-A24YV - or MUZ-A26YV - .
•Refer to the service manual OB319 when MSZ-A18YV - , MSZ-A24YV - or MSZ-A26YV is connected with MXZ-A26WV - or MXZ-A32WV - as multi system units.
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E1E1
1
Grille
(When the grille is opened)
Remote controller
Operation section
Display section
Emergency operation switch
Operation indicator lamp
Air inlet
To Breaker
Power supply cord
Remote control
receiving section
Air cleaning filter (option)
(White bellows type)
Horizontal vane
Vertical vanes
Catechin air filter
Remote control
receiving section
1
2
3
4
5
6
7
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
Felt tape (Used for left or left-rear piping)
1
7
1
2
2
1
1
MSZ-A18YV MSZ-A24YV MSZ-A26YV -
E1
E1
E1
PART NAMES AND FUNCTIONS
INDOOR UNIT
MSZ-A18YV MSZ-A24YV MSZ-A26YV -
E1
E1
E1
ACCESSORIES
Indoor unit
2
REMOTE CONTROLLER
MSZ-A18YV MSZ-A24YV MSZ-A26YV -
E1
E1
E1
Signal transmitting section
Operation display section
OPERATE /STOP
(ON /OFF)button
Open the front lid.
ON/OFF
TOO
WARM
PM
AM
TOO
COOL
TEMPERATURE buttons
Indication of remote controller
model is on back.
VANE button
(Horizontal vane button)
OPERATION SELECT button
ECONO COOL button
WIDE VANE button
(Vertical vane button)
RESET button
TOO
ON/OFF
WARM
COOL
DRY
FAN
VANE
WIDE VANE
LONG
RESET CLOCK
I FEEL
HEAT
MODE
ECONO COOL
3
CLOCK
PM
AM
TOO
COOL
STOP
START
HR.
MIN.
FAN SPEED CONTROL button
OFF-TIMER button
ON-TIMER button
HR. button
MIN. button
(TIME SET button)
CLOCK SET button
LONG button
2
Indoor model
Function
Power supply
Air flow
(High/Med. /Low )
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. /Low )
Fan speed(High/Med. /Low )
Fan speed regulator
Thermistor RT11(at 25:)
Thermistor RT12(at 25:)
Thermistor RT13(at 25:)
Remote controller model
K /h
A
A
W
A(kW)
%
A
"
mm
kg
dB
rpm
k"
k"
k"
MSZ-A18YV -
E1
Single phase
230V, 50Hz
852/690 /498
10
0.30
60
—
87
0.30
RC4V32-AA
WHT-BLK 293
BLK-RED 146
1,100O325O258
16
5
43/38 /31
1,120/940 /720
3
10
10
10
KP0A
Cooling
Heating
MSZ-A24YV -
E1
Single phase
230V, 50Hz
10
0.34
69
—
87
0.34
RC4V40-AA
WHT-BLK 138.2
BLK-RED 159.0
1,100O325O258
16
5
48/40 /32
3
10
10
10
KP0A
Cooling
1,032/768 /522
1,310/1030 /750
Heating
1,032/786 /522
1,310/1050 /750
Electrical
data
Fan
motor
Special
remarks
Capacity
ww
ww
w
w
w
w
w
w
w
w
ww
w
w
w
w
ww
w
w
Indoor model
Function
Power supply
Air flow
(High/Med. /Low )
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. /Low )
Fan speed(High/Med. /Low )
Fan speed regulator
Thermistor RT11(at 25:)
Thermistor RT12(at 25:)
Thermistor RT13(at 25:)
Remote controller model
K /h
A
A
W
A(kW)
%
A
"
mm
kg
dB
rpm
k"
k"
k"
MSZ-A26YV
-
E1
Single phase
230V, 50Hz
10
0.34
69
—
88
0.34
RC4V40-AA
WHT-BLK 138.2
BLK-RED 159.0
1,100O325O258
16
5
48/40 /33
3
10
10
10
KP0A
Cooling
1,032/798 /564
1,310/1,060 /800
Heating
1,032/816 /564
1,310/1,080 /800
Electrical
data
Fan
motor
Special
remarks
Capacity
ww
w
w
w
w
ww
w
w
w
w
w
w
w
w
SPECIFICATION
•Refer to the service manual OB346 when MSZ-A18YV - , MSZ-A24YV - or MSZ-A26YV - is connected with
MUZ-A18YV - , MUZ-A24YV - or MUZ-A26YV - .
E1E1E1
•Refer to the service manual OB319 when MSZ-A18YV - , MSZ-A24YV - or MSZ-A26YV - is connected with
MXZ-A26WV - or MXZ-A32WV - as multi system units.
E1E1
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NOTE: Test conditions are based on ISO 5151.
Cooling : Indoor Dry-bulb temperature 27°C Wet-bulb temperature 19°C
Heating : Indoor Dry-bulb temperature 20°C Wet-bulb temperature 15.5°C
w Reference value
✽1 Measured under rated operating frequency.
Outdoor Dry-bulb temperature 35°C Wet-bulb temperature(24°C)
Outdoor Dry-bulb temperature 7°C Wet-bulb temperature 6°C
Indoor-Outdoor piping length 5m
4
90
80
70
60
50
40
30
20
10
63 125 250 500 1000 2000 4000 8000
NC-60
NC-50
NC-40
NC-30
NC-20
NC-70
BAND CENTER FREQUENCIES, Hz
Test conditions,
Cooling : Dry-bulb temperature 27: Wet-bulb temperature 19:
APPROXIMATE
THRESHOLD OF
HEARING FOR
CONTINUOUS
NOISE
43
SPL(dB(A)) LINE
High
FAN SPEED
Heating : Dry-bulb temperature 20: Wet-bulb temperature 15.5:
OCTAVE BAND SOUND PRESSURE LEVEL, dB re 0.0002 MICRO BAR
Specifications and rating conditions of main electric parts
90
80
70
60
50
40
30
20
10
63 125 250 500 1000 2000 4000 8000
OCTAVE BAND SOUND PRESSURE LEVEL, dB re 0.0002 MICRO BAR
BAND CENTER FREQUENCIES, Hz
APPROXIMATE
THRESHOLD OF
HEARING FOR
CONTINUOUS
NOISE
NC-60
NC-50
NC-40
NC-30
NC-20
NC-70
Test conditions,
Cooling : Dry-bulb temperature 27: Wet-bulb temperature 19:
48
SPL(dB(A)) LINE
High
FAN SPEED
Heating : Dry-bulb temperature 20: Wet-bulb temperature 15.5:
INDOORUNIT
WALL
MICROPHONE
0.8m
1m
INDOOR UNIT
Item
Indoor fan capacitor
Fuse
Vane motor
(MV1/ MV2)
Varistor
Solid state relay
Terminal block
Indoor fan motor thermal fuse
3
MSZ-A18YV -
NOISE CRITERIA CURVES
E1
Model
(C11)
(F11)
(NR11)
(SR141)
(TB)
MSZ-A18YV -
145:
E1
MSZ-A24YV -
TNR10V511K410
MSZ-A24YV MSZ-A26YV -
2.5+ 440V
250V 3.15A
MP20/MP20
S201DH1N
3P
E1
E1
E1
MSZ-A26YV -
E1
5
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 MSZ-A18/A24YV
for MSZ-A26YV
Power supply cord
Lead to right 2.0m
Lead to left 1.0m
OUTLINES AND DIMENSIONS
MSZ-A18YV MSZ-A24YV MSZ-A26YV -
INDOOR UNIT
E1
E1
E1
Unit: mm
6
5
WIRING DIAGRAM
MSZ-A18YV -
INDOOR UNIT
TO OUTDOOR
UNIT
CONNECTING
12V
POWER
SUPPLY
CORD
~/N 230V
50Hz
PE
CIRCUIT
BREAKER
SYMBOL
C11
F11
HIC1
MF
NOTES:
INDOOR FAN CAPACITOR
FUSE (3.15A)
DC/DC CONVERTER
INDOOR FAN MOTOR (INNER FUSE)
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
N
L
BRN
BLU
E1
GRN/YLW
NAME
RED
BLU
BRN
MV2
: Connector
MODEL WIRING DIAGRAM
CN201
3
2
1
TAB12
CN
151
MV2
15
MV1
SYMBOL
MV1
MV2
NR11
RT11
CN
102
DISPLAY
P.C. BOARD
VANE MOTOR (HORIZONTAL)
VANE MOTOR (VERTICAL)
VARISTOR
ROOM TEMPERATURE THERMISTOR
CN
101
33
RECEIVER
P.C. BOARD
NAME
4
CN112
C11
CN
121
3
2
1
3
1
3
4
HIC1
TRANS
F11
NR11
SR141
CN211
CN
ELECTRONIC CONTROL P.C. BOARD
REMOTE
CONTROLLER
111
SYMBOL
RT12
RT13
SR141
INDOOR COIL THERMISTOR (MAIN)
INDOOR COIL THERMISTOR (SUB)
SOLID STATE RELAY
TERMINAL BLOCK
TB
BLK
GRY
YLW
BRN
WHT
RED
NAME
RT13
RT12
RT11
1
2
3
MF
4
5
6
MSZ-A24YV MSZ-A26YV -
INDOOR UNIT
TO OUTDOOR
UNIT
CONNECTING
12V
POWER
SUPPLY
CORD
~/N 230V
50Hz
PE
CIRCUIT
BREAKER
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.
3
N
L
INDOOR FAN CAPACITOR
FUSE (3.15A)
DC/DC CONVERTER
INDOOR FAN MOTOR (INNER PROTECTOR)
VANE MOTOR (HORIZONTAL)
: Terminal block
E1
E1
TB
BRN
BLU
RED
BLU
BRN
GRN/YLW
NAME
: Connector
MV2
MODELS WIRING DIAGRAM
CN201
3
2
1
TAB12
MV1
MV2
NR11
RT11
RT12
RT13
CN
102
CN
101
ELECTRONIC CONTROL P.C. BOARD
33
DISPLAY
P.C. BOARD
RECEIVER
P.C. BOARD
NAME NAME
VANE MOTOR(VERTICAL)
VARISTOR
ROOM TEMPERATURE THERMIST OR
INDOOR COIL THERMISTOR (MAIN)
INDOOR COIL THERMISTOR (SUB)
7
CN
151
MV2
15
SYMBOL
HIC1
TRANS
F11
REMOTE
CONTROLLER
NR11
SR141
SYMBOL
SR141
TB
4
3
2
1
CN112
C11
CN
121
3
1
3
4
CN211
CN
111
SOLID STATE RELAY
TERMINAL BLOCK
RT13
RT12
BLK
GRY
YLW
BRN
WHT
RED
RT11
MF
6
REFRIGERANT SYSTEM DIAGRAM
MSZ-A18YV -
INDOOR UNIT
Indoor
heat
exchanger
Indoor coil
thermistor
RT13(sub)
Room temperature
thermistor
RT11
E1
Indoor coil
thermistor
RT12(main)
Distributor
Refrigerant pipe [12.7
(with heat insulator)
Flared connection
Flared connection
MSZ-A24YV -
INDOOR UNIT
Indoor
heat
exchanger
Indoor coil
thermistor
RT13(sub)
Room temperature
thermistor
RT11
E1
Indoor coil
thermistor
RT12(main)
Distributor
Unit:mm
Refrigerant pipe [15.88
(with heat insulator)
Flared connection
Flared connection
MSZ-A26YV -
INDOOR UNIT
Indoor
heat
exchanger
Indoor coil
thermistor
RT13(sub)
Room temperature
thermistor
RT11
Strainer
E1
Indoor coil
thermistor
RT12(main)
#50
Refrigerant pipe[6.35
(with heat insulator)
Refrigerant pipe [15.88
(with heat insulator)
Flared connection
Flared connection
Refrigerant pipe [6.35
(with heat insulator)
Refrigerant pipe [9.52
(with heat insulator)
Refrigerant flow in cooling
Refrigerant flow in heating
8
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
MSZ-A18YV MSZ-A24YV MSZ-A26YV -
E1
E1
E1
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 :
Remote controller model : KP0A
J2
NOTE : For remodelling, take out the bat-
teries 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.
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.
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 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, 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 FEELCONTROL” mode before power failure, the operation is not memorized. In “I FEEL CONTROL” mode, the operation is decided
by the initial room temperature.
9
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 page 19.)
3Solder jumper wire to the RESISTOR JR07 on the indoor
electronic control P.C. board. (Refer to page 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.
10
8
Lead wiring
Housing point
Lighted
Blinking
Operation Indicator
TROUBLESHOOTING
MSZ-A18YV MSZ-A24YV MSZ-A26YV -
E1
E1
E1
8-1. Cautions on troubleshooting
1. Before troubleshooting, check the following:
(1) Check the power supply voltage.
(2) Check the indoor/outdoor connecting wire for mis-wiring.
2. Take care the following during servicing.
(1) Before servicing the air conditioner, be sure to 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) If the electronic control P.C. board is supposed to be defective, check the copper foil pattern for disconnection and the
components for bursting and discolouration.
(4) When troubleshooting, refer to the flow chart on page 12 and the check table on page 13.
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.
INFORMATION FOR MULTI SYSTEM AIR CONDITIONER
OUTDOOR UNIT : MXZ series
Multi system air conditioner can connect two or more indoor units with one outdoor unit.
•Unit won’t operate in case the total capacity of indoor units exceeds the capacity of outdoor units. Do not
connect indoor units beyond the outdoor unit capacity.
•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 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.
Insert the negative pole
of the batteries first.
Check if the polarity of
the battereis is correct.
RESET button
11
As for outdoor unit MUZ type, refer to service manual OB346.
As for outdoor unit MXZ type, refer to service manual OB319.
Start
Indoor unit
operates.
Outdoor unit
doesn't
operate.
Indoor unit
doesn't receive
the signal from
remote controller.
OPERATION INDICATOR
lamp on the indoor unit is
flashing on and off.
Outdoor unit
operates in
only Test Run
operation.
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".
Refer to
"Check of
inverter/
compressor".
Refer to
"Check of
remote controller
and receiver
P.C. board".
1. Check indoor/ outdoor
connecting wire.
(Check if the power
is supplied to the
indoor unit.)
2. Refer to
"Check of indoor
electronic control
P.C. board".
Unit doesn't
operate
normal
operation in
COOL or
HEAT mode.
Refer to
"Check of
R.V. coil".
Flash on and
off at 0.5second
interval
Cause:
Indoor/
Outdoor unit
• Mis-wiring
or trouble of
serial signal
2-time flash
Cause:
Indoor unit
• Trouble of
room temp erature/
indoor coil
thermistor
3-time flash
Cause:
Indoor unit
• Trouble of
indoor fan
motor
5-time flash
Cause:
Outdoor unit
• Outdoor
power
system
abnormality
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 D
"How to
check miswiring and
serial signal
error (When
outdoor unit
doesn't
work)" on
page 17.
Check room
temperature
thermistor
and indoor
coil thermistor.
Refer to
"Test point
diagram and
voltage".
Refer to A
"Check of
indoor fan
motor" on
page 15.
Refer to
"Check of
inverter/
compressor".
Refer to
"Check of
outdoor
thermistors".
Replace the
outdoor
electronic
control P.C.
board.
4-time flash
Cause:
Indoor unit
• Trouble of
indoor unit
control
system
Replace the
indoor
electronic
control
P.C. board.
Indoor unit operates.
Outdoor unit doesn't
operate normally.
8-2. Instruction of troubleshooting
12
1. Troubleshooting check table
Operation Indicator
Lighted
Not lighted
No.
1
2
4
SymptomOperation indicator lamp Detection method
Checkpoint
0.5-second ON
0.5-second OFF
Mis-Wiring
or Serial
signal
Indoor coil
thermistor
3 minutes after power supply turns ON, when
serial signal is not received.
• Refer to D "How to check
mis-wiring and serial signal
error" on page 17.
3
Indoor fan
motor
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
main indoor coil thermistor,
sub indoor coil thermistor,
and room temperature
thermistor on page 18.
3-time flash
2.5-second OFF
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 emit during 12-second indoor fan
operation.
• Refer to A "Check of
indoor fan motor" on page 15.
4-time flash
2.5-second OFF
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.
5
6
Outdoor
power
system
Outdoor
thermistors
Outdoor
control
system
When compressor has stopped due to over
current protection or start-up failure protection
3 times in a row within 5 seconds after startup.
<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 outdoor electronic
control P.C. board.
• Shortage of refrigerant
• Replace the outdoor control
P.C. board.
Refer to "Check of outdoor
thermistor".
Refer to service manual
OB346 or OB319.
• Refer to "Check of inverter/
compressor".
Refer to service manual
OB346 or OB319.
• Replace the outdoor
electronic control P.C. board.
Refer to service manual
OB346 or OB319.
7
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.
Operation Indicator
MXZ type
Operation
mode
setting
Lighted
Blinking
Outdoor unit
operates but
indoor unit
does not
operate.
When the operation mode of each indoor unit
is differently set to COOL(includes DRY) and
HEAT at same time, the operation mode of
indoor unit that has operated at first has the
priority.
• Unify the operation mode.
Refer to service manual
OB319.
7-time flash
2.5-second OFF
Right lamp flashes.
2.5-second OFF
8
• The following indication applies regardless of shape of the indicator.
· Flashing of the OPERATION INDICATOR lamp (the left-hand side lamp) indicates
possible abnormalities.
· The OPERATION INDICATOR lamp (the left-hand side lamp) is lighting during
normal operation.
Before taking measures, make sure that the symptom reappears, for accurate troubleshooting.
Self check table
NOTE : When the indoor unit has started operation and the above 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.
13
Part name Figure
Check method and criterion
Indoor fan motor(MF)
MSZ-A18YV
INNER FUSE
145: CUT OFF
MSZ-A24/A26YV
INNER
PROTECTOR
135i 5: OPEN
86i 15: CLOSE
Color of
lead wire
WHT – BLK
BLK – RED
Abnormal
Open or
short-circuit
MSZ-A18YV
282 " ~ 305 "
141 " ~ 152 "
Measure the resistance with a tester.
(Part temperature 10˚C ~ 30˚C)
Normal
8 k" ~ 20 k"
Abnormal
Open or short-circuit
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
Abnormal
Remain 0V or 5V
Normal
4.5 ~ 5.5V
Measure the voltage power ON.
(When fan revolved one time)
0V➔5V➔0V
(Approx.)
Normal
282 " ~ 306 "
Abnormal
Open or short-circuit
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
MSZ-A24/A26YV
132 " ~ 144 "
152 " ~ 166 "
Normal
MSZ-A18YV
MSZ-A24/A26YV
YLW
GRNORN
BRN
RED
ROTOR
MAIN
AUX.
P
:INNER PROTECTOR
P
2. Trouble criterion of main parts
MSZ-A18YV MSZ-A24YV MSZ-A26YV -
E1
E1
E1
14
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.
B
Check of remote controller and receiver P.C. board
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, 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
(not clear)
No
Replace the batteries.(Refer to page 11.)
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
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)
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.
Replace the receiver P.C. board.
15
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
Fuse (F11)
Indoor electronic
control P.C. board
No
Replace the indoor
electronic control
P.C. board.
Varistor (NR11)
Replace the varistor.
16
When OPERATION INDICATOR lamp flashes ON and OFF in every 0.5-second.
As for outdoor unit MUZ type, refer to service manual OB346.
As for outdoor unit MXZ type, refer to service manual OB319.
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
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 the OPERATION SELECT button on
the remote controller, press the RESET button.
At first, release the RESET button.
And release the OPERATION SELECT button 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/ 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
•The following indication
applies regardless of shape
of the indicator.
Blinking
Operation Indicator
AMPM
CLOCK
˚C
AMPM
Outdoor unit doesn’t operate.
How to check mis-wiring and serial signal error (when outdoor unit does not work)
D
17
TEST POINT DIAGRAM AND VOLTAGE
Indoor coil thermistor(RT12(main), RT13(sub))
Room temperature thermistor (RT11)
Resistance(k")
MSZ-A18YV - MSZ-A24YV - MSZ-A26YV Indoor electronic control P.C. board
Fuse (F11)
250V AC 3.15A
R132
E1E1E1
Fan motor power supply
Power supply input
}
230V AC
5V DC
}
+
Room temperature thermistor(RT11)
Indoor coil
thermistor(RT12(main))
Receiver P.C. board
Release of “Auto restart function”
Solder jumper wire to JR07.
(Refer to page 10.)
+
}
12V DC
Indoor coil
thermistor(RT13(sub))
Emergency operation
switch
Timer short mode point
(JPS, JPG)
(Refer to page 9.)
18
9
DISASSEMBLY INSTRUCTIONS
<"Terminal with lock mechanism" Detaching points>
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.
(1) Slide the sleeve and check if there is a locking lever or not. (2) The terminal with this connector is a terminal
Sleeve
with lock mechanism
1Slide the sleeve.
2Pull the terminal while
Locking lever
pushing the locking
lever.
MSZ-A18YV - MSZ-A24YV - MSZ-A26YV 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.
1Hold the sleeve, and
pull out the terminal
slowly.
Connector
E1E1E1
Photo 1
Front panel
Screws
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.
19
Photo 2
R.L
holder
Screws of the ground wire
Screw of
the terminal
block
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
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
20
Screws fixing the fan motor
10
MSZ-A18
YV -
(WH)
E1
MSZ-A24
YV -
(WH)
E1
MSZ-A26
YV -
(WH)
E1
E02 527 970
E02 527 234
E02 851 000
E02 408 142
E02 527 067
E02 851 010
E02 534 100
E02 527 975
E02 851 007
INSTALLATION PLATE
BOX (WH)
FRONT PANEL ASSEMBLY(WH)
CATCH
SCREW CAP (WH)
GRILLE (WH)
CATECHIN AIR FIL TER
CORNER BOX RIGHT
LAMP PANEL
Symbol
in Wiring
Diagram
Q'ty/unit
Including No.4,5,6
4PCS/ SET
3PCS/ SET
RemarksPart No.
No.
Part Name
1
2
3
4
5
6
7
8
9
1
1
1
4
3
1
2
1
1
1
1
1
4
3
1
2
1
1
1
1
1
4
3
1
2
1
1
E02 851 620
E02 819 620
E02 179 667
E02 138 666
E02 151 667
E02 527 667
INDOOR HEAT EXCHANGER
INDOOR HEAT EXCHANGER
UNION (GAS)
UNION (GAS)
UNION (LIQUID)
UNION (LIQUID)
{12.7
{15.88
{6.35
{9.52
10
11
12
1
1
1
1
1
1
1
1
1
PARTS LIST
MSZ-A18YV - (WH)
MSZ-A24YV - (WH)
MSZ-A26YV - (WH)
E1
E1
E1
10-1. INDOOR UNIT STRUCTURAL PARTS
1
2
3
4
CATCH
5
SCREW
CAP
6
7
10-2. INDOOR UNIT HEAT EXCHANGER
10
8
Optional parts
(See page 23.)
11
12
10-1. INDOOR UNIT STRUCTURAL PARTS
Part number that is circled is not shown in the illustration.
10-2. INDOOR UNIT HEAT EXCHANGER
21
E02 527 302
E02 408 509
E02 001 504
E02 408 702
E02 527 235
E02 527 040
E02 527 041
E02 127 382
E02 817 385
E02 527 034
E02 817 300
E02 527 300
E02 448 303
E02 408 303
E02 817 333
E02 527 333
E02 528 329
E02 527 468
E02 851 452
E02 852 452
E02 853 452
E02 527 308
E02 819 375
E02 851 307
E02 527 307
E02 528 034
E02 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 (WH)
VANE UPPER (WH)
VANE LOWER (WH)
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
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, RT13
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
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
AUTO RESTART
Including No.16
RC4V40 Including RUBBER MOUNT
MSZ-A18
YV -
(WH)
E1
MSZ-A24
YV -
(WH)
E1
MSZ-A26
YV -
(WH)
E1
MSZ-A18YV - (WH)
23
24
E02 529 426
E02 527 083
REMOTE CONTROLLER
REMOTE CONTROLLER HOLDER
1
1
1
1
1
1
KP0A
MSZ-A24YV - (WH)
MSZ-A26YV - (WH)
E1
E1
E1
10-3. INDOOR UNIT FUNCTIONAL PARTS AND
ELECTRICAL PARTS
1
20
19
10-4. ACCESSORY AND
REMOTE CONTROLLER
23
2
3
SLEEVE
BEARING
4
12
11
ROOM
18
TEMPERATURE
THERMISTOR
5
6
14
13
10
7
FUSE
8
VARISTOR
9
15
16
17
10-3. INDOOR UNIT FUNCTIONAL PARTS AND ELECTRICAL PARTS
Part numbers that are circled are not shown in the illustration.
24
10-4. ACCESSORY AND REMOTE CONTROLLER
22
11
Model Part No.
MAC-1700FT
MSZ-A18YV -
E1
MSZ-A24YV -
E1
MSZ-A26YV -
E1
Air cleanig filter (White bellows type)
OPTIONAL PARTS
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.
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 Apr. 2004. No.OB345 6
Made in Japan
New publication, effective Apr. 2004
Specifications subject to change without notice.
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