Mitsubishi Electric MSZ-GB50VA Series User manual

SERVICE MANUAL
CONTENTS
1. TECHNICAL CHANGES ····································2
2. PART NAMES AND FUNCTIONS······················3
3. SPECIFICATION·················································5
4. NOISE CRITERIA CURVES·······························6
5. OUTLINES AND DIMENSIONS ·························7
6. WIRING DIAGRAM ············································8
7. REFRIGERANT SYSTEM DIAGRAM················8
8. SERVICE FUNCTIONS ······································9
9. TROUBLESHOOTING······································10
10. DISASSEMBLY INSTRUCTIONS·····················24
11. RoHS PARTS LIST···········································27
12. OPTIONAL PARTS···········································30
Wireless type
Models
MSZ-GB50VA - E1
SPLIT-TYPE, HEAT PUMPAIR CONDITIONERS
MSZ-GB50VA
NOTE:
• This service manual describes technical data of the indoor units.
INDOOR UNIT
Outdoor unit service manual
MUZ-GB·VA series (OB455)
MXZ-A·VA series (OB377)
MXZ-8A140VA (OC316)
No. OB454
OB454qxp 06.3.22 4:30 PM Page 1

2
1TECHNICAL CHANGES
MSZ-GA50VA - ➔MSZ-GB50VA -
Indoor unit size has been changed. (W1,100 mm x H325 mm x D258 mm ➔ W780 mm x H298 mm x D210 mm)
E1E1
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3
PART NAMES AND FUNCTIONS
2
INDOOR UNIT
MSZ-GB50VA
Line flow fan
Air outlet
Vertical vane
Air inlet
Display section
Front panel
Panel
Heat exchanger
Horizontal vane
Operation section
(When the front panel is opened)
Remote controller
Remote control
receiving section
Catechin air filter
Air cleaning filter (Option)
(Anti-Allergy Enzyme
Filter,Blue bellows type)
Emergency operation switch
Fan guard
Operation Indicator
lamp
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4
ACCESSORIES
1
2
3
4
5
6
7
Installation plate
Installation plate fixing screw 4 o25 mm
Remote controller holder
Fixing screw for 33.5 o1.6 mm (Black)
Battery (AAA) for remote controller
Wireless remote controller
Felt tape (Used for left or left-rear piping)
1
5
1
2
2
1
1
REMOTE CONTROLLER
ON-TIMER button
CLOCK SET button
TIME SET buttons
FORWARD button
BACKWARD button
OFF-TIMER button
(This diagram shows an overall view.)
Open the front lid.
RESET button VANE CONTROL button
Signal transmitting section
Operation display section
Temperature buttons
OPERATE/STOP
(ON/OFF) button
FAN SPEED CONTROL button
OPERATION SELECT button
ECONO COOL button
Indication of
remote controller
model is on back
MSZ-GB50VA
OB454qxp 06.3.22 4:30 PM Page 4

5
SPECIFICATION
3
MSZ-GB50VA
T3.15AL 250V
MSBPC20M16 12V DC 250"(at 25˚C)
ERZV14D471
3P
INDOOR UNIT
Item
Fuse
Horizontal vane motor
Varistor
Terminal block
(F11)
(MV)
(NR11)
(TB)
Specifications and rating conditions of main electric parts
MSZ-GB50VA
Indoor model
Function
Power supply Single phase
230V,50Hz
684
654/445/414
20
0.35
40
50
0.35
RC0J30-CC
780O298O210
9
4
1,300
1,200/1,100/900
4
KM05B
Cooling
48/44/38/32
Heating
48/42/36/30
Air flow(Super High)
Air flow(High/Med./Low)
Power outlet
Running current ✽1
Power input ✽1
Power factor ✽1
Fan motor current ✽1
Model
Dimensions WOHOD
Weight
Air direction
Sound level(Super High/High/Med./Low)
Fan speed(Super High)
Fan speed(High/Med./Low)
Fan speed regulator
Remote controller model
K/h
K/h
A
A
W
%
A
mm
kg
dB(A)
rpm
rpm
Electrical data
Fan motor
Special remarks
Capacity
NOTE : Test conditions are based on ISO 5151.
Cooling : Indoor Dry-bulb temperature 27:Wet-bulb temperature 19:
Outdoor Dry-bulb temperature 35:Wet-bulb temperature 24:
Heating : Indoor Dry-bulb temperature 20:Wet-bulb temperature 15:
Outdoor Dry-bulb temperature 7:Wet-bulb temperature 6:
Refrigerant piping length (one way): 5m
✽1 Measured under rated operating frequency.
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6
OUTLINES AND DIMENSIONS
5
Unit : mm
INDOOR UNIT
155 155
335 320
41.5 215
42.5 214
3287.5
7055
5555 225 225
or more7
100
90
106
298
102624.5
780
210 5
53.5
19
159
58
14273.5
234
Air in
Air out
Wall hole [65
Indoor unit
Installation plate
Installation plate
11x20 Oblong hole
11x26 Oblong hole
10 or more
75 or more
66 or more
W
75 or more
W
In case of left, left back, or
left under piping (using spacer), 115 or more
Insulation [28
Drain hose [16
(Connected part O.D)
Liquid line [8.0-0.5m
Gas line [9.52-0.43m
Insulation [35 O.D
[19 I.D
{
Required space (Indoor unit)
MSZ-GB50VA
OB454qxp 06.3.22 4:30 PM Page 6

7
4NOISE CRITERIA CURVES
90
80
70
60
50
40
30
20
10 63 125 250 500 1000 2000 4000 8000
OCTAVE BAND SOUND PRESSURE LEVEL, 0dB=20µPa
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:
MSZ-GB50VA
INDOOR UNIT WALL
MICROPHONE
0.8m
1m
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8
6WIRING DIAGRAM
REFRIGERANT SYSTEM DIAGRAM
7
MSZ-GB50VA
Indoor
heat
exchanger
Flared connection
Room temperature
thermistor
RT11
Indoor coil
thermistor
RT13(sub)
Flared connection
Refrigerant flow in cooling
Refrigerant flow in heating
Refrigerant pipe [12.7
(with heat insulator)
Refrigerant pipe [6.35
(with heat insulator)
Indoor coil
thermistor
RT12(main)
Distributor
INDOOR UNIT
Unit : mm
INDOOR UNIT
SYMBOL
DB111
F11
MF
MV
NR11
SYMBOL
RT11
RT12
RT13
T111
TB
NAME
DIODE STACK
FUSE (T3.15AL250V)
INDOOR FAN MOTOR
VANE MOTOR (HORIZONTAL)
VARISTOR
NAME
ROOM TEMPERATURE THERMISTOR
INDOOR COIL THERMISTOR (MAIN)
INDOOR COIL THERMISTOR (SUB)
TRANSFORMER
TERMINAL BLOCK
NOTE: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, : Connector
MSZ-GB50VA
4
3
2
1
S2
POWER MONITOR
RECEIVER P.C.BOARD
26
230V~
BLU
INDOOR ELECTRONIC
CONTROL P.C. BOARD
SW P.C.
BOARD
INTERLOCK
SWITCH(FAN)
5
MV
TO OUTDOOR
UNIT
CONNECTING
BLK
RED
S3
TB TAB3
DB111
NR11
F11
5
6
4
2
2
LD
105(T)
LD
101(A)
12-24V
RT13
1R1
CN
GRN
LD104
CN201
2
1
151
CN
T111
RED
WHT
111
CN
CN
112
CN211 BLU
YLW
BLK
MF
RT11
RT12
1
3
5
S1
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9
SERVICE FUNCTIONS
8
8-2. 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.
8-1. TIMER SHORT MODE
For service, set time can be shortened by short circuit of JPG and JPS the electronic control P.C. board.
The time will be shortened as follows. (Refer to 9-7.)
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.)
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
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 accept 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.
How to modify the remote controller P.C. board
Remove batteries before modification.
The board has a print as shown below :
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.
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.
J2
J1
MSZ-GB50VA
OB454qxp 06.3.22 4:30 PM Page 9

TROUBLESHOOTING
9
10
9-1. 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 turn off the unit first with the remote controller, 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.
Housing point
Lead wiring
MSZ-GB50VA
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 appliance 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.
JR07
CN151 CN211CN112 CN1R1
BZ
8-3. 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.
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.)
How to release “AUTO RESTART FUNCTION”
1Turn off the main power for the unit.
2Solder the Jumper wire JR07 on the indoor electronic control P.C. board. (Refer to 9-7.)
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11
21 Stopper
Lock.
Left
Insert this end first.
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 discoloration.
4) When troubleshooting, refer to 9-2., 9-3. and 9-4.
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.
RESET button
Insert the negative pole of the
batteries first. Check if the polarity
of the batteries are correct.
NOTE : 1. If RESET button is not pressed, the remote controller may not operate correctly.
2. This remote controller 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.
2Press RESET button with tip end of ball point pen
or the like, and then use the remote controller.
1Remove the front lid and insert batteries.
Then reattach the front lid.
If horizontal vane is not installed correctly, all of the operation indicator lamps will blink.
In this case, install the horizontal vane correctly by following the procedures 1to 2.
NOTE: Before installation of the horizontal vane, turn OFF the power supply.
5. How to install the horizontal vane
In procedure 22lock the
stoppers until they click
into place.
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.
Operation indicator lamp flashes as shown in the figure below.
•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.
OPERATION INDICATOR
Not lighted
Blinking
Lighted
OB454qxp 06.3.22 4:30 PM Page 11

12
Outline of the function
This air conditioner can memorize the abnormal condition which has occurred once.
Even though LED indication listed on the troubleshooting check table (9-4.) disappears, the memorized failure details
can be recalled.
This mode is very useful when the unit needs to be repaired for the abnormality which doesn't recur.
9-2. Failure mode recall function
1. Flow chart of failure mode recall function for the indoor/outdoor unit
Operational procedure
Yes
(Blinks)
No
(OFF)
Yes
No
Releasing the failure mode recall function
Note1.Make sure to release the failure mode recall function once it's set up, otherwise the unit cannot operate properly.
2.If the abnormal condition is not deleted from the memory, the last abnormal condition is kept memorized.
W2. Blinking pattern when the indoor unit is abnormal:
W3.Blinking pattern when the outdoor unit is abnormal:
ON
OFF Beeps
Repeated cycle Repeated cycle
ON
OFF No beep Beeps
Repeated cycle
2.5-second OFF Blinking at 0.5-
second interval
2.5-second OFF 3-second ON Blinking at 0.5-
second interval
Beeps Repeated cycle
2.5-second OFF Blinking at 0.5-
second interval
No beep Beeps
Repeated cycle
2.5-second OFF 3-second ON Blinking at 0.5-
second interval
Repeated cycle
Beeps
Does the left lamp of OPERATION INDICATOR
lamp on the indoor unit blink at the interval of 0.5
seconds?
Blinks: Either indoor or outdoor unit is abnormal.
Beep are emitted at the same timing
as the blinking of the left lamp of
OPERATION INDICATOR lamp. W2
The cause of abnormality cannot be found because the abnormality doesn't recur.
Setting up the failure mode recall function
Before blinking, does the left lamp of
OPERATION INDICATOR lamp stay ON for 3
seconds?
Stays ON for 3 seconds (without beep):
The outdoor unit is abnormal.
The indoor unit is abnormal.
Check the blinking pattern, and confirm the abnormal point with the indoor unit
failure mode table(9-2.2.).
Make sure to check at least two consecutive blinking cycles. W2
Turn ON the power supply.
<Preparation of the remote controller>
1While pressing both OPERATION SELECT
button and TOO COOLbutton on the remote controller at the same time, press
RESET button.
2First, release RESET button.
And release the other two buttons after all LCD except the set temperature in
operation display section of the remote controller is displayed after 3 seconds.
Deleting the abnormal memorized condition
1After repairing the unit, recall the failure mode again according to
"Setting up the failure mode recall function" mentioned above.
2Press OPERATE/STOP(ON/OFF) button of the remote controller (the set temperature is displayed)
with the remote controller headed towards the indoor unit.
3Press EMERGENCY OPERATION switch so that the memorized abnormal condition is deleted.
4Release the failure mode recall function according to "Releasing the failure mode recall function"
mentioned above.
Repair the defective parts.
Release the failure mode recall function by the following procedures.
Turn OFF the power supply and turn it ON again.
Press RESET button of the remote controller.
Judgment of indoor/outdoor abnormality
Press OPERATE/STOP(ON/OFF) button of the remote controller (the set temperature
is displayed) with the remote controller headed towards the indoor unit. W1
Indoor unit is normal.
But the outdoor unit might be abnormal because there are some
abnormalities that can't be recalled with this way.
Confirm if outdoor unit is abnormal according to the detailed outdoor
unit failure mode recall function.
The outdoor unit is abnormal.
Check the blinking pattern, and confirm the abnormal point with the
outdoor unit failure mode table (Refer to outdoor unit service manual.)
Make sure to check at least two consecutive blinking cycles. W3
W1. Regardless of normal or abnormal, a short
beep is emitted once as the signal is received.
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13
2. Indoor unit failure mode table
NOTE : Blinking patterns of this mode differ from the ones of Troubleshooting check table(9-4.).
12-time flash
2.5-second OFF Replace the indoor electronic control
P.C. board.
Indoor control system When it cannot properly read data in the
nonvolatile memory of the indoor electronic
control P.C. board.
11-time flash
2.5-second OFF Refer to 9-6.A"Check of indoor fan
motor".
Indoor fan motor When the rotational frequency feedback
signal is not emit during the 12-seconds the
indoor fan operation.
2-time flash
2.5-second OFF
Refer to the characteristics of the main
indoor coil thermistor, the sub indoor coil
thermistor (9-7.).
Indoor coil thermistor When the indoor coil thermistor short or open
circuit is detected every 8 seconds during
operation.
3-time flash
2.5-second OFF Refer to 9-6.D"How to check mis-wiring
and serial signal error".
Serial signal When the serial signal from outdoor unit is
not received for a maximum of 6 minutes.
1-time flash
every 0.5-second Refer to the characteristics of the room
temperature thermistor (9-7.).
Room temperature
thermistor
When the room temperature thermistor short
or open circuit is detected every 8
seconds during operation.
Not lighted –Normal –
Left lamp of OPERATION
INDICATOR lamp
Correspondence
Abnormal point
(Failure mode) Condition
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14
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.w
Outdoor unit
doesn't
operate
even in
Test Run
operation.w
Indoor unit
operates, when
EMERGENCY
OPERATION
switch is pressed.
Indoor unit
doesn't operate,
when
EMERGENCY
OPERATION
switch is pressed.
Check room
temperature
thermistor.
Refer to 9-7.
"Test point
diagram and
voltage".
Refer to
"How to check
inverter/
compressor".
Refer to 9-6.B
"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 9-6.C
"Check of indoor
electronic control
P.C. board and indoor
fan motor".
Unit doesn't
operate
normal
operation in
COOL or
HEAT mode.
Refer to
"Check of
R.V. coil".
Left lamp
Flash on and off
at 0.5-second
intervals
Cause:
Indoor/
Outdoor unit
• Mis-wiring
or trouble
of serial signal
Left
lamp
2-time flash
Cause:
Indoor unit
• Trouble of
room temp-
erature/
indoor coil
thermistor
Left lamp
3-time flash
Cause:
Indoor unit
• Trouble of
indoor fan
motor
Left lamp
5-time flash
Cause:
Outdoor unit
• Outdoor
power
system
abnormality
Left lamp
6-time flash
Cause:
Outdoor unit
• Trouble of
thermistor
in outdoor
unit
Left lamp
7-time flash
Cause:
Outdoor unit
• Trouble of
outdoor
control
system
Refer to 9-6.
D "How to
check
mis-wiring
and serial
signal error
".
All lamps
Flash on and off
at 0.5-second
intervals
Cause:
Indoor unit
• The horizontal
vane is not
installed
correctly.
Refer to 9-6.
E "Check of
installation of
the horizontal
vane".
Check room
temperature
thermistor
and indoor
coil thermis-
tor.
Refer to 9-7.
"Test point
diagram and
voltage".
Refer to 9-6.
A"Check of
indoor fan
motor".
Refer to
"How to check
inverter/
compressor".
Refer to
"Check of
outdoor
thermistors".
Replace the
inverter P.C.
board or
the outdoor
electronic
control P.C.
board.
Left lamp
14-time flash
Cause:
Outdoor unit
• Other
abnormality
Check
"Flow chart of
the detailed
outdoor unit
failure mode
recall function."
Left lamp
4-time flash
Cause:
Indoor unit
• Trouble of
indoor unit
control
system
Replace the
indoor
electronic
control
P.C. board.
Refer to outdoor unit service manual.
Indoor unit operates.
Outdoor unit doesn't
operate normally.
If blinking of OPERATION
INDICATOR lamp cannot be
checked, it can be checked with
failure mode recall function.
w
"Test Run operation" means the
operation within 30 minutes after
EMERGENCY OPERATION switch
is pressed.
9-3. Instruction of troubleshooting
OB454qxp 06.3.22 4:30 PM Page 14

15
No.
1
3
6
7
SymptomOperation indicator lamp Condition Correspondence
Left lamp flashes.
0.5-second ON
0.5-second OFF
Mis-Wiring
or serial
signal
Outdoor
power
system
Outdoor
thermistors
Outdoor
control
system
Indoor coil
thermistor
When the serial signal from the outdoor unit is
not received for a maximum of 6 minutes.
When it consecutively occurs 3 times that the
compressor stops for overcurrent protection or
start-up failure protection within 1 minute after
start-up.
When the outdoor thermistors short or open
circuit during the compressor operation.
When it cannot properly read data in the
nonvolatile memory of the inverter P.C. board
or the outdoor electronic control P.C. board.
• Refer to "Check of outdoor
thermistor".
Refer to outdoor unit service
manual.
• Refer to "How to check
inverter/compressor".
Refer to outdoor unit service
manual.
• Check the stop valve.
• Replace the inverter P.C.
board or the outdoor
electronic control P.C. board.
Refer to outdoor unit service
manual.
• Refer to 9-6.D"How to check
mis-wiring and serial signal
error".
4Indoor fan
motor
8
Abnormal
point
Room
tempera-
ture
thermistor
Left lamp flashes.
2-time flash
2.5-second OFF
When the indoor coil or the room temperature
thermistor is short or open circuit. • Refer to 9-7.the
characteristics of indoor coil
thermistor, and the room
temperature thermistor.
Left lamp flashes.
3-time flash
2.5-second OFF
When the rotational frequency feedback
signal is not emitted during the indoor fan
operation. • Refer to 9-6.A"Check of
indoor fan motor".
Indoor unit
and outdoor
unit do not
operate.
Indoor unit
and outdoor
unit do not
operate.
Left lamp flashes.
5-time flash
2.5-second OFF
Left lamp flashes.
6-time flash
2.5-second OFF
Indoor unit
and outdoor
unit do not
operate.
Indoor unit
and outdoor
unit do not
operate.
Indoor unit
and outdoor
unit do not
operate.
Other
abnormality
An abnormality other than above mentioned is
detected.
• Confirm the abnormality in
detail using the failure mode
recall function for outdoor
unit.
Indoor unit
and outdoor
unit do not
operate.
Indoor unit
and outdoor
unit do not
operate.
9
5
Left lamp flashes.
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.
Indoor unit
and outdoor
unit do not
operate.
•Replace the indoor electronic
control P.C. board.
Outdoor
control
system
When it cannot properly read data in the
nonvolatile memory of the inverter P.C. board
or the outdoor electronic control P.C. board.
• Check the blinking pattern of
the LED on the inverter P.C.
board or the outdoor
electronic
control P.C. board.
2Outdoor unit
does not
operate.
Left lamp lights up
Left lamp flashes.
7-time flash
2.5-second OFF
Left lamp flashes.
14-time flash
2.5-second OFF
9-4. Troubleshooting check table
Not lighted
Blinking
OPERATION INDICATOR
Lighted
· Flashing of OPERATION INDICATOR lamp (left-hand side lamp)
indicates abnormalities.
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
OPERATION INDICATOR lamp flashing.
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16
OPERATION INDICATOR
Not lighted
Blinking
Lighted
OPERATION INDICATOR
Not lighted
Blinking
Lighted
No.
1
SymptomOperation indicator lamp Condition Correspondence
Abnormal
point
0.5-second ON
0.5-second OFF
When the electricity is not conducted to the
interlock switch (Fan) of the horizontal vane. • Refer to 9-6.E"Check of
installation of the horizontal
vane".
Indoor unit
and outdoor
unit do not
operate.
Attachment
of the
horizontal
vane
All lamps flash at the same time.
No. SymptomOperation indicator lamp Condition Correspondence
Abnormal
point
1
MXZ type
Operation
mode
setting
Outdoor unit
operates but
indoor unit
does not
operate.
When the operation mode of the each indoor
unit is differently set to COOL(includes DRY)
and HEAT at the same time, the operation
mode of the indoor unit that has operated at
first has the priority.
• Unify the operation mode.
Refer to outdoor unit service
manual.
2.5-second OFF
Right lamp flash
· Flashing of OPERATION INDICATOR lamp (all lamps) indicates abnormality.
· Flashing of OPERATION INDICATOR lamp (right-hand side lamp) indicates
abnormality.
· OPERATION INDICATOR lamp (left-hand side lamp) is lighted.
9-5. Trouble criterion of main parts
MSZ-GB50VA
Part name FigureCheck method and criterion
Indoor fan motor(MF)
Room temperature
thermistor(RT11)
Indoor coil thermistor
(RT12(MAIN), RT13(SUB))
Horizontal vane
motor(MV)
Measure the resistance between the terminals with a tester.
(Part temperature 10°C ~ 30°C)
Check 9-6. A.
Measure the resistance with a tester.
Refer to 9-7."Test point diagram and voltage",
"Indoor electronic control P.C. board", the chart of thermistor.
Normal
BRN-other one 235 "~ 255 "
Color of the lead wire
RED
YLW
BRN
ORN GRN
ROTOR
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17
Check of indoor fan motor
A
When OPERATION INDICATOR lamp flashes 3-time.
Indoor fan does not operate.
wIf more than 12 seconds or more passes after EMERGENCY OPERATION
switch is pressed, the voltage mentioned above 2 goes 0V DC although
the indoor electric control P.C. board is normal.
Indoor electronic
control P.C. board
Pay careful attention to the high voltage on
the fan motor connector CN211.
Yes
No
No
No
(Changed)
Yes
(Unchanged)
Is there any foreign matter that
interferes the rotation of the
line flow fan?
Turn OFF the power supply.
Remove the foreign matter and
adjust the line flow fan.
Turn ON the power supply, wait 5 seconds or more, and then press
EMERGENCY OPERATION switch.
Measure the supply voltage as follows within 12 seconds
after EMERGENCY OPERATION switch is pressed.
If more than 12 seconds passes by, turn OFF the power supply and
turn ON it again, then measure the voltage. w
1.Measure the voltage between CN211 1(+) and 3(-).
2.Measure the voltage between CN211 5(+) and 3(-).
Is there 325V DC between
CN211 1(+) and 3(-), and does
the voltage between CN211 5(+)
and 3(-) rise to the range of 3 to 6V
DC within 12 seconds after
EMERGENCY OPERATION switch
is pressed?
Yes Replace the indoor fan motor.
CN211
Replace the indoor electronic control P.C. board.
The indoor fan motor error has occurred, and the indoor fan repeats "12-second ON and 30-second OFF" 3times, and then stops.
Measure the voltage between CN211
6(+) and 3(-) while the fan
motor is rotating.
Is it unchanged holding
0V DC or 15V DC?
Replace the indoor fan motor.
Replace the indoor electronic control P.C. board.
The indoor fan motor error has occurred, and the indoor fan doesn't operate.
9-6. Troubleshooting flow
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18
Check of remote controller and receiver P.C. board
B
Indoor unit operates by pressing EMERGENCY OPERATION switch, but does not operate with the remote controller.
wCheck if the remote controller is exclusive for this air conditioner.
Yes
Replace the batteries. (Refer to 9-1.4.)
Turn ON a radio to AM and press switch
ON the remote controller.
Is noise heard from radio?
Are there any fluorescent lights of
inverter or rapid-start type within
the range of 1m?
Replace the indoor electronic
control P.C. board.
Replace the remote controller.
● Reinstall the unit away from lights.
● Attach a filter on receiving part.
Switch ON the remote controller.
Is LCD display on the the remote
controller visible?
Remove the batteries, then set them back
and press RESET button. (Refer to 9-1.4.)
Check if the unit operates with the remote
controller.
Yes
Does the unit operate with the
remote controller?
Yes
OK
No
(not clear)
Yes
No
No
No
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19
The unit does not operate with the remote controller.
Also, OPERATION INDICATOR lamp does not light up by pressing EMERGENCY OPERATION switch.
Check of indoor electronic control P.C. board and indoor fan motor
C
Yes
No
w1. The fan motor connector's 1lead wire is red, whereas 3is black.
w2. Connect "+" of the tester to fan motor connector's 1lead
wire, and "-" to 3lead wire, otherwise the resistance cannot be
measured properly.
Yes
No
Does the unit operate with the remote controller?
Does OPERATION INDICATOR lamp light up by
pressing EMERGENCY
OPERATION switch?
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.
Measure the resistance of the horizontal vane
motor coil.
Refer to 9-5.
Measure the resistance between CN211 3
and 4of the indoor fan motor connector. Short/open circuit:
Replace the indoor fan motor.
Short/open circuit:
Replace the horizontal vane motor and the indoor
electronic control P.C. board.
Turn OFF the power supply.
Check both “parts side” and “pattern
side” of the indoor electronic control P.C.
board visually.
Replace the varistor(NR11) and fuse(F11).
Are the varistor(NR11) burnt
and the fuse(F11) blown?
Be sure to check both the fuse
and the varistor in any case.
No
Yes
No
Is the fuse(F11) blown only?
Yes
No
Is the resistance 1M"
or more?
Measure the resistance between
1(+) and 3(-) of the indoor fan
motor connector (to CN211 on the
indoor electronic control P.C. board) .
w1,w2
Replace the fuse (F11).
Replace the fuse (F11) and the indoor fan motor.
Is the resistance
approx. 4"?
Measure the resistance of cement
resistance R111 on the indoor electronic
control P.C. board.
Replace the indoor electronic control P.C. board.
Replace the indoor electronic control P.C. board
and the indoor fan motor.
Yes
CN211
Fuse(F11)
Varistor(NR11)
Indoor electronic
control P.C.Board
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20
How to check mis-wiring and serial signal error (when outdoor unit does not work)
D
• When unit cannot operate neither by the remote controller nor by EMERGENCY OPERATION switch.
Indoor unit does not operate.
• When OPERATION INDICATOR lamp flashes ON and OFF in every 0.5-second.
Outdoor unit does not operate.
Is there rated voltage in
the power supply?
Is there any mis-wiring,
poor contact, or wire
disconnection of the
indoor/outdoor
connecting wire?
W1. 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.
W3.Be sure to check this within 3 minutes after turning
ON. After 3 minutes, LED blinks 6 times. Even when
the inverter P.C.board or the outdoor electronic control
P.C.board is normal, LED blinks 6 times after
3 minutes.
(Except for outdoor unit of multi system type)
(Lighted or
not lighted)
No
Yes
No
Yes
Yes
No
Yes
No
Yes
W2 Be careful to the residual
voltage of smoothing capacitor.
Be sure to release the failure-mode
recall function after checking.
No
No
Yes
No
Yes
Yes
Yes
No
Yes
Refer to outdoor unit service manual.
Turn OFF the power supply.
Turn ON the power supply.
Is there rated voltage between
outdoor terminal block S1 and
S2?
Does the left lamp of OPERATION INDICATOR
lamp light up?
<Confirmation of the power to the indoor unit>
Press EMERGENCY OPERATION switch once.
Check the power
supply.
A
Turn OFF the power supply.
Check once more if the indoor/outdoor
connecting wire is not mis-wiring.
Short-circuit outdoor terminal block S2 and
S3.
W1
B
Turn ON the power supply.
Check the wiring.
Make them correct.
Turn OFF the power supply.
Remove the short-circuit between
outdoor terminal block S2 and S3.
Turn ON the power supply.
Is there amplitude of 10 to 20V DC
between outdoor terminal block S2
and S3? <Confirmation of serial
signal>
Is there rated voltage between
indoor terminal block S1 and S2?
<Confirmation of power voltage>
Replace the indoor electronic control P.C. board.
Replace the inverter P.C. board or
the outdoor electronic control P.C.board.
W2
Is there any error of the
indoor/outdoor connecting wire,
such as the damage of the wire,
intermediate connection, poor
contact to the terminal block?
Is there any error of the
indoor/outdoor connecting wire,
such as the damage of the wire,
intermediate connection, poor
contact to the terminal block?
No
Replace the
indoor/outdoor
connecting wire.
Replace the
indoor/outdoor
connecting wire.
Is serial signal
error indicated
6 minutes later?
Yes
No
· Turn OFF inverter-controlled lighting
equipment.
· Turn OFF the power supply and then
turn ON again.
· Press EMERGENCY OPERATION
switch.
B
· Reinstall
either the
unit or the
light each
other away.
· Attach a filter
on remote
control
receiving
section of
the indoor
unit.
A
Is serial signal error indicated 6 minutes later?
No
Does the LED on the inverter P.C. board
or the outdoor electronic control P.C. board
repeat "3.6-second-OFF and 0.8-second-ON
quick blinking"? W3
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