Mitsubishi Electric MS-GD80VB-E1 User manual

CONTENTS
1. TECHNICAL CHANGES ··································· 2
2. PART NAMES AND FUNCTIONS····················· 2
3. SPECIFICATION················································ 3
4. NOISE CRITERIA CURVES ······························ 3
5. OUTLINES AND DIMENSIONS ························ 4
6. WIRING DIAGRAM············································ 4
7. REFRIGERANT SYSTEM DIAGRAM ··············· 5
8. SERVICE FUNCTIONS ····································· 6
9. MICROPROCESSOR CONTROL ····················· 8
10. TROUBLESHOOTING····································· 14
11. DISASSEMBLY INSTRUCTIONS···················· 23
SPLIT-TYPE AIR CONDITIONERS
MS-GD80VB - E1
SERVICE MANUAL
Wireless type
Model
INDOOR UNIT
NOTE:
RoHS compliant products have <G> mark on the spec name plate.
Outdoor unit service manual
MU-GD•VB Series (OBH512)
No. OBH511
REVISED EDITION-A
PARTS CATALOG (OBB511)
Revision A:
• Another type of the electronic control P.C.
board (TYPE 2) has been added to the
original one (TYPE 1). They are both com-
patible with MS-GD80VB- E1 .
Please void OBH511.

TECHNICAL CHANGES
2
1
PART NAMES AND FUNCTIONS
2
Front panel
(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
Catechin air filter
Panel
MS-GD80VB
ACCESSORIES
Installation plate
Installation plate fixing screw 4 × 25 mm
Remote controller holder
Fixing screw for × 3.5 × 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
MS-GD80VB
MS-GD80VB - E1
1. New model
Use the specified refrigerant only
Never use any refrigerant other than that specified.
Doing so may cause a burst, an explosion, or fire when the unit is being used, serviced, or disposed of.
Correct refrigerant is specified in the manuals and on the spec labels provided with our products.
We will not be held responsible for mechanical failure, system malfunction, unit breakdown or accidents caused by
failure to follow the instructions.
Revision A:
• Another type of the electronic control P.C. board (TYPE 2) has been added to the original one (TYPE 1). They are both com-
patible with MS-GD80VB- E1 .
OBH511A

3
SPECIFICATION
3
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
Indoor-Outdoor piping length: 5 m
Indoor model
Function
Power supply
Air flow
(High/Med./Low)
Running current
Breaker capacity
Power input
Power factor
Fan motor current
Model
Dimensions W × H × D
Weight
Air direction
Sound level
(High/Med./Low)
Fan speed (High/Med./Low)
Fan speed regulator
Remote controller model
Fan Electrical
datamotor
Special remarks
Cooling
Single phase
230 V, 50 Hz
954/822/684
0.34
10
69
88
0.34
RC4V40-AA
1,100 × 325 × 258
16
5
47/42/37
1,280/1,130/970
3
KM04B
/h
A
A
W
%
A
mm
kg
dB
rpm
MS-GD80VB
NOISE CRITERIA CURVES
4
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˚C Wet-bulb temperature 19˚C
47
SPL(dB(A)) LINE
High
FAN SPEED
MS-GD80VB
INDOOR UNIT
WALL
MICROPHONE
0.8m
1m
OBH511A

OUTLINES AND DIMENSIONS
4
5
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 ø28
Drain hose ø16
(Connected part O.D)
Installation plate
Wall hole ø75
Wireless remote controller
Installation plate Indoor unit
{
Liquid line ø 9.52- 0.5 m
Gas line ø 12-0.43 m
Insulation ø
ø
50 O.D
32 I.D
Power supply cord
Lead to right 2.0 m
Lead to left 1.0 m
MS-GD80VB Unit: mm
WIRING DIAGRAM
6
MS-GD80VB
OBH511A

5
REFRIGERANT SYSTEM DIAGRAM
7
MS-GD80VB
Indoor
heat
exchanger
Flared connection
Room temperature
thermistor
RT11
Indoor coil
thermistor
RT13(sub)
Flared connection
Refrigerant pipe ø15.88
(with heat insulator)
Refrigerant pipe ø9.52
(with heat insulator)
Indoor coil
thermistor
RT12(main)
Strainer
#50
Refrigerant flow in cooling
Unit: mm
OBH511A

6
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.
How to modify the remote controller P.C. board
Remove batteries before modification.
The board has a print as shown below:
8-1. TIMER SHORT MODE
For service, set time can be shortened by short circuit of JPG and JPS on the electronic control P.C. board.
(Refer to 10-6.)
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.)
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.
MS-GD80VB
J2
J1
Table 1
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
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.
NOTE: For modification, take out the bat-
teries and press the OPERATE/
STOP (ON/OFF) button 2 or 3
times at first.
After modification, put back the bat-
teries then press the RESET but-
ton.
OBH511A

7
Operation
If the main power has been cut, the operation settings remain.
After 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 disable “AUTO RESTART FUNCTION”
Turn OFF the main power for the unit.
Solder jumper wire to JR07 on the indoor electronic control P.C.
board. (Refer to 10-6.)
NOTE: •The operation settings are memorized when 10 seconds have passed after the remote controller was operated with
the remote controller.
•If main power is turned OFF or a power failure occurs while AUTO START/STOP timer is active, the timer setting is
cancelled.
•If the unit has been OFF with the remote controller before power failure, the auto restart function does not work as the
power button of the remote controller is OFF.
•To prevent breaker OFF due to the rush of starting current, systematize other home appliances not to turn ON at the
same time.
•When some air conditioners are connected to the same supply system, if they are operated before power failure, the
starting current of all the compressors may flow simultaneously at restart.
Therefore, the special counter-measures are required to prevent the main voltage-drop or the rush of the starting cur-
rent by adding to the system that allows the units to start one by one.
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” automatically starts operation
in the same mode just before the shutoff of the main power. However if the unit is operated in “I FEEL CONTROL” mode
before power failure, the operation is not memorized. In “I FEEL CONTROL” mode, the operation is decided by the initial
room temperature.
8-3. AUTO RESTART FUNCTION
OBH511A

8
MICROPROCESSOR CONTROL
9
MS-GD80VB
ON/OFF
FAN
TOO
WARM TOO COOL
VANE
MODE
ECONO COOL
STOP
START
HR.
MIN.
WIDE VANE
LONG
I FEEL COOL
DRY
AM
RESET CLOCK
OPERATION SELECT button
FAN SPEED CONTROL button
OFF-TIMER button
HR. button
MIN. button
(TIME SET button)
ON-TIMER button
RESET button
ECONO COOL button
VANE button
(Horizontal vane button)
CLOCK SET button
LONG button
WIDE VANE button
(Vertical vane button)
FAN
ON/OFF
TOO
COOL
PM
AM
TOO
WARM
Signal transmitting section
Operation display section
OPERATE/STOP
(ON/OFF) button
TEMPERATURE buttons
WIRELESS REMOTE CONTROLLER
NOTE: • The last setting will be stored after the unit is turned OFF with the remote controller.
• Indoor unit receives the signal of the remote controller with beeps.
Approximate
2 or more
Difference
between target
temperature
and room
temperature
This shows that the
air conditioner is
operating to reach
the target temperature.
Please wait until the
target temperature is
obtained.
This shows that the
room temperature is
approaching the
target temperature.
Operation stateIndication
Approximate
2 or less
OPERATION INDICATOR lamp
The OPERATION INDICATOR at the right side of the indoor
unit indicates the operation state.
INDOOR UNIT DISPLAY SECTION
The following indication applies regardless of
shape of the indicator.
Lighted
Not lighted
OBH511A

9
9-1. COOL ( ) OPERATION
(1) Press OPERATE/STOP (ON/OFF) button.
OPERATION INDICATOR lamp of the indoor unit turns on with a beep tone.
(2) Select COOL mode with OPERATION SELECT button.
(3) Press TEMPERATURE buttons.
(TOO WARM or TOO COOL button) to select the desired temperature.
The setting range is 16 ~ 31˚C
Indoor fan continues to operate regardless of thermostat's OFF-ON at set speed.
1. Coil frost prevention
When the temperature of indoor heat exchanger becomes too low, the coil frost prevention mode works.
The indoor fan operates at the set speed and the compressor stops. This mode continues until the temperature of
indoor heat exchanger rises.
2. Discharge temperature protection
The compressor is controlled by the temperature of discharge temperature thermistor RT62 for excess rise protection
of compressor discharge pressure.
9-2. DRY ( ) OPERATION
(1) Press OPERATE/STOP (ON/OFF) button.
OPERATION INDICATOR lamp of the indoor unit turns ON with a beep tone.
(2) Select DRY mode with OPERATION SELECT button.
(3) The set temperature is determined from the initial room temperature.
(4) DRY operation will not function when the room temperature is 13˚C or below.
1. Indoor fan speed control
Indoor fan operates at the set speed by FAN SPEED CONTROL button.
However, in AUTO fan operation, fan speed becomes Low.
2. The operation of the compressor and indoor/outdoor fan
Compressor operates by room temperature control and time control.
Set temperature is controlled to fall 2˚C from initial room temperature.
Indoor fan and outdoor fan operate in the same cycle as the compressor.
3. Coil frost prevention
• The operation is as same as coil frost prevention during COOL mode.
• Indoor fan operates at the set speed and the compressor stops for 5 minutes, because protection (Coil frost preven-
tion) has the priority.
However, when coil frost prevention works while the compressor is not operating, it's speed becomes Low.
9-3. FAN ( ) OPERATION
(1) Press OPERATE/STOP (ON/OFF) button.
OPERATION INDICATOR lamp of the indoor unit turns ON with a beep tone.
(2) Select FAN mode with OPERATION SELECT button.
(3) Select the desired fan speed. When AUTO, it becomes Low.
Only indoor fan operates. Outdoor unit dose not operate.
9-4. "I FEEL CONTROL" ( ) OPERATION
(1) Press OPERATE/STOP (ON/OFF) button on the remote controller. OPERATION INDICATOR lamp of the indoor unit
turns ON with a beep tone.
(2) Select "I FEEL CONTROL" mode with OPERATION SELECT button.
(3) The operation mode is determined by the room temperature at start-up of the operation.
• Once the mode is fixed, the mode dose not change by room temperature afterwards.
• Under the ON-TIMER ( ) operation, mode is determined as follows.
When the system is stopped on the remote controller, and restarted within 2 hours in " I FEEL CONTROL" ( ) mode,
the system operates in previous mode automatically regardless of the room temperature.
Mode
COOL mode of
"I FEEL CONTROL"
DRY mode of
"I FEEL CONTROL"
Initial room temperature
25 °C or more
more than 13
°C ,
less than 25
°C
OBH511A

10
(4) The initial set temperature is decided by the initial room temperature.
Model Initial room temperature Initial set temperature
COOL mode of
" I FEEL CONTROL"
26˚C or more 24˚C1
25˚C to 26˚C Initial room temperature minus 2˚C
DRY mode of
" I FEEL CONTROL" more than 13˚C, less than 25˚C Initial room temperature minus 2˚C
1 When the system is restarted with the remote controller, the system operates with the previous set temperature
regardless of room temperature at restart.
The set temperature is calculated by the previous set temperature.
(5) TEMPERATURE buttons
In " I FEEL CONTROL " ( ) mode, set temperature is decided by the microprocessor based on the room temperature.
In addition, set temperature can be controlled by TOO WARM or TOO COOL buttons when you feel too cool or too
warm.
Each time the TOO WARM or TOO COOL button is pressed, the indoor unit receives the signal and emits a beep tone.
• Fuzzy control
When the TOO COOL or TOO WARM button is pressed, the microprocessor changes the set temperature, consider-
ing the room temperature, the frequency of pressing TOO COOL or TOO WARM button and the user's preference to
heat or cool. So this is called "Fuzzy control", and works only in "I FEEL CONTROL" mode.
In DRY mode of "I FEEL CONTROL", the set temperature doesn't change.
…To raise the set temperature 1~2˚C …To lower the set temperature 1~2˚C
9-5. AUTO VANE OPERATION
1. Horizontal vane
(1) Vane motor drive
These models are equipped with a stepping motor for the horizontal vane. The rotating direction, speed, and angle of
the motor are controlled by pulse signals (approximate 12 V) transmitted from indoor microprocessor.
(2) The horizontal vane angle and mode change as follows by pressing the VANE button.
OBH511A

11
(3) Positioning
To confirm the standard position, the vane moves until it touches the vane stopper. Then the vane is set to the desired
angle.
Confirming of standard position is performed in the following case:
(a) When the power supply turns ON.
(b) When the operation starts or finishes (including timer operation).
(c) When the test run starts.
(d) When the vane control is changed AUTO to MANUAL (except SWING).
(d) When the SWING is finished (including ECONO COOL).
(4) VANE AUTO ( ) mode
In VANE AUTO mode, the microprocessor automatically determines the horizontal vane angle and operation to make the
optimum room-temperature distribution.
(5) STOP (operation OFF) and ON-TIMER standby
When the following cases occur, the horizontal vane returns to the closed position.
(a) When OPERATE/STOP (ON/OFF) button is pressed (POWER OFF).
(b) When the operation is stopped by the emergency operation.
(c) When ON-TIMER is on standby.
(6) Dew prevention
During COOL or DRY operation at Vane Angle 4 or 5 when the compressor cumulative operation time of compressor
exceeds 1 hour, the vane angle automatically changes to Angle 1 for dew prevention.
(7) SWING ( ) mode
By selecting SWING mode with VANE button, the horizontal vane swings vertically. The remote controller displays " ".
SWING mode is cancelled when VANE button is pressed once again.
(8) ECONO COOL ( ) operation (ECONOmical operation)
When ECONO COOL button is pressed in COOL mode, set temperature is automatically set 2 °C higher.
Also the horizontal vane swings in various cycle.
SWING operation makes you feel cooler than set temperature. So, even though the set temperature is higher, the air
conditioner can keep comfort. As a result, energy can be saved.
To cancel this operation, select a different mode or press one of the following buttons in ECONO COOL operation:
ECONO COOL, VANE or LONG button.
(9) LONG ( ) mode
By pressing LONG button indoor fan speed becomes faster than setting fan speed on the remote controller, and the
horizontal vane moves to the position for LONG mode. The remote controller displays " ".
To cancel this operation, press one of the following buttons:
ECONO COOL button in COOL mode, VANE or LONG button.
• In the following example, the vertical vane is set to (front.).
OBH511A

12
2. Vertical vane
(1) Vane motor drive
These models are equipped with a stepping motor for the vertical vane. The rotating direction, speed, and angle of the
motor are controlled by pulse signals (approximate 12 V) transmitted from microprocessor.
(2) The vertical vane angle and mode change as follows by pressing WIDE VANE button.
(3) Positioning
To confirm the standard position, the vane moves until it touches the vane stopper. Then the vane is set to the desired
angle.
Confirming of standard position is performed in the following case:
(a) When OPERATE/STOP (ON/OFF) button is pressed (POWER ON/OFF).
(b) When SWING is started or finished.
(c) When the power supply turns ON.
(4) SWING ( ) mode
By selecting SWING mode with WIDE VANE button, the vertical vane swings horizontally. The remote controller dis-
plays " ".The vane moves right and left in the width of Angle 4 repeatedly.
(5) WIDE ( ) mode
By selecting WIDE mode with WIDE VANE button, indoor fan speed becomes faster than setting fan speed on the
remote controller ( ). The remote controller displays " ".
Indoor fan speed becomes faster than setting fan speed on the remote controller even when or is selected.
9-6. TIMER OPERATION
1. How to set the timer
(1) Press OPERATE/STOP (ON/OFF) button to start the air conditioner.
(2) Check that the current time is set correctly.
NOTE: Timer operation will not work without setting the current time. Initially "AM0:00" blinks at the current time display
of TIME MONITOR, so set the current time correctly with CLOCK SET button.
(3) Press ON/OFF TIMER buttons to select the operation.
"ON-TIMER" button…AUTO START operation (ON timer)
"OFF-TIMER" button…AUTO STOP operation (OFF timer)
(4) Press HR. and MIN. button to set the timer. Time setting is 10-minute units.
HR. and MIN. button will work when " " or " " mark is flashing.
These marks disappear in 1 minute.
After setting the ON timer, check that OPERATION INDICATOR lamp of the indoor unit lights.
NOTE1: Be sure to place the remote controller at the position where its signal can reach the air conditioner even during
TIMER operation, or the set time may deviate within the range of about 10 minutes.
NOTE2: Reset the timer in the following cases, or the set time may deviate and other malfunctions may occur.
• A power failure occurs.
• The circuit breaker functions.
2. Cancel
TIMER setting can be cancelled with ON/OFF TIMER buttons.
To cancel ON timer, press "ON-TIMER" button.
To cancel OFF timer, press "OFF-TIMER" button.
TIMER is cancelled and the display of set time disappears.
OBH511A

13
PROGRAM TIMER
• OFF timer and ON timer can be used in combination.
• " " and " " display shows the order of OFF timer and ON timer operation.
(Example 1) The current time is 8:00 PM.
The unit turns OFF at 11:00 PM, and ON at 6:00 AM.
(Example 2) The current time is 11:00 AM.
The unit turns ON at 5:00 PM, and OFF at 9:00 PM.
NOTE: TIMER setting will be cancelled by failure or breaker functioning.
9-7. EMERGENCY/TEST OPERATION
In case of test run operation or emergency operation, use EMERGENCY OPERATION switch on the front of the indoor
unit. Emergency operation is available when the remote controller is missing, has failed or batteries of remote controller
run down. The unit will start and OPERATION INDICATOR lamp will light.
The first 30 minutes of operation is the test run operation. This operation is for servicing. The indoor fan speed runs at
High speed and the temperature control does not work.
After 30 minutes of test run operation, the system shifts to EMERGENCY COOL MODE with a set temperature of 24˚C.
The fan speed shifts to Med. speed.
The coil frost prevention works even in the test run or the emergency operation.
In the test run or emergency operation, the horizontal vane operates in VANE AUTO ( ) mode.
Emergency operation continues until EMERGENCY OPERATION switch is pressed again or the unit receives any signal
from the remote controller. In case of latter, normal operation will start.
NOTE: Do not press EMERGENCY OPERATION switch during normal operation.
• The following indication applies regardless of shape of the indicator.
9-8. 3-MINUTE TIME DELAY OPERATION
When the system turns OFF, compressor will not restart for 3 minutes as 3-minute time delay function operates to protect
compressor form overload.
OBH511A

14
TROUBLESHOOTING
10
10-1. CAUTIONS ON TROUBLESHOOTING
1. Before troubleshooting, check the following:
(1) Check the power supply voltage.
(2) Check the indoor/outdoor connecting wire for mis-wiring.
2. Take care the following during servicing.
(1) Before servicing the air conditioner, be sure to turn OFF the main unit first with the remote controller, and 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 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 com-
ponents.
(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 OPERATION INDICATOR lamp is flashing ON and OFF before starting serv-
ice work.
(2) Before servicing check, that the connector and terminal are connected properly.
(3) When the electronic control P.C. board seems to be defective, check the copper foil pattern for disconnection and the
components for bursting and discoloration.
(4) When troubleshooting, refer to 10-2. and 10-3.
4. How to replace batteries
Weak batteries may cause the remote controller malfunction.
In this case, replace the batteries to operate the remote controller normally.
Remove the front lid and insert batteries.
Then reattach the front lid.
Lead wiring Housing point
<Incorrect> <Correct>
NOTE: 1.If the RESET button is not pressed, the remote controller may not operate correctly.
2. Do not use the leaking batteries.
MS-GD80VB
FAN
RESET button
Insert the negative pole
of the batteries first.
Check if the polarity of
the batteries is correct.
FAN
Press the RESET button with a thin instrument, and
then use the remote controller.
OBH511A

15
Start
Indoor unit
operates.
Outdoor unit
does not
operate.
Indoor unit
does not receive
the signal from
remote controller.
Indoor unit
operates.
Outdoor unit
does not operate
normally.
OPERATION INDICATOR
lamp on the indoor unit is
flashing ON and OFF.
Indoor unit
operates when
the EMERGENCY
OPERATION
switch is pressed.
Indoor unit
does not operate
when the
EMERGENCY
OPERATION
switch is pressed.
Check room
temperature
thermistor.
Refer to 10-6.
"Test point
diagram and
voltage".
Refer to
"Check of
outdoor unit".
Refer to 10-5.
"Check of
remote controller
and receiver
P.C. board".
Flash ON and
OFF at 0.5-
second
intervals
Cause:
Indoor/
outdoor unit
• Mis-wiring
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
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 10-5.
"How to
check
mis-wiring
(When
outdoor unit
does not
work)".
Check room
temperature
thermistor
and indoor
coil thermis-
tor.
Refer to 10-6.
"Test point
diagram and
voltage".
Refer to 10-5.
"Check of
indoor fan
motor".
Refer to
"Check of
outdoor
thermistor".
Replace the
deicer
P.C. board.
10-time flash
Cause:
Outdoor unit
• Trouble of
low discharge
temperature
protection
Refer to
"Check of
LEV".
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.
1. Check indoor /
outdoor
connecting wire.
2. Refer to 10-5.
"Check of indoor
electronic control
P.C. board".
Outdoor unit
does not
stop even
if indoor unit
stops.
Refer to
"Check of
outdoor unit".
"Test run operation" means the operation within 30 minutes after EMERGENCY OPERATION switch is pressed.
Outdoor unit
operates only
in “Test run
operation”.
Outdoor unit
does not
operate
even in
“Test run
operation”.
10-2. INSTRUCTION OF TROUBLESHOOTING
OBH511A

16
No.
1
2
4
5
6
SymptomOperation indicator lamp Condition Remedy
0.5-second ON
0.5-second OFF
Mis-Wiring
Outdoor
thermistor
Outdoor
control
system
Indoor coil
thermistor
3 minutes after power supply turns ON,
serial signal is not received.
<Thermistor short>
Thermistors are abnormal when they short
after compressor start-up.
<Thermistor open>
Thermistors are abnormal when they open
after compressor start-up.
However, discharge temperature thermistor is
abnormal when open circuit is detected more
than 10 minutes after compressor start-up.
It cannot properly read data in the nonvolatile
memory of the deicer P.C. board.
• Check the deicer P.C.
board.
• Reconnect the connector.
Refer to "Check of outdoor
thermistor". Refer to outdoor
service manual.
• Check the deicer P.C. board.
Refer to outdoor service
manual.
• Refer to 10-5. "How to
check mis-wiring ".
3Indoor fan
motor
7
Low
discharge
temperature
protection
Discharge temperature has been 50 °C or less
on cool operation.
Abnormal
point
Outdoor unit
does not
operate.
Room
temperature
thermistor
2-time flash
2.5-second OFF
Indoor coil/room temperature thermistor
detects short or open circuit every 8 seconds
during operation.
• Refer to the characteristics of
indoor coil thermistor, and
room temperature thermistor
on 10-6.
3-time flash
2.5-second OFF
Indoor fan repeats
12 seconds ON
and 3 minutes OFF.
When the indoor
fan breaks, the
fan keeps stopping.
The rotational frequency feedback signal is
not emitted for 12 seconds after indoor fan
motor is operated.
• Refer to 10-5. "Check of
indoor fan motor".
4-time flash
2.5-second OFF
Indoor
control
system
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.
6-time flash
2.5-second OFF
• Refer to "Check of LEV".
• Check refrigerant circuit and
refrigerant amount.
Refer to outdoor service
manual.
Outdoor unit
does not
operate.
Outdoor unit
does not
operate.
Outdoor unit
does not
operate.
7-time flash
2.5-second OFF
10-time flash
2.5-second OFF
10-3. TROUBLESHOOTING CHECK TABLE
Lighted
Not lighted
• Before taking measures, make sure that the symptom reappears for accurate troubleshooting.
When the indoor unit has started operation and the following detection method has detected an abnormality
(the first detection after the power ON), the indoor electronic control P.C. board turns OFF the indoor fan motor
with the OPERATION INDICATOR lamp flashing.
· Flashing of the OPERATION INDICATOR lamp (the left-hand side lamp)
indicates possible abnormalities.
OBH511A

17
MS-GD80VB
Part name Figure Check method and criterion
Indoor fan motor (MF)
INNER
PROTECTOR
135± 5 °C OPEN
Color of lead wire
WHT – BLK
BLK – RED
Measure the resistance with a tester.
(Part temperature 10 °C ~ 30 °C )
Refer to 10-6."Test point diagram and voltage",
"Indoor electronic control P.C. board", for the chart of thermistor.
Room temperature
thermistor (RT11)
Indoor coil thermistor
(RT12 (main), RT13 (sub))
Horizontal vane
motor (MV1)
Vertical vane
motor (MV2)
Motor part
Sensor part
Measure the resistance between the terminals with a tester.
(Part temperature 10 °C ~ 30 °C )
Color of lead wire
BRN – YLW
YLW – GRY
Normal
4.5 ~ 5.5 V
Measure the voltage power ON.
(When fan revolved one time)
0 V →5 V →0 V
(Approx.)
Normal
282 Ω~ 306 Ω
Measure the resistance between the terminal with a tester.
(Part temperature 10
°C ~ 30 °C )
BLK
RED
WHT
GRY
YLW BRN
Normal
132 Ω~ 144 Ω
152 Ω~ 166 Ω
YLW
GRNORN
BRN
RED ROTOR
MAIN
AUX.
P
:INNER PROTECTOR
P
10-4. TROUBLE CRITERION OF MAIN PARTS
Check of indoor fan motor
A
When OPERATION INDICATOR lamp flashes 3-time.
Indoor fan motor does not operate.
Disconnect lead wires from connector CN211 on the indoor electronic control P.C. board.
Measure resistance between lead wires No.1 and No.4 and then No.3 and No.4.
Are lead wires connected? Is soldered point of the connector
correctly soldered?
Is resistance 0 (short circuit) or (open circuit)?
Yes ( 0 or )
No
(others)
Yes
No
Yes
No
Resolder it.
Reconnect the lead wires.
Repair or replace the indoor fan motor.
Turn OFF the power supply.
Check connector CN211 visually.
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
voltage between No.2(+) and No.3(-) on CN121.
Replace the indoor electronic control P.C. board.
Does voltage repeat 0 V DC and 5 V DC?
Yes
No
10-5. TROUBLESHOOTING FLOW
OBH511A

18
No
(not clear)
Yes
Yes
Check of remote controller and receiver P.C. board
B
Indoor unit operates by pressing the EMERGENCY OPERATION switch, but does not operate with the remote
controller.
Replace the batteries (Refer to 10-1.4.).
Is noise heard from radio?
Are there any fluorescent lights of
inverter or rapid-start type within
the range of 1 m?
Measure the voltage between receiver P.C. board connector CN301 No.1(+) and No.3(-) when the remote
controller button is pressed (Refer to 10-6.).
Is the voltage approximately 4 V DC?
Is LCD display on the remote con-
troller visible?
Remove the batteries, then set them back
and press the RESET button. Check if the
unit operates with the remote controller.
Yes
Does the unit operate with the
remote controller?
Yes
OK
Yes
No
No
No (5 V or 0 V DC)
No
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.
Check if the remote controller is exclusive for this air conditioner.
Turn ON a radio to AM and press
OPERATE/STOP (ON/OFF) button on the
remote controller.
Press OPERATE/STOP (ON/OFF)
button on the remote controller.
OBH511A

19
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.
Replace the fuse.
Is fuse (F11) blown?
Replace the fan
motor.
Replace the indoor
electronic control
P.C. board.
Is winding
resistance of
fan motor 0 Ω?
Is winding
resistance of
vane motor 0 Ω?
No
Replace the vane
motor.
Yes
Yes
Is varistor (NR11) burnt?
Replace the varistor.
Yes
Turn OFF the power supply.
Remove indoor fan motor connector CN211 and
vane motor connector CN151 from the indoor electronic
control P.C. board and turn ON the power supply.
No
No
Does the unit operate with the remote controller?
Does the OPERATION INDICATOR lamp light up
by pressing the EMERGENCY OPERATION switch?
Yes
No
Yes
Turn OFF the
power supply.
Turn OFF the
power supply.
Varistor (NR11)
Indoor electronic
control P.C. board
Fuse (F11)
No
The unit doesn’t operate with the remote controller. Also, the OPERATION INDICATOR lamp does not light up by
pressing the EMERGENCY OPERATION switch.
OBH511A

20
How to check mis-wiring
D
1. Turn OFF the power supply (indoor/outdoor unit) and disconnect indoor and outdoor
connecting wire at the terminal block □
3of the indoor unit.
2. Short-circuit terminal block □
N-□ 3of indoor unit by lead wire.
3. Turn ON the power supply (indoor unit) and press EMERGENCY OPERATION switch once.
During EMERGENCY OPERATION, is there
10 V DC between both ends of R601 on the
deicer P.C. board?
(By tester, the stylus is between 5 ~10 V.)
Refer to outdoor unit service manual.
Start
No
No
Is there 20 V DC between both ends of
R132 on the indoor electronic control P.C.
board ?
( By tester, the stylus is between 0 ~ 20 V. )
• Turn ON the power supply. (indoor/outdoor unit)
• Press EMERGENCY OPERATION switch once.
Is this mis-wiring, poor contact,
or wire disconnection?
Correct them.
Replace the indoor electronic
control P.C. board.
Is there 230 V AC between □
L-□ N
on the outdoor terminal block?
No Check the outdoor power supply
and connection of wiring.
Yes
No Replace the deicer P.C. board.
Yes
No Make the wiring between CN730
on the deicer P.C. board and
outdoor terminal block correct.
Replace the deicer P.C. board.
Yes
Is there 5 V DC between J101 +-J401
-
on the deicer P.C. board?
Yes
Yes
After 3 minutes, mis-wiring is indicated
(0.5-second ON, 0.5-second OFF)
on OPERATION INDICATOR
lamp on indoor unit.
Short circuit of JPG and JPS on the indoor electronic control
P.C. board enables self -check to be displayed in 3 seconds.
• Turn OFF the power supply. (indoor unit)
• Disconnect the lead wire that terminal
block □
N-□ 3of the indoor unit is
short-circuited.
• Connect indoor/outdoor connecting
wire.
Turn ON the power supply. (outdoor unit)
When OPERATION INDICATOR lamp flashes ON and OFF in every 0.5-second.
Outdoor unit does not operate.
OBH511A