Mitsubishi Electric MS-GF20VA-E1 User manual

CONTENTS
1. TECHNICAL CHANGES ··································· 2
2. PART NAMES AND FUNCTIONS····················· 3
3. SPECIFICATION················································ 4
4. NOISE CRITERIA CURVES ······························ 5
5. OUTLINES AND DIMENSIONS ························ 6
6. WIRING DIAGRAM············································ 6
7. REFRIGERANT SYSTEM DIAGRAM ··············· 7
8. SERVICE FUNCTIONS ····································· 8
9. MICROPROCESSOR CONTROL ··················· 10
10. TROUBLESHOOTING····································· 15
11. DISASSEMBLY INSTRUCTIONS ···················· 25
SPLIT-TYPE AIR CONDITIONERS
Outdoor unit service manual
MU-GF·VA Series (OBH622)
SERVICE MANUAL No. OBH621
INDOOR UNIT
PARTS CATALOG (OBB621)
NOTE:
RoHS compliant products have <G> mark on the spec name plate.
Models
MS-GF20VA -E1
MS-GF25VA -E1
MS-GF35VA -E1

2
MS-GF20VA - E1
MS-GF25VA - E1
MS-GF35VA - E1
1. New model
TECHNICAL CHANGES
1
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.
<Preparation before the repair service>
Prepare the proper tools.
Prepare the proper protectors.
Provide adequate ventilation.
After stopping the operation of the air conditioner, turn off the power-supply breaker and remove the power plug.
Discharge the capacitor before the work involving the electric parts.
<Precautions during the repair service>
Do not perform the work involving the electric parts with wet hands.
Do not pour water into the electric parts.
Do not touch the refrigerant.
Do not touch the hot or cold areas in the refrigeration cycle.
When the repair or the inspection of the circuit needs to be done without turning off the power, exercise great caution not to
touch the live parts.
OBH621

3
ACCESSORIES
PART NAMES AND FUNCTIONS
2
Model
MS-GF20VA
MS-GF25VA
MS-GF35VA
Installation plate 1
Installation plate fixing screw 4 × 25 mm 5
Remote controller holder 1
Fixing screw for 3.5 × 16 mm (Black) 2
Battery (AAA) for remote controller 2
Wireless remote controller 1
Felt tape (For left or left-rear piping) 1
MS-GF20VA MS-GF25VA MS-GF35VA
Air filter
(Nano platinum filter)
Front panel
Air cleaning filter
(Electrostatic anti-allergy
enzyme filter, option)
Operation indicator lamp
Remote control receiving section
Emergency operation switch (E.O. SW)
Horizontal vane
Air outlet Heat exchanger
Display section
Air inlet
Remote controller
OBH621

4
SPECIFICATION
3
Indoor model MS-GF20VA MS-GF25VA MS-GF35VA
Function Cooling
Power supply Single phase 230 V, 50 Hz
Electrical
data
Running current A 0.20 0.22
Power input W 35 43
Fan motor
Model RC4V18-FA
Current A 0.20 0.22
Dimensions W × H × D mm 798 x 295 x 232
Weight kg 9
Special remarks
Air direction 5
Airflow
Super High (POWERFUL)
m3/h
558 624
High 474 558
Med. 378 396
Low 246 288
Sound level
Super High (POWERFUL)
dB (A)
40 44
High 36 40
Med. 31 33
Low 25 26
Fan speed
Super High (POWERFUL)
rpm
1,000 1,100
High 880 1,000
Med. 740 770
Low 540 610
Fan speed regulator 4
Remote controller model KM12A
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
Indoor-Outdoor piping length: 5 m
OBH621

5
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
COOLING
FUNCTION SPL(dB(A)) LINE
Super High
FAN SPEED
40
NC-10
OCTAVE BAND SOUND PRESSURE LEVEL, 0dB re 0.0002 MICRO BAR
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
COOLING
FUNCTION SPL(dB(A)) LINE
Super High
FAN SPEED
40
NC-10
OCTAVE BAND SOUND PRESSURE LEVEL, 0dB re 0.0002 MICRO BAR
Test conditions
Cooling: Dry-bulb temperature 27 °C
Wet-bulb temperature 19 °C
INDOOR UNIT
WALL
MICROPHONE
0.8m
1m
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
COOLING
FUNCTION SPL(dB(A)) LINE
Super High
FAN SPEED
44
NC-10
OCTAVE BAND SOUND PRESSURE LEVEL, 0dB re 0.0002 MICRO BAR
NOISE CRITERIA CURVES
4
MS-GF20VA MS-GF25VA
MS-GF35VA
OBH621

6
Unit: mm
OUTLINES AND DIMENSIONS
5
211.5
231.5
253
21.5
155 155
80
80 225 225
3
5232
56
69
798
785 6.5
130619
50
295
50
42
56
43
42
8
100
107
112
45
56
69
33861
212.5
254
41
42
315 84
11×26 Oblong hole 11×20 Oblong hole
Installation plate
Indoor unit
Wall hole ø65
Air in
Air out
Installation plate
Piping
Drain hose
159
19
58
MS-GF20VA MS-GF25VA MS-GF35VA
Piping
Insulation ø35 O.D
Liquid line ø7 - 0.5 m (Flared connection ø6.35)
Gas line ø9.52 - 0.43 m (Flared connection: ø9.52)
Drain hose Insulation ø28 O.D Connected part ø16 O.D
WIRING DIAGRAM
6
MS-GF20VA MS-GF25VA MS-GF35VA
OBH621

7
Unit: mm
REFRIGERANT SYSTEM DIAGRAM
7
MS-GF20VA MS-GF25VA
Indoor
heat
exchanger
Flared connection
Room temperature
thermistor
RT11
Flared connection
Refrigerant pipe 6.35
(with heat insulator)
Indoor coil
thermistor
RT12
Refrigerant flow in cooling
Refrigerant pipe 9.52
(with heat insulator)
MS-GF35VA
Indoor
heat
exchanger
Flared connection
Room temperature
thermistor
RT11
Flared connection
Refrigerant pipe 6.35
(with heat insulator)
Indoor coil
thermistor
RT12
Refrigerant flow in cooling
Refrigerant pipe 9.52
(with heat insulator)
OBH621

8
8-1. TIMER SHORT MODE
For service, the following set time can be shortened by short circuit of JPG and JPS on the electronic control P.C. board.
(Refer to 10-7.)
Set time: 3 minutes →3 seconds (It takes 3 minutes for the compressor to start operation. However, the starting time is
shortened by short circuit of JPG and JPS.)
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:
NOTE: For modification, take out
the batteries and press
the OPERATE/STOP (ON/
OFF) button 2 or 3 times at
first.
After modification, put back
the batteries then press the
RESET button.
J2
J1
Table 1
1 unit operation 2 units operation 3 units operation 4 units operation
No. 1 unit No modification Same as at left Same as at left Same as at left
No. 2 unit — Solder J1 Same as at left Same as at left
No. 3 unit — — Solder J2 Same as at left
No. 4 unit — — — 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 is turned OFF, or the power supply is shut down.
Please conduct the above setting once again after the power has restored.
SERVICE FUNCTIONS
8
MS-GF20VA MS-GF25VA MS-GF35VA
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.
OBH621

9
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. “AUTO RESTART FUNCTION” automatically starts operation
in the same mode just before the shutoff of the main power.
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 the jumper wire to JR07 on the indoor electronic control P.C. board. (Refer to 10-7.)
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 can-
celled.
• 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
Indoor electronic
control P.C. board
111NCA01NC 151NC 211NC
OBH621

10
WIRELESS REMOTE CONTROLLER
MICROPROCESSOR CONTROL
9
NOTE: 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.
Signal transmitting section
Operation display section
Temperature buttons
OPERATE/STOP
(ON/OFF) button
Indication of
remote controller
model is on back
TIME SET buttons
FORWARD button
BACKWARD button
VANE CONTROL button
OFF-TIMER button
RESET button
FAN SPEED CONTROL button
OPERATION SELECT button
ECONO COOL button ON-TIMER button
CLOCK button
POWERFUL COOL button
MS-GF20VA MS-GF25VA MS-GF35VA
Operation Indicator lamp
The operation indicator at the right side of the indoor unit indicates the operation state.
•The following indication applies regardless of shape of the indication.
Indication Operation state Room temperature
The unit is operating to
reach the set temperature
About 2°C or more away
from set temperature
The room temperature is
approaching the set tem-
perature
About 1 to 2°C from set
temperature
INDOOR UNIT DISPLAY SECTION
Lighted
Blinking
Not lighted
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.
1. Coil frost prevention
The compressor operational frequency is controlled by the temperature of the indoor heat exchanger to prevent the coil
from frosting.
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.
OBH621

11
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.
1. Coil frost prevention
Coil frost prevention is as same as COOL mode. (9-1.1.)
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 does not operate.
Mode
COOL mode of
"I FEEL CONTROL"
DRY mode of
"I FEEL CONTROL"
Initial room temperature
25 or more
more than 13 ,
less than 25
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 the 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 does not change by room temperature afterwards.
• Under ON-TIMER ( ) operation, mode is determined as follows:
When the system is stopped by 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.
Previous operation
COOL mode of
“I FEEL CONTROL”
or COOL mode
Restart
COOL mode of
“I FEEL CONTROL”
Operation timer chart
Example
When the system is restarted after 2 hours and more, the operation mode is determined by the room temperature at
start-up of the operation.
Operation time chart
Example
Previous operation
COOL mode of
“I FEEL CONTROL”
or COOL mode
Restart
COOL or-DRY mode of
“ I FEEL CONTROL” that
determined by room
temperature at start-up
of the operation.
OBH621

12
(4) The initial set temperature is decided by the initial room temperature.
1
Mode Initial room temperature
26 °C or more 24 °C
Initial room temperature
minus 2 °C
25 °C to 26 °C
Initial set temperature
DRY mode of
“I FEEL CONTROL”
COOL 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 regard-
less of the 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 TOO WARM or TOO COOL button is pressed, the indoor unit receives the signal and emits a beep tone.
Fuzzy control
When TOO COOL or TOO WARM button is pressed, the microprocessor changes the set temperature, considering the
room temperature, the frequency of pressing TOO COOL or TOO WARM button and the user’s preference to heat or
cold. So this is called “Fuzzy control”, and works only in “I FEEL CONTROL” mode.
In DRY mode of “I FEEL CONTROL”, the set temperature does not change.
… To raise the set temperature 1 ~ 2
… To lower the set temperature 1 ~ 2
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 (approximately 12 V) transmitted from indoor microprocessor.
(2) The horizontal vane angle and mode change as follows by pressing VANE CONTROL button.
1
AUTO 1 2 3 4 5 SWING
(3) Positioning
To confirm the standard position, the vane moves until it touches the vane stopper. Then the vane is set to the
selected angle.
Confirming of standard position is performed in the following cases:
(a) When the operation starts or finishes (including timer operation).
(b) When the test run starts.
(4) VANE AUTO ( ) mode
In VANE AUTO mode, the microprocessor automatically determines the vane angle to make the optimum room tem-
perature distribution.
Vane angle is fixed to Angle 1.
OBH621

13
(7) SWING ( ) mode
By selecting SWING mode with VANE CONTROL button, the horizontal vane swings vertically.
(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 cycles.
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 CONTROL or POWERFUL button.
(9) POWERFUL ( ) operation
The air conditioner automatically adjusts the fan speed and the set temperature, and operates the POWERFUL mode.
The POWERFUL mode is cancelled automatically 15 minutes after operation starts. To cancel this operation manual-
ly, select a different mode or press one of the following buttons: POWERFUL, OPERATE/STOP (ON/OFF), ECONO
COOL, or
FAN, SPEED CONTROL button.
(5) STOP (operation OFF) and ON TIMER standby
In the following cases, 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 with the vane angle at Angle 4 or 5 when the compressor cumulative operation time
exceeds 1 hour, the vane angle automatically changes to Angle 1 for dew prevention.
1. How to set the time
(1) Check that the current time is set correctly.
NOTE: Timer operation will not work without setting the current time. Initially “0:00” blinks at the current time display
of TIME MONITOR, so set the current time correctly with CLOCK button.
How to set the current time
(a) Press the CLOCK button.
(b) Press the TIME SET buttons ( and ) to set the current time.
• Each time FORWARD button ( ) is pressed, the set time increases by 1 minute, and each time BACKWARD
button ( ) is pressed, the set time decreases by 1 minute.
• Pressing those buttons longer, the set time increases/decreases by 10 minutes.
(c) Press the CLOCK button.
(2) Press OPERATE/STOP (ON/OFF) button to start the air conditioner.
(3) Set the time of timer.
ON timer setting
(a) Press ON TIMER button( ) during operation.
(b) Set the time of the timer using TIME SET buttons ( and ).
OFF timer setting
(a) Press OFF TIMER button ( ) during operation.
(b) Set the time of the timer using TIME SET buttons ( and ).
Each time FORWARD button ( ) is pressed, the set time increases by 10 minutes: each time BACKWARD but-
ton ( ) is pressed, the set time decreases by 10 minutes.
2. To release the timer
To release ON timer, press ON TIMER button ( ).
To release OFF timer, press OFF TIMER button( ).
TIMER is cancelled and the display of set time disappears.
9-6. TIMER OPERATION
OBH621

14
(Example 1) The current time is 8:00 PM.
The unit turns off at 11:00 PM, and on at 6:00 AM.
• OFF timer and ON timer can be used in combination. The timer of the set time that is reached first will operate first.
• “ ” and “ ” display shows the order of OFF timer and ON timer operation.
PROGRAM TIMER
(Example 2) The current time is 11:00 AM.
The unit turns on at 5:00 PM, and off at 9:00 PM.
NOTE: If the main power is turned OFF or a power failure occurs while ON/OFF timer is active, the timer setting is can-
celled. As these models are equipped with an auto restart function, the air conditioner starts operating with timer
cancelled when power is restored.
9-7. EMERGENCY/TEST OPERATION
In case of test run operation or emergency operation, use
EMERGENCY OPERATION switch on the right side of the indoor unit.
Emergency operation is available when the remote controller is miss-
ing, has failed or the batteries of the 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 opera-
tion is for servicing. The indoor fan runs at High speed and the tem-
perature 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.
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.
Operation mode COOL
Set temperature 24°C
Fan speed Med.
Horizontal vane Auto
The operation mode is indicated by the
Operation Indicator lamp as following
Operation Indicator lamp
EMERGENCY COOL
↓
STOP
Lighted
Not lighted
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 from overload.
Emergency
operation switch
(E.O. SW)
OBH621

15
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 miswiring.
2. Take care of the following during servicing
1) Before servicing the air conditioner, be sure to turn OFF the main 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 P.C. board.
3) When removing the 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) 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
service work.
2) Before servicing, check that the connector and terminal are connected properly.
3) When the electronic control P.C. board seems to be defective, check the copper foil pattern for disconnection and the
components for bursting and discoloration.
4) When troubleshooting, Refer to 10-2, 10-3 and 10-4.
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.
Lead wiring Housing point
<Correct>
<Incorrect>
TROUBLESHOOTING
10
RESET button
Insert the negative pole of the
batteries first. Check if the polarity
of the batteries is 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.
3. Do not use the leaking batteries.
Press RESET button with a thin instrument, and
then use the remote controller.
Remove the front lid and insert batteries.
Then reattach the front lid.
MS-GF20VA MS-GF25VA MS-GF35VA
OBH621

16
10-2. FAILURE MODE RECALL FUNCTION
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 (10-4.) disappears, the memorized failure details
can be recalled.
1. Flow chart of failure mode recall function for the indoor unit
Does upper 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 is emitted at the same timing as the
blinking of upper lamp of OPERATION
INDICATOR lamp. 2
Indoor unit is normal.
But the outdoor unit might be abnormal because there are some abnor-
malities that can not be recalled with this way.
The indoor unit is abnormal.
Check the blinking pattern, and confirm the abnormal point with the indoor unit
failure mode table. (Refer to 10-2.2)
Make sure to check at least 2 consecutive blinking cycles. 2
Releasing the failure mode recall function
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.
Repair the defective parts.
Deleting the memorized abnormal condition
After repairing the unit, recall the failure mode again according to "Setting up the failure mode recall
function" mentioned above.
Press OPERATE/STOP (ON/OFF) button of the remote controller (the set temperature is displayed)
with the remote controller headed towards the indoor unit.
Press EMERGENCY OPERATION switch so that the memorized abnormal condition is deleted.
Release the failure mode recall function according to "Releasing the failure mode recall function"
mentioned above.
Yes
(Blinks)
No
(OFF)
NOTE: 1. Make sure to release the failure mode recall function once it is 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.
2. Blinking pattern when the indoor unit is abnormal:
ON
OFF
Beeps
Repeated cycle Repeated cycle
2.5-second OFF
Blinking at 0.5-
second interval
Beeps
Repeated cycle
2.5-second OFF
Blinking at 0.5-
second interval
Beeps
The cause of abnormality cannot be found because the abnormality does not recur.
Setting up the failure mode recall function
Turn ON the power supply.
<Preparation of the remote controller>
While pressing both OPERATION SELECT button and TOO COOL button on the
remote controller at the same time, press RESET button.
First, release RESET button.
Hold down the other two buttons for another 3 seconds. Confirm that the indicators on
the LCD screen shown in the right figure are all displayed. Then release the buttons.
Press OPERATE/STOP (ON/OFF) button of the remote controller (the set temperature is
displayed) with the remote controller headed towards the indoor unit. 1
Operational procedure
1 Regardless of normal or abnormal condition,
a short beep is emitted once the signal is
received.
OBH621

17
2. Indoor unit failure mode table
Upper lamp of OP-
ERATION INDICA-
TOR lamp
Abnormal point
(Failure mode) Condition Remedy
Not lighted Normal — —
1-time flash every
0.5-second
Room temperature
thermistor
The room temperature thermistor short or
open circuit is detected every 8 seconds dur-
ing operation.
Refer to the characteristics of the room temperature
thermistor (10-7.).
2-time flash
2.5-second OFF
Indoor coil
thermistor
The indoor coil thermistor short or open circuit
is detected every 8 seconds during operation.
Refer to the characteristics of the indoor coil thermistor
(10-7.).
11-time flash
2.5-second OFF Indoor fan motor
The rotational frequency feedback signal is
not emitted for 12 seconds after the indoor fan
motor is operated.
Refer to 10-6. "Check of indoor fan motor".
12-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.
Replace the indoor electronic control P.C. board.
14-time flash 1
2.5-second OFF
Refrigerant
circuit Refer to 10-4. No.4 "Condition". Refer to 10-4. No.4 "Remedy".
NOTE: Blinking patterns of this mode differ from the ones of TROUBLESHOOTING CHECK TABLE (10-4.).
ON
OFF
Beeps Beeps
Repeated cycle
2.5-second
OFF
3.0-second
ON
14-time
flash
Repeated cycle
2.5-second
OFF
3.0-second
ON
14-time
flash
1. A blinking pattern when "14-time flash" is displayed :
OBH621

18
10-3. INSTRUCTION OF TROUBLESHOOTING
Indoor unit oper-
ates.
Outdoor unit
does not operate.
Indoor unit does
not receive the
signal from re-
mote controller.
OPERATION INDICATOR
lamp on the indoor unit is
flashing ON and OFF.
Outdoor unit
operates only
in Test Run
operation.
Indoor unit
operates, when
EMERGENCY
OPERATION
switch is pressed.
Indoor unit does
not operate, when
EMERGENCY
OPERATION
switch is pressed.
Check room
temperature
thermistor.
Refer to 10-7.
"Test point
diagram and
voltage".
Refer to 10-6.
"Check of remote
controller and
indoor electronic
control P.C. board".
1. Check indoor/out-
door connecting wire.
(Check if the power is
supplied to the indoor
unit.)
2. Check the outdoor fuse (F).
3. Refer to 10-6. "Check
of indoor P.C. board
and indoor fan motor".
Upper lamp
2-time flash
Cause:
Indoor unit
• Trouble
of room
temperature
/ indoor coil
thermistor
Upper lamp
3-time flash
Cause:
Indoor unit
• Trouble of
indoor fan
motor
Upper lamp
4-time flash
Cause:
Indoor unit
• Trouble
of indoor
unit control
system
Start
Check room
temperature
thermistor
and indoor
coil thermis-
tor. Refer to
10-7. "Test
point diagram
and voltage".
Refer to
10-6.
"Check of
indoor fan
motor".
Replace the
indoor elec-
tronic control
P.C. board.
Outdoor unit
does not
operate even
in "Test run
operation".
1. Check
the wiring
diagram of
the outdoor
unit.
2. Check the
outdoor
fuse.
Check the
indoor fuse
(F11), outdoor
fuse (F) and
the compres-
sor contactor
(52C).
Indoor and
outdoor unit
do not operate.
If blinking of OPERATION INDI-
CATOR lamp cannot be checked,
it can be checked with failure
mode recall function.
Upper lamp
14-time flash
Cause:
Outdoor unit
• Troubles
regarding
refrigerant
circuit
Refer to 10-4
No. 4 "Rem-
edy".
"Test Run operation" means the
operation within 30 minutes af-
ter EMERGENCY OPERATION
switch is pressed.
Refer to outdoor unit service manual.
OBH621

19
10-4. TROUBLESHOOTING CHECK TABLE
Before taking measures, make sure that the symptom reappears for accurate troubleshooting.
When the indoor unit has started operation and detected an abnormality of the following condition (the first detection after the
power ON), the indoor fan motor turns OFF and OPERATION INDICATOR lamp flashes.
OPERATION INDICATOR
Lighted
Blinking
Not lighted
No. Abnormal
point Operation indicator lamp Symptom Condition Remedy
1
Indoor coil
thermistor
Upper lamp flashes.
2-time flash
2.5-second OFF
Indoor unit and
outdoor unit do
not operate.
The indoor coil or the room temperature ther-
mistor is short or open circuit.
Refer to the characteristics of
indoor coil thermistor, and the
room temperature thermistor
(10-7.).
•
Room tem-
perature
thermistor
2Indoor fan
motor
Upper lamp flashes.
3-time flash
2.5-second OFF
The rotational frequency feedback signal is
not emitted during the indoor fan operation.
Refer to 10-6. "Check of in-
door fan motor".
•
3Indoor con-
trol system
Upper lamp flashes.
4-time flash
2.5-second OFF
It cannot properly read data in the nonvolatile
memory of the indoor electronic control P.C.
board.
Replace the indoor electronic
control P.C. board.
•
4
1
Refrigerant
circuit
Upper lamp flashes.
14-time flash
2.5-second OFF
The unit has been pumped down for a long
time. Check the stop valve.
•
The refrigerant amount is low.
Check the connections and the
refrigerant amount for any leak-
age.
•
The unit is short cycling.
Check for short cycle.
If any problem is found, provide
some space for air path around
the outdoor unit.
•
The outdoor fan motor locks up.
Check that the connecting ca-
ble of the outdoor fan motor is
properly connected.
Check the resistance value
of the outdoor fan motor.
If any problem is found, replace
the outdoor fan motor.
•
•
1. When the trouble indicated with 14-time flash occurs, turn off the main power supply.
Otherwise, the operation indicator lamp may flash again even if the power is turned off and on using a remote controller.
Operation Indicator lamp
The operation indicator lamp is at the right side of the indoor unit.
•The following indication applies regardless of shape of the indication.
OBH621

20
A Check of indoor fan motor
10-6. TROUBLESHOOTING FLOW
10-5. TROUBLE CRITERION OF MAIN PARTS
Part name Check method and criterion Figure
Room temperature
thermistor (RT11)
Indoor coil thermistor
(RT12)
Measure the resistance with a tester.
Refer to 10-7. "Test point diagram and voltage", "1. Indoor electronic control
P.C. board", for the chart of thermistor.
Indoor fan motor (MF)
INNER FUSE
145 °C CUT OFF
Measure the resistance with a tester.
(Part temperature 10 ~ 30 °C)
Color of the lead wire Normal
WHT-BLK 334 Ω~ 362 Ω
BLK-RED 370 Ω~ 402 Ω
MAIN
AUX.
BLK RED WHT
FUSE
Horizontal vane motor
(MV)
Measure the resistance between the terminals with a tester.
(Temperature: 10 - 30°C)
Color of the lead wire Normal
RED-BLK 223 Ω~ 268 Ω
BLK
BLK
RED
BLK BLK
ROTOR
CN211
Indoor power P.C.board
Fuse (F11)
Indoor terminal
P.C.board
Varistor
(NR11)
CN121
Are soldered points of the
connector correctly soldered to
the indoor power P.C. board?
Is the resistance 0 (short circuit) or (open circuit)?
Yes ( 0 or )
Yes
Pay enough attention to the high voltage on the
fan motor connector.
No
Yes
No
Turn OFF the power supply.
Check connector CN211 visually.
Disconnect lead wires from connector CN211 on indoor power P.C. board.
Measure the resistance between lead wires No.1 and No.4 and then No.4 and No.7.
Turn ON the power supply. Stop it if the unit operates.
Insert screwdriver into air outlet to rotate indoor fan
motor slowly for 1 revolution or over, and measure the
voltage No.2(+) and No.1(-) on CN121.
No
(others)
Replace the indoor power/terminal P.C. board
and the indoor control P.C. board.
Does the voltage repeat 0 VDC and 5 VDC?
Yes
No
Are lead wires connected?
Reconnect the lead wires. Resolder it.
Replace the indoor fan motor.
OBH621