Mitsubishi Electric MSZ-HJ25VA-E1 User manual

CONTENTS
1. TECHNICAL CHANGES ··································· 3
2. PART NAMES AND FUNCTIONS····················· 4
3. SPECIFICATION················································ 5
4. NOISE CRITERIA CURVES······························ 6
5. OUTLINES AND DIMENSIONS ························ 7
6. WIRING DIAGRAM············································ 7
7. REFRIGERANT SYSTEM DIAGRAM··············· 8
8. SERVICE FUNCTIONS ····································· 9
9. MICROPROCESSOR CONTROL ····················11
10. TROUBLESHOOTING····································· 15
11. DISASSEMBLY INSTRUCTIONS···················· 27
MSZ-HJ25VA -E1
MSZ-HJ35VA -E1
MSZ-HJ50VA -E1
Outdoor unit service manual
MUZ-HJ·VA Series (OBH648)
SERVICE MANUAL No. OBH647
REVISED EDITION-A
INDOOR UNIT
PARTS CATALOG (OBB647)
NOTE:
RoHS compliant products have <G> mark on the spec name plate.
SPLIT-TYPE AIR CONDITIONERS
Models
Revision A:
• MSZ-HJ50VA- E1 has been added.
Please void OBH647.

2
<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.
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:
• MSZ-HJ50VA- E1 has been added.
OBH647A

3
1TECHNICAL CHANGES
MSZ-HJ25VA - E1
MSZ-HJ35VA - E1
MSZ-HJ50VA - E1
1. New model
OBH647A

4
Operation indicator lamp
Remote control
receiving section
Emergency
operation switch
Horizontal vane
Air inlet
Air filter
Front panel
Air outlet Heat exchanger
Emergency operation switch
Remote controller
ACCESSORIES
MSZ-HJ25VA MSZ-HJ35VA MSZ-HJ50VA
Installation plate 1
Installation plate fixing screw 4 ×25 mm 5
Battery (AAA) for remote controller 2
Wireless remote controller 1
Felt tape (Used for left or left-rear piping) 1
2PART NAMES AND FUNCTIONS
OBH647A

5
3SPECIFICATION
Indoor model MSZ-HJ25VA MSZ-HJ35VA MSZ-HJ50VA
Power supply Single phase 230 V, 50 Hz
Breaker Capacity A 10 12
Electrical data
Power input 1 (Total) Cooling W730 1,040 2,050
Heating 870 995 1,480
Running current 1
(Total) Cooling A3.7 4.9 9.0
Heating 4.2 4.8 6.6
Power factor 1 (Total) Cooling %85 92 99
Heating 90 90 97
Starting current 1 (Total) A 4.2 4.9 9.0
Fan motor
Model RC0J40-EF
Current 1 Cooling A0.19 0.24 0.27
Heating 0.20 0.22 0.34
Dimensions W × H × D mm 799 × 290 × 232
Weight kg 9
Special remarks
Air direction 5
Airflow
Cooling
Super High
m3/h
571 654 772
High 438 470 667
Med. 328 341 547
Low 227 227 380
Heating
Super High
m3/h
598 619 861
High 451 451 667
Med. 328 328 497
Low 208 208 364
Sound level
Cooling
Super High
dB(A)
43 45 45
High 37 38 40
Med. 30 31 36
Low 22 22 28
Heating
Super High
dB(A)
43 44 47
High 37 37 41
Med. 30 30 34
Low 23 23 27
Fan speed
Cooling
Super High
rpm
1,080 1,200 1,120
High 880 930 1,000
Med. 710 730 860
Low 550 550 660
Heating
Super High
rpm
1,120 1,150 1,220
High 900 900 1,000
Med. 710 710 800
Low 520 520 640
Fan speed regulator 4
Remote controller model MP13A
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
Heating : Indoor Dry-bulb temperature 20°C
Outdoor Dry-bulb temperature 7°C Wet-bulb temperature 6°C
1 Measured under rated operating frequency.
Specifications and rated conditions of main electric parts
Fuse (F11) T3.15AL250V
Horizontal vane motor (MV) 12 VDC
Varistor
(NR11) S10K320E3K1 (ERZV14D471)
Terminal block (TB) 5P
OBH647A

6
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
OCTAVE BAND SOUND PRESSURE LEVEL, dB re 0.0002 MICRO BAR
BAND CENTER FREQUENCIES, Hz
COOLING
FUNCTION SPL(dB(A)) LINE
Super High
FAN SPEED
HEATING
43
43
NC-10
MSZ-HJ25VA
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
OCTAVE BAND SOUND PRESSURE LEVEL, dB re 0.0002 MICRO BAR
BAND CENTER FREQUENCIES, Hz
COOLING
FUNCTION SPL(dB(A)) LINE
Super High
FAN SPEED
HEATING
Test conditions
Cooling : Dry-bulb temperature 27°C Wet-bulb temperature 19°C
Heating : Dry-bulb temperature 20°C
44
45
NC-10
MSZ-HJ35VA
4NOISE CRITERIA CURVES
MSZ-HJ50VA
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
OCTAVE BAND SOUND PRESSURE LEVEL, dB re 0.0002 MICRO BAR
BAND CENTER FREQUENCIES, Hz
COOLING
FUNCTION SPL(dB(A)) LINE
Super High
FAN SPEED
HEATING
45
47
NC-10
OBH647A

7
MSZ-HJ25VA MSZ-HJ35VA MSZ-HJ50VA Unit : mm
MSZ-HJ25VA MSZ-HJ35VA MSZ-HJ50VA
5OUTLINES AND DIMENSIONS
6WIRING DIAGRAM
2325
69
41
799
785 7
290
12063049
57
80
42
43
69
57
42
7
103
130
100
(57°)
225 225 80.5 80.5
61.5 59.5340338
41
42
249
248 21.5
3
167 157
207.5
206.5
172
14
140
57 18
46
Air in
Installation plate
Piping
Drain hose
Air out
11×26 Oblong hole 11×20 Oblong hole
Installation plate
Indoor unit
Wall hole Φ65
In case of left, left back,or left under piping (using spacer),
108.5 or more
7 or more
33.5 or more
40 or more
20 or more
Piping
Insulation Φ35 O.D
Liquid line Φ6.35 - 0.39m (Flared connection Φ6.35)
Gas line Φ9.52 - 0.34m (Flared connection Φ9.52)
Drain hose
InslationΦ28 Connected part Φ16 O.D active length 370
MSZ-HJ25/35VA
MSZ-HJ50VA
Piping
Insulation Φ37 O.D
Liquid line Φ6.35 - 0.39m (Flared connection Φ6.35)
Gas line Φ9.52 - 0.34m (Flared connection Φ12.7)
Drain hose
InslationΦ28 Connected part Φ16 O.D active length 370
OBH647A

8
MSZ-HJ25VA MSZ-HJ35VA
Indoor
heat
exchanger
Flared connection
Room temperature
thermistor
RT11
Flared connection
Refrigerant flow in cooling
Refrigerant flow in heating
Refrigerant pipe ø9.52
(with heat insulator)
Refrigerant pipe ø6.35
(with heat insulator)
Indoor coil
thermistor
RT12
Indoor coil
thermistor
RT13
Unit : mm
MSZ-HJ50VA
Indoor
heat
exchanger
Flared connection
Room temperature
thermistor
RT11
Flared connection
Refrigerant flow in cooling
Refrigerant flow in heating
Refrigerant pipe ø12.7
(with heat insulator)
Refrigerant pipe ø6.35
(with heat insulator)
Indoor coil
thermistor
RT12
Indoor coil
thermistor
RT13
7REFRIGERANT SYSTEM DIAGRAM
OBH647A

9
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, the following set time can be shortened by short circuiting the timer short mode point on the electronic control
P.C. board. (Refer to 10-7.)
Set time : 3-minute →3-second (It takes 3 minutes for the compressor to start operation. However, the starting time is
shortened by short circuiting the timer short mode point.)
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 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 modification, take out
the batteries and press
the OPERATE/STOP (ON/
OFF) button 2 or 3 times at
first.
After finish modification,
put back the batteries then
press the RESET button.
MSZ-HJ25VA MSZ-HJ35VA MSZ-HJ50VA
J2
J1
8SERVICE FUNCTIONS
OBH647A

10
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.
JR77
Indoor electronic
control P.C. board
CN10ACN111
CN151
CN112
CN110
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.
Cut the Jumper wire to JR77 on the indoor electronic control P.C. board. (Refer to 10-7.)
OBH647A

11
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.
WIRELESS REMOTE CONTROLLER
MSZ-HJ25VA MSZ-HJ35VA MSZ-HJ50VA
Time set buttons
RESET button
Vane control button
Signal transmitting section
Operation display section
Temperature buttons
ON/OFF (operate/stop) button
Fan speed control button
Operation select button
Timer mode select button
ECONO COOL button
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
Lighted
Blinking
Not lighted
9MICROPROCESSOR CONTROL
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.
INDOOR UNIT DISPLAY SECTION
OBH647A

12
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. HEAT ( ) OPERATION
(1) Press OPERATE/STOP (ON/OFF) button.
OPERATION INDICATOR lamp of the indoor unit turns on with a beep tone.
(2) Select HEAT 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. Cold air prevention control
When the compressor is not operating or is starting, and the temperature of indoor heat exchanger and/or the room tem-
perature is low or when defrosting is being done, the indoor fan will stop or rotate in Very Low speed.
2. High pressure protection
The compressor operational frequency is controlled by the temperature of the indoor heat exchanger to prevent the con-
densing pressure from increasing excessively.
When the temperature of indoor heat exchanger becomes too high, the high pressure protection works.
The indoor fan operates following the cold air prevention control. This mode continues until the temperature of indoor
heat exchanger falls.
3. Defrosting
Defrosting starts when the temperature of outdoor heat exchanger becomes too low.
The compressor stops once, the indoor/outdoor fans stop, the 4-way valve reverses, and the compressor re-starts.
This mode continues until the temperature of outdoor heat exchanger rises or the fixed time passes.
(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 tempera-
ture distribution.
9-4. 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.
Horizontal
position
In COOL and DRY operation
Vane angle is fixed to Horizontal position. In HEAT operation Vane angle is fixed to Angle 4.
AUTO 1 2 3 4 5 SWING
OBH647A

13
(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 3 ~ 5 when the compressor cumulative operation time
exceeds 1 hour, the vane angle automatically changes to Angle 2 for dew prevention.
(7) SWING ( ) mode
By selecting SWING mode with VANE CONTROL button, the horizontal vane swings vertically.
(8) Cold air prevention in HEAT operation.
The horizontal vane position is set to Upward.
(9) To change the airflow direction not to blow directly onto your body.
To change the airflow
direction When to use this function? COOL/DRY HEAT
Pressing and holding
VANE CONTROL button
for 2 seconds or more
cause the horizontal vane
to reverse and move to
horizontal position.
Use this function if you
do not want the air
from the indoor unit to
blow directly onto your
body.
• Depending on the
shape of the room,
the air may blow
directly onto your
body.
• Press VANE CON-
TROL button again
to return the vane
to the previously-set
position.
The air conditioner starts the cool-
ing or drying operation approxi-
mately 3 minutes after the vane
has moved to the horizontal posi-
tion.
• When VANE CONTROL button is
pressed again, the vane returns
to the previously-set position and
the air conditioner starts the cool
or dry operation in approximately
3 minutes.
The air conditioner starts heating
operation approximately 3 minutes
after the vane has moved to the
horizontal position.
• Sometimes the area around your
feet may not warm. To warm the
area around the feet, set the hori-
zontal vane to (AUTO) or the
downward-blowing position.
• When VANE CONTROL button is
pressed again, the vane returns
to the previously-set position
and the air conditioner starts the
heat operation in approximately 3
minutes.
NOTE :
• If you make the airflow not to blow directly onto your body by pressing VANE CONTROL button, the compressor stops
for 3 minutes even during the operation of the air conditioner.
• The air conditioner operates with Very Low speed until the compressor turns on again.
( 10 ) 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.
ECONO COOL operation is cancelled when ECONO COOL button is pressed once again or VANE CONTROL button is
pressed or change to other operation mode.
Horizontal
position
9-5. TIMER OPERATION (ON/OFF TIMER)
1. How to set the timer
(1) Press OPERATE/STOP (ON/OFF) button to start the air conditioner.
(2) Select the timer mode by pressing the button during operation.
Each time this button is pressed, the timer mode is changed in sequence:
(OFF TIMER) →(ON TIMER) →TIMER RELEASE
(3) Set the time of the timer using the button.
Each time this button is pressed, the set time increase or decrease by 1 hour to 12 hours.
2. To release the timer
Press the button until (OFF TIMER) and (ON TIMER) are not displayed.
NOTE :
• The OFF TIMER and the ON TIMER cannot be set at the same time.
• The displayed time is the time remaining and will decrease in 1-hour increments as time passes.
OBH647A

14
EMERGENCY OPERATION switch
9-6. 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 missing, 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 operation is for servicing. The indoor fan runs at High
speed and the temperature control does not work.
After 30 minutes of test run operation, the system shifts to EMERGENCY COOL/HEAT 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 once or twice 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 HEAT
Set temperature 24°C 24°C
Fan speed Med. Med.
Horizontal vane Auto Auto
The operation mode is indicated by the
Operation Indicator lamp as following
Operation Indicator lamp
EMERGENCY COOL
↓
EMERGENCY HEAT
↓
STOP
Lighted
Not lighted
9-7. 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.
OBH647A

15
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.
Insert the minus 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 back lid and insert batteries.
Then reattach the back lid.
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.
MSZ-HJ25VA MSZ-HJ35VA MSZ-HJ50VA
10 TROUBLESHOOTING
Lead wiring Housing point
<Incorrect> <Correct>
OBH647A

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.
This mode is very useful when the unit needs to be repaired for the abnormality which does not recur.
1. Flow chart of failure mode recall function for the indoor/outdoor 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't be recalled with this way.
Confirm if outdoor unit is abnormal according to the detailed outdoor unit
failure mode recall function.
No
Yes
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. Make sure that the indicators
on the LCD screen shown in the right figure are all displayed. Then release the but-
tons.
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
Judgment of indoor/outdoor abnormality
Before blinking, does upper 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 identify the abnormal point with the indoor unit
failure mode table. (Refer to 10-2.2)
Make sure to check at least two 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.
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. 3
Repair the failure 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.
Operational procedure
Yes
(Blinks)
No
(OFF)
NOTE: 1. Make sure to release the failure mode recall function after 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:
3.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
1. Regardless of normal or abnormal condi-
tion, a short beep is emitted once the
signal is received.
OBH647A

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 main indoor coil ther- mistor, the sub indoor coil thermistor (10-7.).
3-time flash
2.5-second OFF Serial signal The serial signal from outdoor unit is not re-
ceived for a maximum of 6 minutes. Refer to 10-6. "How to check miswiring and serial
signal error".
11-time flash
2.5-second OFF Indoor fan motor The rotational frequency feedback signal is not
emitted for the 12 seconds after the indoor fan
motor is orperated. 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.
NOTE : Blinking patterns of this mode differ from the ones of TROUBLESHOOTING CHECK TABLE (10-4.).
OBH647A

18
10-3. INSTRUCTION OF TROUBLESHOOTING
Indoor unit oper-
ates.
Outdoor unit
does not operate.
If blinking of OPERATION INDI-
CATOR lamp cannot be checked,
it can be checked with failure
mode recall function.
Indoor unit operates.
Outdoor unit does
not operate normally.
Indoor unit does
not receive
the signal from
remote controller.
OPERATION INDICATOR
lamp on the indoor unit is
flashing on and off.
Outdoor unit
operates only
in Test Run
operation.
Outdoor unit
does not
operate even
in Test Run
operation.
Unit does not
operate nor-
mal operation
in COOL or
HEAT mode.
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 "How
to check
inverter/com-
pressor".
Refer to
"Check of R.V.
coil".
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. Refer to 10-6. "Check
of indoor P.C. board
and indoor fan motor".
Start
"Test Run operation" means
the operation within 30 minutes
after EMERGENCY OPERA-
TION switch is pressed.
Refer to outdoor unit service manual.
Upper lamp
Flash on and
off at 0.5-sec-
ond intervals
Cause:
Indoor/Outdoor
unit
• Miswiring or
trouble of
serial signal
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
Upper lamp
5-time flash
Cause:
Outdoor unit
• Outdoor
power
system
abnormality
Upper lamp
6-time flash
Cause:
Outdoor unit
• Trouble of
thermistor in
outdoor unit
Upper lamp
7-time flash
Cause:
Outdoor unit
• Trouble of
outdoor con-
trol system
Upper lamp
14-time flash
or more
Cause:
Outdoor unit
• Other ab-
normality
Refer to
10-6. "How
to check mis-
wiring and
serial signal
error".
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.
Refer to
"How to
check
inverter/com-
pressor".
Refer to
"Check of
outdoor ther-
mistors".
Replace the
inverter P.C.
board or
the outdoor
electronic
control P.C.
board.
Check "Flow
chart of the
detailed
outdoor unit
failure mode
recall func-
tion."
OBH647A

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.
No. Abnormal
point Operation indicator lamp Symptom Condition Remedy
1Miswiring or serial
signal
Upper lamp flashes.
0.5-second ON
0.5-second OFF
Indoor unit and
outdoor unit do
not operate.
The serial signal from the outdoor unit is not
received for 6 minutes. Refer to 10-6. "How to check
miswiring and serial signal er-
ror".
•
2
Indoor coil
thermistor Upper lamp flashes.
2-time flash
2.5-second OFF
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
3Indoor 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 indoor fan motor".
•
4Indoor 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.
•
5Outdoor power sys-
tem
Upper lamp flashes.
5-time flash
2.5-second OFF
It consecutively occurs 3 times that the com-
pressor stops for overcurrent protection or
start-up failure protection within 1 minute after
start-up.
Refer to "How to check of in-
verter/compressor".
Refer to outdoor unit service
manual
Check the stop valve.
•
•
6Outdoor
thermistors
Upper lamp flashes.
6-time flash
2.5-second OFF
The outdoor thermistors short or open circuit
during the compressor operation.
Refer to "Check of outdoor
thermistor".
Refer to outdoor unit service
manual.
•
7Outdoor control sys-
tem
Upper lamp flashes.
7-time flash
2.5-second OFF
It cannot properly read data in the nonvolatile
memory of the inverter P.C. board or the out-
door electronic control P.C. board.
Replace the inverter P.C. board
or the outdoor electronic con-
trol P.C. board.
Refer to outdoor unit service
manual.
•
8Other ab-
normality
Upper lamp flashes.
14-time flash or more
2.5-second OFF
An abnormality other than above mentioned
is detected.
Check the stop valve.
Check the 4-way valve.
Confirm the abnormality in
detail using the failure mode
recall function for outdoor unit.
•
•
•
9Outdoor control sys-
tem Upper lamp lights up Outdoor unit
does not oper-
ate
It cannot properly read data in the nonvolatile
memory of the inverter P.C. board or the out-
door 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.
•
OPERATION INDICATOR
Lighted
Blinking
Not lighted
OBH647A

20
10-5. TROUBLE CRITERION OF MAIN PARTS
MSZ-HJ25VA MSZ-HJ35VA MSZ-HJ50VA
Part name Check method and criterion Figure
Room temperature
thermistor (RT11) Measure the resistance with a tester.
Refer to 10-7. "Test point diagram and voltage", "2. Indoor electronic control
P.C. board", for the chart of thermistor.
Indoor coil thermistor
(RT12, RT13)
Indoor fan motor (MF) Check 10-6. .
Vane motor (MV)
Measure the resistance between the terminals with a tester.
(Part temperature 10 ~ 30°C)
Color of the lead wire Normal
RED - BLK 235 ~ 255 Ω
BLK
BLK
RED
BLK BLK
ROTOR
OBH647A