Mitsubishi MSZ-SF15VA-E1, MSZ-SF20VA-E1 Service Manual

SPLIT-TYPE AIR CONDITIONERS

INDOOR UNIT

SERVICE MANUAL

Models

No. OBH555

MSZ-SF15VA ­MSZ-SF20VA -

MSZ-SF15VA ­MSZ-SF20VA -

E1
E1

E1

E1

Outdoor unit service manual
MXZ-B·VA Series (OBH554)
MXZ-8A140A (OC316)

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 ············································ 7

7. REFRIGERANT SYSTEM DIAGRAM ··············· 8

8. SERVICE FUNCTIONS ····································· 9

9. MICROPROCESSOR CONTROL ····················11

10. TROUBLESHOOTING ····································· 17

11. DISASSEMBLY INSTRUCTIONS ···················· 29

NOTE:

RoHS compliant products have <G> mark on the spec name plate.

PARTS CATALOG (OBB555)

1

TECHNICAL CHANGES

MSZ-SF15VA ­MSZ-SF20VA -

1. New model

E1
E1

2

2

PART NAMES AND FUNCTIONS

MSZ-SF15VA MSZ-SF20VA

Front panel

Air fi lter

Air inlet

Horizontal vane

Air outlet

Heat exchanger

Remote controller

Emergency operation switch (E.O. SW)

ACCESSORIES

Installation plate 1
Installation plate fi xing 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 (Used for left or left-rear piping) 1

Operation

indicator lamp

Remote control

receiving section

3

3

Electrical

data

Fan

motor
Dimensions W × H × D mm 760 × 250 × 168
Weight kg

Special remarks

Remote controller model SG10D

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

2 For multi system.

SPECIFICATION

Indoor model MSZ-SF15VA MSZ-SF20VA

Power supply Single phase 230 V, 50 Hz

Power
input 1

Running
current 1

Model RC0J40-FM

Current
1

Air direction 5

Airfl ow

Sound level

Fan speed

Fan speed regulator 5

1 Measured under rated operating frequency.

Cooling
Heating 17 19
Cooling
Heating 0.17 0.19

Cooling
Heating 0.17 0.19

Super High
High
Med.

Cooling

Low
Silent
Super High
High
Med.
Low

Heating

Silent
Super High
High
Med.

Cooling

Low
Silent
Super High
High
Med.
Low

Heating

Silent
Super High
High 1,300
Med. 1,130
Low 980

Cooling

Silent 900
Super High
High 1,350
Med. 1,160
Low 1,030

Heating

Silent 910

W

A

A

3

m

/h

3

m

/h

dB(A)

dB(A)

rpm

rpm

17 19

0.17 0.19

0.17 0.19

7.7

384 414

330
276
234
210

408 438

360
300
264
222

40 42

35
30
26
21

40 42

35
30
26
21

1,500 1,600

1,500 1,600

Specifications and rating conditions of main electric parts

Fuse
Horizontal vane motor (MV) 12 VDC
Varistor (NR11) S10K300E2K1
Terminal block

F11)

(

(TB)

T3.15AL250V

3P

4

4

NOISE CRITERIA CURVES

MSZ-SF15VA

FAN SPEED

Super High

90

80

70

60

50

40

30

20

OCTAVE BAND SOUND PRESSURE LEVEL, dB re 0.0002 MICRO BAR

10

63 125 250 500 1000 2000 4000 8000

BAND CENTER FREQUENCIES, Hz

FUNCTION

COOLING
HEATING

SPL(dB(A))

40
40

NC-10

LINE

NC-70

NC-60

NC-50

NC-40

NC-30

NC-20

MSZ-SF20VA

FAN SPEED

Super High

90

80

70

60

50

40

30

20

OCTAVE BAND SOUND PRESSURE LEVEL, dB re 0.0002 MICRO BAR

10

63 125 250 500 1000 2000 4000 8000

BAND CENTER FREQUENCIES, Hz

FUNCTION

COOLING

HEATING

SPL(dB(A))

42
42

NC-10

LINE

NC-70

NC-60

NC-50

NC-40

NC-30

NC-20

Test conditions

Cooling: Dry-bulb temperature 27°C

Wet-bulb temperature 19°C

Heating: Dry-bulb temperature 20°C

INDOOR UNIT

WALL

1m

0.8m

MICROPHONE

5

5

OUTLINES AND DIMENSIONS

MSZ-SF15VA MSZ-SF20VA

1120 Oblong hole

208

42

61

166

45

Installation plate

Indoor unit

295

335

145

760
740

155

145

300

Wall hole 65

Ø

1120 Oblong hole

78

81

10

167

21.5

187

Unit: mm

209

41

5 168

56

45

60

193

202

18

250

47

56

56

505

Insulation

Liquid line

Piping

Gas line

Drain hose

Installation plate

Piping

8

56

110

41

Drain hose

Ø

Ø

179

Air out

56

43

Ø

35 O.D

ØØ

6.35-0.39m (Flared connection 6.35)

Ø

9.52-0.34m (Flared connection 9.52)

Insulation 28 Connected part 16 O.D

Ø

6

6

MSZ-SF15VA MSZ-SF20VA

WIRING DIAGRAM

7

7

REFRIGERANT SYSTEM DIAGRAM

MSZ-SF15VA MSZ-SF20VA

Indoor
heat
exchanger

Indoor coil
thermistor
RT13 (sub)

Room temperature
thermistor
RT11

Indoor coil
thermistor
RT12 (main)

Unit: mm

Refrigerant pipe ø9.52
(with heat insulator)

Flared connection

Flared connection

Refrigerant pipe ø6.35
(with heat insulator)

Refrigerant flow in cooling
Refrigerant flow in heating

8

8

SERVICE FUNCTIONS

MSZ-SF15VA MSZ-SF20VA

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.
The time will be shortened as follows. (Refer to 10-7.)
Set time: 1 minute → 1 second
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:

J1

The P.C. board has the print “J1” and “J2”. Solder “J1” and “J2” according to the number of indoor unit as shown in Table 1.
After modification, press the RESET button.

J2

NOTE: For modification, take out

the batteries and press
the OPERATE/STOP (ON/
OFF) button twice or 3
times at first.

After modification, put back

the batteries then press the
RESET button.

Table 1

1 unit operation 2 units operation 3 units operation 4 units operation

No. 1 unit No modifi cation 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.

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 release “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.)

R111

CN211

CN112

D

JR07

IC112

Indoor electronic
control P.C. board

CN 111

CN151

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.

10

9

MICROPROCESSOR CONTROL

MSZ-SF15VA MSZ-SF20VA

WIRELESS REMOTE CONTROLLER

Signal transmitting section

Operation display section

Temperature buttons

OPERATION SELECT button

ECONO COOL button

i save button

OPERATE/STOP
(ON/OFF) button

Indication of
remote controller
model is on back

FAN SPEED CONTROL button

VANE CONTROL button

TIME, TIMER set buttons
FORWARD button
BACKWARD button

WEEKLY TIMER
set button

RESET button

CLOCK SET button

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.

INDOOR UNIT DISPLAY SECTION

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

Lighted

Blinking

Not lighted

The unit is operating to
reach the set temperature

The room temperature is
approaching the set tem­perature

About 2°C or more away
from set temperature

About 1 to 2°C from set
temperature

Standby mode
(Only during multi system

-

operation)

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.

2. Low outside temperature operation

When the outside temperature is lower, low outside temperature operation starts, and the outdoor fan slows or stops.

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.)

2. Low outside temperature operation

Low outside temperature operation is as same as COOL mode. (9-1.2.)

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 tem­perature 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 con­densing 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.

9-4. AUTO CHANGE OVER ··· AUTO MODE OPERATION

Once desired temperature is set, unit operation is switched automatically between COOL and HEAT operation.

Mode selection

(1) Initial mode

When unit starts the operation with AUTO operation from OFF:

• If the room temperature is higher than the set temperature, operation starts in COOL mode.

• If the room temperature is equal to or lower than the set temperature, operation starts in HEAT mode.

(2) Mode change

COOL mode changes to HEAT mode when about 15 minutes have passed with the room temperature 1°C below the
set temperature.
HEAT mode changes to COOL mode when about 15 minutes have passed with the room temperature 1°C above the
set temperature.

NOTE 1

If two or more indoor units are operating in multi system, there might be a case that the indoor unit, which is operating in
(AUTO), cannot change over to the other operating mode (COOL ↔ HEAT) and becomes a state of standby.

Refer to NOTE 2 “FOR MULTI SYSTEM AIR CONDITIONER”.

NOTE 2
FOR MULTI SYSTEM AIR CONDITIONER OUTDOOR UNIT: MXZ series

Multi system air conditioner can connect two or more indoor units with one outdoor unit.

• When you try to operate two or more indoor units with one outdoor unit simultaneously, one for the cooling and the others for
heating, the operation mode of the indoor unit that operates first is selected. Other indoor units cannot operate, and operation
indicator lamp flashes as shown in the figure below. In this case, please set all the indoor units to the same operation mode.

OPERATION INDICATOR

Lighted

Blinking

Not lighted

• When indoor unit starts the operation while the defrosting of outdoor unit is being done, it takes a few minutes (max. 10 min­utes) to blow out the warm air.

• In the heating operation, though indoor unit that does not operate may get warm or the sound of refrigerant flowing may be
heard, they are not malfunction. The reason is that the refrigerant continuously flows into it.

12

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 VANE CONTROL button.

AUTO

(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.
(c) When standby mode (only during multi system operation) starts or finishes.

(4) VANE AUTO ( ) mode

In VANE AUTO mode, the microprocessor automatically determines the vane angle to make the optimum room tem­perature distribution.

12345

SWING

In COOL and DRY operation
Vane angle is fixed to Horizontal position.

Horizontal

position

(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.

(7) SWING (

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.

NOTE: When 2 or more indoor units are operated with multi outdoor unit, even if any indoor unit turns thermostat off,

(9) 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 CONTROL button.

) mode

this control does not work in the indoor unit.

In HEAT operation
Vane angle is fixed to Angle 4.

4

13

9-6. TIMER OPERATION

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 SET button.

How to set the current time

(a) Press the CLOCK set 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 set 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

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.

).

but-

PROGRAM TIMER

• 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.

(Example 1) The current time is 8:00 PM.

The unit turns off at 11:00 PM, and on at 6:00 AM.

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.

(Example 2) The current time is 11:00 AM.

The unit turns on at 5:00 PM, and off at 9:00 PM.

14

9-7. WEEKLY TIMER OPERATION

• A maximum of 4 ON or OFF timers can be set for individual days of the week.

• A maximum of 28 ON or OFF timers can be set for a week.

NOTE:

The simple ON/OFF timer setting is available while the weekly timer is on. In this case, the ON/OFF timer has priority over the weekly
timer; the weekly timer operation will start again after the simple ON/OFF timer is complete.

1. How to set the weekly timer

* Make sure that the current time and day are set correctly.

(1) Press button to enter the weekly timer setting mode.

blinks.

*

(2) Press

and buttons to select setting day and number.

E.g. : [Mon Tue ... Sun]

and [1] are selected.

Pressing selects the day of
the week to be set.

* All days can be selected.

Pressing selects
the setting number.

(3) Press , , and buttons to set ON/OFF, time, and temperature.

E.g. : [ON], [6:00]

and [24°C] are
selected.

Pressing

selects ON/OFF timer.

Pressing

deletes timer setting.

* Hold down the button to change the time quickly.

Pressing

adjusts the time.

Pressing

adjusts the tem­perature.

Press and buttons to continue setting the timer for other days and/or numbers.

(4) Press

button to complete and transmit the weekly timer setting.

* which was blink-

ing goes out, and the
current time will be
displayed.

NOTE:

• Press

button to transmit the setting information of weekly timer to the indoor unit. Point the remote controller toward the

indoor unit for 3 seconds.

• When setting the timer for more than one day of the week or one number,

setting. Press

• Press

button to enter the weekly timer setting mode, and press and hold button for 5 seconds to erase all weekly

button once after all the settings are complete. All the weekly timer settings will be saved.

button does not have to be pressed per each

timer settings. Point the remote controller toward the indoor unit.

15

(5) Press

2. Checking weekly timer setting

button to turn the weekly timer ON. ( lights.)

•When the weekly timer is ON, the day of the week whose timer setting is complete, will light.

Press

button again to turn the weekly timer OFF. ( goes out.)

NOTE:

The saved settings will not be cleared when the weekly timer is turned OFF.

2. Checking weekly timer setting

(1) Press button to enter the weekly timer setting mode.

*

(2) Press

(3) Press

blinks.

or buttons to view the setting of the particular day or number.

button to exit the weekly timer setting.

NOTE:

When all days of the week are selected to view the settings and a different setting is included among them,
displayed.

9-8. i-save ( ) OPERATION

1. How to set i-save operation

(1) Press OPERATE/STOP (ON/OFF) button.
(2) Select COOL, HEAT or ECONO COOL mode.
(3) Press i-save button.
(4) Set the temperature, fan speed, and airfl ow direction for i-save operation.

NOTE:

• i-save operation cannot be selected during DRY or AUTO mode operation.

• The setting range of HEAT mode i-save operation is 10°C and 16 - 31°C.

• 2 groups of setting can be saved. (One for COOL/ECONO COOL, one for HEAT)

2. How to cancel operation

• Press i-save button again.

• i-save operation can also be cancelled by pressing OPERATION SELECT button to change the operation mode.
The same setting is select from the next time by simply pressing i-save button.

9-9. 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 system
is in continuous operation (The thermostat 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.
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.

Operation mode COOL/HEAT
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

↓

EMERGENCY HEAT

↓

STOP

will be

Lighted

Not lighted

NOTE: Do not press EMERGENCY OPERATION switch during nor-

mal operation.

Emergency
operation switch
(E.O. SW)

9-10. 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.

16

10

TROUBLESHOOTING

MSZ-SF15VA MSZ-SF20VA

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.

Lead wiring

3. Troubleshooting procedure

1) First, check if the OPERATION INDICATOR lamp on the indoor unit is flashing ON and OFF to indicate an abnormal-

ity.

To make sure, check how many times the abnormality indication is flashing ON and OFF before starting service work.

2) Before servicing, check that the connector and terminal are connected properly.

3) If the P.C. board is supposed to be defective, check the copper foil pattern for disconnection and the components for

bursting and discoloration.

4) When troubleshooting, refer to 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.

Remove the front lid and insert batteries.

Then reattach the front lid.

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.

Housing point

Press RESET button with a thin instrument, and

then use the remote controller.

RESET button

17

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/outdoor unit

Operational procedure

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 TEMP button on the remote
controller at the same time, press RESET button.

First, release RESET button.

And release the other two buttons after all LCD in operation display section of the

remote controller is displayed after 3 seconds.

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

Does left lamp of OPERATION INDICATOR lamp
on the indoor unit blink at the interval of 0.5 sec­onds?
Blinks: Either indoor or outdoor unit is abnormal.

Beep is emitted at the same timing as the
blinking of upper lamp of OPERATION
INDICATOR lamp. 2

Judgment of indoor/outdoor abnormality

Releasing the failure mode recall function

Deleting the memorized abnormal condition

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

3.Blinking pattern when the outdoor unit is abnormal:

ON

OFF

Before blinking, does left lamp of
OPERATION INDICATOR lamp stay ON for 3
seconds?
Stays ON for 3 seconds (without beep):
The outdoor unit is abnormal.

The indoor unit is abnormal.
Check the blinking pattern, and confi rm 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

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.

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.

Blinking at 0.5-

2.5-second OFF

2.5-second OFF 3-second ON

second interval

Repeated cycle Repeated cycle

Yes
(Blinks)

No

2.5-second OFF

Beeps

Blinking at 0.5-

second interval

No beep Beeps

Repeated cycle

No
(OFF)

Yes

Blinking at 0.5­second interval

Beeps

2.5-second OFF 3-second ON

Indoor unit is normal.
But the outdoor unit might be abnormal because there are some abnor­malities that can not be recalled with this way.
Confi rm if outdoor unit is abnormal according to the detailed outdoor unit
failure mode recall function.

The outdoor unit is abnormal.
Check the blinking pattern, and confi rm 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

Beeps

Repeated cycle

No beep Beeps

Repeated cycle

1 Regardless of normal or abnormal condition,

a short beep is emitted once the signal is re­ceived.

Blinking at 0.5­second interval

Repeated cycle

18

2. Indoor unit failure mode table

Upper lamp of OP­ERATION INDICA-

TOR lamp

Not lighted Normal — —

1-time fl ash every

0.5-second

2-time fl ash

2.5-second OFF
3-time fl ash

2.5-second OFF

11-time fl ash

2.5-second OFF

12-time fl ash

2.5-second OFF

Abnormal point
(Failure mode)

Room temperature
thermistor

Indoor coil
thermistor

Serial signal

Indoor fan motor

Indoor control
system

Condition Correspondence

The room temperature thermistor short or
open circuit is detected every 8 seconds dur­ing operation.

The indoor coil thermistor short or open circuit
is detected every 8 seconds during operation.

The serial signal from outdoor unit is not re­ceived for a maximum of 6 minutes.

The rotational frequency feedback signal is not
emitted during the 12 seconds the indoor fan
operation.

It cannot properly read data in the nonvolatile
memory of the indoor electronic control P.C.
board.

Refer to the characteristics of the room temperature
thermistor (10-7.).

Refer to the characteristics of the main indoor coil ther­mistor, the sub indoor coil thermistor (10-7.).

Refer to 10-6. "How to check miswiring and serial
signal error".

Refer to 10-6. "Check of indoor fan motor".

Replace the indoor electronic control P.C. board.

NOTE: Blinking patterns of this mode differ from the ones of TROUBLESHOOTING CHECK TABLE (10-4.).

19

10-3. INSTRUCTION OF TROUBLESHOOTING

Start

Indoor unit oper­ates.
Outdoor unit
does not operate.

Outdoor unit
operates only
in Test Run
operation.

Check room
temperature
thermistor.
Refer to 10-7.
"Test point
diagram and
voltage".

Outdoor unit
does not
operate even
in Test Run
operation.

Refer to "How
to check
inverter/com­pressor".

Indoor unit operates.
Outdoor unit does
not operate normally.

Unit does not
operate nor­mal operation
in COOL or
HEAT mode.

Refer to
"Check of R.V.
coil".

Indoor unit does
not receive the
signal from re­mote controller.

Indoor unit
operates, when
EMERGENCY
OPERATION
switch is pressed.

Refer to 10-6.
"Check of remote
controller and
receiver P.C.
board".

OPERATION INDICATOR
lamp on the indoor unit is
fl ashing ON and OFF.

Indoor unit does
not operate, when
EMERGENCY
OPERATION
switch is pressed.

1. Check indoor/out­door 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".

"Test Run operation" means the

operation within 30 minutes af­ter EMERGENCY OPERATION
switch is pressed.

If blinking of OPERATION INDI­CATOR lamp cannot be checked,
it can be checked with failure
mode recall function.

Refer to outdoor unit service manual.

Left lamp
Flash on and
off at 0.5-sec­ond intervals
Cause:
Indoor/Outdoor
unit

• Miswiring or
trouble of
serial signal

Refer to
10-6. "How
to check mis­wiring and
serial signal
error".

Left lamp
2-time fl ash
Cause:
Indoor unit

• Trouble
of room
temperature
/ indoor coil
thermistor

Check room
temperature
thermistor
and indoor
coil thermis­tor. Refer to
10-7."Test
point diagram
and voltage".

Left lamp
3-time fl ash
Cause:
Indoor unit

• Trouble of
indoor fan
motor

Refer to
10-6.
"Check of
indoor fan
motor".

Left lamp
4-time fl ash
Cause:
Indoor unit

• Trouble
of indoor
unit control
system

Replace the
indoor elec­tronic control
P.C. board.

Left lamp
5-time fl ash
Cause:
Outdoor unit

• Outdoor
power
system
abnormality

Refer to
"How to
check
inverter/com­pressor".

Left lamp
6-time fl ash
Cause:
Outdoor unit

• Trouble of
thermistor in
outdoor unit

Refer to
"Check of
outdoor ther­mistors".

Left lamp
7-time fl ash
Cause:
Outdoor unit

• Trouble of
outdoor con­trol system

Replace the
inverter P.C.
board or
the outdoor
electronic
control P.C.
board.

Left lamp
14-time fl ash
Cause:
Outdoor unit

• Other ab­normality

Check "Flow
chart of the
detailed
outdoor unit
failure mode
recall func­tion."

20

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

Abnormal

No.

1

2

3

4

5

6

point

Miswiring
or serial
signal

Indoor coil
thermistor

Room tem­perature
thermistor

Indoor fan
motor

Indoor con­trol system

Outdoor
power sys­tem

Outdoor
thermistors

Operation indicator lamp Symptom Condition Correspondence

Upper lamp fl ashes.

0.5-second ON

0.5-second OFF

Upper lamp fl ashes.
2-time fl ash

2.5-second OFF

Upper lamp fl ashes.
3-time fl ash

Upper lamp fl ashes.
4-time fl ash

Upper lamp fl ashes.
5-time fl ash

Upper lamp fl ashes.
6-time fl ash

2.5-second OFF

2.5-second OFF

2.5-second OFF

2.5-second OFF

Lighted

Blinking

Not lighted

Indoor unit and
outdoor unit do
not operate.

The serial signal from the outdoor unit is not
received for 6 minutes.

The indoor coil or the room temperature ther­mistor is short or open circuit.

The rotational frequency feedback signal is
not emitted during the indoor fan operation.

It cannot properly read data in the nonvolatile
memory of the indoor electronic control P.C.
board.

It consecutively occurs 3 times that the com­pressor stops for overcurrent protection or
start-up failure protection within 1 minute after
start-up.

The outdoor thermistors short or open circuit
during the compressor operation.

Refer to 10-6. "How to check

•
miswiring and serial signal er­ror".

Refer to 10-7. the character-

•
istics of indoor coil thermistor,
and the room temperature ther­mistor.

•

Refer to 10-6.
door fan motor".

Replace the indoor electronic

•
control P.C. board.

Refer to "How to check of in-

•
verter/compressor".
Refer to outdoor unit service
manual
Check the stop valve.

•

Refer to "Check of outdoor

•
thermistor".
Refer to outdoor unit service
manual.

"Check of in-

Outdoor

7

control sys­tem

Other ab-

8

normality

Outdoor

9

control sys­tem

Upper lamp fl ashes.
7-time fl ash

2.5-second OFF

Upper lamp fl ashes.
14-time fl ash

2.5-second OFF

Upper lamp lights up

Outdoor unit
does not oper­ate

It cannot properly read data in the nonvolatile
memory of the inverter P.C. board or the out­door electronic control P.C. board.

An abnormality other than above mentioned
is detected.

It cannot properly read data in the nonvolatile
memory of the inverter P.C. board or the out­door electronic control P.C. board.

21

Replace the inverter P.C. board

•
or the outdoor electronic control
P.C. board.
Refer to outdoor unit service
manual.

Check the stop valve.

•
Confi rm the abnormality in

•
detail using the failure mode
recall function for outdoor unit.

Check the blinking pattern of

•
the LED on the inverter P.C.
board or the outdoor electronic
control P.C. board.

OPERATION INDICATOR

Abnormal

No.

1

point

MXZ type

Operation
mode
setting

Upper lamp lights and lower lamp fl ashes.

2.5-second OFF

Operation indicator lamp Symptom Condition Correspondence

Outdoor unit
operates but
indoor unit does
not operate.

10-5. TROUBLE CRITERION OF MAIN PARTS

MSZ-SF15VA MSZ-SF20VA

Part name Check method and criterion Figure

Room temperature
thermistor (RT11)
Indoor coil thermistor
(RT12, RT13)

Measure the resistance with a tester.

Refer to 10-7. "Test point diagram and voltage", "Indoor electronic control
P.C. board", for the chart of thermistor.

The operation mode of the each indoor unit
is differently set to COOL (includes DRY) and
HEAT at the same time, the operation mode
of the indoor unit that has operated at fi rst has
the priority.

Unify the operation mode.

•
Refer to outdoor unit service
manual.

Indoor fan motor (MF)

Vane motor (MV)

Refer to 10-6. "Check of indoor fan motor."

Measure the resistance between the terminals with a tester.
(Temperature: 10 - 30°C)

Color of the lead wire Normal

RED - YLW 223 - 268 Ω

YLW

YLW
RED

ROTOR

YLW

YLW

22

10-6. TROUBLESHOOTING FLOW

A Check of indoor fan motor

The indoor fan motor error has occurred, and the indoor fan does not operate.

Turn OFF the power supply.

Is there any foreign matter that interferes
the rotation of the line fl ow fan?

Yes

Remove the foreign matter and
adjust the line fl ow fan.

Is there 325 VDC
between CN211 (+)
and (–) ?

No

Yes

No

Pay enough attention to the high voltage on the fan motor connector CN211.

Turn ON the power supply, wait 5 seconds or more, and then press
EMERGENCY OPERATION switch.
Measure the supply voltage as follows within 12 seconds after EMER­GENCY OPERATION switch is pressed.
If more than 12 seconds passes, turn OFF the power supply and turn it
ON again, then measure the voltage.
<Indoor electronic control P.C. board>

1. Measure the voltage between CN211

2. Measure the voltage between CN211 (+) and (–).

If more than 12 seconds passes after EMERGENCY OPERATION switch

is pressed, the voltage measured at 2. above goes 0 VDC although the
indoor P.C. board is normal.

Does the voltage between CN211
(+) and (–) on the indoor electronic
control P.C. board rise to the range
of 2 to 6 VDC within 12 seconds after
EMERGENCY OPERATION switch is
pressed?

No

Yes

(+) and (–).

Replace the indoor fan motor.

Replace the indoor electronic
control P.C. board.

The indoor fan motor error has occurred, and the indoor fan repeats "12-second ON and 30-second OFF" 3 times, and then stops.

Measure the voltage between CN211

(+) and (–) while the fan motor is

rotating.

Is it unchanged holding
0 or 15 VDC?

Yes
(Unchanged)

Replace the indoor fan motor.

No
(Changed)

Replace the indoor
electronic control P.C.
board.

23

B Check of remote controller and indoor electronic control P.C. board

Check if the remote controller is exclusive for this air conditioner.

Press OPERATE/STOP (ON/OFF)

button on the remote controller.

Look at the image of the signal transmitting section of

1

the remote controller through the monitor of a digital

Is LCD display on the remote controller
visible?

Yes

Remove the batteries, then put them back
and press RESET button. (Refer to 10-1.4.)
Check if the unit operates with the remote
controller.

Does the unit operate with the remote
controller?

Yes

No
(Not clear)

No

Replace the batteries. (Refer to 10-1.4.)

Turn ON a radio to AM and press OP­ERATE/STOP (ON/OFF) button on the
remote controller.

1

camera. It is normal if LED of the signal transmitting
section lights up when the OPERATE/STOP (ON/
OFF) button on the remote controller is pressed.

2

If the inverter fluorescent light is turned on when the
room is cool, the unit may have difficulty receiving
the signal from the remote controller or may not be
able to operate with it; if the inverter fluorescent light
is turned on when the room is warm, the unit may be
able to operate with the remote controller.

OK

Measure the voltage between receiver P.C. board connector CN301 No.2(+) and No.3(-) when the remote
controller button is pressed.

Is the voltage approx. 4 VDC - 5 VDC?

No

Replace the receiver P.C board .

Is noise heard from radio?

Yes

Is a signal transmitted from a remote
controller of a different device?

No

Are there any fl uorescent lights of
inverter or rapid-start type within the
range of 1 m.?

2

Yes

No

Replace the indoor electronic control P.C.
board.

No

Yes

Yes

Replace the remote controller.

Stop the transmission of signal between
the different device and its remote control­ler.

Reinstall the unit away from lights.

•
Attach a fi lter on receiving part.

•

24

C Check of indoor P.C. board and indoor fan motor

Turn OFF the power supply.
Remove indoor fan motor connector CN211
and vane motor connector CN151 from the
indoor electronic control P.C. board and turn
ON the power supply.

Does the unit operate with the remote
controller?
Does OPERATION INDICATOR lamp light
up by pressing EMERGENCY OPERATION
switch?

Turn OFF the power supply.
Check both “parts side” and “pattern
side” of the indoor electronic control
P.C. board visually.

No

Measure the resistance of indoor fan
motor.
Refer to 10-5

Measure the resistance of the vane
motor coil.

Yes

Refer to 10-5.

Replace the varistor (NR11)
and fuse (F11). 3

Yes

Is the varistor (NR11)
burnt and the fuse (F11)
blown?

Be sure to check both the fuse
and the varistor in any case.

Is the fuse (F11) blown
only?

Yes

Measure the resistance between
CN211 (+) and (-) of indoor fan
motor connector. 1, 2

No

No

Short circuit:
Replace the indoor fan motor.

Short circuit:
Replace the vane motor and the indoor
electronic control P.C. board.

1. The fan motor connector's lead wire is red,
whereas is black.

2. Connect "+" of the tester to fan motor connector's

lead wire, and “-” to lead wire, otherwise the

resistance cannot be measured properly.

3. Please replace the fuse after removing the indoor
electronic control P.C. board from the electrical box.

Fuse (F11)

Varistor
(NR11)

CN211

CN151

Measure the resistance of resis­tor (R111) on the indoor electronic
control P.C. board.

Indoor electronic control
P.C. board

R111

Is the resistance 1MΩ or more?

Yes

Replace the fuse (F11). 3

Is the resistance of
resistor (R111) approx. 4
Ω?

Replace the indoor electronic control P.C. board.

Replace the fuse (F11) and the
indoor fan motor. 3

No

No

Yes

Replace the indoor
electronic control P.C.
board and the indoor fan
motor.

25

D How to check miswiring and serial signal error

Turn OFF the power supply.

Is there rated voltage in

No

the power supply?

Yes

Turn ON the power supply.

Is there rated voltage between

No

outdoor terminal block S1 and
S2?

Yes

Press EMERGENCY OPERATION switch once.

Does the left lamp of OPERATION
INDICATOR lamp light up?
<Confirmation of the power to the indoor unit>

Yes

Is serial signal error indicated 6 minutes later?

Yes

A

Turn OFF the power supply.
Check once more if the indoor/outdoor
connecting wire is not miswiring.

B

Short-circuit outdoor terminal block S2 and
S3.

1

Check the power
supply.

Check the wiring.

No

Is there any miswiring,
poor contact, or wire

No

disconnection of the

Yes

Correct them.
indoor/outdoor
connecting wire?

No

1. Miswiring may damage indoor electronic control
P.C. board during the operation.
Be sure to confirm the wiring is correct before the
operation starts.

A

Turn OFF inverter-controlled lighting

•
equipment.
Turn OFF the power supply and then

•
turn ON again.
Press EMERGENCY OPERATION

•
switch.

Reinstall

•
either the unit
or the light
away from

No

•

each other.
Attach a fi lter
on remote
control receiv­ing section
of the indoor
unit.

Is serial signal
error indicated 6
minutes later?

Yes

B

Turn ON the power supply.

Does the LED on the outdoor electronic
control P.C. board repeat "3.6-second-OFF
and 0.8-second-ON quick blinking"?

Yes

Turn OFF the power supply.
Remove the short-circuit between
outdoor terminal block S2 and S3.
Turn ON the power supply.
Is there amplitude of 10 to 20V DC
between outdoor terminal block S2
and S3? <Confirmation of serial
signal>

Yes

Is there rated voltage between
indoor terminal block S1 and S2?
<Confirmation of power voltage>

Yes

Replace the indoor electronic control P.C. board.

Be sure to release the failure-mode
recall function after checking.

No

(Lighted
or
not lighted)

Replace the outdoor electronic control
P.C. board.
2

2 Be careful of residual
voltage of smoothing capacitor.

No

Is there any error of the
indoor/outdoor connecting wire,
such as the damage of the wire,
intermediate connection, poor

No

contact to the terminal block?

No

Replace the

Yes

indoor/outdoor
connecting wire.

26

E Electromagnetic noise enters into TV sets or radios

Is the unit earthed?

Yes

Is the distance between the antennas
and the indoor unit within 3 m, or is the
distance between the antennas and the
outdoor unit within 3 m?

No

Is the distance between the TV sets or
radios and the indoor unit within 1 m, or
is the distance between the TV sets or
radios and the outdoor unit within 3 m?

No

Are the antennas damaged?
Is the coaxial cable damaged?
Is there any poor contact in the anten­na wiring?

No

Is the indoor/outdoor connecting wire
of the air conditioner and the wiring of
the antennas close?

No

No

Yes

Yes

Yes

Yes

Earth the unit.

Extend the distance between the antennas and
the indoor unit, and/or the antennas and the
outdoor unit.

Extend the distance between the TV sets and/or
radios and the indoor unit, or the TV sets or
radios and the outdoor unit.

Replace or repair the antenna.
Replace or repair the coaxial cable.

Extend the distance between the indoor/outdoor
connecting wire of the air conditioner and the wir­ing of the antennas.

Even if all of the above conditions are fulfi lled, the electromagnetic noise may enter, depending on the electric fi eld strength
or the installation condition (combination of specifi c conditions such as antennas or wiring).
Check the following before asking for service.

1. Devices affected by the electromagnetic noise
TV sets, radios (FM/AM broadcast, shortwave)

2. Channel, frequency, broadcast station affected by the electromagnetic noise

3. Channel, frequency, broadcast station unaffected by the electromagnetic noise

4. Layout of:
indoor/outdoor unit of the air conditioner, indoor/outdoor wiring, earth wire, antennas, wiring from antennas, receiver

5. Electric fi eld intensity of the broadcast station affected by the electromagnetic noise

6. Presence or absence of amplifi er such as booster

7. Operation condition of air conditioner when the electromagnetic noise enters in

1) Turn OFF the power supply once, and then turn ON the power supply. In this situation, check for the electromagnetic
noise.

2) Within 3 minutes after turning ON the power supply, press OPERATE/STOP (ON/OFF) button on the remote controller
for power ON, and check for the electromagnetic noise.

3) After a short time (3 minutes later after turning ON), the outdoor unit starts running. During operation, check for the
electromagnetic noise.

4) Press OPERATE/STOP (ON/OFF) button on the remote controller for power OFF, when the outdoor unit stops but the
indoor/outdoor communication still runs on. In this situation, check for the electromagnetic noise.

27

10-7. Test point diagram and voltage

MSZ-SF15VA MSZ-SF20VA
Indoor electronic control P.C. board

Power supply/
serial cord (CN201)

Indoor coil thermis­tor RT12, RT13
(CN112)

Room temperature
thermistor RT11
(CN111)

Vane motor
(CN151)

AC230V

Fuse (F11)
T3.15AL250V

Varistor (NR11)

Resistor
(R111)

Indoor fan motor
(CN211)

(+) DC0V or

DC15V

(+) 2-6V
15VDC
(–) Fiducial

terminal of
cathode side
on measuring
high-voltage
DC

(+) 325VDC

12VDC

GND

5VDC

SW P.C. board

Display P.C. board

Emergency operation
switch (E.O. SW) (SW1)

}

Timer short mode
JPG JPS
(Refer to 8-1.)

Connector for optional
interface (CN105)

Release of Auto restart function
Solder the Jumper wire to JR07 ( D )
(Refer to 8-3.)

Room temperature thermistor (RT11)
Indoor coil thermistor (RT12, RT13)

Receiver P.C. board

Resistance (kΩ)

28

Temperature (°C)

11

DISASSEMBLY INSTRUCTIONS

<"Terminal with locking mechanism" Detaching points>

The terminal which has the locking mechanism can be detached as shown below.
There are two types (refer to (1) and (2)) of the terminal with locking mechanism.
The terminal without locking mechanism can be detached by pulling it out.
Check the shape of the terminal before detaching.

(1) Slide the sleeve and check if there is a locking lever or not.

Sleeve

Slide the sleeve.
Pull the terminal while

Locking lever

pushing the locking
lever.

MSZ-SF15VA MSZ-SF20VA

OPERATING PROCEDURE PHOTOS

1. Removing the panel

(1) Remove the horizontal vanes.
(2) Remove the screw caps of the panel. Remove the

screws.
(3) Unhook the lower part ( ) of the panel.
(4) Hold the lower part of both ends of the panel and pull

it slightly toward you, and then remove the panel by

pushing it upward.

(2) The terminal with this connector has the
locking mechanism.

Hold the sleeve, and
pull out the terminal
slowly.

Connector

NOTE: Turn OFF power supply before disassembling.

Photo 1

Horizontal vane

Front panel

A

Screws of the panel

29

OPERATING PROCEDURE PHOTOS

2. Removing the indoor electronic control P.C.
board, receiver P.C. board, display P.C. board,
and SW P.C. board

(1) Remove the panel (refer to 1.) and the corner box.
(2) Remove the screw of the V.A. clamp. Remove the V.A.

clamp and the indoor/outdoor connecting wire. (Photo

2)

(3) Remove the screw of the electrical cover, and then

the electrical cover. (Photo 2)
(4) Remove the display holder and SW holder. (Photo 3)
(5) Open the rear cover of the display holder and pull out

the receiver P.C. board. (Photo 5)
(6) Open the front cover of the display holder and pull out

the display P.C. board. (Photo 5)
(7) Open the SW holder and pull out the SW P.C. board.
(8) Disconnect the following connectors on the electronic

control P.C. board:
CN211 (Indoor fan motor)
CN201 (Terminal block)
CN211 (Indoor coil thermistor)
CN151 (Horizontal vane motor)
CN109 (Receiver P.C. board)
(9) Pull out the electronic control P.C. board from the

electrical box.
(10)

Remove the earth wire connected to the indoor elec-

tronic control P.C. board from the electrical box. (Photo

3)

Photo 2

Photo 3

Earth wire to the
heat exchanger

Screw of the
V.A. clamp

Screw of the
electrical
cover

Drain hose

Release this catch to remove the
electronic control P.C. board.

Indoor electronic
control P.C. board

SW holder

Photo 4

Earth wire to the
indoor electronic
control P.C. board

Fixing screw of
the electrical
cover

Display holder

Room temperature thermistor (RT11)

Be sure to install this thermistor in the
proper direction.

30

OPERATING PROCEDURE PHOTOS

3. Removing the electrical box

(1) Remove the panel (refer to 1.) and the corner box.
(2) Remove the indoor/outdoor connecting wire, the SW

holder, the display holder, the electrical cover and the
earth wire connected to the indoor electronic control
P.C. board from the electrical box. (Refer to 2.)

(3) Remove the earth wire connected to the heat

exchanger from the electrical box.

(4) Disconnect the following connectors on the electronic

control P.C. board:
CN211 (Fan motor)
CN112 (Indoor coil thermistor)

CN151 (Horizontal vane motor)
(5) Remove the fixing screw of the electrical box.
(6) Unhook the catches of the electrical box, and pull out

the electrical box.

4. Removing the nozzle assembly

(1) Remove the panel (refer to 1.) and the corner box.
(2) Remove the V.A. clamp. (Photo 2)
(3) Remove the electrical cover. (Photo 3.)
(4) Disconnect the following connector on the electronic

control P.C. board:

CN151 (Horizontal vane motor)

(5) Pull out the drain hose from the nozzle assembly and

remove the nozzle assembly.

Photo 5

Front cover of the display holder

Release the
catches.

Rear cover of the
display holder

Screws of the horizontal
vane motor unit cover

Photo 6

6. Removing the horizontal vane motor

(1) Remove the nozzle assembly. (Refer to 4.)
(2) Remove the screws of the horizontal vane motor unit,

and pull out the horizontal vane motor unit.

(3) Remove the screws of the horizontal vane motor unit

cover.

(4) Remove the horizontal vane motors from the horizon-

tal vane motor unit.

(5) Disconnect the connectors from the horizontal vane

motor.

Lead wire
connector white

Screws of the horizontal vane motor unit

Lead wire
connector red

31

OPERATING PROCEDURE PHOTOS

7. Removing the indoor fan motor and the line flow fan

(1) Remove the panel (refer to 1.) and the corner box.
(2) Remove the SW holder, the display P.C. board holder,

the electrical box (refer to 3.) and the nozzle assem-

bly (Refer to 4.).
(4) Remove the screws fixing the motor bed. (Photo 7)
(5) Loosen the screw fixing the line flow fan. (Photo 8)
(6) Push the upper part of the water cover and unhook

the catch.
(7) Pull the water cover to the right to remove it.
(8) Remove the motor bed together with fan motor and

motor band.
(9) Release the hooks of the motor band. Remove the

motor band. Pull out the indoor fan motor.
(10)

Remove the screws fixing the left side of the heat

exchanger. (Photo 12)
(11)

Lift the heat exchanger, and pull out the line flow fan

to the lower-left.

Photo 7

Catches of the water cover

Motor band

Screws of the
motor bed

Photo 8

Photo 9

Screws of the
left side of the
heat exchanger

Screw of the
line flow fan

HEAD OFFICE: TOKYO BLDG., 2-7-3, MARUNOUCHI, CHIYODA-KU, TOKYO 100-8310, JAPAN

© Copyright 2009 MITSUBISHI ELECTRIC CO.,LTD

Distributed in Oct. 2009. No. OBH555 7
Made in Japan

New publication, effective Oct. 2009
Specifications subject to change without notice.