Mitsubishi Electric MSZ-AP15VF-E1, MSZ-AP20VF-E1, MSZ-AP15VF-ER1, MSZ-AP20VF-ER1 Service Manual

NOTE:

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

INDOOR UNIT

SERVICE MANUAL

Outdoor unit service manual
MXZ-D·VA Series (OBH626)
MXZ-E·VA Series (OBH723)

No. OBH799

PARTS CATALOG (OBB799)

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 ············································ 8

7. REFRIGERANT SYSTEM DIAGRAM ···············9

8. SERVICE FUNCTIONS ··································· 10

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

10. TROUBLESHOOTING ····································· 18

11. DISASSEMBLY INSTRUCTIONS ···················· 30

Models

MSZ-AP15VF

-

E1,

ER1

MSZ-AP20VF

-

E1,

ER1

2

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.

OBH799

3

TECHNICAL CHANGES

1

MSZ-AP15VF -

E1

MSZ-AP20VF -

E1

MSZ-AP15VF -

ER1

MSZ-AP20VF -

ER1

1. New model

OBH799

4

ACCESSORIES

Installation plate 1
Installation plate fi xing screw 4 × 25 mm 5
Wireless remote controller 1
Felt tape (Used for left or left-rear piping) 1
Battery (AAA) for remote controller 2

MSZ-AP15VF MSZ-AP20VF

PART NAMES AND FUNCTIONS

2

Remote controller

Operation
indicator lamp

Remote control
receiving section

Horizontal vane

Air outlet

Air ¿ lter

Heat exchanger

Emergency
operation switch

Front
panel

Spec name plate

Air inlet

OBH799

5

Indoor model MSZ-AP15VF MSZ-AP20VF

Power supply Single phase 230 V, 50 Hz

Electrical

data

Power
input 1

Cooling

W

17 19

Heating 17 19

Running
current

1

Cooling

A

0.17 0.19

Heating 0.17 0.19

Fan

motor

Model RC0J40-FM
Current 1

Cooling

A

0.17 0.19

Heating 0.17 0.19
Dimensions W × H × D mm 760 × 250 × 178
Weight kg

8.2

Special remarks

Air direction 5

Airfl ow

Cooling

Super High

m

3

/h

384 414

High

330

Med.

276

Low

234

Silent

210

Heating

Super High

m

3

/h

408 438

High

360

Med.

300

Low

264

Silent

222

Sound level

Cooling

Super High

dB(A)

40 42

High

35

Med.

30

Low

26

Silent

21

Heating

Super High

dB(A)

40 42

High

35

Med.

30

Low

26

Silent

21

Fan speed

Cooling

Super High

rpm

1,430 1,530
High 1,250
Med. 1,080
Low 940
Silent 860

Heating

Super High

rpm

1,430 1,530
High 1,290
Med. 1,100
Low 990
Silent 870

Fan speed regulator 5

Remote controller model SG18A

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.
2 For multi system.

Specifications and rating conditions of main electric parts

Fuse

(

F11)

T3.15AL250V
Horizontal vane motor (MV) 12 V DC
Varistor (NR11) 470 V
Terminal block

(TB)

3P

SPECIFICATION

3

OBH799

6

MSZ-AP15VF

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

42
42

NC-10

MSZ-AP20VF

Test conditions

Cooling: Dry-bulb temperature 27°C

Wet-bulb temperature 19°C

Heating: Dry-bulb temperature 20°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

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

40
40

NC-10

NOISE CRITERIA CURVES

4

OBH799

7

Unit: mm

MSZ-AP15VF MSZ-AP20VF

OUTLINES AND DIMENSIONS

5

Piping

Insulation ø35 O.D

Liquid line ø6.35 - 0.39m (Flared connection ø6.35)

Gas line ø9.52 - 0.34m (Flared connection ø9.52)

Drain hose Insulation ø29 Connected part ø16 O.D

193

60 19

155295

167.5

187.5

209

21.5

41

3

299.5

145145

335

(45)

166.5

208

61

78

42

740

760

178

5

250

335.5

14.551

100

11

96

166

80.5

50

10

(66)

505 189

INDOOR UNIT

INSTALLATION PLATE

11×26 OBLONG HOLE

11×20 OBLONG HOLE

WALL HOLE

ø

65

IN CASE OF LEFT,

LEFT BACK,OR

LEFT UNDER PIPING

(USING SPACER),

MIN 120.5mm

MIN 44.5mm

MIN 14mm

MIN 30mm

MIN 20mm

AIR IN

PIPING

DRAIN HOSE

INSTALLATION PLATE

AIR OUT

OBH799

8

MSZ-AP15VF MSZ-AP20VF

WIRING DIAGRAM

6

OBH799

9

Indoor
heat
exchanger

Flared connection

Room temperature
thermistor
RT11

Flared connection

Refrigerant pipe ø9.52
(with heat insulator)

Refrigerant pipe ø6.35
(with heat insulator)

Indoor coil
thermistor
RT12 (main)

Indoor coil
thermistor
RT13 (sub)

Refrigerant flow in cooling
Refrigerant flow in heating

Unit: mm

MSZ-AP15VF MSZ-AP20VF

REFRIGERANT SYSTEM DIAGRAM

7

OBH799

10

8-1. TIMER SHORT MODE

For service, the following set time can be shortened by bridging JPG and JPS on the electronic control P.C. board.
(Refer to 10-7.)

•

The set time for the ON/OFF timer can be reduced to 1 second for each minute.

•

After the breaker is turned on, the time for starting the compressor, which normally takes 3 minutes, can be reduced to 3
seconds. Restarting the compressor, which takes 3 minutes, cannot be reduced.

8-2. HOW TO SET REMOTE CONTROLLER EXCLUSIVELY FOR A PARTICULAR INDOOR UNIT

A maximum of 4 indoor units with wireless remote controllers can be used in a room.
To operate the indoor units individually with each remote controller, assign a number to each remote controller according
to the number of the indoor unit.

This setting can be set only when all the following conditions are met:

• The remote controller is powered OFF.

• Weekly timer is not set.

• Weekly timer is not being edited.
(1) Hold down

button on the remote controller for 2 seconds to enter the pairing mode.

(2) Press

button again and assign a number to each remote controller.

Each press of

button advances the number in the following order: 1 → 2 → 3 → 4.

(3) Press

button to complete the pairing setting.

MSZ-AP15VF MSZ-AP20VF

SERVICE FUNCTIONS

8

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 has 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.

CN112

R111

Indoor electronic
control P.C. board

JR07

IC112

CN151

CN111

CN211

D

OBH799

11

WIRELESS REMOTE CONTROLLER

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.

MICROPROCESSOR CONTROL

9

MSZ-AP15VF MSZ-AP20VF

Signal transmitting section

Operation display section

Battery replacement indicator

TEMPERATURE buttons

STOP/OPERATE
(OFF/ON) button

Indication of
remote controller
model is on back

Distance of signal :
About 6 m
Beep(s) is (are) heard
from the indoor unit
when the signal is received

FAN SPEED CONTROL button

OPERATION SELECT button

ECONO COOL button

CLOCK SET button

WEEKLY TIMER
set button

TIME, TIMER set buttons
FORWARD button
BACKWARD button

RESET button

i save button

VANE CONTROL 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 tem­perature

About 1 to 2°C from set
temperature

Standby mode
(Only during multi system
operation)

-

INDOOR UNIT DISPLAY SECTION

Lit
Blinking

Not lit

OBH799

12

9-2. DRY ( ) OPERATION

(1) Press STOP/OPERATE(OFF/ON) 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 works the same way as that in COOL mode. (9-1.1.)

2. Low outside temperature operation

Low outside temperature operation works the same way as that in COOL mode. (9-1.2.)

9-3. FAN ( ) OPERATION

(1) 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.

9-4. HEAT ( ) OPERATION

(1) Press STOP/OPERATE(OFF/ON) 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 (TEMP

or 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.

9-1. COOL ( ) OPERATION

(1) Press STOP/OPERATE(OFF/ON) 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 (TEMP

or 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.

OBH799

13

9-5. 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 has passed with the room temperature 1°C below the set
temperature.
HEAT mode changes to COOL mode when about 15 minutes has passed with the room temperature 1°C above the set
temperature.

NOTE 1

If 2 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 2 or more indoor units with one outdoor unit.

• When you try to operate 2 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.

• When indoor unit starts the operation while the defrosting of outdoor unit is being done, it takes a few minutes (max. 10 min-

utes) to blow out the warm air.

• In the heating operation, though indoor unit that does not operate may get warm or the sound of refrigerant flowing may be

heard, they are not malfunction. The reason is that the refrigerant continuously flows into it.

OPERATION INDICATOR

Lit
Blinking

Not lit

9-6. 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.

(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.

Horizontal

position

4

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

In HEA

T operation

Vane angle is fixed to Angle 4.

AUTO

12345

SWING

OBH799

14

(5) STOP (operation OFF) and ON TIMER standby

In the following cases, the horizontal vane returns to the closed position.
(a) When STOP/OPERATE(OFF/ON) 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 (

) 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.

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

this control does not work in the indoor unit.

(9) ECONO COOL (

) operation (ECONOmical operation)
When ECONO COOL button is pressed in COOL mode, set temperature is automatically set 2°C higher by the
microprocessor. However, the temperature on the LCD screen on the remote controller is not changed.
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.

9-7. 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 STOP/OPERATE(OFF/ON) 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.

OBH799

15

(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 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.

9-8. 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.

•

When the weekly timer is set, temperature cannot be set to 10°C.

•

The weekly timer operation and i-save operation cannot be used together.

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

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

(2) Press

and buttons to select setting day and number.

* blinks.

Pressing selects the day of
the week to be set.

Pressing selects
the setting number.

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

and [1] are selected.

* All days can be selected.

1. How to set the weekly timer

OBH799

16

(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.

Pressing

adjusts the time.

Pressing

adjusts the tem­perature.

* Hold down the button to change the time quickly.

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,

button does not have to be pressed per each

setting. Press

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

• Press

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

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

(5) Press

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

2. Checking weekly timer setting

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

blinks.

(2) Press

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

(3) Press

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,

will be

displayed.

OBH799

17

9-10. EMERGENCY/TEST OPERATION

In the 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 or has failed, or when the batteries in the remote controller are
running down. The unit will start and OPERATION INDICATOR lamp
will light up.
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 the latter case, normal operation
will start.

NOTE: Do not press EMERGENCY OPERATION switch during normal operation.

Operation mode COOL/HEAT
Set temperature 24°C

Fan speed Medium

Horizontal vane Auto

The operation mode is indicated by the
Operation Indicator lamp as following

Operation Indicator lamp

EMERGENCY COOL

↓

EMERGENCY HEAT

↓

STOP

Lit

Not lit

9-9. i-save ( ) OPERATION

1. How to set i-save operation

(1) Press STOP/OPERATE(OFF/ON) 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)

• i-save operation and the weekly timer operation cannot be used together.

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 selected from the next time by simply pressing i-save button.

9-11. 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)

OBH799

18

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.

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 connector housing. 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 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.

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.

Lead wiring

Connector housing

<Incorrect>

<Correct>

MSZ-AP15VF MSZ-AP20VF

TROUBLESHOOTING

10

OBH799

19

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

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

Indoor unit is normal.
But the outdoor unit might be abnormal because there are some abnor­malities that cannot be recalled with this way.
Check 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.

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.

Hold down the other 2 buttons for another 3 seconds.
Make sure that the indicators on the LCD screen shown in the right fi gure are all

displayed. Then release the buttons.

Press STOP/OPERATE(OFF/ON) button of the remote controller (the set temperature is
displayed) with the remote controller headed towards the indoor unit.

1

Before blinking, does left lamp of
OPERATION INDICATOR lamp stay ON for 3
seconds?
When it 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 by referring to the
indoor unit failure mode table. (Refer to 10-2.2)
Make sure to check at least 2 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.

The outdoor unit is abnormal.
Check the blinking pattern, and identify the abnormal point by referring
to the outdoor unit failure mode table. (Refer to outdoor unit service
manual.)
Make sure to check at least 2 consecutive blinking cycles.

3

Repair the failure parts.

After repairing the unit, recall the failure mode again according to "Setting up the failure mode recall

function" mentioned above.
Press STOP/OPERATE(OFF/ON) 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.

Setting up the failure mode recall function

Judgment of indoor/outdoor abnormality

Releasing the failure mode recall function

Deleting the memorized abnormal condition

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.

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 0.5­second interval

2.5-second OFF 3-second ON

Blinking at 0.5­second interval

Beeps

Repeated cycle

2.5-second OFF

Blinking at 0.5­second interval

No beep Beeps

Repeated cycle

2.5-second OFF 3-second ON

Blinking at 0.5­second interval

Repeated cycle

Beeps

1 Regardless of normal or abnormal condition,

a short beep is emitted once the signal is re­ceived.

OBH799

20

2. Indoor unit failure mode table

Left lamp of OP-

ERATION INDICA-

TOR lamp

Abnormal point

(Failure mode)

Condition Remedy

Not lighted Normal — —
1-time fl ash every

0.5-second

Room temperature
thermistor

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

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

2-time fl ash

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 ther­mistor, the sub indoor coil thermistor (10-7.).

3-time fl ash

2.5-second OFF

Serial signal

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

Refer to 10-6.

"How to check miswiring and serial

signal error".

11-time fl ash

2.5-second OFF

Indoor fan motor

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

Refer to 10-6.

"Check of indoor fan motor".

12-time fl ash

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.).

OBH799

21

10-3. INSTRUCTION OF TROUBLESHOOTING

Indoor unit oper­ates.
Outdoor unit
does not operate.

If blinking of OPERATION INDI­CATOR 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
fl ashing 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 nor­mal 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/com­pressor".

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/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".

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

• Miswiring or
trouble of se­rial signal

Left lamp
2-time fl ash
Cause:
Indoor unit

• Trouble
of room
temperature
/ indoor coil
thermistor

Left lamp
3-time fl ash
Cause:
Indoor unit

• Trouble of
indoor fan
motor

Left lamp
4-time fl ash
Cause:
Indoor unit

• Trouble
of indoor
unit control
system

Left lamp
5-time fl ash
Cause:
Outdoor unit

• Outdoor
power sys­tem abnor­mality

Left lamp
6-time fl ash
Cause:
Outdoor unit

• Trouble of
thermistor in
outdoor unit

Left lamp
7-time fl ash
Cause:
Outdoor unit

• Trouble of
outdoor con­trol system

Left lamp
14-time fl ash
or more
Cause:
Outdoor unit

• Other ab­normality

Start

Refer to 10-

6. "How to
check mis­wiring and
serial signal
error".

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

Refer to 10-

6. "Check
of indoor fan
motor".

Replace the
indoor elec­tronic control
P.C. board.

Refer to
"How to
check
inverter/com­pressor".

Refer to
"Check of
outdoor ther­mistors".

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

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

"Test Run operation" means the

operation within 30 minutes af­ter EMERGENCY OPERATION
switch is pressed.

Refer to outdoor unit service manual.

OBH799

22

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

Lit
Blinking
Not lit

No.

Abnormal

point

Operation indicator lamp Symptom Condition Remedy

1

Miswiring
or serial
signal

Left lamp fl ashes.

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 er­ror".

2

Indoor coil
thermistor

Left lamp fl ashes.
2-time fl ash

2.5-second OFF

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

•

Refer to the characteristics of
indoor coil thermistor, and the
room temperature thermistor.
(10-7.)

Room tem­perature
thermistor

3

Indoor fan
motor

Left lamp fl ashes.
3-time fl ash

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".

4

Indoor con­trol system

Left lamp fl ashes.
4-time fl ash

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.

5

Outdoor
power sys­tem

Left lamp fl ashes.
5-time fl ash

2.5-second OFF

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

•

Refer to "How to check of in­verter/compressor".
Refer to outdoor unit service
manual

•

Check the stop valve.

6

Outdoor
thermistors

Left lamp fl ashes.
6-time fl ash

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.

7

Outdoor
control sys­tem

Left lamp fl ashes.
7-time fl ash

2.5-second OFF

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

•

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

8

Other ab­normality

Left lamp fl ashes.
14-time fl ash or more

2.5-second OFF

An abnormality other than above mentioned
is detected.

•

Check the stop valve.

•

Check the 4-way valve.

•

Check the abnormality in detail
using the failure mode recall
function for outdoor unit.

9

Outdoor
control sys­tem

Left 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.

•

Check the blinking pattern of
the LED on the inverter P.C.
board or the outdoor electronic
control P.C. board.

OBH799

23

OPERATION INDICATOR

No.

Abnormal

point

Operation indicator lamp Symptom Condition Remedy

1

MXZ type

Operation
mode
setting

Left lamp lights and lower lamp fl ashes.

2.5-second OFF

Outdoor unit
operates but
indoor unit does
not operate.

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.

10-5. TROUBLE CRITERION OF MAIN PARTS

MSZ-AP15VF MSZ-AP20VF

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.

Indoor fan motor (MF)

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

Vane motor (MV)

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

YLW

YLW

ROTOR

OBH799

24

A Check of indoor fan motor

10-6. TROUBLESHOOTING FLOW

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

No

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

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

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 (+) and (–).

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?

Replace the indoor fan motor.

Yes

No

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.

Replace the indoor electronic
control P.C. board.

Is it unchanged holding 0
or 15 V DC?

No

(Changed)
Yes
(Unchanged)

Replace the indoor fan motor.

Is there 325 V DC
between CN211 (+)
and (–) ?

Yes

Replace the indoor
electronic control P.C.
board.

No

Indoor electronic control
P.C. board

Fuse (F11)

Varistor
(NR11)

CN211

R111

CN151

OBH799

25

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

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

Does the unit operate with the remote
controller?

OK

Yes

No
(Not clear)

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

Press STOP/OPERATE(OFF/ON) button on
the remote controller.

Is LCD display on the remote controller
visible?

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.

Yes

No

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

1

Is noise heard from radio?

Yes

No

Replace the remote controller.

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

Yes

No

• Reinstall the unit away from lights.

• Attach a fi lter on receiving part.

Yes

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 approximately 4 V DC - 5 V DC?

No

Replace the indoor electronic control P.C.
board.

Replace the receiver P.C board .

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

Yes

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

No

2

1

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.

2

Look at the image of the signal transmitting section of the
remote controller through the monitor of a digital camera or
a camera phone. It is normal if the LED of the signal trans­mitting section lights up when the STOP/OPERATE(OFF/
ON) button on the remote controller is pressed. However,
it may be diffi cult to see the illuminated LED of the signal
transmitting section with a smartphone camera.

OBH799

26

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?

Yes

No

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

Short circuit:
Replace the indoor fan motor.

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

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

3

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

No

No

Yes

Yes

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

Is the fuse (F11) blown
only?

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

1, 2

Yes

Is the resistance 1MΩ or more?

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

3

No

Replace the fuse (F11).

3

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

Is the resistance of
resistor (R111) approxi­mately 4 Ω?

No

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

Replace the indoor electronic control P.C. board.

Measure the resistance of the vane
motor coil.
Refer to 10-5.

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.

Yes

Indoor electronic control
P.C. board

Fuse (F11)

Varistor
(NR11)

CN211

R111

CN151

OBH799

27

D How to check miswiring and serial signal error

• Turn OFF inverter-controlled lighting
equipment.

• Turn OFF the power supply and then
turn ON again.

• Press EMERGENCY OPERATION
switch.

A

Is serial signal
error indicated 6
minutes later?

B

Yes

• Reinstall
either the unit
or the light
away from
each other.

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

No

Is there rated voltage in
the power supply?

Is there any miswiring,
poor contact, or wire
disconnection of the
indoor/outdoor
connecting wire?

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.

(Lighted
or
not lighted)

No

Yes

No

Yes

Yes

No

Yes

No

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

No

No

Yes

No

Yes

Yes

Yes

No

Yes

Turn OFF the power supply.

Turn ON the power supply.

Is there rated voltage between
the outdoor terminal block S1
and S2?

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

Press EMERGENCY OPERATION switch once.

Check the power
supply.

A

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

Bridge the outdoor terminal block S2 and
S3.
1

B

Turn ON the power supply.

Check the wiring.

Correct them.

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

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

Replace the indoor electronic control P.C. board.

2 Be careful of residual
voltage of smoothing capacitor.

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

Is there any error of the
indoor/outdoor connecting wire,
such as the damage of the wire,
intermediate connection, poor
contact to the terminal block?

Replace the
indoor/outdoor
connecting wire.

Is serial signal error indicated 6 minutes later?

No

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

OBH799

28

E Electromagnetic noise enters into TV sets or radios

Yes

Is the unit earthed?

No

Earth the unit.

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

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

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?

Yes

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

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

Yes

No

No

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

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

Yes

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

No

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 STOP/OPERATE(OFF/ON) 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 STOP/OPERATE(OFF/ON) 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.

OBH799

29

Indoor fan motor
(CN211)

(+) 0 V DC or

15 V DC

(+) 2-6 V
15 V DC
(–) Fiducial

terminal of
cathode side
on measuring
high-voltage
DC

(+) 325 V DC

Room temperature
thermistor RT11
(CN111)

Indoor coil thermis­tor RT12, RT13
(CN112)

Vane motor
(CN151)

12 V DC

5 V DC

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

}

To disable "Auto restart function",
solder the Jumper wire to JR07 (

)

(Refer to 8-3.)

MSZ-AP15VF MSZ-AP20VF
Indoor electronic control P.C. board

10-7. TEST POINT DIAGRAM AND VOLTAGE

Display P.C. board

Receiver P.C. board

SW P.C. board

Resistor
(R111)

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

Temperature (°C)

Resistance (kΩ)

Fuse (F11)
T3.15AL250V

Varistor (NR11)

230 V AC

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

Connector for optional
interface (CN105)

GND

Power supply/
serial cord (CN201)

OBH799

11-1. MSZ-AP15VF MSZ-AP20VF

NOTE: Turn OFF the power supply before disassembly.

OPERATING PROCEDURE PHOTOS/FIGURES

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.

Photo 1

30

(1) Slide the sleeve and check if there is a locking lever or not. (2) The terminal with this connector shown below

has the locking mechanism.

Slide the sleeve.
Pull the terminal while
pushing the locking
lever.

Hold the sleeve, and
pull out the terminal
slowly.

Connector

Sleeve

Locking lever

Screws of the panel

Front panel

Horizontal vanes

<Detaching method of the terminal with locking mechanism>

The terminal which has the locking mechanism can be detached as shown below.
There are following 2 types 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.

A

DISASSEMBLY INSTRUCTIONS

11

OBH799

OPERATING PROCEDURE PHOTOS/FIGURES

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) Unhook the catches

, open the cover of the display

holder and remove the receiver P.C. board.
(Photo 5, 6)
(6) Unhook the catches

and remove the display P.C.

board. (Photo 6)
(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)

CN112 (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 elec­tronic control P.C. board from the electrical box. (Photo 3)

NOTE:

MSZ-AP15VF

and

MSZ-AP20VF

have locking mecha-

nism.

Photo 2

Photo 3

Photo 4

31

Earth wire to the
heat exchanger

SW holder

Fixing screw of the
electrical cover

Screw of the
electrical
cover

Screw of the
V.A. clamp

Display holder

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

Indoor electronic
control P.C. board

Room temperature thermistor (RT11)

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

Be sure to install this thermistor in the
proper direction.

OBH799

OPERATING PROCEDURE PHOTOS/FIGURES

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.

Photo 5

Photo 6

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.

5. Removing the horizontal vane motor

(1) Remove the nozzle assembly. (Refer to 4.)
(2) Remove the screw of the lead cover and remove the

lead cover.

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

and pull out the horizontal vane motor unit.

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

cover.

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

tal vane motor unit.

(6) Disconnect the connectors from the horizontal vane

motor.

Photo 7

32

Screws of the horizontal
vane motor unit cover

Screws of the horizontal
vane motor unit

Front cover of the display holder

Catch

Receiver P.C. board

Display P.C.
board

Lead cover

Screw of the
lead cover

Catch

Catch

OBH799

OPERATING PROCEDURE PHOTOS/FIGURES

6. 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 assembly

(Refer to 4.).
(4) Remove the screws fixing the motor bed. (Photo 8)
(5) Loosen the screw fixing the line flow fan. (Photo 9)
(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 10)
(11) Lift the heat exchanger, and pull out the line flow fan

to the lower-left.
*

When attaching the line flow fan, screw the line flow fan

so 5 mm gap is provided between the right end of the
line flow fan and the right wall of the air passage of
the box (Figure 1).

Photo 8

Photo 9

Photo 10

33

Motor band

Screws of the
motor bed

Screw of the
line flow fan

Screws of the
left side of the
heat exchanger

Catches of the water cover

5 mm

OBH799

Fixing the indoor coil thermistor

34

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

© Copyright 2018 MITSUBISHI ELECTRIC CORPORATION

Published: Jan.2018. No. OBH799
Made in Japan Specifications are subject to change without notice.

*

There are 2 forms of parts for fixing the indoor coil thermistor.

NOTE:

Take care to avoid loss and accidental falling of the clip-shape part inside the unit.
Mount the clip-shape part on the marked position.
Do not pull the lead wire when removing the indoor coil thermistor.

Holder shapeClip shape

When fixing the indoor coil thermistor
to the clip-shape/holder-shape part, the
lead wire should point down.

1. Set the indoor coil
thermistor in the center
of the clip-shape part.

2. Check the (marked)
mounting position.

3. Mount the clip-shape
part.

Position and procedure for mounting the clip-shape part

About the
same length