Mitsubishi Electric MS-GF20VA-E1, MS-GF25VA-E1, MS-GF35VA-E1, MS-GF50VA - E1, MS-GF60VA - E1 Service Manual

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CONTENTS

1. TECHNICAL CHANGES ··································· 2

2. PART NAMES AND FUNCTIONS ····················· 3

3. SPECIFICATION ················································ 4

4. NOISE CRITERIA CURVES ······························ 5

5. OUTLINES AND DIMENSIONS ························ 6

6. WIRING DIAGRAM ············································ 6

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

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

9. MICROPROCESSOR CONTROL ··················· 10

10. TROUBLESHOOTING ····································· 15

11. DISASSEMBLY INSTRUCTIONS ···················· 25

SPLIT-TYPE AIR CONDITIONERS

Outdoor unit service manual MU-GF·VA Series (OBH622)

SERVICE MANUAL

No. OBH621

INDOOR UNIT

PARTS CATALOG (OBB621)

NOTE:

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

Models

MS-GF20VA

MS-GF25VA

MS-GF35VA

MS-GF20VA -

MS-GF25VA -

MS-GF35VA -

1. New model

TECHNICAL CHANGES

Use the speciﬁ ed 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.

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.

Do not perform the work involving the electric parts with wet hands. Do not pour water into the electric parts. Do not touch the refrigerant. Do not touch the hot or cold areas in the refrigeration cycle. When the repair or the inspection of the circuit needs to be done without turning off the power, exercise great caution not to

touch the live parts.

OBH621

ACCESSORIES

PART NAMES AND FUNCTIONS

Model

MS-GF20VA MS-GF25VA MS-GF35VA

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 (For left or left-rear piping) 1

MS-GF20VA MS-GF25VA MS-GF35VA

Air ﬁlter (Nano platinum ﬁlter)

Front panel

Air cleaning ﬁlter (Electrostatic anti-allergy

enzyme ﬁlter, option)

Operation indicator lamp

Remote control receiving section

Emergency operation switch (E.O. SW)

Horizontal vane

Air outlet

Heat exchanger

Display section

Air inlet

Remote controller

OBH621

SPECIFICATION

Indoor model MS-GF20VA MS-GF25VA MS-GF35VA

Function Cooling

Power supply Single phase 230 V, 50 Hz

Electrical

data

Running current A

0.20 0.22

Power input W

35 43

Fan

motor

Model RC4V18-FA

Current A

0.20

0.22

Dimensions W × H × D mm 798 x 295 x 232

Weight kg

Special remarks

Air direction

Airﬂ ow

Super High (POWERFUL)

m3/h

558 624

High 474 558

Med. 378 396

Low 246 288

Sound level

Super High (POWERFUL)

dB (A)

40 44

High 36 40

Med. 31 33

Low 25 26

Fan speed

Super High (POWERFUL)

rpm

1,000 1,100

High 880 1,000

Med. 740 770

Low 540 610

Fan speed regulator 4

Remote controller model KM12A

NOTE: Test conditions are based on ISO 5151. Cooling: Indoor Dry-bulb temperature 27 Wet-bulb temperature 19 Outdoor Dry-bulb temperature 35 Wet-bulb temperature 24 Indoor-Outdoor piping length: 5 m

OBH621

63 125 250 500 1000 2000 4000 8000

NC-60

NC-50

NC-40

NC-30

NC-20

NC-70

BAND CENTER FREQUENCIES, Hz

COOLING

FUNCTION

SPL(dB(A))

LINE

Super High

FAN SPEED

NC-10

OCTAVE BAND SOUND PRESSURE LEVEL, 0dB re 0.0002 MICRO BAR

63 125 250 500 1000 2000 4000 8000

NC-60

NC-50

NC-40

NC-30

NC-20

NC-70

BAND CENTER FREQUENCIES, Hz

COOLING

FUNCTION

SPL(dB(A))

LINE

Super High

FAN SPEED

NC-10

OCTAVE BAND SOUND PRESSURE LEVEL, 0dB re 0.0002 MICRO BAR

Test conditions

Cooling: Dry-bulb temperature 27 °C

Wet-bulb temperature 19 °C

INDOOR UNIT

WALL

MICROPHONE

0.8m

63 125 250 500 1000 2000 4000 8000

NC-60

NC-50

NC-40

NC-30

NC-20

NC-70

BAND CENTER FREQUENCIES, Hz

COOLING

FUNCTION

SPL(dB(A))

LINE

Super High

FAN SPEED

NC-10

OCTAVE BAND SOUND PRESSURE LEVEL, 0dB re 0.0002 MICRO BAR

NOISE CRITERIA CURVES

MS-GF20VA MS-GF25VA

MS-GF35VA

OBH621

Unit: mm

OUTLINES AND DIMENSIONS

211.5

231.5

253

21.5

155 155

225 225

232

798 785 6.5

130619

295

100

107

112

33861

212.5

254

315 84

11×26 Oblong hole

11×20 Oblong hole

Installation plate

Indoor unit

Wall hole ø65

Air in

Air out

Installation plate

Piping

Drain hose

159

MS-GF20VA MS-GF25VA MS-GF35VA

Piping

Insulation ø35 O.D Liquid line ø7 - 0.5 m (Flared connection ø6.35) Gas line ø9.52 - 0.43 m (Flared connection: ø9.52)

Drain hose Insulation ø28 O.D Connected part ø16 O.D

WIRING DIAGRAM

MS-GF20VA MS-GF25VA MS-GF35VA

OBH621

Unit: mm

REFRIGERANT SYSTEM DIAGRAM

MS-GF20VA MS-GF25VA

Indoor heat exchanger

Flared connection

Room temperature thermistor RT11

Flared connection

Refrigerant pipe 6.35 (with heat insulator)

Indoor coil thermistor RT12

Refrigerant flow in cooling

Refrigerant pipe 9.52 (with heat insulator)

MS-GF35VA

Indoor heat exchanger

Flared connection

Room temperature thermistor RT11

Flared connection

Refrigerant pipe 6.35 (with heat insulator)

Indoor coil thermistor RT12

Refrigerant flow in cooling

Refrigerant pipe 9.52 (with heat insulator)

OBH621

8-1. TIMER SHORT MODE

For service, the following set time can be shortened by short circuit of JPG and JPS on the electronic control P.C. board. (Refer to 10-7.) Set time: 3 minutes → 3 seconds (It takes 3 minutes for the compressor to start operation. However, the starting time is shortened by short circuit of JPG and JPS.)

8-2. P.C. BOARD MODIFICATION FOR INDIVIDUAL OPERATION

A maximum of 4 indoor units with wireless remote controllers can be used in a room. In this case, to operate each indoor unit individually by each remote controller, P.C. boards of remote controller must be modified according to the number of the indoor unit.

How to modify the remote controller P.C. board

Remove batteries before modification. The board has a print as shown below:

NOTE: For modification, take out

the batteries and press the OPERATE/STOP (ON/ OFF) button 2 or 3 times at first.

After modification, put back

the batteries then press the RESET button.

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.

SERVICE FUNCTIONS

MS-GF20VA MS-GF25VA MS-GF35VA

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

OBH621

8-3. AUTO RESTART FUNCTION

When the indoor unit is controlled with the remote controller, the operation mode, the set temperature, and the fan speed are memorized by the indoor electronic control P.C. board. “AUTO RESTART FUNCTION” automatically starts operation in the same mode just before the shutoff of the main power.

Operation

If the main power has been cut, the operation settings remain. After the power is restored, the unit restarts automatically according to the memory.

(However, it takes at least 3 minutes

for the compressor to start running.)

How to disable “AUTO RESTART FUNCTION”

Turn off the main power for the unit. Solder the jumper wire to JR07 on the indoor electronic control P.C. board. (Refer to 10-7.)

NOTE:

• The operation settings are memorized when 10 seconds have passed after the indoor unit was operated with the remote

controller.

• If main power is turned OFF or a power failure occurs while AUTO START/STOP timer is active, the timer setting is can-

celled.

• If the unit has been off with the remote controller before power failure, the auto restart function does not work as the

power button of the remote controller is OFF.

• To prevent breaker OFF due to the rush of starting current, systematize other home appliance not to turn ON at the same

time.

• When some air conditioners are connected to the same supply system, if they are operated before power failure, the

starting current of all the compressors may flow simultaneously at restart.

Therefore, the special counter-measures are required to prevent the main voltage-drop or the rush of the starting current

by adding to the system that allows the units to start one by one.

JR07

Indoor electronic control P.C. board

111NCA01NC 151NC

211NC

OBH621

WIRELESS REMOTE CONTROLLER

MICROPROCESSOR CONTROL

NOTE: Last setting will be stored after the unit is turned OFF with the remote controller. Indoor unit receives the signal of the

remote controller with beeps.

Signal transmitting section

Operation display section

Temperature buttons

OPERATE/STOP (ON/OFF) button

Indication of remote controller model is on back

TIME SET buttons FORWARD button BACKWARD button

VANE CONTROL button

OFF-TIMER button

RESET button

FAN SPEED CONTROL button

OPERATION SELECT button

ECONO COOL button

ON-TIMER button

CLOCK button

POWERFUL COOL button

MS-GF20VA MS-GF25VA MS-GF35VA

Operation Indicator lamp

The operation indicator at the right side of the indoor unit indicates the operation state.

•The following indication applies regardless of shape of the indication.

Indication Operation state Room temperature

The unit is operating to reach the set temperature

About 2°C or more away from set temperature

The room temperature is approaching the set temperature

About 1 to 2°C from set temperature

INDOOR UNIT DISPLAY SECTION

Lighted

Blinking

Not lighted

9-1. COOL ( ) OPERATION

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

OPERATION INDICATOR lamp of the indoor unit turns on with a beep tone. (2) Select COOL mode with OPERATION SELECT button. (3) Press TEMPERATURE buttons (TOO WARM or TOO COOL button) to select the desired temperature. The setting range

is 16 - 31°C.

1. Coil frost prevention

The compressor operational frequency is controlled by the temperature of the indoor heat exchanger to prevent the coil

from frosting.

When the temperature of indoor heat exchanger becomes too low, the coil frost prevention mode works.

The indoor fan operates at the set speed and the compressor stops. This mode continues until the temperature of indoor

heat exchanger rises.

OBH621

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.)

-3. FAN ( )OPERATION

(1) Press OPERATE/STOP (ON/OFF) button. OPERATION INDICATOR lamp of the indoor unit turns ON with a beep tone. (2) Select FAN mode with OPERATION SELECT button. (3) Select the desired fan speed. When AUTO, it becomes Low. Only indoor fan operates. Outdoor unit does not operate.

Mode

COOL mode of

"I FEEL CONTROL"

DRY mode of

"I FEEL CONTROL"

Initial room temperature

25 or more

more than 13 ,

less than 25

9-4. “I FEEL CONTROL” ( ) OPERATION

(1) Press OPERATE/STOP (ON/OFF) button on the remote controller. OPERATION INDICATOR lamp of the indoor unit

turns ON with a beep tone.

(2) Select “I FEEL CONTROL” mode with the OPERATION SELECT button. (3) The operation mode is determined by the room temperature at start-up of the operation.

• Once the mode is fixed, the mode does not change by room temperature afterwards.

• Under ON-TIMER (

) operation, mode is determined as follows:

When the system is stopped by the remote controller, and restarted within 2 hours in “I FEEL CONTROL” ( ) mode,

the system operates in previous mode automatically regardless of the room temperature.

Previous operation

COOL mode of “I FEEL CONTROL” or COOL mode

Restart

COOL mode of “I FEEL CONTROL”

Operation timer chart Example

When the system is restarted after 2 hours and more, the operation mode is determined by the room temperature at

start-up of the operation.

Operation time chart Example

Previous operation

COOL mode of “I FEEL CONTROL” or COOL mode

Restart

COOL or-DRY mode of “

I FEEL CONTROL”

that

determined

by room temperature at start-up of the operation.

OBH621

(4) The initial set temperature is decided by the initial room temperature.

Mode

Initial room temperature

26 °C or more 24 °C

Initial room temperature

minus 2

°C

25 °C to 26 °C

Initial set temperature

DRY mode of

“I FEEL CONTROL”

COOL mode of

“I FEEL CONTROL”

more than 13 °C, less than 25 °C

Initial room temperature minus 2

°C

1 When the system is restarted with the remote controller, the system operates with the previous set temperature regard-

less of the room temperature at restart.

The set temperature is calculated by the previous set temperature.

(5) TEMPERATURE buttons

In “I FEEL CONTROL” mode, set temperature is decided by the microprocessor based on the room temperature.

In addition, set temperature can be controlled by TOO WARM or TOO COOL buttons when you feel too cool or too warm.

Each time TOO WARM or TOO COOL button is pressed, the indoor unit receives the signal and emits a beep tone.

Fuzzy control

When TOO COOL or TOO WARM button is pressed, the microprocessor changes the set temperature, considering the room temperature, the frequency of pressing TOO COOL or TOO WARM button and the user’s preference to heat or cold. So this is called “Fuzzy control”, and works only in “I FEEL CONTROL” mode. In DRY mode of “I FEEL CONTROL”, the set temperature does not change.

… To raise the set temperature 1 ~ 2

… To lower the set temperature 1 ~ 2

9-5. AUTO VANE OPERATION

1. Horizontal vane

(1) Vane motor drive

These models are equipped with a stepping motor for the horizontal vane. The rotating direction, speed, and angle of the motor are controlled by pulse signals (approximately 12 V) transmitted from indoor microprocessor.

(2) The horizontal vane angle and mode change as follows by pressing VANE CONTROL button.

AUTO

1 2 3 4 5

SWING

(3) Positioning

To confirm the standard position, the vane moves until it touches the vane stopper. Then the vane is set to the selected angle. Confirming of standard position is performed in the following cases:

(a) When the operation starts or finishes (including timer operation). (b) When the test run starts.

(4) VANE AUTO ( ) mode

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

Vane angle is fixed to Angle 1.

OBH621

(7) SWING ( ) mode

By selecting SWING mode with VANE CONTROL button, the horizontal vane swings vertically.

(8) ECONO COOL (

) operation (ECONOmical operation) When ECONO COOL button is pressed in COOL mode, set temperature is automatically set 2°C higher. Also the horizontal vane swings in various cycles. SWING operation makes you feel cooler than set temperature. So, even though the set temperature is higher, the air conditioner can keep comfort. As a result, energy can be saved. To cancel this operation, select a different mode or press one of the following buttons in ECONO COOL operation: ECONO COOL, VANE CONTROL or POWERFUL button.

(9) POWERFUL ( ) operation

The air conditioner automatically adjusts the fan speed and the set temperature, and operates the POWERFUL mode.

The POWERFUL mode is cancelled automatically 15 minutes after operation starts. To cancel this operation manual-

ly, select a different mode or press one of the following buttons: POWERFUL, OPERATE/STOP (ON/OFF), ECONO COOL, or

FAN, SPEED CONTROL button.

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

In the following cases, the horizontal vane returns to the closed position.

(a) When OPERATE/STOP (ON/OFF) button is pressed (POWER OFF). (b) When the operation is stopped by the emergency operation. (c) When ON TIMER is ON standby.

(6) Dew prevention

During COOL or DRY operation with the vane angle at Angle 4 or 5 when the compressor cumulative operation time exceeds 1 hour, the vane angle automatically changes to Angle 1 for dew prevention.

1. How to set the time

(1) Check that the current time is set correctly.

NOTE: Timer operation will not work without setting the current time. Initially “0:00” blinks at the current time display

of TIME MONITOR, so set the current time correctly with CLOCK button.

How to set the current time

(a) Press the CLOCK button. (b) Press the TIME SET buttons ( and ) to set the current time.

• Each time FORWARD button ( ) is pressed, the set time increases by 1 minute, and each time BACKWARD button ( ) is pressed, the set time decreases by 1 minute.

• Pressing those buttons longer, the set time increases/decreases by 10 minutes.

(c) Press the CLOCK button. (2) Press OPERATE/STOP (ON/OFF) button to start the air conditioner. (3) Set the time of timer.

ON timer setting

(a) Press ON TIMER button( ) during operation.

(b) Set the time of the timer using TIME SET buttons (

and ).

OFF timer setting

(a) Press OFF TIMER button (

) during operation.

(b) Set the time of the timer using TIME SET buttons ( and ).

Each time FORWARD button ( ) is pressed, the set time increases by 10 minutes: each time BACKWARD

but-

ton ( ) is pressed, the set time decreases by 10 minutes.

2. To release the timer

To release ON timer, press ON TIMER button ( ).

To release OFF timer, press OFF TIMER button( ). TIMER is cancelled and the display of set time disappears.

9-6. TIMER OPERATION

OBH621

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

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

• OFF timer and ON timer can be used in combination. The timer of the set time that is reached first will operate first.

• “

” and “ ” display shows the order of OFF timer and ON timer operation.

PROGRAM TIMER

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

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

NOTE: If the main power is turned OFF or a power failure occurs while ON/OFF timer is active, the timer setting is can-

celled. As these models are equipped with an auto restart function, the air conditioner starts operating with timer cancelled when power is restored.

9-7. EMERGENCY/TEST OPERATION

In case of test run operation or emergency operation, use EMERGENCY OPERATION switch on the right side of the indoor unit. Emergency operation is available when the remote controller is missing, has failed or the batteries of the remote controller run down. The unit will start and OPERATION INDICATOR lamp will light. The first 30 minutes of operation is the test run operation. This operation is for servicing. The indoor fan runs at High speed and the temperature control does not work. After 30 minutes of test run operation, the system shifts to EMERGENCY COOL MODE with a set temperature of 24°C. The fan speed shifts to Med. The coil frost prevention works even in the test run or the emergency operation. In the test run or emergency operation, the horizontal vane operates in VANE AUTO (

) mode. Emergency operation continues until EMERGENCY OPERATION switch is pressed again or the unit receives any signal from the remote controller. In case of latter, normal operation will start.

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

Operation mode COOL Set temperature 24°C

Fan speed Med.

Horizontal vane Auto

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

Operation Indicator lamp

EMERGENCY COOL

↓

STOP

Lighted

Not lighted

9-8. 3-MINUTE TIME DELAY OPERATION

When the system turns OFF, compressor will not restart for 3 minutes as 3-minute time delay function operates to protect compressor from overload.

Emergency operation switch (E.O. SW)

OBH621

10-1. CAUTIONS ON TROUBLESHOOTING

1. Before troubleshooting, check the following

1) Check the power supply voltage.

2) Check the indoor/outdoor connecting wire for miswiring.

2. Take care of the following during servicing

1) Before servicing the air conditioner, be sure to turn OFF the main unit first with the remote controller, and then after confirming the horizontal vane is closed, turn OFF the breaker and/or disconnect the power plug.

2) Be sure to turn OFF the power supply before removing the front panel, the cabinet, the top panel, and the P.C. board.

3) When removing the P.C. board, hold the edge of the board with care NOT to apply stress on the components.

4) When connecting or disconnecting the connectors, hold the housing of the connector. DO NOT pull the lead wires.

3. Troubleshooting procedure

1) Check if the OPERATION INDICATOR lamp on the indoor unit is flashing ON and OFF to indicate an abnormality.

To make sure, check how many times the OPERATION INDICATOR lamp is flashing ON and OFF before starting

service work.

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

3) When the electronic control P.C. board seems to be defective, check the copper foil pattern for disconnection and the

components for bursting and discoloration.

4) When troubleshooting, Refer to 10-2, 10-3 and 10-4.

4. How to replace batteries

Weak batteries may cause the remote controller malfunction. In this case, replace the batteries to operate the remote controller normally.

Lead wiring

Housing point

TROUBLESHOOTING

RESET button

Insert the negative pole of the batteries first. Check if the polarity of the batteries is correct.

NOTE: 1. If RESET button is not pressed, the remote controller may not operate correctly.

2. This remote controller has a circuit to automatically reset the microcomputer when batteries are replaced. This function is equipped to prevent the microcomputer from malfunctioning due to the voltage drop caused by the

battery replacement.

3. Do not use the leaking batteries.

Press RESET button with a thin instrument, and

then use the remote controller.

Remove the front lid and insert batteries.

Then reattach the front lid.

MS-GF20VA MS-GF25VA MS-GF35VA

OBH621

10-2. FAILURE MODE RECALL FUNCTION

Outline of the function This air conditioner can memorize the abnormal condition which has occurred once. Even though LED indication listed on the troubleshooting check table (10-4.) disappears, the memorized failure details can be recalled.

1. Flow chart of failure mode recall function for the indoor unit

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

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

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

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 2 consecutive blinking cycles. 2

Releasing the failure mode recall function

Release the failure mode recall function by the following procedures. Turn OFF the power supply and turn it ON again. Press RESET button of the remote controller.

Repair the defective parts.

Deleting the memorized abnormal condition

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

function" mentioned above. Press OPERATE/STOP (ON/OFF) button of the remote controller (the set temperature is displayed)

with the remote controller headed towards the indoor unit. Press EMERGENCY OPERATION switch so that the memorized abnormal condition is deleted. Release the failure mode recall function according to "Releasing the failure mode recall function"

mentioned above.

Yes (Blinks)

No (OFF)

NOTE: 1. Make sure to release the failure mode recall function once it is set up, otherwise the unit cannot operate properly.

2. If the abnormal condition is not deleted from the memory, the last abnormal condition is kept memorized.

2. Blinking pattern when the indoor unit is abnormal:

OFF

Beeps

Repeated cycle Repeated cycle

2.5-second OFF

Blinking at 0.5second interval

Beeps

Repeated cycle

2.5-second OFF

Blinking at 0.5second interval

Beeps

The cause of abnormality cannot be found because the abnormality does not recur.

Setting up the failure mode recall function

Turn ON the power supply. <Preparation of the remote controller>

While pressing both OPERATION SELECT button and TOO COOL button on the

remote controller at the same time, press RESET button. First, release RESET button.

Hold down the other two buttons for another 3 seconds. Conﬁ rm that the indicators on the LCD screen shown in the right ﬁ gure are all displayed. Then release the buttons.

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

Operational procedure

1 Regardless of normal or abnormal condition,

a short beep is emitted once the signal is received.

OBH621

2. Indoor unit failure mode table

Upper lamp of OPERATION 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 indoor coil thermistor (10-7.).

11-time ﬂ ash

2.5-second OFF

Indoor fan motor

The rotational frequency feedback signal is not emitted for 12 seconds after the indoor fan motor is operated.

Refer to 10-6.

"Check of indoor fan motor".

12-time 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.

14-time ﬂ ash 1

2.5-second OFF

Refrigerant circuit

Refer to 10-4. No.4 "Condition". Refer to 10-4. No.4 "Remedy".

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

OFF

Beeps Beeps

Repeated cycle

2.5-second OFF

3.0-second ON

14-time

flash

Repeated cycle

2.5-second OFF

3.0-second ON

14-time

flash

1. A blinking pattern when "14-time flash" is displayed :

OBH621

10-3. INSTRUCTION OF TROUBLESHOOTING

Indoor unit operates. Outdoor unit does not operate.

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.

Indoor unit operates, when EMERGENCY OPERATION switch is pressed.

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

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

Refer to 10-6. "Check of remote controller and indoor electronic control P.C. board".

1. Check indoor/outdoor connecting wire. (Check if the power is supplied to the indoor unit.)

Check the outdoor fuse (F).

3. Refer to 10-6. "Check of indoor P.C. board and indoor fan motor".

Upper lamp 2-time ﬂ ash Cause: Indoor unit

• Trouble of room temperature / indoor coil thermistor

Upper lamp 3-time ﬂ ash Cause: Indoor unit

• Trouble of indoor fan motor

Upper lamp 4-time ﬂ ash Cause: Indoor unit

• Trouble of indoor unit control system

Start

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.

Outdoor unit does not operate even in "Test run operation".

1. Check the wiring diagram of the outdoor unit.

2. Check the outdoor fuse.

Check the indoor fuse (F11), outdoor fuse (F) and the compressor contactor (52C).

Indoor and outdoor unit do not operate.

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

Upper lamp 14-time ﬂ ash Cause: Outdoor unit

• Troubles regarding refrigerant circuit

Refer to 10-4 No. 4 "Remedy".

"Test Run operation" means the

operation within 30 minutes after EMERGENCY OPERATION switch is pressed.

Refer to outdoor unit service manual.

OBH621

10-4. TROUBLESHOOTING CHECK TABLE

Before taking measures, make sure that the symptom reappears for accurate troubleshooting. When the indoor unit has started operation and detected an abnormality of the following condition (the first detection after the power ON), the indoor fan motor turns OFF and OPERATION INDICATOR lamp flashes.

OPERATION INDICATOR

Lighted Blinking Not lighted

No.

Abnormal

point

Operation indicator lamp Symptom Condition Remedy

Indoor coil thermistor

Upper lamp ﬂ ashes. 2-time ﬂ ash

2.5-second OFF

Indoor unit and outdoor unit do not operate.

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

Indoor fan motor

Upper 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".

•

Indoor control system

Upper 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.

•

Refrigerant circuit

Upper lamp ﬂ ashes. 14-time ﬂ ash

2.5-second OFF

The unit has been pumped down for a long time.

Check the stop valve.

•

The refrigerant amount is low.

Check the connections and the refrigerant amount for any leakage.

•

The unit is short cycling.

Check for short cycle. If any problem is found, provide some space for air path around the outdoor unit.

•

The outdoor fan motor locks up.

Check that the connecting cable of the outdoor fan motor is properly connected. Check the resistance value of the outdoor fan motor. If any problem is found, replace the outdoor fan motor.

•

1. When the trouble indicated with 14-time ﬂ ash occurs, turn off the main power supply. Otherwise, the operation indicator lamp may ﬂ ash again even if the power is turned off and on using a remote controller.

Operation Indicator lamp

The operation indicator lamp is at the right side of the indoor unit.

•The following indication applies regardless of shape of the indication.

OBH621

A Check of indoor fan motor

10-6. TROUBLESHOOTING FLOW

10-5. TROUBLE CRITERION OF MAIN PARTS

Part name Check method and criterion Figure

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

Measure the resistance with a tester.

Refer to 10-7. "Test point diagram and voltage", "1. Indoor electronic control P.C. board", for the chart of thermistor.

Indoor fan motor (MF) INNER FUSE 145 °C CUT OFF

Measure the resistance with a tester. (Part temperature 10 ~ 30 °C)

Color of the lead wire Normal

WHT-BLK 334 Ω ~ 362 Ω BLK-RED 370 Ω ~ 402 Ω

MAIN

AUX.

BLK

RED WHT

FUSE

Horizontal vane motor (MV)

Measure the resistance between the terminals with a tester.

(Temperature: 10 - 30°C)

Color of the lead wire Normal

RED-BLK 223 Ω ~ 268 Ω

BLK

BLK RED

BLK

ROTOR

CN211

Indoor power P.C.board

Fuse (F11)

Indoor terminal P.C.board

Varistor (NR11)

CN121

Are soldered points of the

connector correctly soldered to

the indoor power P.C. board?

Is the resistance 0 (short circuit) or (open circuit)?

Yes ( 0 o r )

Yes

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

Yes

Turn OFF the power supply. Check connector CN211 visually.

Disconnect lead wires from connector CN211 on indoor power P.C. board. Measure the resistance between lead wires No.1 and No.4 and then No.4 and No.7.

Turn ON the power supply. Stop it if the unit operates. Insert screwdriver into air outlet to rotate indoor fan motor slowly for 1 revolution or over, and measure the voltage No.2(+) and No.1(-) on CN121.

(others)

Replace the indoor power/terminal P.C. board and the indoor control P.C. board.

Does the voltage repeat 0 VDC and 5 VDC?

Yes

Are lead wires connected?

Reconnect the lead wires.

Resolder it.

Replace the indoor fan motor.

OBH621

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?

Yes

No (Not clear)

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

Press OPERATE/STOP (ON/OFF)

button on the remote controller.

Is LCD display on the remote controller visible?

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

Yes

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

Is noise heard from radio?

Yes

Replace the remote controller.

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

Yes

Reinstall the unit away from lights. Attach a ﬁ lter on receiving part.

•

Replace indoor electronic control P.C. board.

OBH621

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

1. Please replace the fuse after removing

the indoor terminal P.C. board from

the electrical box.

Yes

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

OPERATION switch?

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

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

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

Short circuit Replace the indoor fan motor.

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

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

Replace the varistor (NR11) and fuse (F11). 1

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

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

Yes

Is the fuse (F11) blown only?

Yes

Is there approximately 5 VDC between 5 VDC (+) and JPG (GND) (-) of the indoor electronic control P.C.board? Is there approximately 9 VDC to 13 VDC between 12 VDC (+) and JPG (GND) (-) of the indoor electronic control P.C. board?

Replace the fuse (F11). 1

Replace the fuse (F11) and indoor fan motor. 1

Is the resistance of resistor

Measure the resistance of the reisistor (R111) on the indoor power P.C. board.

Yes

Connect the connector or repair disconnection.

Yes

Are connector CN10A on the indoor electronic control P.C. board or lead wires disconnected?

Replace the indoor power/terminal P.C. board.

Replace the indoor power/terminal P.C. board and the indoor fan motor.

Yes

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

Is the resistance normal?

Yes

Replace the fan motor.

JPG (GND)

12 VDC

5 VDC

CN10A

Indoor power P.C.board

Indoor electronic control P.C.board

Fuse (F11)

Indoor terminal P.C.board

Varistor (NR11)

R111

CN211

(R111) approximately 4Ω?

OBH621

D Electromagnetic noise enters into TV sets or radios

Yes

Is the unit earthed?

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?

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

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.

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.

OBH621

MS-GF20VA MS-GF25VA MS-GF35VA

10-7. TEST POINT DIAGRAM AND VOLTAGE

1. Indoor electronic control P.C. board

Room temperature thermistor RT11 (CN111)

Indoor coil thermistor RT12 (CN112)

GND

Vane motor (CN151)

Connector to Indoor power P.C. board (CN10A)

12 VDC

5 VDC

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

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

To disable" Auto restart function", solder the Jumper wire to JR07 (Refer to 8-3.)

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

Temperature (°C)

Resistance (kΩ)

2. Indoor terminal P.C. board Indoor power P.C. board

}

Indoor fan motor (CN211) 230 V AC

Please replace the fuse after removing the indoor terminal P.C. board from the electrical box.

Fuse (F11)( )

Connector to indoor electronic control P.C. board (CN20A)

12 VDC

GND

5 VDC

Terminal block

CN121

Varistor (NR11)

R111

Indoor Power P.C. boardIndoor terminal P.C. board

OBH621

11-1. MS-GF20VA MS-GF25VA MS-GF35VA

NOTE: Turn OFF power supply before disassembly.

OPERATING PROCEDURE PHOTOS

1. Removing the panel

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

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

slightly toward you, and then remove the panel by

pushing

it upward.

Photo 1

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

<"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.

Screws of the panel

Front panel

Horizontal vanes

DISASSEMBLY INSTRUCTIONS

OBH621

OPERATING PROCEDURE PHOTOS

2. Removing the indoor electronic control P.C. board and the room temperature thermistor

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

clamp.

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

electrical cover. (4) Remove the indoor/outdoor connecting wire. (5) Open the indoor electronic control P.C. board holder (to

right side). (6) Disconnect the following connectors: <Indoor electronic control P.C. board> CN10A (To the indoor power P.C. board) CN112 (Indoor coil thermistor) CN151 (Vane motor) (7) Unhook the catches of the indoor electronic control P.C.

board holder from the nozzle and the electrical box

(right side). (8) Remove the room temperature thermistor from the

hook of the indoor electronic control P.C. board hold-

er. (9) Open the back side of the indoor electronic control P.C.

board holder, and remove the indoor electronic con-

trol P.C. board. (10)

Remove the room temperature thermistor from the

indoor electronic control P.C. board.

Photo 2

Photo 3

3. Remove the indoor power P.C. board, the indoor terminal P.C. board, and the electrical box

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

2 (2)-(4).).

(3) Remove the earth wire connected to the indoor heat

exchanger from the electrical box.

(4) Unhook first the lower, then the upper catches of the

electrical box, and pull out the electrical box.

(5) Disconnect all the connectors on the indoor power P.C.

board and unhook all lead wires.

(6) Remove the screw of terminal block on the indoor ter-

minal P.C. board.

(7) Remove the indoor power P.C. board and the indoor

terminal P.C. board.

Lower catch

Indoor terminal P.C. board

Terminal block

Indoor power P.C. board

Catch of indoor electronic control P.C. board holder

Upper catch

Screw of the V.A. clamp

Indoor electronic control P.C. board holder

Screw of the electrical cover

Catch of indoor electronic control P.C. board holder

Electrical box

Earth wire

OBH621

OPERATING PROCEDURE PHOTOS

4. Removing the nozzle assembly

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

2 (2)-(4).).

(3)

Remove the indoor electronic control P.C. board holder.

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

remove the nozzle assembly.

Photo 4

5. Removing the horizontal vane motor

(1) Remove the nozzle assembly. (Refer to 4.) (2) Remove the screws of the horizontal vane motor unit. (3) Disconnect the connector from the horizontal vane

motor. (4) Remove the screws of the horizontal vane motor. (5) Remove the horizontal vane motor from the horizontal

vane motor unit.

Screws of horizontal vane motor unit

OBH621

OPERATING PROCEDURE PHOTOS

6. Removing the indoor fan motor, the indoor coil thermistor, and the line flow fan

(1) Remove the panel (Refer to 1.) and the corner box. (2) Remove the indoor electronic control P.C. board hold-

er, the electrical box and the nozzle assembly. (3) Remove the screws fixing the motor bed. (4) Loosen the screw fixing the line flow fan. (5) Remove the motor bed together with fan motor and

motor band. (6) Release the hooks of the motor band. Remove the

motor band. Pull out the indoor fan motor. (8) Remove the indoor coil thermistor from the heat

exchanger. ( ) Install the indoor coil thermistor in its former position

when assembling it. (Refer to Photo 8) (9) Remove the screws fixing the left side of the heat

exchanger. (10)

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

to the lower-left.

Photo 8

Photo 5

Photo 6

Photo 7

Screw of the line flow fan

Screws of the motor bed

Motor band

Indoor coil thermistor (main) RT12

Screws of the left side of the heat exchanger

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

Distributed in Oct. 2012. No. OBH621 Made in Japan

New publication, effective Oct. 2012 Specifications are subject to change without notice.

Mitsubishi Electric MS-GF20VA-E1, MS-GF25VA-E1, MS-GF35VA-E1, MS-GF50VA - E1, MS-GF60VA - E1 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual