Mitsubishi OBH483A Service Manual

SPLIT-TYPE AIR CONDITIONERS

INDOOR UNIT

SERVICE MANUAL

Models

Revision A:

• MLZ-KA25/35/50VA-

added.

Please void OBH483.

No. OBH483

REVISED EDITION-A

E2

have been

MLZ-KA25VA ­MLZ-KA25VA ­MLZ-KA35VA ­MLZ-KA35VA ­MLZ-KA50VA ­MLZ-KA50VA -

MLZ-KA25VA
MLZ-KA35VA
MLZ-KA50VA

E1

E2

E1

E2

E1

E2

Outdoor unit service manual
MXZ-A VA Series (OB377)
MXZ-B VA Series (OBH554)

CONTENTS

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

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

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

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

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

6. WIRING DIAGRAM ············································ 7

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

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

9. MICROPROCESSOR CONTROL ··················· 12

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

11. DISASSEMBLY INSTRUCTIONS ···················· 31

NOTE:

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

PARTS CATALOG (OBB483)

Revision A :

• MLZ-KA25/35/50VA-

E2

have been added.

1

MLZ-KA25VA-E1 MLZ-KA25VA­MLZ-KA35VA-E1 MLZ-KA35VA­MLZ-KA50VA-E1 MLZ-KA50VA-

1. Fan motor has been changed (RC0J30-KC RC0J30-KK).

2. Control of auto fan speed has been changed. (When indoor units are connected with a multi type outdoor
unit, and operated in heat mode.)
Air flow in auto fan speed is changed depending on air outlet temperature of indoor unit.

3. Electronic control P.C. board has been changed.

TECHNICAL CHANGES

E2

E2

E2

2

2

Vertical vane

Air outlet

Horizontal vane

Air filter
(Catechin air filter, option)

Air cleaning filter
(Anti-Allergy Enzyme
Filter, option)

Safety string

Intake grille

Remote control
receiving section

Display and operation section (When the intake grille is opened)

Operation indicator lamp

Emergency operation switch

Air inlet

PART NAMES AND FUNCTIONS

INDOOR UNIT

MLZ-KA25VA
MLZ-KA35VA
MLZ-KA50VA

ACCESSORIES

Alkaline battery (AAA) for remote controller
Drain hose (with insulation)
Special washer (with cushion, 4pcs)
Installation template
Fixing screw for M5 х 30
Band
Fixing screw for 4 х 16
Remote controller
Remote controller holder
Fixing screw for

MLZ-KA25VA
MLZ-KA35VA

MLZ-KA50VA

2
1
8
1
4
1
2
1
1
2

3

3

SPECIFICATION

Indoor model

Function

Power supply

Capacity

Air flow (High/Med./Low)
Running current 1
Power input 1
Auxiliary heater
Power factor 1

Electrical

data

Fan motor current 1

Fan motor

Model

Dimensions W x H x D
Weight
Air direction
Sound level (High/Med./Low)
Fan speed (High/Med./Low)

Special

remarks

Fan speed regulator
Remote controller model

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 Wet-bulb temperature 24°C
Heating: Indoor Dry-bulb temperature 20°C
Outdoor Dry-bulb temperature 7°C Wet-bulb temperature 6°C
Refrigerant piping length (one way): 5m

1 Measured under rated operating frequency.

3

m

/h

A

W

A(kW)

%

A

mm

kg

dB(A)

rpm

Cooling

Single phase

230V,50Hz

528/ 480/ 432

E1

RC0J30-KC

E2 E2

RC0J30-KK

1,102

35/ 32/ 29

1,120/1,030/950

Heating

552/ 492/ 420

0.3
40
—
58

0.3

175

x

KM07E

360

x

15

5

36/ 32/ 28

1,160/ 1,060/ 930

3

MLZ-KA35VAMLZ-KA25VA MLZ-KA50VA

Cooling

Single phase

230V,50Hz

564/ 504/ 438

E1 E1

RC0J30-KC
RC0J30-KK

1,102

37/ 34/ 31

1,180/ 1,080/ 960

Heating

594/ 528/ 462

0.3
40
—
58

0.3

175

x

KM07E

360

x

15

5

38/ 35/ 31

1,230/ 1,120/ 1,000

3

Cooling

Single phase

230V,50Hz

684/ 588/ 498

RC0J30-KC

E2

RC0J30-KK

1,102

43/ 38/ 34

1,380/1,220/1,070

708/ 618/ 528

0.3
40
—
58

0.3

175

x

x

15

5

43/ 39/ 34

1,420/ 1,270/ 1,120

3

KM07E

Heating

360

Specifications and rating conditions of main electric parts

Item

Fuse

Horizontal vane motor

Vertical vane motor

Varistor

DRAIN PUMP

FLOAT SENSOR

Model

(F11)

(MV1)

(MV2)

(NR11)

(DP)

(FS)

MLZ-KA25VA MLZ-KA35VA MLZ-KA50VA

T3.15AL 250V

12V 300Ω

12V 300Ω

ERZV14D471

230V 6.4W

DC 12V

4

4

NOISE CRITERIA CURVES

MLZ-KA25VA

FAN SPEED

High

FUNCTION

COOLING

HEATING

SPL(dB(A))

35

36

Test conditions,
Cooling: Dry-bulb temperature 27ºC Wet-bulb temperature 19ºC

Heating: Dry-bulb temperature 20ºC

90

80

70

60

50

40

30

APPROXIMATE

20

THRESHOLD OF
HEARING FOR
CONTINUOUS

OCTAVE BAND SOUND PRESSURE LEVEL, dB re 0.0002 MICRO BAR

NOISE

10

63 125 250 500 1000 2000 4000 8000

BAND CENTER FREQUENCIES, Hz

LINE

MLZ-KA35VA

FAN SPEED

High

FUNCTION

COOLING

HEATING

Test conditions,
Cooling: Dry-bulb temperature 27ºC Wet-bulb temperature 19ºC

Heating: Dry-bulb temperature 20ºC

90

80

NC-70

70

60

NC-60

50

NC-50

40

NC-40

30

NC-30

APPROXIMATE

20

THRESHOLD OF

NC-20

OCTAVE BAND SOUND PRESSURE LEVEL, dB re 0.0002 MICRO BAR

HEARING FOR
CONTINUOUS
NOISE

10

63 125 250 500 1000 2000 4000 8000

BAND CENTER FREQUENCIES, Hz

SPL(dB(A))

LINE

37

38

NC-70

NC-60

NC-50

NC-40

NC-30

NC-20

MLZ-KA50VA

FAN SPEED

High

FUNCTION

COOLING

HEATING

SPL(dB(A))

43

43

Test conditions,
Cooling: Dry-bulb temperature 27ºC Wet-bulb temperature 19ºC

Heating: Dry-bulb temperature 20ºC

90

80

70

60

50

40

30

APPROXIMATE

20

THRESHOLD OF
HEARING FOR
CONTINUOUS

OCTAVE BAND SOUND PRESSURE LEVEL, dB re 0.0002 MICRO BAR

NOISE

10

63 125 250 500 1000 2000 4000 8000

BAND CENTER FREQUENCIES, Hz

LINE

NC-70

NC-60

NC-50

NC-40

NC-30

NC-20

INDOOR UNIT

1.4m

MICROPHONE

CEILING

GRILLE

5

5

OUTLINES AND DIMENSIONS

MLZ-KA25VA MLZ-KA35VA MLZ-KA50VA

INDOOR UNIT

(Top)

180

(51.6)

49.7

20

(Front)

Grille (MLP-440W)

Receiving section

172.4

166.5

81.8

0

166.5
173

R6

(Top)

38

15

13.5

Electrical box

Air outlet

Electrical box

466.5

Center of ceiling opening, suspension bolt pitch
and grille are located in one position.

Drain hose
connecting part

1051 Suspension bolt pitch

1102

960

Outlet opening area

2

0.04m

1200

CL

0

10

Center of ceiling opening,
suspension bolt pitch and grille
are located in one position.

Drain hose

Drain pan

15

2

2

26

58

Pipe
cover

230

20

78

Pipe cover

48

No gaps between

Φ58

the ceiling surface and grille

466.5

26

(Right side)

Drain hose
connecting
part (drain pipe
VP20)

Drain pipe
VP20

R6

CL

414

Hole position for the
installation of grille

How to connect drain pipe on indoor
unit by lifting drain hose.
Drain hose can be used by cutting it.

Wireless
remote controller

58 18

308

116

25

158

Suspension bolt pitch

Gas pipe
MLZ-KA25/35: Φ9.52
MLZ-KA50 : Φ12.7
(Flared)

Liquid pipe

110

Φ6.35
(Flared)

112

Ceiling
surface

Φ6.35

Φ9.52 (MLZ-KA25/35)
Φ12.7 (MLZ-KA50)

110

34

Refrigerant

Pipe

360

244

170

60

Display and
receiving section

Liquid

Gas

Length of drain hose 540

Drain pipe

VP20

NOTE: Drain hose can be used by cutting it.

Drain pipe VP20

Unit : mm

175

31

308 Suspension bolt pitch

384 Ceiling opening

414 Outer side of grille

38

15

54.5

20

(Front)

175

180 or more

Ceiling surface

Air outlet

Outlet

1051 Suspension bolt pitch

1160 Ceiling opening

1200 Outer side of grille

Grille

54.5

20

Suspension bolt M10

Ceiling surface

6

500mm or less

Decline 1/100

Drain hose

6

WIRING DIAGRAM

INDOOR UNIT

MLZ-KA25VA­MLZ-KA35VA-

E1

E1

MLZ-KA25VA­MLZ-KA35VA-

E2

E2

7

MLZ-KA50VA-

E1

MLZ-KA50VA-

E2

8

7

REFRIGERANT SYSTEM DIAGRAM

INDOOR UNIT

MLZ-KA25VA
MLZ-KA35VA

MLZ-KA50VA

Unit : mm

Indoor
heat
exchanger

Indoor coil
thermistor
RT13 (sub)

Room temperature
thermistor
RT11

Indoor coil
thermistor
RT12 (main)

Refrigerant pipe Φ9.52
(with heat insulator)

Flared connection

Flared connection

Refrigerant pipe Φ6.35
(with heat insulator)

Indoor
heat
exchanger

Indoor coil
thermistor
RT13 (sub)

Room temperature
thermistor
RT11

Indoor coil
thermistor
RT12,RT14,
RT15 (main)

Refrigerant pipe Φ12.7
(with heat insulator)

Flared connection

Flared connection

Refrigerant pipe Φ6.35
(with heat insulator)

Refrigerant flow in cooling
Refrigerant flow in heating

9

8

SERVICE FUNCTIONS

MLZ-KA25VA
MLZ-KA35VA
MLZ-KA50VA

8-1. TIMER SHORT MODE

For service, set time can be shortened by short circuit of JPG and JPS on the electronic control P.C. board.
The time will be shortened as follows. (Refer to 10-7.)
Set time : 1-minute → 1-second
Set time : 3-minute → 3-second (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, both the P.C. boards of remote controller

and the electronic control P.C. boards 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 bat-

teries 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.

J1

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

J2

Table 1

1 unit operation

No. 1 unit

No. 2 unit

No. 3 unit

No. 4 unit

How to modify the electronic control P.C. board

Turn OFF the power supply before modification. Cut off “JR05” and “JR06” on the electronic control P.C. board according
to the number of indoor unit as shown in Table 2. (Refer to 10-7.)

No modification

–

–

–

2 units operation

Same as at left

Solder J1

–

–

Table 2

No. 1 unit

No. 2 unit

No. 3 unit

No. 4 unit

JR05

No modification

Cut off JR05

No modification

Cut off JR05

JR06

No modification

No modification

Cut off JR06

Cut off JR06

3 units operation

Same as at left

Same as at left

Solder J2

–

Fuse (F11)

VARISTOR (NR11)

R111

Indoor electronic
control P.C. Board

C111

4 units operation

Same as at left

Same as at left

Same as at left

Solder both J1 and J2

JR06

JR05

IC101

T11

CN151

CN211

NOTE: After modification, turn ON the power supply and with the remote controller headed towards the indoor unit, press the

OPERATE/STOP (ON/OFF) button. If one or two beeps is heard from the indoor unit, modification is completed
correctly.

10

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. The “AUTO RESTART FUNCTION” sets to work the moment
power has restored after power failure. Then, the unit will restart automatically.

Operation

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

(However, it takes at least 3 minutes

for the compressor to start running.)

How to release “AUTO RESTART FUNCTION”

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

F11

NR11

CN 111

CN112 CN113

IC101

CN106

NOTE:

• The operation settings are memorized when 10 seconds have passed after

JR07

the indoor unit was operated with the remote controller.

• If main power is turned OFF or a power failure occurs while AUTO

START/STOP timer is active, the timer setting is cancelled.

• If the unit has been off with the remote controller before power failure, the

auto restart function does not work as the power button of the remote con­troller is off.

• To prevent breaker tripping 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.

R111

C111

CN151

T11

CN211

8-4. P.C. BOARD MODIFICATION FOR CHANGING AIRFLOW VOLUME

Change dip switch SW3 setting according to the height of ceiling.

Dip switch SW3

Ceiling height

NOTE: When the ceiling is above 2.7 m, airflow volume may be insufficient even with the Dip switch (SW3)
set to "increase airflow.

Normal

2.4 m or below

Increase airflow volume

above 2.4 m and 2.7 m or below

How to change Dip switch (SW3) setting (Default setting is Normal)

1. Turn OFF the power supply for the air conditioner.

2. Remove electrical cover A and B.

3. Slide out electronic control P.C. board, and switch
up or down Dip switch (SW3).

4. Put electronic control P.C. board back to
the original position, and install electrical cover A and B.

NOTE:

To prevent damage of P.C. board due to static electricity,
make sure to perform static elimination before setting.

Electrical
cover B

11

Electrical
cover A

Electronic control P.C. board

Dip switch SW3

Normal

Increase
airflow volume