Mitsubishi OB455E Service Manual

OUTDOOR UNIT

Revision E:

• MUZ-GB50VA-E3 has been added.

Please void OB455 REVISED EDITION-D.

SERVICE MANUAL

Wireless type
Models

MUZ-GB50VA ­MUZ-GB50VA ­MUZ-GB50VA -

E1

E2

E3

HFC

utilized

R410A

No. OB455

REVISED EDITION-E

Indoor unit service manual

MSZ-GB·VA Series (OB454)

CONTENTS

1. TECHNICAL CHANGES ··································· 3

2. PART NAMES AND FUNCTIONS ····················· 4

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

4. NOISE CRITERIA CURVES ······························ 6

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

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

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

8. PERFORMANCE CURVES ····························· 11

9. ACTUATOR CONTROL ··································· 16

10. SERVICE FUNCTIONS ···································· 17

11. TROUBLESHOOTING ····································· 18

12. DISASSEMBLY INSTRUCTIONS ···················· 42

13. RoHS PARTS LIST ·········································· 46

NOTE:

• This service manual describes technical data of the outdoor units.

Revision A:

• Compressor has been changed.

Model

Previous SNB130FLDH E12 851 900
New SNB130FLDH1 E12 939 900

RoHS PARTS LIST number

Revision B:

• REFRIGERANT SYSTEM DIAGRAM has been changed.

• Oil separator has been added.

• Capillary tube has been added. (ø1.8 × ø0.6 × 1000)

• MUZ-GB50VA-

• Check of outdoor thermistors (10-6.

E2

has been added.

) has been corrected.

Revision C:

• RoHS PARTS LIST has been changed.

Revision D:

• RoHS PARTS LIST has been changed.

Revision E:

• MUZ-GB50VA-E3 has been added.

2

1

TECHNICAL CHANGES

MUZ-GA50VA -E1 MUZ-GB50VA -

1. Refrigerant filling capacity has been changed.

2. Outdoor electronic control P.C. board has been changed.

MUZ-GB50VA -E1 MUZ-GB50VA -

1. Compressor has been changed. (SNB130FLDH1 SNB130FLEH1)

2. Outdoor electronic control P.C. board has been changed.

MUZ-GB50VA -E2 MUZ-GB50VA -

1. Compressor has been changed. (SNB130FLEH1 SNB130FGBH)

2. Outdoor electrical parts have been changed.

3. Refrigerant circuit has been changed.

E1

E2

E3

3

2

PART NAMES AND FUNCTIONS

MUZ-GB50VA

Air inlet

(back and side)

ACCESSORIES

Piping

Drain hose

Air outlet

Drain outlet

3

Capacity Rated frequency (Min.-Max.) kW 5.0 (0.9-5.8) 5.8 (0.9-7.8)

Electrical

Coeffi cient of performance (C.O.P) 1 3.03 3.41

Compressor

Fan motor

Dimensions W × H × D mm 840 × 850 × 330
Weight kg 53
Dehumidifi cation
Air fl ow 1 (High/Low) m3/h 2,940/1,650 2,940/2,210

Special

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 Wet-bulb temperature 15°C
Outdoor Dry-bulb temperature 7°C Wet-bulb temperature 6°C
Refrigerant piping length (one way) : 5 m
1 Measured under rated operating frequency.

SPECIFICATION

Outdoor model MUZ-GB50VA

Function Cooling Heating

Power supply Single phase 230 V, 50 Hz

Breaker capacity A 20
Running current 1 A 7.23 7.43
Power input 1 W 1,610 1,660

data

Power factor
Starting current 1 A 7.46

Sound level 1 (High/Low) dB(A) 52/51 55/53
Fan speed (High/Low) rpm 800/480 800/620
Fan speed regulator 2
Refrigerant fi lling capacity (R410A) kg 1.50

remarks

Refrigeration oil (Model) NEO22

1% 97

E1

E1, E2

E3

E2

E3

W

/h 2.2 —

Model

Output

Compressor motor current 1 A 6.91 7.11

Model RC0J60-AA

Current

1 A 0.32

Drain socket 1

Drain cap ø33 2

SNB130FLDH or SNB130FLDH1

SNB130FLEH1

SNB130FGBH

850
900

44

Specifi cations and rating conditions of main electric parts

Item

Current transformer

Model

(CT1,2) 20 A

(CT61) 20 A

MUZ-GB50VA­MUZ-GB50VA-

Smoothing capacitor (CB1,2,3) 560 μF 450 V

(F64) 250 V 2 A

Fuse

(F801) 250 V 3.15 A

(F911) 250 V 1 A

Expansion valve coil (LEV) DC 12 V

Intelligent power module

(IPM) 15 A 600 V

(HC930) 3 A 600 V

Reactor (L) 340 μH 20 A

Power factor controller (PFC) 20 A 600 V

(R64A,B) 10 Ω 10 W

Resistor

(R937A,B) 1.1 Ω 2 W 2%

(RS1~4) 0.04 Ω 7 W

Solenoid coil relay (SSR61) 0.5 A 600 V

Terminal block (TB1,TB2) 3 P

Relay (X64) 20 A 250 V

R.V. coil (21S4) AC 220 - 240 V

E1

E2

Item

Current transformer

Model

(CT) 20 A

(CT761, CT781) 15 A

MUZ-GB50VA-

Smoothing capacitor (C61, C62, C63) 620 μF 420 V

Diode module

Fuse

(F701, F801, F901) T3.15AL250V

(DB61) 25 A 600 V
(DB65) 25 A 600 V

(F61) T20AL250V

Intelligent power module (IPM) 20 A 600 V
Expansion valve coil (LEV) DC 12 V
Reactor (L61) 23.0 mH

(R61, R62) 180 mΩ 5 W (2 elements)

Current-detecting resistor

(R825) 25 mΩ 5 W

(R937A, R937B) 1.1 Ω 2 W

Current-limiting PTC thermistor (PTC64, PTC65) 33 Ω
Terminal block (TB1, TB2) 3 P

Relay

(X63) 3 A 250 V

(X64) 20 A 250 V
R.V. coil (21S4) AC 220 - 240 V
IGBT (TR821) 30 A 600 V

E3

55

4

NOISE CRITERIA CURVES

MUZ-GB50VA

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

5

NOISE

10

63 125 250 500 1000 2000 4000 8000

BAND CENTER FREQUENCIES, Hz

OUTLINES AND DIMENSIONS

MUZ-GB50VA

515

330

299

66

51

34

40

FAN SPEED

NC-70

NC-60

Test conditions

NC-50

NC-40

NC-30

NC-20

Cooling : Dry-bulb temperature 35°C
Wet-bulb temperature (24°C)
Heating : Dry-bulb temperature 7°C
Wet-bulb temperature 6°C

REQUIRED SPACE

100 mm or more

360

High

FUNCTION

COOLING

HEATING

OUTDOOR UNIT

MICROPHONE

Open as a rule
500 mm or more if
the front and both
sides are open

SPL(dB(A)) LINE

52

55

1m

Unit: mm

100 mm or more
200 mm or more if
there are obstacles
to both sides

850

430

121

500

840

80

Open as a rule

500 mm or more if the back,

both sides and top are open

350 mm or more

Service panel

Liquid refrigerant
pipe joint
Refrigerant pipe
(flared) ø6.35

30°

155

90

35°

Gas refrigerant
pipe joint
Refrigerant pipe

198

(flared) ø12.7

6

6

n

WIRING DIAGRAM

MUZ-GB50VA­MUZ-GB50VA-

RED

W

CT2

PFC

R

S

E1

E2

CB3

CB2

CB1

W

V

V

MC

IPM

CN5

21

U

BLK

WHT

U

CT1

RS3

RS1

27

21

RS4

RS2

CN2

CN3

CN4

6543 1

RT64

POWER

BOARD

LD9

LD1LD2

12

GRN

WHT

RED

BLK
BLK

ORN

PNK

GRY

CN801

13

12

CN701

MF

YLW

BLU

CN931

F801

RED

R937A

T801

BLK

WHT

23134512

CN932

HC930

R937B

diagram for servicing.

refer to the indoor unit electric wiring

1.About the indoor side electric wiringNOTES:

NAME

:Terminal block :Connector

3.Symbols below indicate.

2.Use copper conductors only (for field wiri

RED

1

L

2

RED

3X64

TAB1

BRN

TB1

CIRCUIT

BREAKER

POWER SUPPLY

~/N 230V 50Hz

YLW

R64B

R64A

F64

NF

L

4

3

BLK

YLW

TAB4

NR64

BLU

N

BLK

TAB2

PE

21

CN903

CT61

BLK

SSR61

F911

21

CN902

GRN/YLW

5123

CN901

12

CN912

LDE2

LDE1

13

CN61

NOISE

FILTER

BLU
BLU

GRN

GRN

P.C.BOARD

TO INDOOR

BLK
BLK
BLK

1 567

BLK

5321

BLK

BLK
BLK
BLK

21S4

ELECTRONIC

1

WHT

BLU
WHT

TB2

230V~

UNIT

CONNECTING

CN702

CN661

CN781

CN663

CONTROL

P.C.BOARD

CN601

3

BLU

S2

S1

12-24V

CN7954123 78

21

5

RED

S3

6

LEV

AMBIENT TEMPERATURE THERMISTOR

FIN TEMPERATURE THERMISTOR

RT65

RT64

SYMBOL

NAME

OUTDOOR HEAT EXCHANGER

RT68

TERMINAL BLOCK

TRANSFORMER

SOLENOID COIL RELAY

TEMPERATURE THERMISTOR

TB1

T801

SSR61

TERMINAL BLOCK

R.V. COIL

RELAY

X64

TB2

21S4

RT61 RT62 RT68

RT65

OUTDOOR FAN MOTOR

COMPRESSOR

VAR ISTO R

NOISE FILTER

NF

MF

MC

SYMBOL

NAME

NR64

FUSE (T2AL 250V)

CURRENT TRANSFORMER

SMOOTHING CAPACITOR

CURRENT TRANSFORMER

DEFROST THERMISTOR

DISCHARGE TEMPERATURE THERMISTOR

RESISTOR

POWER FACTOR CONTROLLER

RESISTOR

RESISTOR

PFC

R64A,B

FUSE (T1AL 250V)

FUSE (T3.15AL 250V)

RT62

RT61

RS1~4

R937A, B

EXPANSION VALVE COIL

INTELLIGENT POWER MODULE

REACTOR

INTELLIGENT POWER MODULE

F911

IPM

HC930

L

LEV

F64

F801

CT61

CT1, 2

CB1~3

SYMBOL

7

7

MUZ-GB50VA-

E3

8

7

REFRIGERANT SYSTEM DIAGRAM

MUZ-GB50VA-

Refrigerant pipe ø12.7
(with heat insulator)

Flared connection

Flared connection

Refrigerant pipe ø6.35
(with heat insulator)

E1

Muffler

4-way valve

Stop valve
(with service port)

Receiver

Stop valve

Strainer

#100

#100

Discharge
temperature
thermistor
RT62

Compressor

Capillary tube
ø3.6×ø2.4×50

LEV

Strainer

#100

Defrost
thermistor
RT61

Outdoor
heat
exchanger

Outdoor heat
exchanger
temperature
thermistor
RT68

R.V. coil
OFF
ON

Ambient
temperature
thermistor
RT65

Refrigerant flow in cooling
Refrigerant flow in heating

Unit:mm

MUZ-GB50VA­MUZ-GB50VA-

Refrigerant pipe ø12.7
(with heat insulator)

Flared connection

Flared connection

Refrigerant pipe
(with heat insulator)

E1

E2

ø

Stop valve

6.35

Capillary tube
ø1.8×ø0.6×1000

4-way valve

Stop valve
(with service port)

Receiver

Strainer

#100

Oil separator

Compressor

Capillary tube
ø3.6×ø2.4×50

Strainer

LEV

#100

Discharge
temperature
thermistor
RT62

Strainer

#100

Defrost
thermistor
RT61

Refrigerant flow in cooling
Refrigerant flow in heating

Outdoor
heat
exchanger

Outdoor
heat
exchanger
temperature
thermistor
RT68

R.V. coil
heating ON
cooling OFF

Ambient
temperature
thermistor
RT65

Unit:mm

9

MUZ-GB50VA-

Refrigerant pipe ø12.7
(with heat insulator)

Flared connection

E3

Muffler

4-way valve

Stop valve
(with service port)

#100

Discharge
temperature
thermistor
RT62

Defrost
thermistor
RT61

Outdoor
heat
exchanger

Ambient
temperature
thermistor
RT65

Unit:mm

Flared connection

Refrigerant pipe ø6.35
(with heat insulator)

Receiver

Stop valve
(with strainer)

Compressor

Capillary tube
ø3.6×ø2.4×50

LEV

Strainer

#100

Outdoor heat
exchanger
temperature
thermistor
RT68

R.V. coil
OFF
ON

Refrigerant flow in cooling
Refrigerant flow in heating

MAX. REFRIGERANT PIPING LENGTH and MAX. HEIGHT DIFFERENCE

Refrigerant piping : m

Max. Length

A

Max. Height difference

B

MUZ-GB50VA 30 15 12.7 6.35

Piping size O.D : mm

Gas Liquid

Indoor
unit

Max. Height

difference

B

Max. Length
A

Outdoor unit

ADDITIONAL REFRIGERANT CHARGE (R410A : g)

Model

MUZ-GB50VA 1,500

Outdoor unit

precharged

7 m 10 m 15 m 20 m 25 m 30 m

0 60 160 260 360 460

NOTE : Refrigerant piping exceeding 7 m requires additional refrigerant charge according to the calculation.

Refrigerant piping length (one way)

Calculation : X g = 20 g/m × (Refrigerant piping length (m) - 7)

10

PERFORMANCE CURVES8

MUZ-GB50VA

The standard specifications apply only to the operation of the air conditioner under normal conditions. Since operating condi-

tions vary according to the areas where these units are installed, the following information has been provided to clarify the
operating characteristics of the air conditioner under the conditions indicated by the performance curve.

(1) GUARANTEED VOLTAGE

198 ~ 264 V, 50 Hz

(2) AIR FLOW

Air flow should be set at MAX.

(3) MAIN READINGS

(1) Indoor intake air wet-bulb temperature : °C [WB]
(2) Indoor outlet air wet-bulb temperature : °C [WB]
(3) Outdoor intake air dry-bulb temperature : °C [DB]
(4) Total input: W
(5) Indoor intake air dry-bulb temperature : °C [DB]
(6) Outdoor intake air wet-bulb temperature : °C [WB]
(7) Total input : W
Indoor air wet/dry-bulb temperature difference on the left side of the following chart shows the difference between the
indoor intake air wet/dry-bulb temperature and the indoor outlet air wet/dry-bulb temperature for your reference at service.

How to measure the indoor air wet-bulb/dry-bulb temperature difference

1. Attach at least 2 sets of wet and dry-bulb thermometers to the indoor air intake as shown in the figure, and at least
2 sets of wet and dry-bulb thermometers to the indoor air outlet. The thermometers must be attached to the position
where air speed is high.

2. Attach at least 2 sets of wet and dry-bulb thermometers to the outdoor air intake.

Cover the thermometers to prevent direct rays of the sun.

3. Check that the air filter is cleaned.

4. Open windows and doors of room.

5. Press the EMERGENCY OPERATION switch once (twice) to start the EMERGENCY COOL (HEAT) MODE.

6. When system stabilizes after more than 15 minutes, measure temperature and take an average temperature.

7. 10 minutes later, measure temperature again and check that the temperature does not change.

}

}

Cooling

Heating

INDOOR UNIT

Wet and dry-bulb
thermometers

8-1. CAPACITY AND INPUT CURVES

14.1

12.9

11.8

10.7

9.6

8.6

difference (°C)

7.6

Indoor air Wet-bulb temperature

1.5

Indoor intake air Wet-bulb

1.4

temperature(

1.3

1.2

1.1

1.0

Capacity correction factors

0.9

-10-5 0 5 1015202530354043
Outdoor intake air Dry-bulb temperature(

Cooling capacity

°C

)

OUTDOOR UNIT

Wet and dry-bulb
thermometers

26

24

22
20

18

°C

)

at Rated frequency

MUZ-GB50VA

11

11.8

10.7

difference (°C)

Indoor air Wet-bulb temperature

1.3

1.2

1.1

9.6

8.6

1.0

0.9

7.6

0.8

6.6

Input correction factors

at Rated frequency

MUZ-GB50VA

Total input (Cooling)

26

Indoor intake air Wet-bulb
temperature(°C)

-10-5 0 5 10152025303540
Outdoor intake air Dry-bulb temperature (

°C

)

24

22
20
18

43

33.6

31.0

28.4

25.8

23.3

20.7

18.1

15.5

difference (°C)

12.9

Indoor air Dry-bulb temperature

10.3

1.3

1.2

1.1

1.0

0.9

0.8

0.7

0.6

0.5

Capacity correction factor

0.4

-15 -10 -5 0 5 10 15

at Rated frequency

MUZ-GB50VA

Heating capacity

)

°C

Indoor intake air Dry-bulb temperature (

Outdoor intake air Wet-bulb temperature (°C)

15

26

1.3

20

1.2

1.1

1.0

0.9

0.8

0.7

0.6

Input correction factor

0.5

0.4

-15 -10 -5 0 5 10 15

Indoor intake air Dry-bulb temperature (

Outdoor intake air Wet-bulb temperature (°C)

Total input(Heating)

)

°C

NOTE : The above broken lines are for the heating operation without any frost and defrost operation.

8-2. CAPACITY AND INPUT CORRECTION BY OPERATIONAL FREQUENCY OF COMPRESSOR

Correction of Cooling capacity

1.5

1.0

0.5

Capacity correction factors

0.0
0 50 100 150

The operational frequency

of compressor (Hz)

Correction of Cooling total input

1.5

1.5

1.0

1.0

0.5

0.5

Input correction factors

0.0

0.0
0 50 100 150

0 50 100 150

The operational frequency

of compressor (Hz)

Correction of Heating capacity

1.5

1.0

0.5

Capacity correction factors

0.0
0 50 100 150

The operational frequency

of compressor (Hz)

Correction of

2.0

1.5

1.0

0.5

Input correction factors

0.0
0 50 100 150

The operational frequency

of compressor (Hz)

26
20
15

Heating total input

8-3. TEST RUN OPERATION (How to operate fixed-frequency operation)

1. Press EMERGENCY OPERATION switch to start COOL or HEAT mode (COOL : Press once, HEAT : Press twice).

2. Test run operation starts and continues to operate for 30 minutes.

3. Compressor operates at rated frequency in COOL mode or 58 Hz in HEAT mode.

4. Indoor fan operates at High speed.

5. After 30 minutes, test run operation finishes and EMERGENCY OPERATION starts (Operation frequency of compressor var­ies).

6. To cancel test run operation (EMERGENCY OPERATION), press EMERGENCY OPERATION switch or any button on
remote controller.

12

8-4. OUTDOOR LOW PRESSURE AND OUTDOOR UNIT CURRENT

COOL operation

Both indoor and outdoor unit are under the same temperature/

humidity condition.

Operation : TEST RUN OPERATION (Refer to 8-3.)

MUZ-GB50VA

(kgf/ [Gauge])

10

9

8

7

Outdoor low pressure

6

5

(MPa [Gauge])

1.0

0.9

0.8

0.7

0.6

0.5

15 2050256030

18 32

Ambient temperature(°C)
Ambient humidity(%)

35(°C)

70 (%)

8

7

6

5

Outdoor unit current(A)

4

15 2050256030

18 32

Ambient temperature(°C)
Ambient humidity(%)

70 (%)

35(°C)

Dry-bulb temperature (°C) Relative humidity (%)

20 50
25 60
30 70

NOTE: The unit of pressure has been changed to MPa based on the international system of units (SI unit system).
The conversion factor is: 1 (MPa [Gauge] = 10.2 (Kgf/cm2 [Gauge])

HEAT operation

Condition :

Dry bulb temperature (°C) 20.0 2 7 15 20.0

Wet bulb temperature (°C) 14.5 1 6 12 14.5

Operation : TEST RUN OPERATION (Refer to 8-3.)

8

Indoor Outdoor

7

6

5

Outdoor unit current (A)

4

0 5 10 15 20 25

2

Ambient temperature(°C)

13

PERFORMANCE DATA COOL operation at Rated frequency

MSZ-GB50VA : MUZ-GB50VA

CAPACITY : 5.0 kW SHF : 0.69 INPUT : 1650 W

INDOOR

DB (°C)

INDOOR

WB (°C)

21 18 5.88 3.00 0.51 1320 5.63 2.87 0.51 1386 5.40 2.75 0.51 1452 5.20 2.65 0.51 1518

21 20 6.13 2.39 0.39 1386 5.88 2.29 0.39 1469 5.70 2.22 0.39 1502 5.50 2.15 0.39 1568

22 18 5.88 3.23 0.55 1320 5.63 3.09 0.55 1386 5.40 2.97 0.55 1452 5.20 2.86 0.55 1518

22 20 6.13 2.63 0.43 1386 5.88 2.53 0.43 1469 5.70 2.45 0.43 1502 5.50 2.37 0.43 1568

22 22 6.38 1.98 0.31 1436 6.15 1.91 0.31 1526 6.00 1.86 0.31 1568 5.75 1.78 0.31 1634

23 18 5.88 3.47 0.59 1320 5.63 3.32 0.59 1386 5.40 3.19 0.59 1452 5.20 3.07 0.59 1518

23 20 6.13 2.88 0.47 1386 5.88 2.76 0.47 1469 5.70 2.68 0.47 1502 5.50 2.59 0.47 1568

23 22 6.38 2.23 0.35 1436 6.15 2.15 0.35 1526 6.00 2.10 0.35 1568 5.75 2.01 0.35 1634

24 18 5.88 3.70 0.63 1320 5.63 3.54 0.63 1386 5.40 3.40 0.63 1452 5.20 3.28 0.63 1518

24 20 6.13 3.12 0.51 1386 5.88 3.00 0.51 1469 5.70 2.91 0.51 1502 5.50 2.81 0.51 1568

24 22 6.38 2.49 0.39 1436 6.15 2.40 0.39 1526 6.00 2.34 0.39 1568 5.75 2.24 0.39 1634

24 24 6.70 1.81 0.27 1502 6.45 1.74 0.27 1584 6.30 1.70 0.27 1634 6.10 1.65 0.27 1716

25 18 5.88 3.94 0.67 1320 5.63 3.77 0.67 1386 5.40 3.62 0.67 1452 5.20 3.48 0.67 1518

25 20 6.13 3.37 0.55 1386 5.88 3.23 0.55 1469 5.70 3.14 0.55 1502 5.50 3.03 0.55 1568

25 22 6.38 2.74 0.43 1436 6.15 2.64 0.43 1526 6.00 2.58 0.43 1568 5.75 2.47 0.43 1634

25 24 6.70 2.08 0.31 1502 6.45 2.00 0.31 1584 6.30 1.95 0.31 1634 6.10 1.89 0.31 1716

26 18 5.88 4.17 0.71 1320 5.63 3.99 0.71 1386 5.40 3.83 0.71 1452 5.20 3.69 0.71 1518

26 20 6.13 3.61 0.59 1386 5.88 3.47 0.59 1469 5.70 3.36 0.59 1502 5.50 3.25 0.59 1568

26 22 6.38 3.00 0.47 1436 6.15 2.89 0.47 1526 6.00 2.82 0.47 1568 5.75 2.70 0.47 1634

26 24 6.70 2.35 0.35 1502 6.45 2.26 0.35 1584 6.30 2.21 0.35 1634 6.10 2.14 0.35 1716

26 26 6.90 1.59 0.23 1584 6.70 1.54 0.23 1667 6.60 1.52 0.23 1716 6.40 1.47 0.23 1766

27 18 5.88 4.41 0.75 1320 5.63 4.22 0.75 1386 5.40 4.05 0.75 1452 5.20 3.90 0.75 1518

27 20 6.13 3.86 0.63 1386 5.88 3.70 0.63 1469 5.70 3.59 0.63 1502 5.50 3.47 0.63 1568

27 22 6.38 3.25 0.51 1436 6.15 3.14 0.51 1526 6.00 3.06 0.51 1568 5.75 2.93 0.51 1634

27 24 6.70 2.61 0.39 1502 6.45 2.52 0.39 1584 6.30 2.46 0.39 1634 6.10 2.38 0.39 1716

27 26 6.90 1.86 0.27 1584 6.70 1.81 0.27 1667 6.60 1.78 0.27 1716 6.40 1.73 0.27 1766

28 18 5.88 4.64 0.79 1320 5.63 4.44 0.79 1386 5.40 4.27 0.79 1452 5.20 4.11 0.79 1518

28 20 6.13 4.10 0.67 1386 5.88 3.94 0.67 1469 5.70 3.82 0.67 1502 5.50 3.69 0.67 1568

28 22 6.38 3.51 0.55 1436 6.15 3.38 0.55 1526 6.00 3.30 0.55 1568 5.75 3.16 0.55 1634

28 24 6.70 2.88 0.43 1502 6.45 2.77 0.43 1584 6.30 2.71 0.43 1634 6.10 2.62 0.43 1716

28 26 6.90 2.14 0.31 1584 6.70 2.08 0.31 1667 6.60 2.05 0.31 1716 6.40 1.98 0.31 1766

29 18 5.88 4.88 0.83 1320 5.63 4.67 0.83 1386 5.40 4.48 0.83 1452 5.20 4.32 0.83 1518

29 20 6.13 4.35 0.71 1386 5.88 4.17 0.71 1469 5.70 4.05 0.71 1502 5.50 3.91 0.71 1568

29 22 6.38 3.76 0.59 1436 6.15 3.63 0.59 1526 6.00 3.54 0.59 1568 5.75 3.39 0.59 1634

29 24 6.70 3.15 0.47 1502 6.45 3.03 0.47 1584 6.30 2.96 0.47 1634 6.10 2.87 0.47 1716

29 26 6.90 2.42 0.35 1584 6.70 2.35 0.35 1667 6.60 2.31 0.35 1716 6.40 2.24 0.35 1766

30 18 5.88 5.11 0.87 1320 5.63 4.89 0.87 1386 5.40 4.70 0.87 1452 5.20 4.52 0.87 1518

30 20 6.13 4.59 0.75 1386 5.88 4.41 0.75 1469 5.70 4.28 0.75 1502 5.50 4.13 0.75 1568

30 22 6.38 4.02 0.63 1436 6.15 3.87 0.63 1526 6.00 3.78 0.63 1568 5.75 3.62 0.63 1634

30 24 6.70 3.42 0.51 1502 6.45 3.29 0.51 1584 6.30 3.21 0.51 1634 6.10 3.11 0.51 1716

30 26 6.90 2.69 0.39 1584 6.70 2.61 0.39 1667 6.60 2.57 0.39 1716 6.40 2.50 0.39 1766

31 18 5.88 5.35 0.91 1320 5.63 5.12 0.91 1386 5.40 4.91 0.91 1452 5.20 4.73 0.91 1518

31 20 6.13 4.84 0.79 1386 5.88 4.64 0.79 1469 5.70 4.50 0.79 1502 5.50 4.35 0.79 1568

31 22 6.38 4.27 0.67 1436 6.15 4.12 0.67 1526 6.00 4.02 0.67 1568 5.75 3.85 0.67 1634

31 24 6.70 3.69 0.55 1502 6.45 3.55 0.55 1584 6.30 3.47 0.55 1634 6.10 3.36 0.55 1716

31 26 6.90 2.97 0.43 1584 6.70 2.88 0.43 1667 6.60 2.84 0.43 1716 6.40 2.75 0.43 1766

32 18 5.88 5.58 0.95 1320 5.63 5.34 0.95 1386 5.40 5.13 0.95 1452 5.20 4.94 0.95 1518

32 20 6.13 5.08 0.83 1386 5.88 4.88 0.83 1469 5.70 4.73 0.83 1502 5.50 4.57 0.83 1568

32 22 6.38 4.53 0.71 1436 6.15 4.37 0.71 1526 6.00 4.26 0.71 1568 5.75 4.08 0.71 1634

32 24 6.70 3.95 0.59 1502 6.45 3.81 0.59 1584 6.30 3.72 0.59 1634 6.10 3.60 0.59 1716

32 26 6.90 3.24 0.47 1584 6.70 3.15 0.47 1667 6.60 3.10 0.47 1716 6.40 3.01 0.47 1766

Q SHC SHF INPUT Q SHC SHF INPUT Q SHC SHF INPUT Q SHC SHF INPUT

21 25 27 30

NOTE Q : Total capacity (kW) SHF : Sensible heat factor DB : Dry-bulb temperature
SHC : Sensible heat capacity (kW) INPUT : Total power input (W) WB : Wet-bulb temperature

OUTDOOR DB (°C)

14

PERFORMANCE DATA COOL operation at Rated frequency

MSZ-GB50VA : MUZ-GB50VA

CAPACITY : 5.0 kW SHF : 0.69 INPUT : 1650 W

INDOOR

DB (°C)

INDOOR

WB (°C)

21 18 4.90 2.50 0.51 1617 4.50 2.30 0.51 1716 4.30 2.19 0.51 1749

21 20 5.15 2.01 0.39 1683 4.80 1.87 0.39 1766 4.60 1.79 0.39 1815

22 18 4.90 2.70 0.55 1617 4.50 2.48 0.55 1716 4.30 2.37 0.55 1749

22 20 5.15 2.21 0.43 1683 4.80 2.06 0.43 1766 4.60 1.98 0.43 1815

22 22 5.45 1.69 0.31 1749 5.10 1.58 0.31 1848 4.90 1.52 0.31 1881

23 18 4.90 2.89 0.59 1617 4.50 2.66 0.59 1716 4.30 2.54 0.59 1749

23 20 5.15 2.42 0.47 1683 4.80 2.26 0.47 1766 4.60 2.16 0.47 1815

23 22 5.45 1.91 0.35 1749 5.10 1.79 0.35 1848 4.90 1.72 0.35 1881

24 18 4.90 3.09 0.63 1617 4.50 2.84 0.63 1716 4.30 2.71 0.63 1749

24 20 5.15 2.63 0.51 1683 4.80 2.45 0.51 1766 4.60 2.35 0.51 1815

24 22 5.45 2.13 0.39 1749 5.10 1.99 0.39 1848 4.90 1.91 0.39 1881

24 24 5.75 1.55 0.27 1815 5.40 1.46 0.27 1898 5.25 1.42 0.27 1947

25 18 4.90 3.28 0.67 1617 4.50 3.02 0.67 1716 4.30 2.88 0.67 1749

25 20 5.15 2.83 0.55 1683 4.80 2.64 0.55 1766 4.60 2.53 0.55 1815

25 22 5.45 2.34 0.43 1749 5.10 2.19 0.43 1848 4.90 2.11 0.43 1881

25 24 5.75 1.78 0.31 1815 5.40 1.67 0.31 1898 5.25 1.31 0.25 1947

26 18 4.90 3.48 0.71 1617 4.50 3.20 0.71 1716 4.30 3.05 0.71 1749

26 20 5.15 3.04 0.59 1683 4.80 2.83 0.59 1766 4.60 2.71 0.59 1815

26 22 5.45 2.56 0.47 1749 5.10 2.40 0.47 1848 4.90 2.30 0.47 1881

26 24 5.75 2.01 0.35 1815 5.40 1.89 0.35 1898 5.25 1.21 0.23 1947

26 26 6.05 1.39 0.23 1881 5.70 1.31 0.23 1964 5.50 1.27 0.23 2013

27 18 4.90 3.68 0.75 1617 4.50 3.38 0.75 1716 4.30 3.23 0.75 1749

27 20 5.15 3.24 0.63 1683 4.80 3.02 0.63 1766 4.60 2.90 0.63 1815

27 22 5.45 2.78 0.51 1749 5.10 2.60 0.51 1848 4.90 2.50 0.51 1881

27 24 5.75 2.24 0.39 1815 5.40 2.11 0.39 1898 5.25 1.10 0.21 1947

27 26 6.05 1.63 0.27 1881 5.70 1.54 0.27 1964 5.50 1.49 0.27 2013

28 18 4.90 3.87 0.79 1617 4.50 3.56 0.79 1716 4.30 3.40 0.79 1749

28 20 5.15 3.45 0.67 1683 4.80 3.22 0.67 1766 4.60 3.08 0.67 1815

28 22 5.45 3.00 0.55 1749 5.10 2.81 0.55 1848 4.90 2.70 0.55 1881

28 24 5.75 2.47 0.43 1815 5.40 2.32 0.43 1898 5.25 1.00 0.19 1947

28 26 6.05 1.88 0.31 1881 5.70 1.77 0.31 1964 5.50 1.71 0.31 2013

29 18 4.90 4.07 0.83 1617 4.50 3.74 0.83 1716 4.30 3.57 0.83 1749

29 20 5.15 3.66 0.71 1683 4.80 3.41 0.71 1766 4.60 3.27 0.71 1815

29 22 5.45 3.22 0.59 1749 5.10 3.01 0.59 1848 4.90 2.89 0.59 1881

29 24 5.75 2.70 0.47 1815 5.40 2.54 0.47 1898 5.25 0.89 0.17 1947

29 26 6.05 2.12 0.35 1881 5.70 2.00 0.35 1964 5.50 1.93 0.35 2013

30 18 4.90 4.26 0.87 1617 4.50 3.92 0.87 1716 4.30 3.74 0.87 1749

30 20 5.15 3.86 0.75 1683 4.80 3.60 0.75 1766 4.60 3.45 0.75 1815

30 22 5.45 3.43 0.63 1749 5.10 3.21 0.63 1848 4.90 3.09 0.63 1881

30 24 5.75 2.93 0.51 1815 5.40 2.75 0.51 1898 5.25 0.79 0.15 1947

30 26 6.05 2.36 0.39 1881 5.70 2.22 0.39 1964 5.50 2.15 0.39 2013

31 18 4.90 4.46 0.91 1617 4.50 4.10 0.91 1716 4.30 3.91 0.91 1749

31 20 5.15 4.07 0.79 1683 4.80 3.79 0.79 1766 4.60 3.63 0.79 1815

31 22 5.45 3.65 0.67 1749 5.10 3.42 0.67 1848 4.90 3.28 0.67 1881

31 24 5.75 3.16 0.55 1815 5.40 2.97 0.55 1898 5.25 0.68 0.13 1947

31 26 6.05 2.60 0.43 1881 5.70 2.45 0.43 1964 5.50 2.37 0.43 2013

32 18 4.90 4.66 0.95 1617 4.50 4.28 0.95 1716 4.30 4.09 0.95 1749

32 20 5.15 4.27 0.83 1683 4.80 3.98 0.83 1766 4.60 3.82 0.83 1815

32 22 5.45 3.87 0.71 1749 5.10 3.62 0.71 1848 4.90 3.48 0.71 1881

32 24 5.75 3.39 0.59 1815 5.40 3.19 0.59 1898 5.25 0.58 0.11 1947

32 26 6.05 2.84 0.47 1881 5.70 2.68 0.47 1964 5.50 2.59 0.47 2013

Q SHC SHF INPUT Q SHC SHF INPUT Q SHC SHF INPUT

35 40 43

NOTE Q : Total capacity (kW) SHF : Sensible heat factor DB : Dry-bulb temperature
SHC : Sensible heat capacity (kW) INPUT : Total power input (W) WB : Wet-bulb temperature

OUTDOOR DB (°C)

15

PERFORMANCE DATA HEAT operation at Rated frequency

MSZ-GB50VA : MUZ-GB50VA

CAPACITY : 5.8 kW INPUT : 1700 W

INDOOR

DB (°C)

15 3.65 1105 4.41 1326 5.16 1496 5.92 1615 6.67 1717 7.37 1768 8.12 1802

21 3.48 1190 4.18 1411 4.93 1564 5.63 1683 6.38 1768 7.08 1819 7.80 1887

26 3.13 1275 3.89 1496 4.58 1649 5.34 1768 6.09 1853 6.79 1904 7.54 1955

-10 -5 0 5 10 15 20

Q INPUT Q INPUT Q INPUT Q INPUT Q INPUT Q INPUT Q INPUT

NOTE Q : Total capacity (kW) INPUT : Total power input (W) DB : Dry-bulb temperature WB : Wet-bulb temperature

OUTDOOR WB (°C)

9

ACTUATOR CONTROL

MUZ-GB50VA

9-1. OUTDOOR FAN MOTOR CONTROL

The fan motor turns ON/OFF, interlocking with the compressor.
[ON] The fan motor turns ON 5 seconds before the compressor starts up.
[OFF] The fan motor turns OFF 15 seconds after the compressor has stopped running.

5 seconds 15 seconds

ON

Compressor

OFF

ON

Outdoor fan
motor

OFF

9-2. R.V. COIL CONTROL

Heating
Cooling

Dry

NOTE: The 4-way valve reverses for 5 seconds right before start-up of the compressor.

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . .

ON
OFF
OFF

<COOL>

5 seconds

<HEAT>

5 seconds

Compressor

R.V.coil

Outdoor fan

motor

ON

OFF

ON

OFF

ON

OFF

ON or OFF

ON or OFF

16

9-3. RELATION BETWEEN MAIN SENSOR AND ACTUATOR

MUZ-GB50VA

Sensor Purpose

Discharge temperature thermistor Protection

Indoor coil temperature thermistor

Defrost thermistor Heating : Defrosting

Fin temperature thermistor Protection

Ambient temperature thermistor

Outdoor heat exchanger tempera­ture thermistor

Cooling : Coil frost prevention

Heating : High pressure protection

Cooling : Low ambient temperature
operation

Cooling : Low ambient temperature
operation

Cooling : High pressure protection

Actuator

Compressor

LEV

Outdoor fan

motor

R.V. coil

Indoor fan

motor

○○
○
○○
○○○○○
○○

○○○
○○○

○○○

10

MUZ-GB50VA-

10-1. CHANGE IN DEFROST SETTING

10-2. PRE-HEAT CONTROL SETTING

SERVICE FUNCTIONS

E3

Changing defrost finish temperature

<JS> To change the defrost finish temperature, cut/solder the JS wire of the outdoor inverter P.C. board.
(Refer to 11-6-4.)

Jumper wire Defrost fi nish temperature (°C)

Soldered

(Initial setting)

JS

PRE-HEAT CONTROL

When moisture gets into the refrigerant cycle, it may interfere the start-up of the compressor at low outside temperature.
The pre-heat control prevents this interference. The pre-heat control turns ON when outside temperature is 20°C or
below. When pre-heat control is turned ON, compressor is energized. (About 50 W)

<JK> To activate the pre-heat control, cut the JK wire of the inverter P.C. board. (Refer to 11-6.4)

NOTE: When the inverter P.C. board is replaced, check the Jumper wires, and cut/solder them if necessary.

None

(Cut)

9

18

17

11

TROUBLESHOOTING

MUZ-GB50VA

11-1. 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, 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 electronic
control P.C. board.

3) When removing the electrical parts, be careful to the residual voltage of smoothing capacitor.

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

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

Lead wiring

3. Troubleshooting procedure

1) First, check if the OPERATION INDICATOR lamp on the indoor unit is flashing on and off to indicate an abnormality.
To make sure, check how many times the abnormality indication is flashing on and off before starting service work.

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

3) 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 11-2. and 11-3.

Housing point

1818

11-2. 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 (11-3.) disappears, the memorized failure details
can be recalled.
This mode is very useful when the unit needs to be repaired for the abnormality which doesn't recur.

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

Operational procedure

The cause of abnormality cannot be found because the abnormality doesn't 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.

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

remote controller is displayed after 3 seconds.

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

Does the 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 emit-

ted at the same timing as the blinking of the left lamp
of OPERATION INDICATOR lamp. 2

Yes

Judgment of indoor/outdoor abnormality

Releasing the failure mode recall function

Deleting the memorized abnormal condition

NOTE: 1. Make sure to release the failure mode recall function once it's 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.

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

The indoor unit is abnormal.
Check the blinking pattern, and confi rm the abnormal point with the indoor unit
failure mode table. (Refer to indoor unit service manual.)
Make sure to check at least two consecutive blinking cycles.

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

Repair the defective parts.

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

function" mentioned above.

Press OPERATE/STOP (ON/OFF) button of the remote controller (the set temperature is displayed)

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

mentioned above.

(Blinks)

No

1

1. Regardless of normal or abnormal condition, a short

Indoor unit is normal.
But the outdoor unit might be abnormal because there are some abnor-

No
(OFF)

Yes

2

malities that can't be recalled with this way.
Confi rm if outdoor unit is abnormal according to the detailed outdoor
unit failure mode recall function. (Refer to 11-2.2)

The outdoor unit is abnormal.
Check the blinking pattern, and confi rm the abnormal point with the
outdoor unit failure mode table. (Refer to 11-2.3)
Make sure to check at least two consecutive blinking cycles.

beep is emitted once the signal is received.

2. Blinking pattern when the indoor unit is abnormal:

2.5-second OFF

Blinking at 0.5-

second interval

2.5-second OFF

Blinking at 0.5­second interval

ON

OFF

Repeated cycle Repeated cycle

Beeps

3.Blinking pattern when the outdoor unit is abnormal:

2.5-second OFF 3-second ON

Blinking at 0.5­second interval

Beeps

Repeated cycle

2.5-second OFF 3-second ON

ON

OFF

No beep Beeps

Repeated cycle

No beep Beeps

Repeated cycle

3

Beeps

Blinking at 0.5­second interval

Repeated cycle

1919

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

Operational procedure

The outdoor unit might be abnormal.
Confi rm if outdoor unit is abnormal according to the following procedures.

Confi rm that the remote controller is in the failure mode recall function.

With the remote controller headed towards the indoor unit, press TOO
COOL or TOO WARM button to adjust the set temperature to 25°C.

1

1. Regardless of normal or abnormal condition, 2 short
beeps are emitted as the signal is received.

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

at the same timing as the blinking of the left
lamp of OPERATION INDICATOR lamp. 2

Yes

)

(Blinks

No
(OFF)

The outdoor unit is abnormal.
Check the blinking pattern, and confi rm the abnormal point with the out-
door unit failure mode table (11-2.3.).
Make sure to check at least two consecutive blinking cycles.

2

The outdoor unit is normal.

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.

Release the failure mode recall function accord­ing to the left mentioned procedure.

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" (11-2.1.).

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" men-

tioned above.

NOTE: 1. Make sure to release the failure mode recall function once it's 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 outdoor unit is abnormal:

2.5-second OFF 3-second ON

ON

OFF

No beep

Repeated cycle

Blinking at 0.5­second interval

Beeps

2.5-second OFF 3-second ON

No beep Beeps

Repeated cycle

2020

Blinking at 0.5-

second interval

Repeated cycle

3. Outdoor unit failure mode table

E1

E2

MUZ-GB50VA-

The left lamp of
OPERATION INDICATOR
lamp (Indoor unit)

OFF None (Normal) — — — — —

2-time fl ash Outdoor power system Lighting Lighting Overcurrent protection stop is continuously

3-time fl ash Discharge temperature

(Failure mode / protection)

thermistor
Defrost thermistor Lighting Once

/

Abnormal point

LED indication

(Outdoor P.C.

board)

LED1 LED2

performed 3 times within 1 minute after the
compressor gets started, or when converter
protection stop or bus-bar voltage protection
stop is continuously performed 3 times within 3
minutes after start-up.

Lighting Once Thermistor shorts or opens during compressor

running.

Condition Correspondence

• Check the connection of the
compressor connecting wire.

• Refer to 11-5.
check inverter/compressor".

• Check the stop valve.

• Refer to 11-5. "Check of
outdoor thermistors".

"How to

Indoor/

outdoor unit

failure mode

recall function

○

Ambient temperature
thermistor

Fin temperature thermistor Lighting 3 times

P.C. board temperature
thermistor

Outdoor heat exchanger
temperature thermistor

4-time fl ash Overcurrent Once Goes out 28 A current fl ows into intelligent power module. • Reconnect compressor

5-time fl ash Discharge temperature Lighting Lighting Discharge temperature exceeds 116°C during

6-time fl ash High pressure Lighting Lighting The outdoor heat exchanger temperature

7-time fl ash Fin temperature 3 times Goes out The fi n temperature exceeds 87°C during

P.C. board temperature 4 times Goes out The P.C. board temperature exceeds 70°C during

8-time fl ash Outdoor fan motor Lighting Lighting Failure occurs continuously three times within 30

9-time fl ash Nonvolatile memory data Lighting 5 times Nonvolatile memory data cannot be read

10-time fl ash Discharge temperature Lighting Lighting The frequency of the compressor is kept 80 Hz

11-timefl ash Communication error between

P.C. boards

Current sensor Lighting 7 times A short or open circuit is detected in the current

Zero cross detecting circuit 5 times Goes out Zero cross signal cannot be detected while the

Converter 5 times Goes out A failure is detected in the operation of the

Bus-bar voltage
(1)

Bus-bar voltage
(2)

Even if this protection stop

is performed continuously 3
times, it does not mean the
abnormality in outdoor power
system.

Lighting Twice

Lighting 4 times • Replace the outdoor

Lighting 9 times • Refer to 11-5.

operation. Compressor can restart if discharge
temperature thermistor reads 100°C or less 3
minutes later.

exceeds 70°C during cooling or the indoor gas
pipe temperature exceeds 70°C during heating.

operation.

operation.

seconds after the fan gets started.

properly.

or more and the discharge temperature is kept
under 39°C for more than 20 minutes.

Lighting 6 times Communication error occurs between the

5 times Goes out The bus-bar voltage exceeds 400 V or falls to

6 times Goes out The bus-bar voltage exceeds 400 V or falls to 50

electronic control P.C. board and power board for
more than 10 seconds.

The communication between boards protection
stop is continuously performed twice.

sensor during compressor operating.
Current sensor protection stop is continuously

performed twice.

compressor is operating.
The protection stop of the zero cross detecting

circuit is continuously performed 10 times.

converter during operation.

200 V or below during compressor operating.

V or below during compressor operating.

electronic control P.C. board.

outdoor thermistors".

connector.

• Refer to 11-5.
check inverter/ compressor.

• Check the stop valve.

• Check refrigerant circuit and
refrigerant amount.

• Refer to 11-5.
LEV".

• Check refrigerant circuit and
refrigerant amount.

• Check the stop valve.

• Check around outdoor unit.

• Check outdoor unit air
passage.

• Refer to 11-5.
outdoor fan motor".

• Refer to 11-5.
outdoor fan motor".

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

• Check refrigerant circuit and
refrigerant amount.

• Refer to 11-5. "Check of
LEV".

•

Check the connecting wire

between outdoor electronic
control P.C. board and power
board.

•

Replace the power board.

•

Check the connecting wire

among electronic control P.C.
board, noise fi lter P.C. board
and power board.

•

Replace the power board.

"Check of

"How to

"Check of

"Check of

"Check of

NOTE : Blinking patterns of this mode differ from the ones of Troubleshooting check table (11-3.).

○

—

—

—

—

—

○

—

—

○

—

○

—

○

—

2121

MUZ-GB50VA-

The left lamp of
OPERATION INDICATOR
lamp (Indoor unit)

OFF None (Normal) — — — — —

2-time fl ash

2.5 seconds
OFF

3-time fl ash

2.5 seconds
OFF

4-time fl ash

2.5 seconds
OFF

5-time fl ash

2.5 seconds
OFF

(Failure mode / protection)

Outdoor power system

Discharge temperature
thermistor

Defrost thermistor

Fin temperature thermistor 3-time fl ash

P.C. board temperature
thermistor

Ambient temperature
thermistor

Overcurrent 11-time fl ash

Compressor synchronous
abnormality (Compressor start­up failure protection)

Discharge temperature

E3

Abnormal point

LED indication

(Outdoor P.C. board)

—

1-time fl ash every

2.5 seconds

2.5 seconds OFF

4-time fl ash

2.5 seconds OFF

2-time fl ash

2.5 seconds OFF

2.5 seconds OFF

12-time fl ash

2.5 seconds OFF

—

Condition Correspondence

Overcurrent protection stop is
continuously performed 3 times within
1 minute after the compressor gets
started.

Thermistor shorts or opens during
compressor running.

Large current fl ows into intelligent
power module.

Waveform of compressor current is
distorted.

Temperature of discharge temperature
thermistor exceeds 116°C, compressor
stops.
Compressor can restart if discharge
temperature thermistor reads 100°C or
less 3 minutes later.

Reconnect connectors.

•
Refer to 11-5. "How

•
to check inverter/
compressor".
Check stop valve.

•

Refer to 11-5. "Check

•
of outdoor thermistors".
Defective outdoor
thermistors can be
identifi ed by checking
the blinking pattern of
LED.

Reconnect compressor

•
connector.
Refer to 11-5. "How

•
to check inverter/
compressor".
Check stop valve.

•

Reconnect compressor

•
connector.
Refer to 11-5. "How

•
to check inverter/
compressor".

Check refrigerant circuit

•
and refrigerant amount.
Refer to 11-5. "Check

•
of LEV".

Indoor/outdoor

unit failure

mode recall

function

Outdoor unit
failure mode

recall function

○○

○○

—

—

—

○

○

○

6-time fl ash

2.5 seconds
OFF

7-time fl ash

2.5 seconds
OFF

8-time fl ash

2.5 seconds
OFF

9-time fl ash

2.5 seconds
OFF

10-time fl ash

2.5 seconds
OFF

11-time fl ash

2.5 seconds
OFF

12-time fl ash

2.5 seconds
OFF

14-time fl ash

2.5 seconds
OFF

High pressure

—

Fin temperature/ P.C. board
temperature

Outdoor fan motor

Nonvolatile memory data 5-time fl ash

Discharge temperature

DC voltage 8-time fl ash

Each phase current of
compressor

Overcurrent Compressor open­phase

Stop valve (Closed valve) 14-time fl ash

7-time fl ash

2.5 seconds OFF

—

2.5 seconds OFF

—

2.5 seconds OFF

9-time fl ash

2.5 seconds OFF

10-time fl ash

2.5 seconds OFF

2.5 seconds OFF

Temperature indoor coil thermistor
exceeds 70°C in HEAT mode.
Temperature defrost thermistor
exceeds 70°C in COOL mode.

Temperature of fi n temperature
thermistor on the inverter P.C. board
exceeds 75 ~ 80°C, or temperature of
P.C. board temperature thermistor on
the inverter P.C. board exceeds 70 ~
75°C.

Outdoor fan has stopped 3 times in a
row within 30 seconds after outdoor
fan start-up.

Nonvolatile memory data cannot be
read properly.

Temperature of discharge temperature
thermistor has been 50°C or less for 20
minutes.

DC voltage of inverter cannot be
detected normally.

Each phase current of compressor
cannot be detected normally.

Large current fl ows into intelligent
power module (IPM).
The open-phase operation of
compressor is detected.
The interphase short out occurs in the
output of the intelligent power module
(IPM).
The compressor winding shorts out.

Closed valve is detected by
compressor current.

Check refrigerant circuit

•
and refrigerant amount.
Check stop valve.

•

Check around outdoor

•
unit.
Check outdoor unit air

•
passage.
Refer to 11-5. "Check

•
of outdoor fan motor".

Refer to 11-5. "Check

•
of outdoor fan motor".
Refer to 11-5. "Check
of inverter P.C. board".

Replace the inverter

•
P.C. board.

Refer to 11-5. "Check

•
of LEV".
Check refrigerant circuit

• —
and refrigerant amount.

Refer to 11-5. "How

•
to check inverter/
compressor".

Reconnect compressor

•
connector.
Refer to 11-5. "How

•
to check inverter/
compressor".

Check stop valve •

NOTE: Blinking patterns of this mode differ from the ones of Troubleshooting check table (11-3.).

—

—

—

○

○

○

○○

○

—

—

○

○

○○

2222

11-3. TROUBLESHOOTING CHECK TABLE

E1

E2

MUZ-GB50VA-

No. Symptom

Outdoor unit
does not oper­ate.

1

2

3

4

5

6

7

8

LED1(Red)

Lightning

Lightning

Lightning

Lightning

Lightning

Lightning

Lightning

Lightning

/

LED indication

LED2(Yellow)

Twice

3 times

4 times

5 times

6 times

7 times

8 times

11 times

Abnormal point/ Con-

dition

Outdoor power system

Discharge temperature
thermistor

Fin temperature
thermistor

P.C. board tempera­ture thermistor

Ambient temperature
thermistor

Outdoor heat exchanger
temperature thermistor

Defrost thermistor A short circuit is detected in the thermistor during operation, or

Serial signal The communication fails between the indoor and outdoor unit 3

Nonvolatile memory
data

Current sensor Current sensor protection stop is continuously performed twice. • Replace the power board.

Communication error
between P.C. boards

Condition Correspondence

Overcurrent protection stop is continuously performed 3 times
within 1 minute after the compressor gets started, or when
converter protection stop or bus-bar voltage protection stop is
continuously performed three times within 3 minutes after start­up.

A short circuit is detected in the thermistor during operation, or
when an open circuit is detected in the thermistor after 10 min­utes of compressor start-up.

A short or open circuit is detected in the thermistor during op­eration.

A short or open circuit is detected in the thermistor during op­eration.

A short circuit is detected in the thermistor during operation, or
an open circuit is detected in the thermistor after 5 minutes (in
cooling) and 10 minutes (in heating) of compressor start-up.

an open circuit is detected in the thermistor after 5 minutes of
compressor stat-up.

minutes.
The nonvolatile memory data cannot be read properly. • Replace the outdoor electronic

The communication protection stop between boards is continu­ously performed twice.

• Check the connection of the com­pressor connecting wire.

• Refer to 11-5. "How to check in­verter/compressor".

• Check the stop valve.

• Refer to 11-5. "Check of outdoor
thermistor".

• Refer to 11-5.
thermistor".

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

• Refer to 11-5. "Check of outdoor
thermistor".

• Refer to 11-5. "How to check
miswiring and serial signal error.

control P.C. board.

• Check the connecting wire be­tween outdoor electronic control
P.C. board and power board.

"Check of outdoor

Zero cross detecting

9

’Outdoor unit
stops and
restarts 3 min­utes later’ is

10

repeated.

11 3 times Goes out

12 4 times Goes out

13 5 times Goes out

14 8 times Goes out

15 9 times Goes out

16 13 times Goes out

17 Lighting 8 times

18 Lighting 11 times

19 Lighting 12 times

NOTE: 1. The location of LED is illustrated at the right fi gure. Refer to 10-6.3.

2. LED is lighted during normal operation.

The fl ashing frequency shows the number of times the LED blinks after every 2.5-second OFF.
(Example) When the fl ashing frequency is “2”.

Lightning

12 times

Twice Goes out

circuit

lPM protection Overcurrent is detected after 30 minutes of compressor start-

Lock protection Overcurrent is detected within 30 minutes of compressor start-

Discharge tempera­ture protection

Fin temperature pro­tection

P.C. board temperature
protection

High-Pressure pro­tection

Converter protection A failure is detected in the operation of the converter during

Bus-bar voltage pro­tection (1).

Bus-bar voltage pro­tection (2)

Outdoor fan motor Failure occurs continuously three times within 30 seconds after

Current sensor pro­tection

Communication be­tween P.C. boards
protection

Zero cross detecting
circuit protection

The protection stop of the zero cross detecting circuit is con­tinuously performed 10 times.

up.

up.

Discharge temperature exceeds 116°C during operation and
compressor stops. Compressor can restart if discharge tem­perature thermistor reads 100°C or less 3 minutes later.

The fi n temperature exceeds 87°C during operation. • Check around outdoor unit.

The P.C. board temperature exceeds 70°C during operation.

The outdoor heat exchanger temperature exceeds 70°C during
cooling or indoor gas pipe temperature exceeds 70°C during
heating.

operation.
The bus-bar voltage exceeds 400 V or falls to 200 V or below

during compressor operating.
The bus-bar voltage exceeds 400 V or falls to 50 V or below

during compressor operating.

the fan gets started.
A short or open circuit is detected in the current sensor during

compressor operating.
Communication error occurs between the outdoor electronic

control P.C. board and power board for more than 10 seconds

Zero cross signal cannot be detected while the compressor is
operating.

• Check the connecting wire among
outdoor electronic control P.C.
board, noise fi lter P.C. board and
power board.

• Reconnect compressor connector.

• Refer to 11-5.
verter/compressor".

• Check the stop valve.

• Check the power module (PAM
module).

• Check the amount of gas and re­frigerant circuit.

• Refer to 11-5.

• Check outdoor unit air passage.

• Refer to 11-5.
fan motor".

• Check the amount of gas and the
refrigerant circuit.

• Check the stop valve.

• Replace the power board.

• Replace the power board.

• Refer to 11-5. "Check of outdoor
fan motor".

• Replace the power board.

• Check the connecting wire be­tween outdoor electronic control
P.C. board and power board.

• Check the connecting wire among
outdoor electronic control P.C.
board, noise fi lter P.C. board and
power board.

"How to check in-

"Check of LEV".

"Check of outdoor

Outdoor electronic control P.C. board (Parts side)

LED1

LED2

Lighting

ON

OFF

2.5-second OFF

0.5-second ON

2.5-second OFF

23

0.5-second ON

No. Symptom

Outdoor unit
operates.

20

21

22

23

LED indication

LED1(Red)

Once

Twice

3 times

4 times

Abnormal point/ Con-

LED2(Yellow)

Primary current pro­tection

Lighting

Secondary current pro­tection

High-Pressure protec­tion

Lighting

Defrosting in cooling

Discharge temperature
protection

Lighting

Low discharge tem­perature protection

Lighting

dition

Condition Correspondence

The input current exceeds 15 A. These symptoms do not mean any

The current of the compressor exceeds 15 A.

The indoor gas pipe temperature exceeds 45°C during heating.

The indoor gas pipe temperature falls 3°C or below during
cooling.

The discharge temperature exceeds 100°C during operation. • Check refrigerant circuit and refrig-

The frequency of the compressor is kept 80 Hz or more and
the discharge temperature is kept under 39°C for more than 20
minutes.

abnormality of the product, but
check the following points.

• Check if indoor fi lters are clogged.

• Check if refrigerant is short.

• Check if indoor/outdoor unit aircir­culation is short cycled.

erant amount.

• Refer to 11-5. "Check of LEV".

• Refer to 11-5. "Check of outdoor
thermistors’’.

• Refer to 11-5. "Check of LEV".

• Check refrigerant circuit and refrig­erant amount.

24

Outdoor unit

25

operates

26

5 times

9 times

Lighting

Cooling high-pressure
protection

Lighting

Inverter check mode The unit is operated with emergency operation switch.

Lighting

Normal

Lighting

The outdoor heat exchanger temperature exceeds 58°C during
operation.

——

This symptom does not mean any
abnormality of the product, but
check the following points.

• Check if indoor fi lters are clogged.

• Check if refrigerant is short.

• Check if indoor/outdoor unit air cir­culation is short cycled.

—

24

MUZ-GB50VA-

No. Symptom LED indication

Outdoor unit
does not oper-

1

ate.

2

3

4

5

6

'Outdoor unit
stops and

7

restarts 3 min­utes later' is
repeated.

8

9

10

11

12

13

14

Outdoor unit

15

operates.

16

17

Outdoor unit
operates.

18

E3

1-time fl ash every

2.5 seconds

6-time fl ash

2.5 seconds OFF
11-time fl ash

2.5 seconds OFF
14-time fl ash

2.5 seconds OFF

2-time fl ash

2.5 seconds OFF

3-time fl ash

2.5 seconds OFF

4-time fl ash

2.5 seconds OFF

5-time fl ash

2.5 seconds OFF

8-time fl ash

2.5 seconds OFF

10-time fl ash

2.5 seconds OFF

12-time fl ash

2.5 seconds OFF
13-time fl ash

2.5 seconds OFF
1-time fl ash

2.5 seconds OFF
3-time fl ash

2.5 seconds OFF

4-time fl ash

2.5 seconds OFF

7-time fl ash

2.5 seconds OFF

Abnormal point/ Con-

dition

Outdoor power sys­tem

Outdoor thermistors Discharge temperature thermistor, fi n temperature thermistor,

Outdoor control sys­tem

Serial signal The communication fails between the indoor and outdoor unit

Stop valve/
Closed valve

Outdoor unit
(Other abnormality)

Overcurrent protec­tion

Discharge tempera­ture overheat protec­tion

Fin temperature /P.C.
board temperature
thermistor overheat
protection

High pressure protec­tion

Compressor synchro­nous abnormality

Outdoor fan motor Outdoor fan has stopped 3 times in a row within 30 seconds

Each phase current
of compressor

DC voltage DC voltage of inverter cannot be detected normally. Refer to 11-5. "How to check in-

Frequency drop by
current protection

Frequency drop by
high pressure protec­tion

Frequency drop by
defrosting in COOL
mode

Frequency drop by
discharge tempera­ture protection

Low discharge tem­perature protection

Overcurrent protection stop is continuously performed 3 times
within 1 minute after the compressor gets started, or failure of
restart of compressor has repeated 24 times.

defrost thermistor, P.C. board temperature thermistor or ambi­ent temperature thermistor shorts or opens during compressor
running.

Nonvolatile memory data cannot be read properly.

(The left lamp of OPERATION INDICATOR lamp of the indoor
unit lights up or fl ashes 7-time.)

for 3 minutes.
Closed valve is detected by compressor current. Check stop valve. •

Outdoor unit is defective. Refer to 11-2.2. "Flow chart of the

Large current fl ows into intelligent power module, or compres-
sor repeats after 15 seconds when overcurrent protection oc­curs within 10 seconds after compressor starts.
(Repeated 24 times at Maximum)

Temperature of discharge temperature thermistor exceeds 116
°C, compressor stops. Compressor can restart if discharge
temperature thermistor reads 100°C or less 3 minutes later.

Temperature of fi n temperature thermistor on the heat sink
exceeds 75 ~ 80°C or temperature of P.C. board temperature
thermistor on the inverter P.C.board exceeds 70 ~ 75°C.

Indoor coil thermistor exceeds 70°C in HEAT mode. Defrost
thermistor exceeds 70°C in COOL mode.

The waveform of compressor current is distorted. Reconnect connector of compres-

after outdoor fan start-up.

Each phase current of compressor cannot be detected nor­mally

Current from power outlet reaches the protection current, and
compressor frequency lowers.

Temperature of indoor coil thermistor exceeds 55°C in HEAT
mode, compressor frequency lowers.

Indoor coil thermistor reads 8°C or less in COOL mode, com­pressor frequency lowers.

Temperature of discharge temperature thermistor exceeds 111
°C, compressor frequency lowers.

Temperature of discharge temperature thermistor has been 50
°C or less for 20 minutes.

Condition Correspondence

Reconnect connector of compres-

•
sor.
Refer to 11-5. "How to check in-

•
verter/ compressor".
Check stop valve.

•
Refer to 11-5. "Check of outdoor

•
thermistors".

Replace inverter P.C. board. •

Refer to 11-5. "How to check mis-

•
wiring and serial signal error.

•
detailed outdoor unit failure mode
recall function".

Reconnect connector of compres-

•
sor.
Refer to 11-5. "How to check in-

•
verter/compressor".
Check stop valve.

•
Check refrigerant circuit and refrig-

•
erant amount.
Refer to 11-5. "Check of LEV".

•

Check around outdoor unit.

•
Check outdoor unit air passage.

•
Refer to 11-5. "Check of outdoor

•
fan motor".

Check refrigerant circuit and refrig-

•
erant amount.
Check stop valve.

•

•
sor.
Refer to 11-5. "How to check in-

•
verter/compressor".

Refer to 11-5. "Check of outdoor

•
fan motor.
Refer to 11-5. "Check of inverter

•
P.C. board.

Refer to 11-5. "How to check in-

•
verter/compressor".

•
verter/compressor".

The unit is normal, but check the
following.
Check if indoor fi lters are clogged.

•
Check if refrigerant is short.

•
Check if indoor/outdoor unit air cir-

•
culation is short cycled.

Check refrigerant circuit and refrig-

•
erant amount.
Refer to 11-5.

•
Refer to 11-5. "Check of outdoor

•
thermistors".

Refer to 11-5. "Check of LEV".

•
Check refrigerant circuit and refrig-

•
erant amount.

"Check of LEV".

8-time fl ash

2.5 seconds OFF

19

9-time fl ash

20

NOTE: 1. The location of LED is illustrated at the right fi gure. Refer to 11-6.1.

2. LED is lighted during normal operation.

The fl ashing frequency shows the number of times the LED blinks after every 2.5-second OFF.
(Example) When the fl ashing frequency is “2”.

ON

2.5-second OFF

OFF

2.5 seconds OFF

PAM protection PAM:
Pulse Amplitude
Modulation

Inverter check mode The connector of compressor is disconnected, inverter check

0.5-second ON

2.5-second OFF

The overcurrent fl ows into IGBT (Insulated Gate Bipolar tran-
sistor : TR821) or when the bus-bar voltage reaches 320 V or
more, PAM stops and restarts.

mode starts.

25

0.5-second ON

This is not malfunction. PAM protec­tion will be activated in the following
cases;
1 Instantaneous power voltage drop
(Short time power failure)
2 When the power supply voltage is
high.

Check if the connector of the com-

•
pressor is correctly connected.
Refer to 11-5. "How to check in­verter/ compressor".

Inverter P.C. board(Parts side)

LED

Flashing →

11-4. TROUBLE CRITERION OF MAIN PARTS

MUZ-GB50VA

Part name Check method and criterion Figure

Defrost thermistor (RT61)

Ambient temperature
thermistor (RT65)

Outdoor heat exchanger tem­perature thermistor
(RT68)

Discharge temperature
thermistor
(RT62)

Fin temperature
thermistor (RT64)

Compressor

Outdoor fan motor

Measure the resistance with a tester.

Refer to 11-6. "Test point diagram and voltage", 1. "Outdoor electronic

con-

trol P.C. board” or 4. "Inverter P.C. board", the chart of thermistor.

Measure the resistance with a tester.
Before measurement, hold the thermistor with your hands to warm it up.

Refer to 11-6. "Test point diagram and voltage", 1. "Outdoor electronic

con-

trol P.C. board" or 4. "Inverter P.C. board", the chart of thermistor.

Measure the resistance between terminals using a tester.
(Winding temperature : -10 ~ 40°C)

Normal

E1 E2 E3

0.40 ~ 0.49 Ω 0.86 ~ 1.06 Ω

Measure the resistance between lead wires using a tester.
(Part temperature : -10 ~ 40°C)

Color of lead wire Normal

RED – BLK

13.4 ~ 16.4 ΩBLK – WHT

WHT – RED

V

WHT

W

RED

U

BLK

RED

(W)

U

WHT

(V)

V

BLK

(U)

W

R. V. coil

Linear expansion valve

Measure the resistance using a tester.
(Part temperature : -10 ~ 40°C)

Normal

E1 E2 E3

2.6 ~ 3.3 kΩ 01.32 ~ 1.62 Ω

Measure the resistance using a tester.
(Part temperature : -10 ~ 40°C)

Color of lead wire Normal

WHT – RED
RED – ORN
YLW – BRN

37.4 ~ 53.9 Ω

BRN – BLU

WHT

RED

ORN

YLW

LEV

BRN

BLU

2626

11-5. TROUBLESHOOTING FLOW

A How to check inverter/compressor

E1

E2

MUZ-GB50VA-

Disconnect the terminal of the compressor. 3 minutes after turn­ing on the power supply, start EMERGENCY OPERATION.

Measure the voltage between each lead wire lead­ing to the compressor.
U (BLK) - V (WHT)
V (WHT) - W (RED)
W (RED) - U (BLK)
Is voltage output on right table?

Is output balanced?

Is the input voltage to the outdoor electronic control
P.C. board 370 V or more?

Turn off power supply of indoor and outdoor unit, and
measure the compressor winding resistance between
the compressor terminals.
Is the resistance between each terminal normal?

/

Yes

Yes

Yes

Yes

After the outdoor fan starts running, wait for 1 minute or more before

•
measuring the voltage.
The output voltage values have the tolerance of ±20%.

•

No

No

Replace the power board.

No

No

Replace the compressor.

Reconnect the lead wire of compressor, and turn on power
supply to indoor and outdoor unit.
3 minutes later, starts EMERGENCY OPERATION.

Clarify the causes by counting time until the inverter stops.
0 to 10 seconds: compressor rare short
10 to 60 seconds : compressor lock
60 seconds to 5 minutes: refrigerant circuit defective
5 minutes or more: normal

MUZ-GB50VA-

E3

Disconnect the connector (CN61) between
compressor and the intelligent power module
(IPM).

Check the voltage between terminals.

Are the voltages balanced?

Yes

Check the compressor.

No

See 11-5. “Check of open phase”.

Replace the inverter P.C. board.

See 11-5. “Check of compressor”.

2727

B Check of open phase

MUZ-GB50VA-

● With the connector between the compressor and the intelligent power module disconnected, activate the inverter and check if

the inverter is normal by measuring the balance of voltage between the terminals.

The output voltage values have the tolerance of ±20%.

<< Operation method>>
Start cooling or heating operation by pressing EMERGENCY OPERATION switch on the indoor unit. (TEST RUN OPERATION

: Refer to 8-3.)
<<Measurement point>>
at 3 points
BLK (U) - WHT (V)
BLK (U) - RED (W)
WHT (V) - RED (W)

NOTE: 1. Output voltage varies according to power supply voltage.

2. Measure the voltage by analog type tester.

3. During this check, LED of the inverter P.C. board fl ashes 9 times. (Refer to 11-6.4.)

E3

Measure AC voltage between the
lead wires at 3 points.

9-time flash

2.5-second OFF

C Check of compressor

MUZ-GB50VA-

Refer to 11-5. “Check of compressor
winding”.
Is the compressor normal?

E3

No

Yes

Replace the compressor.

Refer to 11-5. “Check of compressor
operation time”.
Does the compressor operate continuously?

Yes

OK.

No

Refer to 11-5. “Check of compressor start failure”.

D Check of compressor winding

MUZ-GB50VA-

● Disconnect the connector (CN61) between the compressor and intelligent power module, and measure the resistance be-

tween the compressor terminals.
<<Measurement point>>
at 3 points
BLK-WHT
BLK-RED
WHT-RED
<<Judgement>>
Refer to 11-4.
0 [Ω] ················Abnormal [short]
Infinite [Ω] ·······Abnormal [open]
NOTE: Be sure to zero the ohmmeter before measurement.

E3

Measure the resistance between the lead wires at 3 points.

28

E Check of compressor operation time

MUZ-GB50VA-

●Connect the compressor and activate the inverter. Then measure

the time until the inverter stops due to over current.
<<Operation method>>
Start heating or cooling operation by pressing EMERGENCY

OPERATION switch on the indoor unit.
(TEST RUN OPERATION : Refer to 8-3.)
<<Measurement>>
Measure the time from the start of compressor to the stop of

compressor due to overcurrent.

E3

F Check of compressor start failure

<<Judgement>>

0 second

1 second

2 seconds

10 seconds

10 minutes

Compressor starts

Abnormal
(IPM failure)
(Compressor winding short)

Abnormal
(Compressor lock out)
(Starting defect)

Abnormal
(Poor contact,)
(Outdoor P.C. board defect)
(Disconnected connector)

Abnormal
(Refrigerant circuit defect)
(Closed valve)

Normal

MUZ-GB50VA-

E3

Confi rm that 1~4 is normal.

•Electrical circuit check
Contact of the compressor connector (including CN61)

1.
Output voltage of inverter P.C. board and balance of them (See 11-5. )

2.
Direct current voltage between DB61(+) and (-) on the inverter P.C.board

3.
Voltage between outdoor terminal block S1-S2

4.

Does the compressor run for 10 seconds or
more after it starts?

Yes

Check the refrigerant circuit.
Check the stop valve.

No

After the compressor is heated with a drier,
does the compressor start? 1

No

Replace the compressor.

Yes

Compressor start failure. Activate pre-heat control.
(Refer to 10-2. "PRE-HEAT CONTROL SETTING")

1
Heat the compressor with
a drier for about 20 minutes.
Do not recover refrigerant
gas while heating.

Heating part

29

G Check of outdoor thermistors

Disconnect the connector of thermistor in the outdoor P.C. board (see
below table), and measure the resistance of thermistor.

Is the thermistor normal? (Refer to 11-6.1.
or 4.)

Yes

Reconnect the connector of thermistor.
Turn ON the power supply and press EMERGENCY OPERATION switch.

Does the unit operate for 10 minutes or more
without showing thermistor abnormality?

Yes

OK.
(Cause is poor contact.)

E1

E2

MUZ-GB50VA-

Thermistor Symbol Connector, Pin No. Board
Defrost RT61 Between CN661 pin 1 and pin 2
Discharge temperature RT62 Between CN661 pin 3 and pin 4
Outdoor heat exchanger temperature RT68 Between CN661 pin 7 and pin 8
Ambient temperature RT65 Between CN663 pin 1 and pin 2
Fin temperature RT64 Between CN3 pin 1 and pin 2 Outdoor power board

MUZ-GB50VA-

Thermistor Symbol Connector, Pin No. Board
Defrost RT61 Between CN641 pin1 and pin2
Discharge temperature RT62 Between CN641 pin3 and pin4
Fin temperature RT64 Between CN642 pin1 and pin2
Ambient temperature RT65 Between CN643 pin1 and pin2
Outdoor heat exchanger temperature RT68 Between CN644 pin1 and pin3

/

E3

No

No

Replace the thermistor except RT64.
When RT64 is abnormal, replace the inverter P.C.
board or the outdoor power board.

Replace the inverter P.C. board
or the outdoor power board.

Outdoor electronic control P.C. board

Inverter P.C. board

H Check of R.V. coil

E1

E2

MUZ-GB50VA-

Heating operation does not work.•

Disconnect the lead wire leading to the compressor.

1.
3 minutes after turning on the power supply, start EMERGENCY

2.
OPERATION in HEAT mode.

Is there voltage of 230 VAC between pin1 and
pin 2 at connector CN912?

Yes

Turn OFF power supply of indoor and outdoor unit.

Disconnect the connec­tor CN912 in noise fi lter
P.C. board. Is there normal
resistance to R.V. coil?

Yes

Replace the 4-way valve.

/

No

Replace the R.V. coil.

No

Turn off power supply of indoor and outdoor unit, and discon-

1.
nect the connector CN781 in the outdoor electronic control P.C.
board.
3 minutes after turning ON the power supply, start EMER-

2

.

GENCY OPERATION in HEAT mode.

Is there voltage 12 VDC be­tween the connector CN781
pin 5 (+) and pin 3 (-)?

Yes

Replace the noise fi lter P.C. board.

30

Replace the outdoor
electronic control P.C.

No

board.

Cooling operation does not work.•

Disconnect the lead wire leading to the compressor.

1.
3 minutes after turning on the power supply, start EMERGENCY

2.
OPERATION in COOL mode.

Is there voltage of 230 VAC between pin1 and
pin 2 at connector CN912?

Turn OFF power supply of indoor and outdoor unit, and

1.
disconnect the connector CN781 in the outdoor electronic
control P.C. board.

.

3 minutes after turning ON the power supply, start EMER-

2

GENCY OPERATION in COOL mode.

Is there voltage 12 VDC between the connector
CN781 pin 5 (+) and pin 3 (-)?

Yes

Replace the outdoor electronic control P.C. board.

MUZ-GB50VA-

First of all, measure the resistance of R.V. coil to check if the coil is defective. Refer to 11-4.
In case CN721 is not connected or R.V. coil is open, voltage is generated between the terminal pins of the connector

although any signal is not being transmitted to R.V. coil.

Check if CN721 is connected.

E3

No

No

Replace the 4-way valve.

Replace the noise fi lter P.C. board.

If the connector CN912 is not connected or

R.V. coil is open, voltage occurs between
terminals even when the control is OFF.

Unit operates COOL mode even if it is set to HEAT mode.

Disconnect connector (CN61)
between the compressor and the
intelligent power module.
Turn ON the power supply and press
EMERGENCY OPERATION switch
twice (HEAT mode).

Is there 230 VAC between CN721 and

on the inverter P.C. board 3 minutes

after the power supply is turned ON?

Replace the 4-way valve.

Unit operates HEAT mode even if it is set to COOL mode.

Disconnect connector (CN61)
between the compressor and the
intelligent power module.
Turn ON the power supply and
press EMERGENCY OPERATION
switch once (COOL mode).

Is there 230 VAC between CN721 and

on the inverter P.C. board 3 minutes

after the power supply is turned ON?

Replace the 4-way valve.

Yes

No

Replace the inverter

No

P.C. board.

Replace the inverter

Yes

P.C. board.

31

I Check of outdoor fan motor

Check the connection between the
connector CN931 and CN932.

Is the resistance between each ter­minal of outdoor fan motor normal?
(Refer to 11-4.)

No

Yes

Disconnect CN932 from outdoor electronic control P.C. board or
the inverter P.C. board, and turn on the power supply.

Rotate the outdoor fan motor manually and measure the voltage
of CN931.
Between 1(+) and 5(-)
Between 2(+) and 5(-)
Between 3(+) and 5(-)

(Fixed to either 5 or 0 VDC)

Replace the outdoor fan motor.

Does the voltage between each terminal become 5 and 0

No

VDC repeatedly?

Yes

Does the outdoor fan motor rotate smoothly?

No

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

Yes

3232

J Check of power supply

E1

E2

MUZ-GB50VA-

Check the connecting of parts of main power
supply circuit.

Turn ON power supply.

/

Is there voltage of 230 VAC in the power sup­ply terminal block?

Yes

Is the output voltage from the noise fi lter P.C.
board 230 VAC?

Yes

Is the input voltage to the power board 230
VAC?

Yes

Is the input voltage to the outdoor electronic
control P.C. board 325 VDC?

Yes

Replace the outdoor electronic control P.C. board.

MUZ-GB50VA-

Disconnect the connector (CN61)
between compressor and intelligent
power module.
Turn ON power supply and press
EMERGENCY OPERATION switch.

E3

No

No

No

No

Check the power supply cable.

Is fuse (F64) blown?

Replace the fuse.

Replace the reactor.

Replace the power board.

Rectify indoor/outdoor
connecting wire.

Yes

No

Replace the noise fi lter
P.C. board.

Does the left lamp of OPERATION
INDICATOR lamp on the indoor unit
light up?

Yes

Is there voltage 280 - 370 VDC
between DB61 (+) and DB61 (–) on
the inverter P.C. board? (Refer to
11-6.4.)

No

Check the electric parts in main circuit.

No

Yes

Yes

Is there voltage 230 VAC
between the indoor terminal
block S1 and S2?

Dose LED on the inverter P.C.
board light up or fl ash? (Refer
to 11-6.4.)

Yes

If light up, OK.
If fl ash, refer to 11-3.

33

Replace the indoor
electronic control P.C.

No

board.

Replace the inverter

No

P.C. board.

DB61

Inverter P.C. board
(Solder side)

280 - 370 VDC

K Check of LEV

E1

E2

MUZ-GB50VA-

Turn ON power supply to the outdoor unit after checking
LEV coil is mounted to the LEV body securely.

/

Is "click - click" sound heard?
Or, do you feel vibration of the LEV coil with a hand?

No

Disconnect the connector CN795.
Is there normal resistance to LEV coil?

No

Replace the LEV coil.

MUZ-GB50VA-

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.

And release the other two buttons after all LCD except

the set temperature in operation display section of the
remote controller is displayed after 3 seconds.

Press OPERATE/STOP (ON/OFF) button of the remote
controller (the set temperature is displayed) with the
remote controller headed towards the indoor unit. 1

E3

Yes

Yes

Normal

Replace the outdoor electronic control P.C. board.

Expansion valve operates in full-opening direction.

Do you hear the expansion valve "click,
click·······"?
Do you feel the expansion valve vibrate
on touching it ?

No

Is LEV coil properly fi xed to
the expansion valve?

Yes

Does the resistance of LEV
coil have the characteristics?
(Refer to 11-4.)

No

Replace the LEV coil.

NOTE : After check of LEV, do the undermentioned operations.

1. Turn OFF the power supply and turn ON it again.

2. Press RESET button on the remote controller.

No

Yes

Properly fi x the LEV coil to the expansion valve.

Measure each voltage between connector
pins of CN724 on the inverter P.C. board.

1. Pin (-) — Pin (+)

2. Pin (-) — Pin (+)

3. Pin (-) — Pin (+)

4. Pin (-) — Pin (+)
Is there about 3 ~ 5 VAC between each?
NOTE: Measure the voltage by an analog

OK

Yes

tester.

Replace the expansion valve.

1. Regardless of normal or abnormal condition, a short beep
is emitted once the signal is received.

Replace the inverter P.C.

No

board.

Yes

34

L Check of inverter P.C. board

MUZ-GB50VA-

Check the outdoor fan motor.
(Refer to 11-5. .)

Is the fuse (F901) blown on the in­verter P.C. board?

Check the connection of the connectors
(CN931, CN932) of the outdoor fan mo­tor.
If the connection is poor, make it correct.

Operate the outdoor unit by starting
EMERGENCY OPERATION.

Check the LED indication on the in­verter P.C. board.
Does the LED fl ash 10 times?

E3

No

Yes
(10-time fl ash)

Yes

No

Check the corresponding parts
following LED indication.
(Refer to 11-3.)

Replace the inverter P.C. board.

35

M How to check miswiring and serial signal error

Turn OFF the power supply.

Is there rated voltage in the
power supply?

Turn ON the power supply.

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

Press EMERGENCY OPERATION switch once.

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

Is serial signal error indicated 6 minutes later?

Turn OFF the power supply.
Check once more if the indoor/outdoor

B

connecting wire is not miswiring.
Short-circuit outdoor terminal block S2
and S3.

Turn ON the power supply.

Yes

Yes

Yes

Yes

A

1

No

Check the power supply.

No

No

No

1. Miswiring may damage indoor electronic control P.C. board
during the operation.

Be sure to confi rm the wiring is correct before the operation

starts.

3. Be sure to check this within 3 minutes after turning ON. After
3 minutes, LED blinks 6 times. Even when the inverter P.C.
board or the outdoor electronic control P.C. board is normal,
LED blinks 6 times after 3 minutes.

Check the wiring.

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

No

Yes

Correct them.

A

Turn OFF inverter-controlled lighting

•
equipment.
Turn OFF the power supply and then

•
turn ON again.
Press EMERGENCY OPERATION

•
switch.

Reinstall

•
either the unit
or the light
each other

No

•

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

Is serial signal
error indicated 6
minutes later?

Yes

B

Does the LED on the inverter P.C. board or
the outdoor electronic control P.C. board
repeat "3.6-second-OFF and 0.8-second­ON quick blinking"? 3

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

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

Replace the indoor electronic control P.C. board.

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

Yes

Yes

Yes

No
(Lighted
or not
lighted)

No

No

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

2

2. Be careful to the residual voltage of smoothing
capacitor.

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?

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?

No

No

Replace the indoor/
outdoor connecting

Yes

wire.

Replace the indoor/
outdoor connecting

Yes

wire.

36

36

N Electromagnetic noise enters into TV sets or radios

Is the unit earthed?

Yes

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

No

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

No

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

No

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

No

No

Yes

Yes

Yes

Yes

Earth the unit.

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

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

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

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

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

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

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

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

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

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

6. Presence or absence of amplifi er such as booster

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

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

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

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

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

37

11-6. TEST POINT DIAGRAM AND VOLTAGE

1. Outdoor electronic control P.C. board

E1

E2

MUZ-GB50VA-

Discharge temperature thermistor (RT62)

700

600

500

400

300

200

Resistance (kΩ)

100

0

0 102030405060708090100110120

/

Temperature ( )

(

CN932

20-90 VAC

(

To fan

motor

5 VDC

(

CN931

pulse wave

5 V

GND

CN661

(

Discharge temperature

thermistor (RT62)

Defrost thermistor (RT61)

(

Outdoor heat exchanger

(

(

Fin temperature thermistor (RT64)

200

180

160

140

120

100

80

Resistance (kΩ)

60

40

20

0

0 1020304050607080

CN663

(

(

CN701

Signal transmission

(To power board)

5 VDC pulse wave

(–)

(+)

Ambient temperature

thermistor (RT65)

(

temperature thermistor (RT68)

(+)

Temperature ( )

CN702

Signal reception

(From power board)

5 VDC pulse wave

(–)

15 V

15 V

GND

Defrost thermistor (RT61)
Ambient temperature thermistor (RT65)
Outdoor heat exchanger temperature thermistor (RT68)

100

90

80

70

60

50

Resistance (kΩ)

40

30

20

10

0

-20-100 10203040

(+)

(

LEV

(

(

Temperature ( )

CN795

12 VDC

pulse wave

(–)

(

12 VDC

CN781

(+)

Rush current relay

GND (power board)

(–)R.V. coil

(–)

LED 1

LED 2

CN801

325 ~

370 VDC

Input

F801

FUSE

250 V 3.15 A

CN601

(

230 VAC
Input

(

Serial signal

5~10 VDC

38

2. Noise filter P.C. board

E1

MUZ-GB50VA-

CN912
R.V. coil
230 VAC

{

230 VAC
Output

/

CN901
To electronic
control
P.C. board

{

E2

CN902
To power
board

CN903
To power
board

{

230 VAC
Input

{

230 VAC
Output

NR64 VARISTOR

F64 FUSE
250 V 2 A

F911 FUSE
250 V 1 A

39

3. Outdoor power board

E1

MUZ-GB50VA-

/

E2

Connect to the compressor
Voltage among phases: 5 V to
180 V

325-370 VDC
Output

(+)

(–)

(Red)

1

3

(White)

Connect to the earth

CN2
Connect to the controller board
(+)1-5(–): Signal transmission
(To electronic control P.C. board)
5 VDC pulse wave
(+)2-5(–): Zero cross signal
3-4 : Not used
(+)6-5(–): 15 V
(+)7-5(–): 15 V

CN3
Fin temperature thermistor RT64

Signal reception (From electronic

)

control P.C. board)
5 V DC pulse wave

CN5
Primary current detection
(Connect to the noise filter)

Connect to the compressor
Voltage among phases: 5 V to 180 V

325-370 VDC
Output

(+)

(–)

(Red)

1

3

(White)

40

Connect to the earth

CN2
Connect to the controller board
(+)1-5(–): Signal transmission
(To electronic control P.C. board)
5 V DC pulse wave
(+)2-5(–): Zero cross signal
3-4 : Not used
(+)6-5(–): 15 V
(+)7-5(–): 15 V

CN3
Fin temperature thermistor RT64

Signal reception (From electronic

)

control P.C. board)
5 V DC pulse wave

CN5
Primary current detection
(Connect to the noise filter)

4. Inverter P.C. board

MUZ-GB50VA-

Back side of unit

AC 230 V

Fuse (F901)
250 V 3.15 A

Output to
drive
compressor
(LDU,
LDV,
LDW)

E3

Smoothing

DB61
DC 260 ~300 V

(-)

capacitor
(C63)

(+)

Smoothing
capacitor
(C62)

Fuse (F801)
250 V 3.15 A

Smoothing
capacitor
(C61)

Fuse (F701)
250 V 3.15 A

R.V.coil
(CN721)
230 VAC

AC 230 V

Front side of unit

Fin temperature

thermistor /RT64

(CN642)

Defrost thermistor(RT61)
Ambient temperature thermistor(RT65)
Outdoor heat exchanger temperature thermistor(RT68)

100

90

80

70

60

50

40

30

Resistance(k )

20

10

0

-20 -10 0 10 20 30 40

Temperature( )

Resistance(k )

Defrost thermistor

/RT61(CN641)

Ambient temperature

thermistor /RT65

(CN643)

Outdoor heat exchanger

temperature thermistor

/RT68(CN644)

Discharge temperature thermistor(RT62)

700

600

500

400

300

200

100

0

0 10 20 30 40 50 60 70 80 90 100 110 120

Temperature( )

Discharge temperature

thermistor /RT62

Signal of outdoor fan

(CN641)

Output to drive outdoor

fan motor (CN932)

motor (CN931)

Fin temperature thermistor(RT64)

200

180

160

140

120

100

80

60

Resistance(k )

40

20

0

0 1020304050607080

LEV connector (CN724)

Jumper wire for changing

defrost setting (JS)

Jumper wire for pre-heat

Temperature( )

control setting (JK)

41

12

DISASSEMBLY INSTRUCTIONS

<"Terminal with locking mechanism" Detaching points>

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

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

Sleeve

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

Slide the sleeve.
Pull the terminal while

Locking lever

pushing the locking
lever.

MUZ-GB50VA

OPERATING PROCEDURE

1. Removing the cabinet

(1) Remove the screws of the service panel.
(2) Remove the screws of the top panel.
(3) Remove the screw of the valve cover.
(4) Remove the service panel.
(5) Remove the top panel.
(6) Remove the valve cover.
(7) Disconnect the power supply and indoor/outdoor connecting

wire.
(8) Remove the screws of the cabinet.
(9) Remove the cabinet.
(10)

Remove the screws of the back panel.

(11)

Remove the back panel.

Hold the sleeve, and
pull out the terminal
slowly.

Connector

PHOTOS

Photo 1

Screw of the top panel

Screws
of the
cabinet

Photo 3

Screws
of the
back
panel

Screw of the motor support

Set screws of the back panel

Screws of the cabinet

Photo 2

Screw of the service panel

Screws
of the top
panel

Set screws
of the back
panel

Screws of
the cabinet

Screw of
the valve
cover

42

OPERATING PROCEDURE

E1

E2

MUZ-GB50VA-

2. Removing the inverter assembly, inverter P.C. board
and power board

(1) Remove the top panel, cabinet and service panel. (Refer to 1.)
(2) Remove the back panel. (Refer to 1.)
(3) Disconnect the following connectors;

<Electronic control P.C. board>
CN931 and CN932 (Fan motor)
CN795 (LEV)
CN661 (Discharge temperature thermistor, defrost thermistor

and outdoor heat exchanger temperature thermistor)
CN663 (Ambient temperature thermistor)
<Noise filter P.C. board>
CN912 (R.V. coil)

(4) Remove the compressor connector.
(5) Remove the screws fixing the relay panel.
(6) Remove the inverter assembly.
(7) Disconnect all connectors and lead wires on the electronic

control P.C. board.

(8) Remove the electronic control P.C. board from the inverter

assembly.

(9) Remove the screws fixing the power board assembly.
(10)

Disconnect all connectors and lead wires on the power

board.

(11)

Remove the power board from the inverter assembly.

(12)

Disconnect all connectors and lead wires on the noise filter

P.C. board.

(13)

Remove the noise filter P.C. board from the inverter assem-

bly.

/

PHOTOS

Photo 4 (MUZ-GB50VA-

Screws of the power board assembly

Screws of the relay panel

Photo 5 (MUZ-GB50VA-

E1

E3

)

/

E2

)

Screws of the
relay panel

MUZ-GB50VA-

E3

3. Removing the inverter assembly, inverter P.C. board

(1) Remove the cabinet and panels. (Refer to 1.)
(2) Disconnect the lead wire to the reactor and the following con-

nectors;

<Inverter P.C. board>
CN721 (R.V.coil)
CN932 (Fan motor)
CN641 (Defrost thermistor and discharge temperature ther-

mistor)
CN643 (Ambient temperature thermistor)
CN644 (Outdoor heat exchanger temperature thermistor)
CN724 (LEV)

(3) Remove the compressor connector (CN61).
(4) Remove the screws fixing the relay panel. (Photo 5)
(5) Remove the inverter assembly. (Photo 6)
(6) Remove the screw of the earth wire and screw of the

T.B.support. (Photo 6)

(7) Remove the screw of the PB fixture.
(8) Remove the relay panel from the PB support.
(9) Remove the inverter P.C. board from the inverter assembly.

Screws of
the reactor

Photo 6 (Inverter assembly : MUZ-GB50VA-

Heat sink

Hook of the
PB support

Inverter P.C.
board

PB support

Screw of the
T.B.support

T.B.support

E3

)

43

Hook of the
PB support

Relay panel

Screw of the
PB fixture

Screw of the
earth wire

OPERATING PROCEDURE PHOTOS

4. Removing R.V. coil

(1) Remove the top panel, cabinet and service panel. (Refer to 1.)
(2) Remove the back panel. (Refer to 1.)
(3) Disconnect the following connectors;

E1

E2

MUZ-GB50VA-

/
<Noise filter P.C. board>
CN912 (R.V. coil)

MUZ-GB50VA-

E3

<Inverter P.C. board>
CN721 (R.V. coil)

(4) Remove the R.V. coil. (Photo 11)

5. Removing the defrost thermistor, discharge tempera­ture thermistor, outdoor heat exchanger temperature
thermistor and ambient temperature thermistor

(1) Remove the top panel, cabinet and service panel.
(Refer to 1.)
(2) Remove the back panel. (Refer to 1.)
(3) Disconnect the following connectors;

<Electronic control P.C. board>
CN661 (Discharge temperature thermistor, defrost thermistor

and outdoor heat exchanger temperature thermistor)

CN663 (Ambient temperature thermistor)
(4) Pull out the defrost thermistor from its holder. (Photo 8)
(5) Pull out the discharge temperature thermistor from its holder.

(Photo 7)
(6) Pull out the outdoor heat exchanger temperature thermistor

from its holder. (Photo 8)
(7) Pull out the ambient temperature thermistor from its holder.

(Photo 8)

Photo 7

Discharge temperature thermistor

Photo 8

Outdoor heat exchanger
temperature thermistor

Ambient
temperature
thermistor

Defrost
thermistor

6. Removing outdoor fan motor

(1) Remove the top panel, cabinet and service panel.
(Refer to 1.)
(2) Remove the back panel. (Refer to 1.)
(3) Disconnect the following connectors;

E1

E2

MUZ-GB50VA-

<Electronic control P.C. board>

CN931 and CN932 (Fan motor)

MUZ-GB50VA-

<Inverter P.C. board>

CN931 and CN932 (Fan motor)

(4) Remove the propeller.
(5) Remove the screws fixing the fan motor.
(6) Remove the fan motor.

/

E3

44

Photo 9

Propeller

Screws of the outdoor fan motor

OPERATING PROCEDURE PHOTOS

7. Removing the compressor and 4-way valve

(1) Remove the top panel, cabinet and service panel.
(Refer to 1.)
(2) Remove the back panel. (Refer to 1.)
(3) Remove the inverter assembly. (Refer to 2.)
(4) Recover gas from the refrigerant circuit.

NOTE: Recover gas from the pipes until the pressure gauge

shows 0 kg/cm2 (0 MPa).

(5) Detach the welded part of the suction and the discharge pipe

connected with compressor. (Photo 11)
(6) Remove the compressor nuts.
(7) Remove the compressor.
(8) Detach the welded part of 4-way valve and pipe. (Photo 10)

Photo 10

Welded parts of 4-way valve

Photo 11

R.V. coil

8. Removing the reactor

(1) Remove the top panel, cabinet, service panel and the back

panel. (Refer to 1.)

(2) Disconnect the reactor lead wire.
(3) Remove the screws of the reactor, and remove the reactor.

(Photo 5,12)

Photo 12 (MUZ-GB50VA-

Welded part
of the dis­charge pipe

Welded part
of the suction
pipe

)

/

E1

E2

45

Screws of the reactor

13

RoHS PARTS LIST (RoHS compliant)

MUZ-GB50VA- E1 MUZ-GB50VA-

E2

13-1. OUTDOOR UNIT STRUCTURAL PARTS, ELECTRICAL PARTS AND FUNCTIONAL

PARTS

2829

27

1

2

3

4

26

25

24

23

22

21

20

19

5

6

7

8

10

16

15

13

14

12911

18

17

46

13-1. OUTDOOR UNIT STRUCTURAL PARTS, ELECTRICAL PARTS AND FUNCTIONAL

PARTS

Part number that is circled is not shown in the illustration.

No.

Part No. Part Name

RoHS

in Wiring

Diagram

1 G E12 819 297 TOP PANEL 1 1
2 G E12 851 630 OUTDOOR HEAT EXCHANGER 1 1
3 G E12 938 301 OUTDOOR FAN MOTOR MF 1 1 RC0J60­4 G E12 851 501 PROPELLER 1 1
5 G E12 851 290 BASE 1 1
6 G E12 819 232 CABINET 1 1
7 G E12 819 009 HANDLE 1 1
8 G E12 819 521 FAN GUARD 1 1
9 G E12 C34 506 COMPRESSOR RUBBER SET 3 3 3 RUBBERS/SET

Symbol

G E12 939 900

10

G E12 C06 900 1 SNB130FLEH1

COMPRESSOR MC

11 G E12 851 661 STOP VALVE (GAS) 1 1 ø12.7
12 G E12 821 662 STOP VALVE (LIQUID) 1 1 ø6.35
13 G E12 851 640 EXPANSION VALVE 1 1
14 G E12 851 493 EXPANSION VALVE COIL LEV 1 1
15 G E12 935 490 R.V. COIL 21S4 1 1
16 G E12 891 961 4-WAY VALVE 1 1
17 G E12 819 650 VALVE COVER 1 1
18 G E12 819 245 SERVICE PANEL 1 1

19 G E12 C95 450

OUTDOOR ELECTRONIC CONTROL P.C.

BOARD
20 G E12 935 374 TERMINAL BLOCK TB1 1 1 3 P
21 G E12 823 375 TERMINAL BLOCK TB2 1 1 3 P
22 G E12 A87 337 REACTOR L 1 1
23 G E12 935 444 NOISE FILTER P.C. BOARD 1 1
24 G E12 935 309 AMBIENT TEMPERATURE THERMISTOR RT65 1 1

25 G E12 851 308 THERMISTOR SET

RT61,RT62,RT68
26 G E12 935 440 POWER BOARD 1 1
27 G E12 819 233 BACK PANEL (OUT) 1 1
28 G E12 817 009 HANDLE 1 1
29 G E12 851 515 MOTOR SUPPORT 1 1

30 G E12 127 382 FUSE F801 1 1 T3.15AL250V
31 G E12 737 382 FUSE F911 1 1 T1AL250V
32 G E12 935 385 FUSE & VARISTOR F64, NR64 1 1 T2AL250V
33 G E12 851 936 CAPILLARY TUBE (TAPER PIPE) 1 1 ø3.6 × ø2.4 × 50
34 G E12 853 299 OIL SEPARATOR 1 1
35 G E12 861 936 CAPILLARY TUBE 1 1 ø1.8 × ø0.6 × 1000

Q'ty/unit

MUZ-GB50VA-

E1 E2

Remarks

□□

1 SNB130FLDH1

11

11

DEFROST, DISCHARGE, OUTDOOR
HEAT EXCHANGER

Including heat sink and RT64

47

MUZ-GB50VA-

E3

13-2. OUTDOOR UNIT STRUCTURAL PARTS, ELECTRICAL PARTS AND FUNCTIONAL

PARTS

26

29

1

2

3

4

5

272830

19

25

20

24

23

22

21

6

7

8

10

16

15

13

14

12911

18

17

48

13-2. OUTDOOR UNIT STRUCTURAL PARTS, ELECTRICAL PARTS AND FUNCTIONAL

PARTS

Part number that is circled is not shown in the illustration.

Symbol

No.

1 G E12 819 297 TOP PANEL 1
2 G E12 851 630 OUTDOOR HEAT EXCHANGER 1
3 G E12 938 301 OUTDOOR FAN MOTOR MF 1 RC0J60­4 G E12 851 501 PROPELLER 1
5 G E12 851 290 BASE 1
6 G E12 819 232 CABINET 1
7 G E12 819 009 HANDLE 1
8 G E12 819 521 FAN GUARD 1
9 G E12 C34 506 COMPRESSOR RUBBER SET 3 3 RUBBERS/SET

10 G E12 C37 900 COMPRESSOR MC 1 SNB130FGBH
11 G E12 D58 661 STOP VALVE (GAS) 1 ø12.7
12 G E12 D58 662 STOP VALVE (LIQUID) 1 ø6.35
13 G E12 851 640 EXPANSION VALVE 1
14 G E12 D58 493 EXPANSION VALVE COIL LEV 1
15 G E12 D58 490 R.V. COIL 21S4 1
16 G E12 C18 961 4-WAY VALVE 1
17 G E12 819 650 VALVE COVER 1
18 G E12 819 245 SERVICE PANEL 1
19 G E12 D58 306 THERMISTOR SET
20 G E12 D58 309 AMBIENT TEMPERATURE THERMISTOR RT65 1

21 G E12 C34 307

22 G E12 735 241 FUSE HOLDER 1
23 G E12 735 382 FUSE F61 1 T20AL250V
24 G E12 927 374 TERMINAL BLOCK TB1 1 3 P
25 G E12 823 375 TERMINAL BLOCK TB2 1 3 P
26 G E12 D58 451 INVERTER P.C. BOARD 1
27 G E12 D58 337 REACTOR L 1
28 G E12 819 233 BACK PANEL (OUT) 1
29 G E12 817 009 HANDLE
30 G E12 851 515 MOTOR SUPPORT 1
31 G E12 851 936 CAPILLARY TUBE (TAPER PIPE) 1 ø3.6 × ø2.4 × 50
32 G E12 127 382 FUSE
33 G E12 661 385 VARISTOR NR61-64 1

Part No. Part Name

RoHS

OUTDOOR HEAT EXCHANGER
TEMPERATURE THERMISTOR

in Wiring

Diagram

RT61,RT62

RT68 1

F701,F801,F901

Q'ty/unit

MUZ-GB50VA-

1

1

1 T3.15AL250V

E3

Remarks

□□

DEFROST, DISCHARGE

Including heat sink and RT64

49

MUZ-GB50VA
13-3. ACCESSORY

1

No.

1 G E12 817 704 DRAIN SOCKET 1 1 1
2 G E12 444 705 DRAIN CAP 2 2 2 ø33

Part No. Part Name

RoHS

2

Symbol

in Wiring

Diagram

Q'ty/unit

MUZ-GB50VA-

E1 E2 E3

Remarks

50

51

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

Copyright 2006 MITSUBISHI ELECTRIC ENGINEERING CO.,LTD
Distributed in Apr. 2008. No. OB455 REVISED EDITION-E 6
Distributed in Sep. 2007. No. OB455 REVISED EDITION-D 6
Distributed in Jun. 2007. No. OB455 REVISED EDITION-C 6
Distributed in Apr. 2007. No. OB455 REVISED EDITION-B 6
Distributed in Aug. 2006. No. OB455 REVISED EDITION-A 6
Distributed in Mar. 2006. No. OB455 6
Made in Japan

New publication, effective Apr. 2008
Specifications subject to change without notice.