Mitsubishi MUZ-HM18NA2-U1, MUZ-HM18NA-U1, MUZ-HM24NA-U1, MUZ-HM24NA2-U1 Service Manual

HFC

utilized

R410A

INDOOR UNIT

OUTDOOR UNIT

SERVICE MANUAL

Models

Revision C:

U1

• MUZ-HM09/12NA

have been added.

OBH747 REVISED EDITION-B is void.

-

, MUZ-HM09/12NA2

No. OBH747

REVISED EDITION-C

U1

-

MUZ-HM09NA

-

MUZ-HM09NA2
MUZ-HM12NA

-

MUZ-HM12NA2
MUZ-HM15NA

-

MUZ-HM15NA2

MUZ-HM24NA

U1

,

U1,U8

-

U1,U8

U1,U8

-

U1

U1

-

U8

MUZ-HM18NA
MUZ-HM18NA2
MUZ-HM24NA
MUZ-HM24NA2

Indoor unit service manual
MSZ-HM•NA Series (OBH746)

CONTENTS

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

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

3. SPECIFICATION ················································ 5

4. OUTLINES AND DIMENSIONS ······················ 10

5. WIRING DIAGRAM ·········································· 12

6. REFRIGERANT SYSTEM DIAGRAM ·············15

7. DATA ································································ 19

8. ACTUA TOR CONTROL ··································· 32

9. SERVICE FUNCTIONS ··································· 33

10. TROUBLESHOOTING ····································· 34

11. DISASSEMBLY INSTRUCTIONS ···················· 59

PARTS CATALOG (OBB747)

U1

-

U1

-

U1

-

U1

-

NOTE:

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

Use the specifi ed refrigerant only

OBH747C

Never use any refrigerant other than that specified.

Doing so may cause a burst, an explosion, or fire when the unit is being used, serviced, or disposed of.
Correct refrigerant is specified in the manuals and on the spec labels provided with our products.
We will not be held responsible for mechanical failure, system malfunction, unit breakdown or accidents caused by
failure to follow the instructions.

Revision A:

• MUZ-HM09/12NA-U8, MUZ-HM09/12NA2-U8, MUZ-HM15/18NA-U1, MUZ-HM15/18NA2-U1 and MUZ-HM24NA2-U1 have
been added.

Revision B:

• 3. SPECIFICATION has been modified.

Revision C:

• MUZ-HM09/12NA

U1

-

, MUZ-HM09/12NA2

U1

-

have been added.

2

1

OBH747C

TECHNICAL CHANGES

MUZ-HM24NA

1. New model

MUZ-HM09NA
MUZ-HM09NA2
MUZ-HM12NA
MUZ-HM12NA2
MUZ-HM15NA
MUZ-HM15NA2
MUZ-HM18NA
MUZ-HM18NA2
MUZ-HM24NA2

1. New model

MUZ-HM09NA
MUZ-HM09NA2
MUZ-HM12NA
MUZ-HM12NA2

1. New model

U1

-

U8

-

U8

-

U8

-

U8

-

U1

-

U1

-

U1

-

U1

-

U1

-

U1

-

U1

-

U1

-

U1

-

3

Piping

Air outlet

Drain outlet

Air inlet

(back and side)

Drain hose

2

OBH747C

PART NAMES AND FUNCTIONS

MUZ-HM09NA MUZ-HM09NA2 MUZ-HM12NA MUZ-HM12NA2
MUZ-HM15NA MUZ-HM15NA2 MUZ-HM18NA MUZ-HM18NA2

Air inlet

(back and side)

Piping

Air outlet

Drain hose

Drain outlet

MUZ-HM24NA MUZ-HM24NA2

4

3

OBH747C

SPECIFICATION

Outdoor unit model
Capacity

Rated (Minimum~Maximum)

Capacity

Rated (Maximum)

Power consumption

Rated (Minimum~Maximum)

Power consumption

Rated (Maximum)

1

EER
HSPF IV

[SEER]

4

Cooling 1
Heating 47 1

Heating 17 2
Cooling 1

Heating 47 1
Heating 17 2

3

Cooling 12.0 [ 18.0 ]
Heating 10.0 [NA] / 8.5 [NA2]

COP Heating
Power factor

Cooling (208/230) % 87/87 84/84
Heating (208/230) % 90/90 90/89

1

MUZ-HM09NA

MUZ-HM09NA2

U1

-

U1

­Btu/h 9,000 ( 3,800 ~ 10,000 )
Btu/h 10,900 ( 4,500 ~ 11,800 )

Btu/h 6,700 (7,200)
W 750 (240 - 850) 750 (205 - 850)

W 900 (240 - 1,000) 900 (255 - 1,000)
W 700 (780)

3.55

MUZ-HM09NA

MUZ-HM09NA2

Power supply V , phase , Hz 208/230 , 1 , 60
Max. fuse size (time delay) A 15
Min. circuit ampacity A 9 12
Fan motor F.L.A A 0.50

Model KNB073FRVMC KNB073FQDHC

Compressor

R.L.A A 6.2 6.6
L.R.A A 7.7 8.2
Refrigeration oil

fl oz. (L) (Model)

9.1 (0.27) (FV50S) 10.8 (0.32) (NEO22)

Refrigerant control Linear expansion valve
Sound level

1

Airfl ow
High - Med. - Low

Fan speed
High - Med. - Low

Cooling dB(A) 46
Heating

dB(A) 50

Cooling CFM 1,063
Heating

CFM 1,282 - 1,105 1,240 - 1,105

Cooling rpm 740
Heating rpm 890 - 770 860 - 770

Defrost method Reverse cycle

W in. 31-1/2

Dimensions

D in. 11-1/4

H in. 21-5/8
Weight Ib. 73
External fi nish Munsell 3Y 7.8/1.1
Refrigerant piping Not supplied

Refrigerant pipe size
(Min. wall thickness)

Connection method
Between the indoor &

outdoor units
Refrigerant charge (R410A)

Liquid in. 1/4 (0.0315)

Gas in. 3/8 (0.0315)

Indoor Flared

Outdoor Flared

Height difference ft. 40

Piping length ft. 65

1 lb. 12 oz.

NOTE: Test conditions are based on AHRI 210/240.

1: Rating conditions (Cooling) — Indoor: 80˚FDB, 67˚FWB, Outdoor: 95˚FDB, (75˚FWB)
(Heating) — Indoor: 70˚FDB, 60˚FWB, Outdoor: 47˚FDB, 43˚FWB
2: (Heating) — Indoor: 70˚FDB, 60˚FWB, Outdoor: 17˚FDB, 15˚FWB
3: Test condition (Refer to page 9.)
4: Test condition (Refer to page 9.)

U8

-

U8

-

5

Outdoor unit model

OBH747C

Capacity

Rated (Minimum~Maximum)

Capacity

Rated (Maximum)

Power consumption

Rated (Minimum~Maximum)

Power consumption

Rated (Maximum)

1

EER
HSPF IV

[SEER]

4

Cooling 1
Heating 47 1

Heating 17 2
Cooling 1

Heating 47 1
Heating 17 2

3

Cooling 9.9 [ 18.0 ]
Heating 10.0 [NA] / 8.5 [NA2]

COP Heating
Power factor

Cooling (208/230) % 95/95 94/94
Heating (208/230) % 93/93 95/96

MUZ-HM12NA

MUZ-HM12NA2

Btu/h 12,000 ( 3,800 ~ 12,200 )
Btu/h 12,200 ( 4,500 ~ 14,500 ) 12,200 ( 5,500 ~ 14,500 )

Btu/h 7,600 (9,000)
W 1,210 (240 - 1,300) 1,210 (205 - 1,300)

W 990 (240 - 1,220) 990 (340 - 1,660)
W 800 (990)

1

U1

-

U1

-

MUZ-HM12NA

MUZ-HM12NA2

3.61

Power supply V , phase , Hz 208/230 , 1 , 60
Max. fuse size (time delay) A 15
Min. circuit ampacity A 9 12
Fan motor F.L.A A 0.50

Compressor

Model
R.L.A A 6.2 6.6
L.R.A A 7.7 8.2
Refrigeration oil

fl oz. (L) (Model)

KNB073FRVMC KNB092FQAHC

9.1 (0.27) (FV50S) 10.8 (0.32) (NEO22)

Refrigerant control Linear expansion valve
Sound level

1

Airfl ow
High - Med. - Low

Fan speed
High - Med. - Low

Cooling dB(A) 49
Heating

dB(A) 51
Cooling CFM 1,063 1,102 - 639
Heating

CFM 1,282 - 1,105 1,186 - 1,116 - 1,045
Cooling rpm 740 810 - 490
Heating rpm 890 - 770 870 - 820 - 770

Defrost method Reverse cycle

W in. 31-1/2

Dimensions

D in. 11-1/4
H in. 21-5/8

Weight Ib. 73
External fi nish Munsell 3Y 7.8/1.1
Refrigerant piping Not supplied

Refrigerant pipe size
(Min. wall thickness)

Connection method
Between the indoor &

outdoor units
Refrigerant charge (R410A)

Liquid in. 1/4 (0.0315)
Gas in. 3/8 (0.0315)
Indoor Flared
Outdoor Flared
Height difference ft. 40
Piping length ft. 65

1 lb. 12 oz. 2 lb. 9 oz.

NOTE: Test conditions are based on AHRI 210/240.

1: Rating conditions (Cooling) — Indoor: 80˚FDB, 67˚FWB, Outdoor: 95˚FDB, (75˚FWB)
(Heating) — Indoor: 70˚FDB, 60˚FWB, Outdoor: 47˚FDB, 43˚FWB
2: (Heating) — Indoor: 70˚FDB, 60˚FWB, Outdoor: 17˚FDB, 15˚FWB
3: Test condition (Refer to page 9.)
4: Test condition (Refer to page 9.)

U8

-

U8

-

6

Outdoor unit model

OBH747C

Capacity

Rated (Minimum~Maximum)

Capacity

Rated (Maximum)

Power consumption

Rated (Minimum~Maximum)

Power consumption

Rated (Maximum)

1

EER
HSPF IV

[SEER]

4

Cooling 1
Heating 47 1

Heating 17 2
Cooling 1

Heating 47 1
Heating 17 2

3

Cooling 12.0 [18.0] 10.5 [18.0]
Heating 10.0 [NA] / 8.5 [NA2] 10.0 [NA] / 8.5 [NA2]

COP Heating
Power factor

Cooling (208/230) % 98/98 98/98
Heating (208/230) % 98/98 97/97

1

MUZ-HM15NA

MUZ-HM15NA2

Btu/h 14,000 (3,100 - 16,000) 17,200 (5,800 - 18,000)
Btu/h 18,000 (4,800 - 18,500) 18,000 (5,400 - 20,900)

Btu/h 11,500 (14,000) 11,500 (15,000)
W 1,127 (187 - 1,957) 1,598 (308 - 2,028)

W 1,570 (190 - 1,980) 1,548 (288 - 2,208)
W 1,290 (1,820) 1,258 (1,908)

3.30 3.32

MUZ-HM18NA

MUZ-HM18NA2

Power supply V , phase , Hz 208/230, 1 , 60 208/230, 1 , 60
Max. fuse size (time delay) A 15 15
Min. circuit ampacity A 10 10
Fan motor F.L.A A 0.50 0.50

Model SNB130FQBMT SNB130FQBMT

Compressor

R.L.A A 7.4 7.4
L.R.A A 9.3 9.3
Refrigeration oil

fl oz. (L) (Model)

11.8 (0.35) (FV50S) 11.8 (0.35) (FV50S)

Refrigerant control Linear expansion valve
Sound level

1

Airfl ow
High - Med. - Low

Fan speed
High - Med. - Low

Cooling dB(A) 49 49
Heating

dB(A) 51 51
Cooling CFM 1,102 - 639 1,102 - 639
Heating

CFM 1,186 - 1,045 - 1,045 1,186 - 1,045 - 1,045
Cooling rpm 810 - 490 810 - 490
Heating rpm 870 - 770 - 770 870 - 770 - 770

Defrost method Reverse cycle

W in. 31-1/2 31-1/2

Dimensions

D in. 11-1/4 11-1/4
H in. 21-5/8 21-5/8

Weight Ib. 81 81
External fi nish Munsell 3Y 7.8/1.1
Refrigerant piping Not supplied

Refrigerant pipe size
(Min. wall thickness)

Connection method
Between the indoor &

outdoor units

Liquid in. 1/4 (0.0315) 1/4 (0.0315)
Gas in. 1/2 (0.0315) 1/2 (0.0315)
Indoor Flared Flared
Outdoor Flared Flared
Height difference ft. 40 40
Piping length ft. 65 65

Refrigerant charge (R410A) 2 lb. 9 oz. 2 lb. 10 oz.

NOTE: Test conditions are based on AHRI 210/240.

1: Rating conditions (Cooling) — Indoor: 80˚FDB, 67˚FWB, Outdoor: 95˚FDB, (75˚FWB)
(Heating) — Indoor: 70˚FDB, 60˚FWB, Outdoor: 47˚FDB, 43˚FWB
2: (Heating) — Indoor: 70˚FDB, 60˚FWB, Outdoor: 17˚FDB, 15˚FWB
3: Test condition (Refer to page 9.)
4: Test condition (Refer to page 9.)

7

Outdoor unit model

OBH747C

Capacity

Rated (Minimum~Maximum)

Capacity

Rated (Maximum)

Power consumption

Rated (Minimum~Maximum)

Power consumption

Rated (Maximum)

Cooling 1 Btu/h 22,500 (5,800 ~ 22,500)
Heating 47

1 Btu/h 26,000 (5,400 ~ 26,000)
Heating 17 2 Btu/h 18,500 (18,500)
Cooling 1 W 2,575 (275 ~ 2,575)

Heating 47

1 W 2,445 (265 ~ 2,445)
Heating 17 2 W 2,245 (2,245)

MUZ-HM24NA

MUZ-HM24NA2

EER 1 [SEER] 3 Cooling 8.6 [18.0]
HSPF IV
COP Heating

Power factor

4 Heating 9.5 [NA] / 8.5 [NA2]

1 3.05
Cooling (208/230) % 99/99
Heating (208/230) % 99/99

Power supply V , phase , Hz 208/230, 1 , 60
Max. fuse size (time delay) A 15
Min. circuit ampacity A 14
Fan motor F.L.A 0.93

Model SNB130FQBMT

Compressor

Refrigeration oil

R.L.A 10
L.R.A 12.5
fl oz. (L) (Model)

11.8 (0.35) (FV50S)

Refrigerant control Linear expansion valve
Sound level

1

Airfl ow
High - Med. - Low

Fan speed
High - Med. - Low

Cooling dB(A) 54
Heating dB(A) 55
COOL CFM 1,742 - 922
HEAT CFM 1,691 - 1,691 - 1,372
Cooling rpm 840 - 450
Heating rpm 810 - 810 - 650

Defrost method Reverse cycle

W in. 33-1/16

Dimensions

D in. 13
H in. 34-5/8

Weight Ib. 121
External fi nish Munsell 3Y 7.8/1.1
Refrigerant piping Not supplied
Refrigerant pipe size

(Min. wall thickness)
Connection method
Between the indoor &

outdoor units

Liquid in. 3/8 (0.0315)
Gas in. 5/8 (0.0315)
Indoor Flared
Outdoor Flared
Height difference ft. 50
Piping length ft. 100

Refrigerant charge (R410A) 3 lb. 9 oz.

NOTE: Test conditions are based on AHRI 210/240.

1: Rating conditions (Cooling) — Indoor: 80˚FDB, 67˚FWB, Outdoor: 95˚FDB, (75˚FWB)
(Heating) — Indoor: 70˚FDB, 60˚FWB, Outdoor: 47˚FDB, 43˚FWB

2: (Heating) — Indoor: 70˚FDB, 60˚FWB, Outdoor: 17˚FDB, 15˚FWB

8

Test condition

OBH747C

3, 4

Mode Test

ARI

"A-2" Cooling Steady State
at rated compressor Speed

"B-2" Cooling Steady State
at rated compressor Speed

SEER

(Cooling)

HSPF

(Heating)

5

: At Intermediate compressor Speed

"B-1" Cooling Steady State
at minimum compressor Speed

"F-1" Cooling Steady State
at minimum compressor Speed

"E-V" Cooling Steady State
at Intermediate compressor Speed

"H1-2" Heating Steady State
at rated compressor Speed

"H3-2" Heating
at rated compressor Speed

"H0-1" Heating Steady State
at minimum compressor Speed

"H1-1" Heating Steady State
at minimum compressor Speed

"H2-V" Heating
at Intermediate compressor Speed

5

5

= ("Rated compressor speed" - "minimum compressor speed") / 3 + "minimum compressor speed".

Indoor air condition (°F) Outdoor air condition (°F)

Dry bulb Wet bulb Dry bulb Wet bulb

80 67 95 (75)

80 67 82 (65)

80 67 82 (65)

80 67 67 (53.5)

80 67 87 (69)

70 60 47 43

70 60 17 15

70 60 62 56.5

70 60 47 43

70 60 35 33

OPERATING RANGE

(1) POWER SUPPLY

Outdoor unit

(2) OPERATION

Mode Condition

Standard temperature 80 67 95 —

Cooling

Heating

Maximum temperature 90 73 115 —
Minimum temperature 67 57 14 —
Maximum humidity 78 % —
Standard temperature 70 60 47 43
Maximum temperature 80 67 75 65
Minimum temperature 70 60 -4 (NA), 5(NA2) -5 (NA), 4 (NA2)

Rated voltage Guaranteed voltage (V)

208/230 V

1 phase

60 Hz

Min. 187

DB WB DB WB

208 230 Max. 253

Intake air temperature (°F)

Indoor Outdoor

9

4

OBH747C

OUTLINES AND DIMENSIONS

MUZ-HM09NA MUZ-HM09NA2 MUZ-HM12NA MUZ-HM12NA2
MUZ-HM15NA MUZ-HM15NA2 MUZ-HM18NA MUZ-HM18NA2

REQUIRED SPACE

*1

4 in. (100 mm) or more when

front and sides of the unit are clear

4 in. (100 mm)

or more

8 in. (200 mm)

or more *2

*2

When any 2 sides of left, right

and rear of the unit are clear

holes

Liquid refrigerant pipe joint
Refrigerant pipe (flared)

Gas refrigerant pipe joint
Refrigerant pipe (flared)

Ø 1/2 (HM15/18)

clear *1

4 in. (100 mm)

14 in. (350 mm)

or more

Ø 1/4

Ø 3/8 (HM09/12)

Unit: inch

or more

10

MUZ-HM24NA MUZ-HM24NA2

OBH747C

Unit: inch

REQUIRED SPACE

Air in

13

34-5/8

2

17-25/32

6-7/8

16-7/16

Air in

4-5/16

Air out

19-11/16

33-1/16

*1 20 in. (500 mm) or more when front
and sides of the unit are clear

Drain hole

1-9/16

1-5/8

14-3/16

2-holes 13/32 13/16

3-3/16

4 in. (100 mm)

or more

Clear *1

20 in. (500 mm)

or more *2

*2 When any 2 sides of left, right
and rear of the unit are clear

Service panel

Liquid refrigerant pipe joint
Refrigerant pipe (flared)

35

44

4 in. (100 mm)

or more

14 in. (350 mm)

or more

Ø 3/8

6-1/2

3-29/32

7-11/16

Gas refrigerant pipe joint
Refrigerant pipe (flared)

Ø 5/8

11

5

OBH747C

WIRING DIAGRAM

MUZ-HM09NA

U1

-

MUZ-HM09NA2

U1

-

MUZ-HM12NA

U1

-

MUZ-HM12NA2

U1

-

MUZ-HM09NA

U8

-

MUZ-HM09NA2

U8

-

MUZ-HM12NA

U8

-

MUZ-HM12NA2

U8

-

12

MUZ-HM15NA

OBH747C

U1

-

MUZ-HM15NA2

U1

-

MUZ-HM18NA

U1

-

MUZ-HM18NA2

U1

-

13

MUZ-HM24NA

OBH747C

U1

-

MUZ-HM24NA2

U1

-

14

6

OBH747C

REFRIGERANT SYSTEM DIAGRAM

MUZ-HM09NA

Refrigerant pipe ø3/8 (ø9.52)
(with heat insulator)

Flared connection

Flared connection

Refrigerant pipe ø1/4 (ø6.35)
(with heat insulator)

U1

-

MUZ-HM09NA2

Stop valve
(with service port)

Stop valve
(with strainer)

U1

-

MUZ-HM12NA

4-way valve

Muffler

Discharge
temperature
thermistor
RT62

Service port

Capillary tube

O.D. 0.118 × I.D. 0.055
× 10-1/4
(ø3.0 × ø1.4

×

260)

LEV

-

Muffler

Service port

Compressor

Defrost
thermistor
RT61

U1

MUZ-HM12NA2

Outdoor heat
exchanger
temperature

Outdoor
heat
exchanger

Refrigerant flow in cooling
Refrigerant flow in heating

thermistor
RT68

Ambient
temperature
thermistor
RT65

Strainer
#100

R.V. coil
heating ON
cooling OFF

U1

-

Unit: Inch (mm)

MUZ-HM09NA

Refrigerant pipe ø3/8 (ø9.52)
(with heat insulator)

Flared connection

Flared connection

Refrigerant pipe ø1/4 (ø6.35)
(with heat insulator)

U8

-

MUZ-HM09NA2

Stop valve
(with service port)

Stop valve
(with strainer)

U8

-

4-way valve

Muffler

Discharge
temperature
thermistor
RT62

Service port

Capillary tube

O.D. 0.118 × I.D. 0.079
× 9-7/16
(ø3.0 × ø2.0

×

240)

LEV

Muffler

Service port

Compressor

Defrost
thermistor
RT61

Outdoor heat
exchanger
temperature

Outdoor
heat
exchanger

Refrigerant flow in cooling
Refrigerant flow in heating

thermistor
RT68

Ambient
temperature
thermistor
RT65

Strainer
#100

R.V. coil
heating ON
cooling OFF

15

Outdoor
heat
exchanger

Flared connection

Defrost
thermistor
RT61

Discharge
temperature
thermistor
RT62

Flared connection

Stop valve
(with strainer)

Refrigerant flow in cooling

Compressor

4-way valve

Refrigerant flow in heating

Refrigerant pipe ø1/4 (ø6.35)
(with heat insulator)

R.V. coil
heating ON
cooling OFF

Strainer
#100

LEV

Ambient
temperature
thermistor
RT65

Muffler

Capillary tube
O.D. 0.157 ×
I.D. 0.094 × 9-7/16
(

ø4.0 × ø2.4 × 240

)

Outdoor heat
exchanger
temperature
thermistor
RT68

Capillary tube

O.D. 0.118 ×
I.D. 0.079 × 8-9/32
(ø3.0 × ø2.0 × 210)

Service
port

Service
port

Refrigerant pipe ø1/2 (ø12.7)
(with heat insulator)

Stop valve
(with service port)

Muffler

MUZ-HM12NA

OBH747C

U8

-

MUZ-HM12NA2

U8

-

Unit: Inch (mm)

Refrigerant pipe ø3/8 (ø9.52)
(with heat insulator)

Stop valve
(with service port)

Flared connection

Flared connection

Stop valve
(with strainer)

Refrigerant pipe ø1/4 (ø6.35)
(with heat insulator)

4-way valve

Muffler

Discharge
temperature
thermistor
RT62

Service port

Capillary tube

O.D. 0.118 × I.D. 0.079
× 9-7/16

×

(ø3.0 × ø2.0

240)

Muffler

Service port

Compressor

Defrost
thermistor
RT61

Capillary tube

O.D. 0.118 × I.D. 0.071
× 23-5/8

3.0

× ø

(ø

1.8

LEV

Outdoor
heat
exchanger

×

600

)

(×2)

Strainer
#100

R.V. coil
heating ON
cooling OFF

Refrigerant flow in cooling
Refrigerant flow in heating

Outdoor heat
exchanger
temperature
thermistor
RT68

Ambient
temperature
thermistor
RT65

MUZ-HM15NA MUZ-HM15NA2 MUZ-HM18NA MUZ-HM18NA2

16

MUZ-HM24NA MUZ-HM24NA2

OBH747C

Unit: Inch (mm)

Refrigerant pipe
(with heat insulator)

Flared connection

Flared connection

Refrigerant pipe
(with heat insulator)

ø5/8 (ø

ø3/8 (ø

15.88)

Stop valve
(with service port)

Strainer

#100

Stop valve

9.52)

4-way
valve

Service
port

Muffler

Discharge
temperature
thermistor
RT62

Compressor

Capillary tube

O.D. 0.118×
I.D. 0.079× 7-7/8

(ø3.0×ø2.0×200(×4))

Capillary tube

O.D. 0.157×
I.D. 0.094×
3-15/16

(ø

4.0×ø

2.4×100)

Muffler
with #100 mesh strainer

Service port

LEV

Capillary tube

Strainer

O.D. 0.157×
I.D. 0.094×7-7/8

(ø

4.0×ø

2.4×200)

#100

Outdoor

Defrost
thermistor
RT61

Refrigerant flow in cooling
Refrigerant flow in heating

heat
exchanger

Outdoor heat
exchanger
temperature
thermistor
RT68

R.V. coil
heating ON
cooling OFF

17

MAX. REFRIGERANT PIPING LENGTH and MAX. HEIGHT DIFFERENCE

OBH747C

Refrigerant piping: ft. Piping size O.D: in.

Model

MUZ-HM09NA
MUZ-HM09NA2
MUZ-HM12NA
MUZ-HM12NA2

MUZ-HM15NA
MUZ-HM15NA2
MUZ-HM18NA
MUZ-HM18NA2

MUZ-HM24NA
MUZ-HM24NA2

Max. Length

A

Max. Height difference

B

Gas Liquid

3/8

65 40

1/2

100 50 5/8 3/8

Indoor
unit

Max. Height

difference

B

Max. Length
A

Outdoor unit

1/4

ADDITIONAL REFRIGERANT CHARGE (R410A: oz.)

NOTE: Refrigerant piping exceeding 25 ft. requires additional refrigerant charge according to the calculation.

Model

MUZ-HM09NA
MUZ-HM09NA2

MUZ-HM12NA
MUZ-HM12NA2

MUZ-HM12NA
MUZ-HM12NA2

MUZ-HM15NA
MUZ-HM15NA2

MUZ-HM18NA
MUZ-HM18NA2

Model

MUZ-HM24NA
MUZ-HM24NA2

U1

-

U1

-

U8

-

U8

-

Outdoor unit

precharged

25 30 40 50 60 65

1 lb. 12 oz.

0 1.08 3.24 5.40 7.56 8.64

2 lb. 9 oz.

2 lb. 10 oz.

Outdoor unit

precharged

25 30 40 50 60 70 80 90 100

3 lb. 9 oz. 0 1.08 3.24 5.40 7.56 9.72 11.88 14.04 16.20

Refrigerant piping length (one way): ft.

Calculation: X oz. = 1.08/5 oz./ft. × (Refrigerant piping length (ft.) - 25)

Refrigerant piping length (one way): ft.

Calculation: X oz. = 1.08/5 oz./ft. × (Refrigerant piping length (ft.) - 25)

18

DATA7

OBH747C

MUZ-HM09NA MUZ-HM09NA2 MUZ-HM12NA MUZ-HM12NA2
MUZ-HM15NA MUZ-HM15NA2 MUZ-HM18NA MUZ-HM18NA2
MUZ-HM24NA MUZ-HM24NA2

7-1. PERFORMANCE DATA

1) COOLING CAPACITY

Indoor air Outdoor intake air DB temperature (˚F)

Model

MUZ-HM09NA
MUZ-HM09NA2

MUZ-HM12NA
MUZ-HM12NA2

MUZ-HM15NA
MUZ-HM15NA2

MUZ-HM18NA
MUZ-HM18NA2

MUZ-HM24NA
MUZ-HM24NA2

NOTE: 1. IWB : Intake air wet-bulb temperature TC : Total Capacity (x10

2. SHC is based on 80˚F of indoor Intake air DB temperature.

IWB (˚F)

71 11.0 7.6 0.67 10.3 7.1 0.73 9.7 6.6 0.79 9.0 6.2 0.83 8.3 5.7 0.86
67 10.4 8.6 0.63 9.7 8.0 0.69 9.0 7.4 0.75 8.4 6.9 0.80 7.7 6.3 0.83
63 9.8 9.4 0.60 9.1 8.7 0.66 8.5 8.1 0.72 7.7 7.3 0.77 7.0 6.7 0.80
71 14.7 9.4 1.08 13.7 8.7 1.18 12.9 8.2 1.27 12.0 7.6 1.34 11.0 7.0 1.39
67 13.9 10.7 1.02 13.0 10.0 1.12 12.0 9.2 1.21 11.2 8.6 1.28 10.3 7.9 1.34
63 13.1 11.8 0.97 12.1 10.9 1.07 11.3 10.2 1.16 10.3 9.3 1.23 9.4 8.5 1.28
71 17.2 11.1 1.04 16.0 10.4 1.14 15.1 9.7 1.23 14.0 9.1 1.29 12.9 8.3 1.35
67 16.2 12.7 0.98 15.1 11.8 1.08 14.0 10.9 1.17 13.0 10.2 1.24 12.0 9.3 1.30
63 15.3 13.9 0.94 14.1 12.9 1.04 13.2 12.0 1.12 12.0 10.9 1.19 10.9 10.0 1.24
71 21.1 15.3 1.46 19.7 14.3 1.60 18.5 13.4 1.72 17.2 12.5 1.81 15.8 11.5 1.89
67 20.0 17.2 1.38 18.6 16.0 1.52 17.2 14.8 1.64 16.0 13.8 1.74 14.7 12.6 1.82
63 18.7 18.6 1.31 17.4 17.3 1.45 16.2 16.1 1.57 14.7 14.6 1.67 13.4 13.3 1.74
71 27.6 20.9 2.34 25.8 19.5 2.56 24.2 18.3 2.76 22.5 17.0 2.91 20.7 15.7 3.02
67 26.1 23.2 2.21 24.3 21.6 2.43 22.5 20.0 2.63 20.9 18.6 2.79 19.2 17.1 2.92

63 24.5 25.1 2.10 22.7 23.3 2.33 21.2 21.6 2.51 19.2 19.7 2.68 17.6 18.0 2.79

SHC : Sensible Heat Capacity (x10

75 85 95 105 115

TC SHC TPC TC SHC TPC TC SHC TPC TC SHC TPC TC SHC TPC

3

3

Btu/h) TPC : Total Power Consumption (kW)

Btu/h)

2) COOLING CAPACITY CORRECTIONS

Refrigerant piping length (one way: ft.)

Model 25 (std.) 40 65 100

MUZ-HM09NA
MUZ-HM09NA2
MUZ-HM12NA
MUZ-HM12NA2
MUZ-HM15NA
MUZ-HM15NA2

MUZ-HM18NA
MUZ-HM18NA2
MUZ-HM24NA
MUZ-HM24NA2

1.0 0.954 0.878 —

1.0 0.954 0.878 0.771

19

3) HEATING CAPACITY

OBH747C

Indoor air Outdoor intake air WB temperature (˚F)

Model

MUZ-HM09NA
MUZ-HM09NA2

MUZ-HM12NA
MUZ-HM12NA2

MUZ-HM15NA
MUZ-HM15NA2

MUZ-HM18NA
MUZ-HM18NA2

MUZ-HM24NA
MUZ-HM24NA2

NOTE: 1. IDB : Intake air dry-bulb temperature

2. Above data is for heating operation without any frost.

How to operate with fixed operational frequency of the compressor.

1. Press the EMERGENCY OPERATION switch on the front of the indoor unit, and select either EMERGENCY COOL
mode or EMERGENCY HEAT mode before starting to operate the air conditioner.

2. The compressor starts with operational frequency.

3. The fan speed of the indoor unit is High.

4. This operation continues for 30 minutes.

5. In order to release this operation, press the EMERGENCY OPERATION switch or press any button on the remote con­troller.

IDB (˚F)

75 4.8 0.53 6.3 0.67 7.9 0.79 9.4 0.88 10.6 0.92 11.0 0.94 12.4 0.97
70 5.2 0.51 6.7 0.65 8.2 0.77 9.6 0.86 10.9 0.90 11.2 0.92 12.7 0.95
65 5.5 0.49 6.9 0.62 8.6 0.74 10.0 0.83 11.2 0.88 11.6 0.89 13.0 0.94
75 5.4 0.58 7.1 0.74 8.8 0.87 10.6 0.97 11.9 1.01 12.3 1.03 13.9 1.07
70 5.8 0.56 7.5 0.71 9.2 0.85 10.8 0.94 12.2 0.99 12.6 1.01 14.2 1.05
65 6.1 0.53 7.7 0.68 9.6 0.82 11.2 0.92 12.6 0.97 12.9 0.98 14.5 1.03
75 7.9 0.94 10.4 1.19 13.1 1.40 15.6 1.56 17.6 1.64 18.1 1.66 20.5 1.73
70 8.6 0.90 11.1 1.15 13.5 1.37 15.9 1.52 18.0 1.60 18.5 1.63 21.0 1.70
65 9.0 0.86 11.3 1.10 14.1 1.32 16.5 1.48 18.5 1.56 19.1 1.58 21.4 1.66
75 7.9 0.94 10.4 1.18 13.1 1.39 15.6 1.55 17.6 1.63 18.1 1.65 20.5 1.72
70 8.6 0.90 11.1 1.14 13.5 1.36 15.9 1.51 18.0 1.59 18.5 1.62 21.0 1.69
65 9.0 0.86 11.3 1.10 14.1 1.31 16.5 1.47 18.5 1.55 19.1 1.57 21.4 1.65
75 11.4 1.48 15.1 1.86 18.9 2.19 22.5 2.44 25.4 2.56 26.1 2.60 29.6 2.70
70 12.4 1.41 16.0 1.80 19.5 2.14 23.0 2.38 26.0 2.50 26.8 2.55 30.3 2.65
65 13.0 1.35 16.4 1.73 20.4 2.06 23.8 2.31 26.8 2.44 27.6 2.48 30.9 2.60

TC : Total Capacity (x10

5 152535434555

TC TPC TC TPC TC TPC TC TPC TC TPC TC TPC TC TPC

3

Btu/h) TPC : Total Power Consumption (kW)

20

7-2. PERFORMANCE CURVE

Cooling capacity (

at Rated frequency)

0.9

1.0

1.1

1.2

1.3

1.4

1.5

14 23 32 41 50 59 68 77 86 95 104 113

Outdoor intake air DB temperature(°F)

Capacity correction factors

79

75

68
64

72

Indoor intake air Wet-bulb
temperature( F)

Indoor air Wet-bulb temperature

difference (°F)

71
67
63

65 75 85 95 105 115

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Indoor intake air WB temperature (°F)

SHF at rating condition = 0.82

= 399 CFM

Airflow

Outdoor intake air DB temperature (°F)

Total power consumption

(kW)

71
67
63

65 75 85 95 105 115

0.9

1.0

1.1

1.2

1.3

1.4

1.5

Indoor intake air WB temperature (°F)

SHF at rating condition = 0.77

= 399 CFM

Airflow

Outdoor intake air DB temperature (°F)

Total power consumption

(kW)

OBH747C

Cooling

MUZ-HM09NA MUZ-HM09NA2 MUZ-HM12NA MUZ-HM12NA2

MUZ-HM15NA MUZ-HM15NA2

SHF at rating condition = 0.78

1.5

1.4

1.3

1.2

1.1

(kW)

1.0

0.9

0.8

0.7
65 75 85 95 105 115

Total power consumption

Indoor intake air WB temperature (°F)

Outdoor intake air DB temperature (°F)

Airflow

MUZ-HM24NA MUZ-HM24NA2

SHF at rating condition = 0.89

3.2

3.0

2.8

2.6

2.4

(kW)

2.2

2.0

1.8
65 75 85 95 105 115

Total power consumption

This value of frequency is not the same as the actual frequency in operating. Refer to 7-5 and 7-6 for the relationships
between frequency and capacity.

Indoor intake air WB temperature (°F)

Outdoor intake air DB temperature (°F)

Airflow

= 533 CFM

= 702 CFM

MUZ-HM18NA MUZ-HM18NA2

SHF at rating condition = 0.86

71
67
63

2.0

1.8

1.6

(kW)

1.4

1.2

Total power consumption

65 75 85 95 105 115

Indoor intake air WB temperature (°F)

Outdoor intake air DB temperature (°F)

71
67
63

21

Airflow

= 625 CFM

71
67
63

Heating

p

)

OBH747C

Heating capacity (

1.3

1.2

1.1

1.0

0.9

0.8

0.7

difference (°F)

0.6

0.5

Capacity correction factor

Indoor air Dry-bulb temperature

0.4

-4 5 142332415059
Outdoor intake air WB temperature (°F)

Indoor intake air Dry-bulb temperature ( F)

at Rated frequency)

59
68
79

MUZ-HM09NA MUZ-HM09NA2 MUZ-HM12NA MUZ-HM12NA2

= 406 CFM

1.1

0.9

0.7

(kW)

0.5

Total power consumption

0.3
0 10203040506070

Indoor intake air DB temperature (°F)

Outdoor intake air WB temperature (°F)

Airflow

75
70
65

1.2

1.1

1.0

0.9

0.8

(kW)

0.7

0.6

0.5

Total power consumption

0.4
0 10203040506070

Indoor intake air DB temperature (°F)

Outdoor intake air WB temperature (°F)

Airflow

= 406 CFM

MUZ-HM15NA MUZ-HM15NA2 MUZ-HM18NA MUZ-HM18NA2

2.0

1.7

1.4

(kW)

1.1

0.8

Total power consumption

0.5

-5 5 1525354555

Indoor intake air DB temperature (°F)

Outdoor intake air WB temperature (°F)

Airflow

= 463 CFM

75
70
65

65

2.0

1.7

1.4

(kW)

1.1

0.8

Total power consumption

0.5

-5 5 1525354555

Indoor intake air DB temperature (°F)

Outdoor intake air WB temperature (°F)

Airflow

= 625 CFM

MUZ-HM24NA MUZ-HM24NA2

= 702 CFM

3.2

2.9

2.6

2.3

2.0

(kW)

1.7

1.4

1.1

Total power consumption

0.8

-5 5 1525354555

Indoor intake air DB temperature (°F)

Outdoor intake air WB tem

This value of frequency is not the same as the actual frequency in operating. Refer to 7-5 and 7-6 for the relationships
between frequency and capacity.

Airflow

erature (°F

75
70
65

65

75
70
65

75
70
65

65

22

7-3. CONDENSING PRESSURE

(PSIG)

6870 75 80 85 90

95

100 105

(°F)

260

300

340

380

420

(PSIG)

6870 75 80 85 90

95

100 105

(°F)

110

130

150

170

190

Condensing pressure

86
80
75
70

Suction pressure

Indoor DB temperature (°F)

Outdoor ambient temperature

86

80
75

70

Indoor DB temperature (°F)

Outdoor ambient temperature

4

86

807570

Indoor DB temperature (°F)

e

OBH747C

Cooling

Data are based on the condition of indoor humidity 50 %.
Air flow should be set to High speed.

MUZ-HM09NA MUZ-HM09NA2

440

400

360

86
80
75
70

(PSIG)(PSIG)

200

180

160

Indoor DB temperature (°F)

86

80
75

70

Condensing pressure

320

280

6870 75 80 85 90

MUZ-HM12NA

500

445

390

335

280

70 75 80 85 90 95 100 105

MUZ-HM12NA

Indoor DB temperature (°F)

Outdoor ambient temperature

U1

-

MUZ-HM12NA2

Outdoor ambient temperature

U8

-

MUZ-HM12NA2

95

100 105

U1

-

U8

-

(°F)

Suction pressure

140

120

6870 75 80 85 90 95 100 105

(PSIG)(PSIG)

180

160

140

Suction pressure

120

100

Outdoor ambient temperature

Indoor DB temperature (°F)

70 75 80 85 90 95 100 105

Outdoor ambient temperature

(°F)

86
80

75
70

23

70 75 80 85 90 95 100 105

270

310

350

390

430

470

510

(°F) (°F)

70 75 80 85 90 95 100 105

90

105

120

135

150

165

180

(PSIG)

Condensing pressure

Suction pressure

Outdoor ambient temperature

Indoor DB temperature (°F)

(PSIG)

Indoor DB temperature (°F)

Outdoor ambient temperature

86
80
75
70

86
80

75
70

65 70 75 80 85 90 95 100 105

250

300

350

400

450

500

550

(°F) (°F)

65 70 75 80 85 90 95 100 105

80

100

120

140

160

180

200

(PSIG)

Condensing pressure

Suction pressure

Outdoor ambient temperature

Indoor DB temperature (°F)

(PSIG)

Indoor DB temperature (°F)

Outdoor ambient temperature

86
80
75
70

86
80
75
70

65 70 75 80 85 90 95 100 105

200

250

300

350

400

450

500

(°F) (°F)

65 70 75 80 85 90 95 100 105

60

80

100

120

140

160

180

(PSIG)

Condensing pressure

Suction pressure

Outdoor ambient temperature

Indoor DB temperature (°F)

(PSIG)

Indoor DB temperature (°F)

Outdoor ambient temperature

86
80
75
70

86
80
75
70

MUZ-HM15NA MUZ-HM15NA2

OBH747C

MUZ-HM18NA MUZ-HM18NA2

MUZ-HM24NA MUZ-HM24NA2

Heating

Data are based on the condition of outdoor humidity 75%.
Air flow should be set to High speed.
Data are for heating operation without any frost.

24

MUZ-HM09NA MUZ-HM09NA2 MUZ-HM12NA

75
70

65

75
70
65

(PSIG)

Condensing pressure

Outdoor ambient temperature

(°F) (°F)

(PSIG)

Suction pressure

Outdoor ambient temperature

5 15253545556575

250

300

350

400

450

500

58Hz

Indoor DB temperature (°F)

5 15253545556575

40

65

90

115

140

165

190

Indoor DB temperature (°F)

58Hz

OBH747C

(PSIG) (PSIG)

370

345

75
70
65

U1

-

MUZ-HM12NA2

210

185

U1

-

75
70
65

320

295

270

Condensing pressure

245

220

MUZ-HM12NA

(PSIG) (PSIG)

460

420

380

340

Condensing pressure

300

Indoor DB temperature (°F)

58Hz

5 15253545556575(°F) 5 15253545556575(°F)

Outdoor ambient temperature

U8

-

MUZ-HM12NA2

Indoor DB temperature (°F)

58Hz

U8

-

75
70
65

160

135

110

Suction pressure

85

60

210

185

160

135

110

Suction pressure

85

Indoor DB temperature (°F)

Outdoor ambient temperature

Indoor DB temperature (°F)

58Hz

58Hz

75
70

65

260

5 15253545556575(°F) 5 15253545556575(°F)

Outdoor ambient temperature

MUZ-HM15NA MUZ-HM15NA2

60

Outdoor ambient temperature

25

75
70
65

75
70
65

(PSIG)

Condensing pressure

Outdoor ambient temperature

(°F) (°F)

(PSIG)

Suction pressure

Outdoor ambient temperature

5 15253545556575

250

300

350

400

450

500

550

81Hz

Indoor DB temperature (°F)

5 15253545556575

50

75

100

125

150

175

200

Indoor DB temperature (°F)

81Hz

75
70

65

75
70
65

(PSIG)

Condensing pressure

Outdoor ambient temperature

(°F) (°F)

(PSIG)

Suction pressure

Outdoor ambient temperature

5 15253545556575

250

300

350

400

450

500

58Hz

Indoor DB temperature (°F)

5 15253545556575

50

75

100

125

150

175

200

Indoor DB temperature (°F)

58Hz

MUZ-HM18NA MUZ-HM18NA2

OBH747C

MUZ-HM24NA MUZ-HM24NA2

26

7-4. STANDARD OPERATION DATA

OBH747C

Model MSZ-HM09NA

U1

-

MSZ-HM09NA

U8

-

Item Unit Cooling Heating Cooling Heating
Capacity Btu/h 9,000 10,900 9,000 10,900
SHF — 0.82 — 0.82 —

Total

Input kW 0.750 0.900 0.750 0.900
Rated frequency Hz 59.5 79.0 59.5 77.5
Indoor unit MSZ-HM09NA MSZ-HM09NA

V,

Power supply

phase,

208/230, 1, 60

Hz
Input kW 0.022 0.023 0.022 0.023
Fan motor current A 0.24/0.22 0.25/0.23 0.24/0.22 0.25/0.23

Outdoor unit

Electrical circuit

Power supply

V,

phase,

MUZ-HM09NA

MUZ-HM09NA2

U1

-

U1

-

208/230, 1, 60

MUZ-HM09NA

MUZ-HM09NA2

U8

-

U8

-

Hz
Input kW 0.728 0.877 0.728 0.877
Comp. current A 3.64/3.29 4.25/3.85 3.32/3.00 3.66/3.31
Fan motor current A 0.27/0.24 0.30/0.27 0.27/0.24 0.30/0.27
Condensing pressure PSIG 384 331 389 331
Suction pressure PSIG 152 102 151 103
Discharge temperature ˚F 151 155 154 152
Condensing temperature ˚F 113 101 115 103
Suction temperature ˚F58415939
Comp. shell bottom temperature ˚F 146 149 151 149

Refrigerant circuit

Ref. pipe length ft. 25
Refrigerant charge (R410A) 1 lb. 12 oz.

Intake air temperature

Discharge air temperature

Indoor unit

Fan speed (High) rpm 1,020 1,040 1,020 1,040

DB ˚F80708070

WB ˚F67606760

DB ˚F60976097

WB ˚F58—58—

Airfl ow (High) CFM 367 (Wet) 413 367 (Wet) 413
Intake air temperature

DB ˚F95479547

WB ˚F—43—43
Fan speed rpm 800 850 800 850
Airfl ow CFM 1 151 1225 1151 1225

Outdoor unit

27

7-4. STANDARD OPERATION DATA

OBH747C

Model MSZ-HM12NA

U1

-

MSZ-HM12NA

U8

-

Item Unit Cooling Heating Cooling Heating
Capacity Btu/h 12,000 12,200 12,000 14,400
SHF — 0.77 — 0.77 —

Total

Input kW 1.210 0.990 1.210 0.990
Rated frequency Hz 89.0 90.0 69.0 77.0
Indoor unit MSZ-HM12NA MSZ-HM12NA

V,

Power supply

phase,

208/230, 1, 60

Hz
Input kW 0.022 0.023 0.022 0.023
Fan motor current A 0.24/0.22 0.25/0.23 0.24/0.22 0.25/0.23

Outdoor unit

Electrical circuit

Power supply

V,

phase,

MUZ-HM12NA

MUZ-HM12NA2

U1

-

U1

-

208/230, 1, 60

MUZ-HM12NA

MUZ-HM12NA2

U8

-

U8

-

Hz
Input kW 1.188 0.967 1.188 0.967
Comp. current A 5.61/5.08 4.56/4.13 4.39/3.97 5.41/4.89
Fan motor current A 0.27/0.24 0.30/0.27 0.34/0.31 0.31/0.28
Condensing pressure PSIG 429 347 389 397
Suction pressure PSIG 135 99 133 104
Discharge temperature ˚F 180 165 163 162
Condensing temperature ˚F 120 104 115 116
Suction temperature ˚F60415635
Comp. shell bottom temperature ˚F 174 157 158 158

Refrigerant circuit

Ref. pipe length ft. 25
Refrigerant charge (R410A) 1 lb. 12 oz. 2 lb. 9 oz.

Intake air temperature

Discharge air temperature

Indoor unit

Fan speed (High) rpm 1,020 1,040 1,020 1,040

DB ˚F80708070

WB ˚F67606760

DB ˚F 56 108 56 108

WB ˚F 55 — 55 —

Airfl ow (High) CFM 367 (Wet) 413 367 (Wet) 413
Intake air temperature

DB ˚F95479547

WB ˚F—43—43
Fan speed rpm 800 850 900 860
Airfl ow CFM 1 151 1225 1229 1172

Outdoor unit

28

7-4. STANDARD OPERATION DATA

OBH747C

Model MSZ-HM15NA MSZ-HM18NA MSZ-HM24NA

Item Unit Cooling Heating Cooling Heating Cooling Heating
Capacity Btu/h 14,000 18,000 17,200 18,000 22,500 26,000
SHF — 0.78 — 0.86 — 0.89 —

Total

Input kW 1.17 1.60 1.64 1.59 2.63 2.5
Rated frequency Hz 56.5 74 68 74 98 108
Indoor unit MSZ-HM15NA MSZ-HM18NA MSZ-HM24NA

Power supply

Input kW 0.043 0.030 0.042 0.042 0.055
Fan motor current A 0.43/0.39 0.34/0.31 0.44/0.40 0.44/0.40 0.55/0.50

Outdoor unit

Electrical circuit

Power supply

Input kW 1.127 1.570 1.598 1.548 2.575 2.445
Comp. current A 4.91/4.44 7.11/6.43 7.22/6.53 7.11/6.43 11.11/10.05 10.56/9.55
Fan motor current A 0.41/0.37 0.40/0.36 0.41/0.37 0.40/0.36 1.05/0.95 1.05/0.95
Condensing pressure PSIG 396 427 423 361 404 403
Suction pressure PSIG 138 98 144 99 127 94
Discharge temperature ˚F 168 178 165 161 174 194
Condensing temperature ˚F 115 120 120 108 116 116
Suction temperature ˚F613154355444
Comp. shell bottom temperature ˚F 152 158 149 143 173 192

Refrigerant circuit

Ref. pipe length ft. 25
Refrigerant charge (R410A) 2 lb. 9 oz. 2 lb. 10 oz. 3 lb 9 oz.

Intake air temperature

Discharge air temperature

Indoor unit

Fan speed (High) rpm 1,280 1,140 1,140 1,140 1,250 1,250
Airfl ow (High) CFM 498 (Wet) 463 562 (Wet) 625 632 (Wet) 702

Intake air temperature
Fan speed rpm 910 900 910 900 810 810

Airfl ow CFM 1,243 1,229 1,243 1,229 1,691 1,691

Outdoor unit

V,

phase,

Hz

MUZ-HM15NA

MUZ-HM15NA2

V,

phase,

Hz

DB ˚F807080708070

WB ˚F676067606760

DB ˚F 58 114 58 114 57 108

WB ˚F56—56—56—

DB ˚F954795479547

WB ˚F — 43 — 43 — 43

208/230, 1, 60

MUZ-HM18NA

MUZ-HM18NA2

208/230, 1, 60

MUZ-HM24NA

MUZ-HM24NA2

29

7-5. CAPACITY AND INPUT CORRECTION BY INVERTER OUTPUT FREQUENCY

OBH747C

MUZ-HM09NA - U1 MUZ-HM09NA2 - U1

Correction of Cooling capacity

1.5

1.0

0.5

Capacity correction factors

0.0
0 50 100

The operational frequency of compressor

MUZ-HM09NA - U8 MUZ-HM09NA2 - U8

Correction of Cooling capacity

1.5

1.0

0.5

Capacity correction factors

0 50 100(Hz)

The operational frequency of compressor

Correction of Cooling total input

1.5

1.0

0.5

0.0
050100

The operational frequency of compressor

Correction of Cooling total input

1.5

1.0

0.5

0 50 100(Hz)

The operational frequency of compressor

Correction of Heating capacity

1.5

1.0

0.5

0.0
0 50 100 150

The operational frequency of compressor

Correction of Heating capacity

1.5

1.0

0.5

0 50 100 150(Hz)

The operational frequency of compressor

Correction of Heating total input

2.0

1.5

1.0

0.5

0.0
0 50 100 150

The operational frequency of compressor

Correction of Heating total input

2.0

1.5

1.0

0.5

0 50 100 150(Hz)

The operational frequency of compressor

MUZ-HM12NA - U1 MUZ-HM12NA2 - U1

Correction of Cooling capacity

1.5

1.0

0.5

Capacity correction factors

0.0
0 50 100

The operational frequency of compressor

MUZ-HM12NA - U8 MUZ-HM12NA2 - U8

Correction of Cooling capacity

1.5

1.0

0.5

Capacity correction factors

0 50 100(Hz)

The operational frequency of compressor

Correction of Cooling total input

1.5

1.0

0.5

0.0
050100

The operational frequency of compressor

Correction of Cooling total input

1.5

1.0

0.5

0 50 100(Hz)

The operational frequency of compressor

Correction of Heating capacity

1.5

1.0

0.5

0.0
0 50 100 150

The operational frequency of compressor

Correction of Heating capacity

1.5

1.0

0.5

0 50 100 150(Hz)

The operational frequency of compressor

Correction of Heating total input

2.0

1.5

1.0

0.5

0.0
0 50 100 150

The operational frequency of compressor

Correction of Heating total input

2.0

1.5

1.0

0.5

0 50 100 150(Hz)

The operational frequency of compressor

30

MUZ-HM15NA MUZ-HM15NA2

OBH747C

Correction of Cooling capacity

2.0

Correction of Cooling total input

2.0

Correction of Heating capacity

2.0

Correction of Heating total input

2.0

1.5

1.0

0.5

Capacity correction factors

0 25 50 75 100

The operational frequency of compressor

1.5

1.0

0.5

Input correction factors

(Hz) (Hz)

The operational frequency of compressor

MUZ-HM18NA MUZ-HM18NA2

Correction of Cooling capacity

2.0

1.5

1.0

0.5

Capacity correction factors

0 25 50 75 100

The operational frequency of compressor

2.0

1.5

1.0

0.5

Input correction factors

(Hz) (Hz)

The operational frequency of compressor

MUZ-HM24NA MUZ-HM24NA2

Correction of Cooling capacity

2.0

2.0

0 25 50 75 100

Correction of Cooling total input

0 25 50 75 100

Correction of Cooling total input

1.5

1.0

0.5

Capacity correction factors

0 50 100

The operational frequency of compressor

Correction of Heating capacity

2.0

1.5

1.0

0.5

150

Capacity correction factors

0 50 100

The operational frequency of compressor

Correction of Heating capacity

2.0

150

1.5

1.0

0.5

Input correction factors

(Hz) (Hz)

0 50 100

The operational frequency of compressor

Correction of Heating total input

2.0

1.5

1.0

0.5

150

Input correction factors

(Hz) (Hz)

0 50 100

The operational frequency of compressor

Correction of Heating total input

2.0

150

1.5

1.0

0.5

Capacity correction factors

30 60 90 120 150

0

The operational frequency of compressor

1.5

1.0

0.5

Input correction factors

(Hz) (Hz)

30 60 90 120 150

0

The operational frequency of compressor

1.5

1.0

0.5

Capacity correction factors

30 60 90 120 150

0

The operational frequency of compressor

(Hz) (Hz)

1.5

1.0

0.5

Input correction factors

30 60 90 120 150

0

The operational frequency of compressor

7-6. HOW TO OPERATE FIXED-FREQUENCY OPERATION (Test run 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.

31

8

OBH747C

ACTUATOR CONTROL

MUZ-HM09NA MUZ-HM09NA2 MUZ-HM12NA MUZ-HM12NA2
MUZ-HM15NA MUZ-HM15NA2 MUZ-HM18NA MUZ-HM18NA2
MUZ-HM24NA MUZ-HM24NA2

8-1. 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

8-2. R.V. COIL CONTROL

Heating
Cooling

Dry

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

8-3. RELATION BETWEEN MAIN SENSOR AND ACTUATOR

Discharge temperature
thermistor

Indoor coil temperature
thermistor

Defrost thermistor Heating: Defrosting
Fin temperature thermistor Protection

Ambient temperature
thermistor

Outdoor heat exchanger tem­perature thermistor

Optional parts

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

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

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

Compressor

R.V.coil

Outdoor fan
motor

Sensor Purpose

ON
OFF
OFF

<COOL>

ON
OFF

ON
OFF

ON
OFF

Protection
Cooling: Coil frost prevention

Heating: High pressure protec­tion

Cooling: Low ambient tempera­ture operation

Heating: Defrosting (Heater)

Cooling: Low ambient tempera­ture operation

Cooling: High pressure protec­tion

5 seconds

<HEAT>

5 seconds

Compressor

LEV

○○
○

○○
○○○○○

○○
○○○

○○○
○○○

Actuator

Outdoor fan

motor

R.V. coil

Indoor fan

motor

Defrost

heater

○

32

9

OBH747C

SERVICE FUNCTIONS

MUZ-HM09NA MUZ-HM09NA2 MUZ-HM12NA MUZ-HM12NA2
MUZ-HM15NA MUZ-HM15NA2 MUZ-HM18NA MUZ-HM18NA2
MUZ-HM24NA MUZ-HM24NA2

9-1. CHANGE IN DEFROST SETTING

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 10-6.1.).

Jumper

(Initial setting)

JS

Soldered

None

(Cut)

MUZ-HM09/12

52°F (11°C) 41°F (5°C) 50°F (10°C) 41°F (5°C) 50°F (10°C)

52°F (11°C) 46°F (8°C) 55°F (13°C) 50°F (10°C) 64°F (18°C)

-

U1

MUZ-HM09

9-2. PRE-HEAT CONTROL SETTING

When moisture gets into the refrigerant cycle, it may interfere with the start-up of the compressor at low outside tempera­ture. The pre-heat control prevents this interference. The pre-heat control turns ON when the discharge temperature ther­mistor is 68°F (20°C) or below. When the pre-heat control turns ON, the compressor is energized. (About 50 W)

Pre-heat control setting

<JK>
ON: To activate the pre-heat control, cut JK wire of the inverter P.C. board.
OFF: To deactivate the pre-heat control, solder JK wire of the inverter P.C. board.
(Refer to 10-6.1)

Defrost fi nish temperature

U8

-

MUZ-HM12

-

U8

MUZ-HM15/18 MUZ-HM24

Jumper Pre-heat control setting

Soldered

JK

Cut Activated

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

Deactivated

(Factory setting)

33

10

Lead wiring

<Incorrect>

Connector housing

<Correct>

OBH747C

TROUBLESHOOTING

MUZ-HM09NA MUZ-HM09NA2 MUZ-HM12NA MUZ-HM12NA2
MUZ-HM15NA MUZ-HM15NA2 MUZ-HM18NA MUZ-HM18NA2
MUZ-HM24NA MUZ-HM24NA2

10-1. CAUTIONS ON TROUBLESHOOTING

1. Before troubleshooting, check the following

1) Check the power supply voltage.

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

2. Take care of the following during servicing

1) Before servicing the air conditioner, be sure to turn OFF the main unit first with the remote controller, 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 of 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 connector housing. DO NOT pull the lead wires.

3. Troubleshooting procedure

1)

Check if the OPERATION INDICATOR lamp on the indoor unit is flashing on and off to indicate an abnormality. To make

sure, check how many times the OPERATION INDICATOR lamp is flashing on and off before starting service work. (See
the service manual of the indoor unit for a description of those failure codes.)

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) Refer to 10-2 and 10-3.

34

10-2. FAILURE MODE RECALL FUNCTION

OBH747C

Outline of the function
This air conditioner can memorize the abnormal condition which has occurred once.
Even though LED indication listed on the troubleshooting check table (10-3.) disappears, the memorized failure details can be recalled.

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

Operational procedure

Setting up the failure mode recall function

Judgment of indoor/outdoor abnormality

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

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

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

controller at the same time, press RESET button.

First, release RESET button.

Hold down the other 2 buttons for another 3 seconds. Make sure that the indicators on

the LCD screen shown in the right fi gure are all displayed. Then release the buttons.

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

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

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

Before blinking, does the upper lamp of the OPERATION
INDICATOR lamp stay ON for 3 seconds?
When it stays ON for 3 seconds (without beep): The outdoor unit

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

1

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

No
(OFF)

Yes
(Blinks)

No

2

is abnormal.

2

Indoor unit is normal.
But the outdoor unit might be abnormal because there are some abnor­malities that cannot be recalled with this way.
Check if outdoor unit is abnormal according to the detailed outdoor unit
failure mode recall function. (Refer to 10-2.2)

Yes

The outdoor unit is abnormal.
Check the blinking pattern, and identify the abnormal point by referring
to the outdoor unit failure recall mode table. (Refer to 10-2.3)
Make sure to check at least 2 consecutive blinking cycles.

3

Releasing the failure mode recall function

Deleting the memorized abnormal condition

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 failure parts.

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

function" mentioned above.

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

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

mentioned above.

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

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

2. Blinking pattern when the indoor unit is abnormal:

2.5-second OFF

Blinking at 0.5­second interval

2.5-second OFF

Blinking at 0.5-

second 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

35

Beeps

Blinking at 0.5­second interval

Repeated cycle

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

OBH747C

Operational procedure

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

Make sure that the remote controller is set to the failure mode recall function.

With the remote controller headed towards the indoor unit, press TOO
COOL button to adjust the set temperature to 77°F (25°C).

Does the upper lamp of the 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 upper lamp
of the OPERATION INDICATOR lamp.

Yes
(Blinks

The outdoor unit is abnormal.
Check the blinking pattern, and identify the abnormal point by referring to
the table of outdoor unit failure mode recall function (10-2.3.).
Make sure to check at least 2 consecutive blinking cycles.

Releasing the failure mode recall function

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

Repair the failure parts.

Deleting the memorized abnormal condition

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

function" (10-2.1.).

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

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

tioned above.

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

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

)

1

No

2

(OFF)

2

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

The outdoor unit is normal.

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

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

36

Blinking at 0.5­second interval

Repeated cycle

3. Table of outdoor unit failure mode recall function

OBH747C

NOTE: Blinking patterns of this mode differ from the ones of
TROUBLESHOOTING CHECK TABLE (10-3.).

MUZ-HM09NA MUZ-HM09NA2 MUZ-HM12NA MUZ-HM12NA2

OPERATION

INDICATOR

upper 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

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

Abnormal point

(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

High pressure

Fin temperature/ P.C. board
temperature

Outdoor fan motor

Nonvolatile memory data 5-time fl ash

Discharge temperature

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

—

—

7-time fl ash

2.5 seconds OFF

—

2.5 seconds OFF

—

Condition Remedy

Overcurrent protection cut-out operates
3 consecutive times within 1 minute
after the compressor gets started.

Thermistor shorts or opens during
compressor running.

Large current fl ows into intelligent
power module/ power module

Waveform of compressor current is
distorted.

Temperature of discharge temperature
thermistor exceeds 241°F (116°C),
compressor stops.
Compressor can restart if discharge
temperature thermistor reads 212°F
(100°C) or less 3 minutes later.

Temperature of indoor coil thermistor
exceeds 158°F (70°C) in HEAT mode.
Temperature of outdoor heat exchanger
temperature thermistor exceeds 158°F
(70°C) in COOL mode.

Temperature of fi n temperature
thermistor on the inverter P.C. board
exceeds 167 - 176°F (75 - 80°C), or
temperature of P.C. board temperature
thermistor on the inverter P.C. board
exceeds 158 - 167°F (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 122°F (50°C) or
less for 20 minutes.

1.

Reconnect connectors.

•
Refer to 10-5.

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

•
Refer to 10-5. "Check

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

Reconnect compressor

•
connector.
Refer to 10-5.

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

•
Reconnect compressor

•
connector.
Refer to 10-5.

•
to check inverter/
compressor".

Check the refrigerant

•
circuit and the
refrigerant amount.
Refer to 10-5.

•
of LEV".

Check the refrigerant

•
circuit and the
refrigerant amount.
Check the stop valve.

•

Check around the

•
outdoor unit.
Check the outdoor unit

•
air passage.
Refer to 10-5.

•
of outdoor fan motor".

Refer to 10-5. "Check

•
of outdoor fan motor".
Refer to 10-5.
of inverter P.C. board".

Replace the inverter

•
P.C. board.

Refer to 10-5. "Check

•
of LEV".
Check the refrigerant

•
circuit and the
refrigerant amount.

"How

"How

"How

"Check

"Check

"Check

Indoor/

outdoor unit

failure mode

recall function

Outdoor unit
failure mode

recall function

○○

○○

—

—

—

—

—

—

○○

—

○

○

○

○

○

○

○

37

OPERATION

OBH747C

INDICATOR

upper lamp

(Indoor unit)

11-time fl ash

2.5 seconds
OFF

12-time fl ash

2.5 seconds
OFF

14-time fl ash

2.5 seconds
OFF

Abnormal point

(Failure mode / protection)
DC voltage 8-time fl ash
Each phase current of

compressor
Overcurrent Compressor open-

phase

Stop valve (Closed valve) 14-time fl ash

4-way valve/
Pipe temperature

Outdoor refrigerant
system abnormality (MUZ-

HM09/12NA(2)

U1

-

)

LED indication

(Outdoor P.C. board)

2.5 seconds OFF
9-time fl ash

2.5 seconds OFF
10-time fl ash

2.5 seconds OFF

2.5 seconds OFF

16-time fl ash

2.5 seconds OFF

1-time fl ash

2.5 seconds OFF

NOTE: Blinking patterns of this mode differ from the ones of
TROUBLESHOOTING CHECK TABLE (10-3.).

Condition Remedy

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)/power module

1.

(IPM)
The open-phase operation of
compressor is detected.
The interphase short circuit occurs
in the output of the intelligent power
module (IPM)/power module (IPM)
The compressor winding shorts circuit.

Closed valve is detected by compressor
current.

The 4-way valve does not work
properly.
The indoor coil thermistor detects an
abnormal temperature.

A closed valve and air trapped in the
refrigerant circuit are detected based on
the temperature sensed by the indoor
and outdoor thermistors and the current
of the compressor.

1.

Refer to 10-5.

•
to check inverter/

compressor".

Reconnect compressor

•
connector.
Refer to 10-5.

•
to check inverter/
compressor".

Check the stop valve

•

Check the 4-way valve.

•

Replace the inverter

•

P.C. board.

Check for a gas leak

•

in a connecting piping
etc.
Check the stop valve.

•

Refer to 10-5.

•

“Check of outdoor
refrigerant circuit”.

"How

"How

Indoor/

outdoor unit

failure mode

recall function

—

—

Outdoor unit
failure mode

recall function

○

○

○○

○○

38

MUZ-HM15NA MUZ-HM15NA2

OBH747C

MUZ-HM18NA MUZ-HM18NA2
MUZ-HM24NA MUZ-HM24NA2

The upper

lamp of the

OPERATION

INDICATOR

lamp

(Indoor unit)

OFF None (Normal) — — — — —
1-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

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

Abnormal point

(Failure mode/protection)

Indoor/outdoor communication,
receiving error

Indoor/outdoor communication,
receiving error

Outdoor power system

Discharge temperature
thermistor

Defrost thermistor
Fin temperature thermistor 3-time fl ash

P.C. board temperature
thermistor

Ambient temperature
thermistor

Outdoor heat exchanger
temperature thermistor

Overcurrent 11-time fl ash

Compressor synchronous
abnormality (Compressor start­up failure protection)

Discharge temperature

High pressure

Fin temperature/ P.C. board
temperature

Outdoor fan motor

Nonvolatile memory data 5-time fl ash
Power module (IPM) (MUZ-

HM09/12NA(2)
(MUZ-HM09/12/15/18/24NA(2)

U1

-

)

-

U8

)/(IC700)

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

—

—

7-time fl ash

2.5 seconds OFF

—

2.5 seconds OFF

6-time fl ash

2.5 seconds OFF

Any signals from the inverter P.C.
board cannot be received normally for
3 minutes.

Although the inverter P.C. board
sends signal "0", signal "1" has been
received 30 consecutive times.
Overcurrent protection cut-out
operates 3 consecutive times within
1 minute after the compressor gets
started.

Thermistor shorts or opens during
compressor running.

Large current fl ows into the
power module (IPM) (MUZ-

HM09/12NA(2)
HM09/12/15/18/24NA(2)

Waveform of compressor current is
distorted.

Temperature of discharge temperature
thermistor exceeds 241°F (116°C),
compressor stops.
Compressor can restart if discharge
temperature thermistor reads
212°F (100°C) or less 3 minutes later.

Temperature indoor coil thermistor
exceeds 158°F (70°C) in HEAT
mode. Temperature defrost thermistor
exceeds 158°F (70°C) in COOL mode.

Temperature of the fi n temperature
thermistor on the inverter P.C. board
exceeds 167 - 187°F (75 - 86°C), or
temperature of P.C. board temperature
thermistor on the inverter P.C. board
exceeds 162 - 185°F (72 - 85°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.

The interface short circuit occurs in
the output of the power module (IPM)

(MUZ-HM09/12NA(2)
(MUZ-HM09/12/15/18/24NA(2)
The compressor winding shorts circuit.

NOTE: Blinking patterns of this mode differ from the ones of
TROUBLESHOOTING CHECK TABLE (10-3.).

Indoor/outdoor

Condition Remedy

How

How

"How

"How

"How

"Check

"Check

"Check

"How

U8

-

)/(IC700) (MUZ-

-

U1

-

U8

)/(IC700)

•Refer to 10-5.
to check miswiring and
serial signal error.

•Refer to 10-5.
to check miswiring and
serial signal error.
Reconnect

•
connectors.
Refer to 10-5.

•
to check inverter/

compressor".
Check stop valve.

•
Refer to 10-5.

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

Reconnect

•
compressor connector.
Refer to 10-5.

•

).

to check inverter/
compressor".
Check stop valve.

•
Reconnect

•
compressor connector.
Refer to 10-5.

•
to check inverter/
compressor".

Check refrigerant

•
circuit and refrigerant
amount.
Refer to 10-5.

•
of LEV".

Check refrigerant

•
circuit and refrigerant
amount.
Check stop valve.

•
Check around outdoor

•
unit.
Check outdoor unit air

•
passage.
Refer to 10-5.

•
of outdoor fan motor".

Refer to 10-5. "Check

•
of outdoor fan motor".
Refer to 10-5.
of inverter P.C. board".

Replace the inverter

•
P.C. board.

Refer to 10-5.

•
to check inverter/
compressor".

U1

-

).

unit failure

mode recall

function

○○

○○

○○

—

—

—

—

—

—

○○

Outdoor unit
failure mode

recall function

○

○

○

○

○

○

39

The upper

OBH747C

lamp of the

OPERATION

INDICATOR

lamp

(Indoor unit)

10-time fl ash

2.5 seconds
OFF

11-time fl ash

2.5 seconds
OFF

14-time fl ash
or more

2.5 seconds
OFF

Abnormal point

(Failure mode/protection)

Discharge temperature

DC voltage 8-time fl ash

Each phase current of
compressor

Stop valve (Closed valve) 14-time fl ash

4-way valve/
Pipe temperature

Outdoor refrigerant system
abnormality

LED indication

(Outdoor P.C. board)

—

2.5 seconds OFF
9-time fl ash

2.5 seconds OFF

2.5 seconds OFF

16-time fl ash

2.5 seconds OFF

1-time fl ash

2.5 seconds OFF

NOTE: Blinking patterns of this mode differ from the ones of
TROUBLESHOOTING CHECK TABLE (10-3.).

Condition Remedy

Temperature of discharge temperature
thermistor has been 122°F (50°C) or
less for 20 minutes.

DC voltage of inverter cannot be
detected normally.

Each phase current of compressor
cannot be detected normally.

Closed valve is detected by
compressor current.

The 4-way valve does not work
properly.
The indoor coil thermistor detects an
abnormal temperature.

A closed valve and air trapped in the
refrigerant circuit are detected based
on the temperature sensed by the
indoor and outdoor thermistors and the
current of the compressor.

Refer to 10-5.

•
of LEV".

Check refrigerant

•
circuit and refrigerant
amount.

Refer to 10-5. "How

•
to check inverter/
compressor".

Check stop valve.

•

Check the 4-way

•
valve.
Replace the inverter

•
P.C. board.

Check for a gas leak

•
in a connecting piping
etc.
Check the stop valve.

•
Refer to 10-5.

•
“Check of outdoor

refrigerant circuit”.

"Check

Indoor/outdoor

unit failure

mode recall

function

—

—

Outdoor unit
failure mode

recall function

○

○

○○

○○

40

10-3. TROUBLESHOOTING CHECK TABLE

OBH747C

No. Symptom LED indication

Outdoor unit
does not op­erate.

1

2

3

4
5

6

7

'Outdoor unit
stops and
restarts 3

8

minutes later'
is repeated.

9

10

11

12

13

14
15

NOTE: 1. The location of LED is illustrated at the right fi gure. Refer to 10-6.1.

2. LED is lighted during normal operation.

3. Blinking patterns of this mode differ from the ones of the failure recall mode.
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

1-time fl ash every

2.5 seconds

6-time fl ash

2.5 seconds OFF
11-time fl ash

2.5 seconds OFF

16-time fl ash

2.5 seconds OFF

17-time fl ash

2.5 seconds OFF
(MUZ-

HM09/12/15/18/
24NA(2)

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

U1

-

Abnormal point/

Condition
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
4-way valve/

Pipe temperature

Outdoor refrigerant
system 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.

0.5-second ON

2.5-second OFF

Overcurrent protection cut-out operates 3 consecutive times
within 1 minute after the compressor gets started.

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

Nonvolatile memory data cannot be read properly.
(The upper lamp of the OPERATION INDICATOR lamp on the

indoor unit lights up or fl ashes 7-time.)

for 3 minutes.
Closed valve is detected by compressor current.

The 4-way valve does not work properly.
The indoor coil thermistor detects an abnormal temperature.

A closed valve and air trapped in the refrigerant circuit are
detected based on the temperature sensed by the indoor and
outdoor thermistors and the current of the compressor.

Large current fl ows into the power module (IPM) (MUZ-

HM09/12NA(2)

U1

-

).

When overcurrent protection occurs within 10 seconds after

compressor starts, compressor restarts after 15 seconds
(MUZ-HM09/12NA).

Temperature of discharge temperature thermistor exceeds
241°F (116°C), compressor stops. Compressor can restart if
discharge temperature thermistor reads 212°F (100°C) or less
3 minutes later.

Temperature of the fi n temperature thermistor on the heat sink
exceeds 167 - 176°F (75 - 80°C) (MUZ-HM09/12NA(2))/167 ­187°F
(75 - 86°C) (MUZ-HM15/18/24NA(2)) or temperature of P.C.
board temperature thermistor on the inverter P.C. board ex­ceeds 158 - 167°F (70 - 75°C) (MUZ-HM09/12NA(2))/162 ­185°F (72 - 85°C) (MUZ-HM15/18/24NA(2)).
Indoor coil thermistor exceeds 158°F (70°C) in HEAT mode.
Defrost thermistor exceeds 158°F (70°C) in COOL mode.

The waveform of compressor current is distorted.

after outdoor fan start-up.

Each phase current of compressor cannot be detected nor­mally.

-

Condition Remedy

U8

)/(IC700) (MUZ-HM09/12/15/18/24NA(2)

0.5-second ON

Reconnect connector of compres-

•
sor.
Refer to 10-5.

•
inverter/compressor".

Check stop valve.

•
Refer to 10-5.

•
thermistors".

Replace inverter P.C. board.

•

Refer to 10-5.

•
miswiring and serial signal error.

Check stop valve.

•
Refer to 10-5.

•
coil".
Replace the inverter P.C. board.

•
Check for a gas leak in a

•
connecting piping etc.
Check the stop valve.

•
Refer to 10-5.

•
refrigerant circuit”.

Reconnect connector of compressor.

•
Refer to 10-5. "How to check

•
inverter/compressor".
Check stop valve.

•

Check refrigerant circuit and refrig-

•
erant amount.
Refer to 10-5.

•
Check around outdoor unit.

•
Check outdoor unit air passage.

•
Refer to 10-5.

•
fan motor".

Check refrigerant circuit and refrig-

•
erant amount.
Check stop valve.

•
Reconnect connector of compressor.

•
Refer to 10-5.

•
inverter/compressor".

Refer to 10-5.

•
fan motor.
Refer to 10-5.

•
P.C. board.

Refer to 10-5.

•
inverter/compressor".

Refer to 10-5.

•
verter/compressor".

Inverter P.C. board

MUZ-HM09/12NA(2)

MUZ-HM15/18/24NA(2)

Flashing →

"How to check

"Check of outdoor

"How to check

"Check of R.V.

“Check of outdoor

"Check of LEV".

"Check of outdoor

"How to check

"Check of outdoor
"Check of inverter

"How to check
"How to check in-

LED

Flashing →

LED

41

No. Symptom LED indication

OBH747C

Outdoor unit
operates.

16

16

18

19

Outdoor unit
operates.

20

21

22

NOTE: 1. The location of LED is illustrated at the right fi gure. Refer to 10-6.1.

2. LED is lighted during normal operation.

3. Blinking patterns of this mode differ from the ones of the failure recall mode.
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

1-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

7-time fl ash

2.5 seconds OFF

8-time fl ash

2.5 seconds OFF

9-time fl ash

2.5 seconds OFF

Abnormal point/

Condition
Frequency drop by
current protection

Frequency drop by
high pressure pro­tection

Frequency drop by
defrosting in COOL
mode

Frequency drop by
discharge tempera­ture protection

Outside temperature
thermistor protec­tion

Low discharge tem­perature protection

PAM protection
PAM: Pulse Ampli­tude Modulation

Zero cross detecting
circuit
(MUZ-HM09/12NA(2))

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

0.5-second ON

2.5-second OFF

MUZ-HM
09/12NA(2)

MUZ-HM15/
18/24NA(2)

Temperature of indoor coil thermistor exceeds 131 °F (55°C)
in HEAT mode, compressor frequency lowers.

Indoor coil thermistor reads 46°F (8°C) or less in COOL mode,
compressor frequency lowers.

Temperature of discharge temperature thermistor exceeds
232°F (111°C), compressor frequency lowers.

When the outside temperature thermistor shorts or opens,
protective operation without that thermistor is performed.

Temperature of discharge temperature thermistor has been
122°F (50°C) or less for 20 minutes.

The overcurrent fl ows into IGBT (Insulated Gate Bipolar tran-
sistor: TR821) (MUZ-HM09/12NA(2)

correction: IC820) (MUZ-HM09/12/15/18/24NA(2)
DC voltage reaches 320 V (MUZ-HM09/12NA(2)
(MUZ-HM09/12/15/18/24NA(2)

restarts.

Zero cross signal for PAM control cannot be detected.

mode starts.

Current from power outlet is nearing Max. fuse
size.

When the input current exceeds approximately

10.5 A, compressor frequency lowers.

Condition Remedy

U8

-

)/PFC (Power factor

U1

-

) or more, PAM stops and

0.5-second ON

-

-

U8

U1

) or the

)/394 V

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

•
circulation is short cycled.

Check refrigerant circuit and refrig-

•
erant amount.
Refer to 10-5.

•
Refer to 10-5.

•
thermistors".

Refer to 10-5.

•
thermistors.

Refer to 10-5.

•
Check refrigerant circuit and refrig-

•
erant amount.

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 10-5.
inverter/compressor".

Inverter P.C. board

MUZ-HM09/12NA(2)

MUZ-HM15/18/24NA(2)

Flashing →

"Check of LEV".
"Check of outdoor

Check of outdoor

"Check of LEV".

"How to check

Flashing →

LED

LED

42

10-4. TROUBLE CRITERION OF MAIN PARTS

OBH747C

MUZ-HM09NA MUZ-HM09NA2 MUZ-HM12NA MUZ-HM12NA2
MUZ-HM15NA MUZ-HM15NA2 MUZ-HM18NA MUZ-HM18NA2
MUZ-HM24NA MUZ-HM24NA2

Part name Check method and criterion Figure

Defrost thermistor (RT61)
Fin temperature

thermistor (RT64)

Measure the resistance with a tester.

Ambient temperature thermis­tor (RT65)

Outdoor heat exchanger tem­perature thermistor (RT68)

Discharge temperature ther­mistor (RT62)

Compressor

Outdoor fan motor

R. V. coil (21S4)

Refer to 10-6. “Test point diagram and voltage”, 1. “Inverter P.C.
board”, for the chart of thermistor.

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

Refer to 10-6. “Test point diagram and voltage”, 1. “Inverter P.C.
board”, for the chart of thermistor.

Measure the resistance between terminals using a tester.
[Temperature: 14 - 104°F (-10 - 40°C)]

Normal (Ω)

HM09/12

-

U1

HM09

-

U8

HM12

-

U8

HM15/18/24

U-V

U-W

1.26 - 1.72 1.36 - 1.93 1.52 - 2.17 0.82 - 1.11

V-W

Measure the resistance between lead wires using a tester.
[Temperature: 14 - 104°F (-10 - 40°C)]

Color of lead wire

HM09/12/15/18 HM24

Normal (Ω)

RED – BLK

BLK – WHT

29 - 40 12 - 16

WHT – RED

Measure the resistance using a tester.
[Temperature: 14 - 104°F (-10 - 40°C)]

Normal (kΩ)

0.97 - 1.38

WHT

V

WHT

V

RED BLK

W

U

RED BLK

W

U

Measure the resistance using a tester.
[Temperature: 14 - 104°F (-10 - 40°C)]

Expansion valve coil (LEV)

Measure the resistance using a tester.

Defrost heater

[Temperature: 14 - 104°F (-10 - 40°C)]

(Optional parts)

Color of lead wire Normal (Ω)

RED – ORN
RED – WHT

RED – BLU

37 - 54

RED – YLW

Normal (Ω)

349 - 428

43

WHT
ORN

RED

(+12V)

LEV

YLW

BLU

10-5. TROUBLESHOOTING FLOW

OBH747C

A How to check inverter/compressor

Disconnect the connector between the compressor and the

-

power module (IPM) (MUZ-HM09/12NA(2)

-

(MUZ-HM09/12NA(2)

U1

, MUZ-HM

Check the voltage between terminals.

Are the voltages balanced?

Yes

Check the compressor.

U8

)/(IC700)

15/18/24NA(2))

No

See 10-5. “Check of open phase”.

Replace the inverter P.C. board.

See 10-5. “Check of compressor”.

B Check of open phase

-

● With the connector between the compressor and the power module (IPM) (MUZ-HM09/12NA(2)

-

U1

HM09/12NA(2)

, MUZ-HM15/18/24NA(2)) disconnected, activate the inverter and check if the inverter is normal by meas-

uring the voltage balance between the terminals.
Output voltage is 50 - 130 V. (The voltage may differ according to the tester.)
<< Operation method>>

Start cooling or heating operation by pressing EMERGENCY OPERATION switch on the indoor unit. (TEST RUN OPERA-

TION: Refer to 7-6.)
<<Measurement point>>
At 3 points
BLK (U)-WHT (V)

Measure AC voltage between the lead wires at 3 points.

BLK (U)-RED (W)
WHT(V)-RED (W)

U8

)/(IC700) (

MUZ-

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 10-6.1.)

C Check of compressor

Refer to 10-5. “Check of compressor
winding”.
Is the compressor normal?

Yes

Refer to 10-5. “Check of compressor
operation time”.
Does the compressor operate continuously?

Yes

OK

No

No

Replace the compressor.

Refer to 10-5.

“Check of compressor start failure”.

44

D Check of compressor winding

OBH747C

●Disconnect the connector between the compressor and the power module (IPM) (MUZ-HM09/12NA(2)

HM09/12NA(2)

<<Measurement point>>
At 3 points
BLK-WHT
BLK-RED
WHT-RED
<<Judgement>>
Refer to 10-4.
0 [Ω] ················Abnormal [short]
Infinite [Ω] ·······Abnormal [open]
NOTE: Be sure to zero the ohmmeter before measurement.

-

U1

, MUZ-HM15/18/24NA(2)), and measure the resistance between the compressor terminals.

Measure the resistance between the lead wires at 3 points.

E Check of compressor operation time

<<Judgement>>

-

U8

)/(IC700) (

MUZ-

● Connect the compressor and activate the inverter. Then measure
the time until the inverter stops due to overcurrent.
<<Operation method>>
Start heating or cooling operation by pressing EMERGENCY
OPERATION switch on the indoor unit. (TEST RUN OPERATION:
Refer to 7-6.)
<<Measurement>>
Measure the time from the start of compressor to the stop of
compressor due to overcurrent.

F Check of compressor start failure

Confi rm that ~ is normal.

•Electrical circuit check
. Contact of the compressor connector
. Output voltage of inverter P.C. board and balance of them (See 10-5. )
. Direct current voltage between DB61(+) and (-) on the inverter P.C. board
. Voltage between outdoor terminal block S1-S2

0 second
1 second

2 seconds

10 seconds

10 minutes

Compressor starts
Abnormal

((IPM) (MUZ-HM09/12NA(2)
(IC700) (
MUZ-HM15/18/24NA(2)) failure)
(Compressor winding short)

Abnormal
(Compressor lock out)
(Starting defect)

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

Abnormal
(Refrigerant circuit defect)
(Closed valve)

Normal

MUZ-HM09/12NA(2)

-

-

U8

)/

U1

,

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

No

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

1

Yes

Compressor start failure. Activate pre-heat control.
(Refer to 9-2. "PRE-HEAT CONTROL SETTING")

Yes

No

Check the refrigerant circuit.
Check the stop valve.

Replace the compressor.

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

Heating part

45

G Check of outdoor thermistors

OBH747C

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

Is the resistance of thermistor normal?
(Refer to 10-6.1.)

Yes

No

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

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?

No

Replace the inverter P.C. board.

Yes

OK
(Cause is poor contact.)

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

Inverter P.C. board
Ambient temperature RT65 Between CN643 pin1 and pin2
Outdoor heat exchanger temperature RT68 Between CN644 pin1 and pin3

H Check of R.V. coil

First of all, measure the resistance of R.V. coil to check if the coil is defective. Refer to 10-4.
Check if there is 208/230 VAC at L1 - L2.
In case CN721 is disconnected or R.V. coil is open, voltage is generated between the terminal pins of the connector

although no signal is being transmitted to R.V. coil.

Check if CN721 is connected.

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

Disconnect connector between the
compressor and the power module

-

(IPM) (MUZ-HM09/12NA(2)
(IC700) (

MUZ-HM09/12NA(2)

U8

)/

-

U1

, MUZ-

HM15/18/24NA(2)).

Turn ON the power supply and press
EMERGENCY OPERATION switch twice
(HEAT mode).

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

Disconnect connector between the
compressor and the power module
(IPM) (MUZ-HM09/12NA(2)
(IC700) (

MUZ-HM09/12NA(2)

HM15/18/24NA(2)).

Turn ON the power supply and press
EMERGENCY OPERATION switch once
(COOL mode).

-

U8

)/

-

U1

, MUZ-

Is there 208/230 VAC between CN721
and

on the inverter P.C. board
3 minutes after the power supply is turned
ON?

Yes

Replace the 4-way valve.

Is there 208/230 VAC between CN721
and

on the inverter P.C. board
3 minutes after the power supply is turned
ON?

No

Replace the 4-way valve.

46

Replace the inverter
P.C. board.

No

Replace the inverter
P.C. board.

Yes

I Check of outdoor fan motor

OBH747C

Check the connection between the
connector CN931 and CN932.
Disconnect the connectors CN931
and CN932 from the inverter P.C.
board.

Is the resistance between each ter­minal of outdoor fan motor normal?
(Refer to 10-4.)

No

Yes

Disconnect CN932 from 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 inverter P.C. board.

Yes

47

J Check of power supply

OBH747C

Disconnect the connector between the
compressor and the power module (IPM)
(MUZ-HM09/12NA(2)

HM09/12NA(2)

Turn ON power supply and press
EMERGENCY OPERATION switch.

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

-

U8

-

U1

)/(IC700) (

, MUZ-HM15/18/24NA(2)).

Yes

MUZ-

No

Rectify indoor/outdoor
connecting wire.

No

Is there voltage 208/230 VAC
between the indoor terminal
block S1 and S2?

Replace the indoor
electronic control P.C.

Yes

board.

Is there DC voltage 260 - 325 VDC

-

(MUZ-HM09/12NA(2)
370 VDC (

MUZ-HM09/12NA(2)

U8

)/260 -

-

U1

, MUZ-HM15/18/24NA(2)) between

DB61 (+) and DB61 (–) on the
inverter P.C. board?
(Refer to 10-6.1.)

No

Check the electric parts in main circuit.

260 - 325 VDC (MUZ-HM09/12NA(2)
260 - 370 VDC (MUZ-HM09/12NA(2)

DB61

Inverter P.C. board
(Solder side)

Yes

Does LED on the inverter P.C.
board light up or fl ash?
(Refer to 10-6.1.)

Yes

If lights up, OK.
If fl ashes, refer to 10-3.

-

U8

)

-

U1

, MUZ-HM15/18/24NA(2))

Replace the inverter

No

P.C. board.

48

K Check of LEV (Expansion valve)

OBH747C

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

While pressing both OPERATION SELECT button
and TOO COOL button on the remote controller at the
same time, press RESET button.
First, release RESET button.

Hold down the other 2 buttons for another 3 seconds.

Make sure that the indicators on the LCD screen
shown in the right fi gure are all displayed. Then re-
lease the buttons.

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

Expansion valve operates in full-opening direction.

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

No

Yes

OK

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

Is LEV coil properly fi xed to
the expansion valve?

Yes

Does the resistance of LEV
coil have the characteristics?
(Refer to 10-4.)

No

Replace the LEV coil.

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

1. Turn OFF the power supply and turn it ON 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

tester.

Replace the expansion valve.

Yes

Replace the inverter P.C.

No

board.

49

L Check of inverter P.C. board

OBH747C

Check the outdoor fan motor.
(Refer to 10-5.

.)

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

No

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?

Yes
(10-time fl ash)

Replace the inverter P.C. board.

Yes

No

Check the corresponding parts
following LED indication.
(Refer to 10-3.)

50

M How to check miswiring and serial signal error

OBH747C

MUZ-HM09/12NA(2)

Is the bus-bar voltage of the inverter P.C. board normal? (Refer to "TEST POINT DIAGRAM AND
VOLTAGE" in the outdoor service manual.)

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 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.
Bridge the outdoor terminal block S2 and

1

S3.

Turn ON the power supply.

Yes

Yes

Yes

Yes

A

Yes

No

No

No

1. Miswiring may damage indoor electronic control P.C.

3. Be sure to check this within 3 minutes after turning ON.

Check the power supply.

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

board during the operation.
Be sure to confi rm the wiring is correct before the opera-
tion starts.

After 3 minutes, LED blinks 6 times. Even when the
inverter P.C. board is normal, LED blinks 6 times after 3
minutes.

No

No

Check the wiring.

Correct them.

Yes

Check of power supply.
(Refer to 10-5. .)

No

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

Turn OFF the power supply.
Remove the bidge between the outdoor terminal block S2 and S3.
Turn ON the power supply.

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

Is there amplitude of 10 to 20 VDC between the indoor terminal block
S2 and S3? <Confi rmation of serial signal>

A

• Turn OFF inverter-controlled lighting
equipment.

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

• Press EMERGENCY OPERATION
switch.

• Reinstall
either the unit
or the light
away from

Is serial signal
error indicated 6
minutes later?

Yes

B

each other.

• Attach a fi lter

No

on remote
control receiv­ing section
of the indoor
unit.

3

Yes

Yes

Yes

Is there 2 VDC or less between CN10A (+)
and JPG (GND)(-) on the indoor electronic
control P.C. board?

Yes

Is there 2 VDC or less between
CN10A (+) and JPG (GND)(-) on
the indoor electronic control P.C.
board?

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

No

No Yes No

No
(Lighted
or not
lighted)

Check the wiring
If there are any error of the indoor/outdoor connecting wire:
such as the damage of the wire, intermediate connection,

No

and/or poor contact to the terminal block, replace the indoor/
outdoor connecting wire.

No

Replace the indoor elec­tronic control P.C. board.

Replace the inverter P.C. board. 2

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

Is there 2 VDC or less between
CN10A (+) and JPG (GND)(-) on
the indoor electronic control P.C.
board?

Yes

51

MUZ-HM15/18/24NA(2)

OBH747C

Turn OFF the power supply.

NOTE: Refer to the indoor unit service manual.

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 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.
Bridge the outdoor terminal block S2 and

1

S3.

Turn ON the power supply.

Is the bus-bar voltage of the inverter P.C. board normal? (Refer to "TEST POINT DIAGRAM AND
VOLTAGE" in the outdoor service manual.)

Yes

Yes

Yes

Yes

A

Yes

No

No

No

1. Miswiring may damage indoor electronic control P.C.

3. Be sure to check this within 3 minutes after turning ON.

(Except for outdoor unit of multi system type)

Check the power supply.

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

board during the operation.
Be sure to confi rm the wiring is correct before the opera-
tion starts.

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.

No

No

Check the wiring.

Correct them.

Yes

No

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

Is there amplitude of 10 to 20 VDC between the indoor terminal block
S2 and S3? <Confi rmation of serial signal>

A

• Turn OFF inverter-controlled lighting
equipment.

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

• Press EMERGENCY OPERATION
switch.

• Reinstall
either the unit
or the light
away from

Is serial signal
error indicated 6
minutes later?

Yes

B

each other.

• Attach a fi lter

No

on remote
control receiv­ing section
of the indoor
unit.

3

Yes

Turn OFF the power supply.
Remove the bridge between outdoor terminal block S2 and S3.

Turn on the power supply.

No

Yes

Is there 2 VDC or less between CN10A (+)
and GND (-) on the indoor electronic control
P.C. board?

Yes

Is there 2 VDC or less between
CN10A
the indoor electronic control P.C.
board?

Replace the indoor power
P.C. board.

No

(+) and GND (-) on

No Yes No

Replace the indoor elec­tronic control P.C. board.

52

No
(Lighted
or not
lighted)

Replace the inverter P.C. board. 2

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

Is there 2 VDC or less between
CN10A
the indoor electronic control P.C.
board?

(+) and GND (-) on

Yes

N Check of defrost heater

OBH747C

Check the following points before checking electric continuity.

1. Does the resistance of ambient temperature thermistor have the characteristics? Refer to 10-6.1.

2. Is the resistance of defrost heater normal? Refer to 10-4.

3. Does the heater protector remain conducted (not open)?

4. Are both ambient temperature thermistor and circuit of defrost heater securely connected to connectors?
In HEAT mode, for more than 5 minutes, let the ambient temperature thermistor continue to read

32°F (0°C) or below, and let the defrost thermistor continue to read 30°F (-1°C) or below.

NOTE: In case both thermistors are more than the above temperature, cool them with cold

(Optional parts)

water etc...

Is there 208/230 VAC between CN722 and
on the inverter P.C. board? Refer to 10-6.1.

No

Replace the inverter P.C. board.

O Check of outdoor refrigerant circuit

Has the operation stopped
during pump down?

Yes

The operation has stopped to pre­vent the diesel explosion caused by
air trapped in the refrigerant circuit.
Close the stop valve, and disconnect
the power plug or turn the breaker
OFF.

No

Was the operation started with
the stop valve closed, and was
it opened during operation?

The refrigerant gas amount may be
60% or less than the normal amount.
Identify where the gas is leaking from,
and fi x the leak.

Yes

Not the problem of the inverter P.C. board.

(MUZ-HM09/12/15/18/24NA(2)

Yes

No

-

U1

)

The unit occasionally stops when the
stop valve is opened or closed during
operation. Open the stop valve and
start the cooling operation again.

CAUTION : Do not start the opera-

tion again to prevent
hazards.

53

P Electromagnetic noise enters into TV sets or radios

OBH747C

Is the unit grounded?

Yes

Is the distance between the antennas
and the indoor unit within 9.91 ft.
or is the distance between the antennas
and the outdoor unit within 9.91 ft.

No

Is the distance between the TV sets or ra­dios and the indoor unit within 3.28 ft.
or is the distance between the TV sets or
radios and the outdoor unit within

9.91 ft.

(3m)

?

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

(3m)

(3m)

(1m)

No

,

Yes

?

,

Yes

Yes

Yes

Ground 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, ground wire, antennas, wiring from antennas, receiver

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

6. Presence or absence of amplifi er such as booster

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

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

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

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

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

54

10-6. TEST POINT DIAGRAM AND VOLTAGE

-4 14 32 50 68 86 104

0

10

20

30

40

50

60

70

80

90

100

Temperature(°F)

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

32 50 68 86 104 122 140 158 176

0

20

40

60

80

100

120

140

160

180

200

Temperature(°F)

Fin temperature thermistor(RT64)

5HVLVWDQFHN

5HVLVWDQFHN

Temperature (°F)

Discharge temperature thermistor (RT62)

5HVLVWDQFHN

0

100

200

300

400

500

600

700

800

32 50 68 86 104 122 140 158 176 194 212 230 248

OBH747C

1. Inverter P.C. board

U1

MUZ-HM09NA
MUZ-HM09NA2

Back side of unit

208/230 VAC

Fuse (F901)
T3.15AL250V

Output to
drive outdoor
fan motor
(CN932)

Output to
drive
compressor
(LDU,
LDV,
LDW)

-

MUZ-HM12NA

U1

-

MUZ-HM12NA2

DB61
260 - 370 VDC

-

(+)(-)

U1

U1

-

Smoothing
capacitor (C62)

Smoothing
capacitor (C61)

Fuse (F801)
T3.15AL250V

R.V.coil
(CN721)
208/230 VAC

Fuse (F701)
T3.15AL250V

LED

Front side of unit

Fin temperature

thermistor/RT64

(CN642)

Signal of outdoor

fan motor (CN931)

Defrost thermistor

Ambient temperature

thermistor/RT65

/RT61(CN641)

(CN643)

55

Discharge temperature

thermistor/RT62

(CN641)

Outdoor heat exchanger

temperature thermistor

/RT68 (CN644)

LEV connector

(CN724)

208/230 VAC

Jumper wire for pre­heat control setting
(JK)

Jumper wire for
changing defrost
setting (JS)

-4 14 32 50 68 86 104

0

10

20

30

40

50

60

70

80

90

100

Temperature(°F)

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

32 50 68 86 104 122 140 158 176

0

20

40

60

80

100

120

140

160

180

200

Temperature(°F)

Fin temperature thermistor(RT64)

5HVLVWDQFHN

5HVLVWDQFHN

Temperature (°F)

Discharge temperature thermistor (RT62)

5HVLVWDQFHN

0

100

200

300

400

500

600

700

800

32 50 68 86 104 122 140 158 176 194 212 230 248

1. Inverter P.C. board

OBH747C

U8

MUZ-HM09NA
MUZ-HM09NA2

-

-

MUZ-HM12NA

U8

MUZ-HM12NA2

U8

-

U8

-

Back side of unit

208/230 VAC

Fuse (F901)
T3.15AL250V

Output to
drive
compressor
(LDU,
LDV,
LDW)

Bus-bar voltage
DB61
260-325 VDC

(-)

(+)

Smoothing
capacitor
(C63)

Smoothing
capacitor
(C62)

Fuse (F801)
T3.15AL250V

Fuse (F701)
T3.15AL250V

R.V.coil
(CN721)
208/230
VAC

Signal of
outdoor
fan motor
(CN931)

208/230
VAC

Front side of unit

Output to drive outdoor
fan motor (CN932)

Fin temperature
thermistor/RT64 (CN642)

Outdoor heat exchanger
temperature thermistor
/RT68 (CN644)

Discharge temperature
thermistor/RT62
(CN641)

Defrost thermistor
/RT61(CN641)

Ambient temperature
thermistor/RT65 (CN643)

56

LEV

LED

connector
(CN724)

Jumper wire for
changing defrost
setting (JS)

Jumper wire
for pre-heat
control setting
(JK)

1. Inverter P.C. board

OBH747C

MUZ-HM15NA MUZ-HM18NA
MUZ-HM15NA2 MUZ-HM18NA2

Back side of unit

208/230 VAC

Fuse (F901)
T3.15AL250V

Output to
drive outdoor
fan motor
(CN932)

Output to
drive
compressor
(LDU,
LDV,
LDW)

DB61
260 - 370 VDC

Smoothing
capacitor (C63)

Smoothing
capacitor (C62)

(+)(-)

Fuse (F801)
T3.15AL250V

Smoothing
capacitor (C61)

R.V.coil
(CN721)
208/230 VAC

Fuse (F701)
T3.15AL250V

LED

Front side of unit

Fin temperature

thermistor/RT64

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

100

90
80
70
60
50
40
30

5HVLVWDQFHN

20
10

0

-4 14 32 50 68 86 104
Temperature(°F)

(CN642)

Signal of outdoor

fan motor (CN931)

Defrost thermistor

Ambient temperature

thermistor/RT65

Discharge temperature thermistor (RT62)

800
700
600
500
400
300

5HVLVWDQFHN

200
100

0

32 50 68 86 104 122 140 158 176 194 212 230 248

/RT61(CN641)

(CN643)

Temperature (°F)

Discharge temperature

57

thermistor/RT62

(CN641)

Outdoor heat exchanger

temperature thermistor

/RT68 (CN644)

200
180
160
140
120
100

5HVLVWDQFHN

208/230 VAC

Jumper wire for pre­heat control setting
(JK)

Jumper wire for
changing defrost
setting (JS)

LEV connector

(CN724)

Fin temperature thermistor(RT64)

80
60
40
20

0

32 50 68 86 104 122 140 158 176

Temperature(°F)

1. Inverter P.C. board

OBH747C

MUZ-HM24NA
MUZ-HM24NA2

Back side of unit

208/230 VAC

Fuse (F901)
T3.15AL250V

Output to
drive outdoor
fan motor
(CN932)

Output to
drive
compressor
(LDU,
LDV,
LDW)

Smoothing
capacitor (C63)

DB61
260 - 370 VDC

(+)(-)

Smoothing
capacitor (C62)

Fuse (F801)
T3.15AL250V

Smoothing
capacitor (C61)

R.V.coil
(CN721)
208/230 VAC

Heater connector
(CN722) (Optional parts)

Fuse (F701)
T3.15AL250V

Front side of unit

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

100

90
80
70
60
50
40
30

5HVLVWDQFHN

20
10

0

-4 14 32 50 68 86 104
Temperature(°F)

LED

Fin temperature

thermistor/RT64

(CN642)

Signal of outdoor

fan motor (CN931)

Discharge temperature thermistor (RT62)

800
700
600
500
400
300

5HVLVWDQFHN

200
100

0

32 50 68 86 104 122 140 158 176 194 212 230 248

Defrost thermistor

Ambient temperature

thermistor/RT65

/RT61(CN641)

(CN643)

Temperature (°F)

Discharge temperature

thermistor/RT62

58

(CN641)

Outdoor heat exchanger

temperature thermistor

/RT68 (CN644)

LEV connector

(CN724)

Fin temperature thermistor(RT64)

200
180
160
140
120
100

80
60

5HVLVWDQFHN

40
20

0

32 50 68 86 104 122 140 158 176

208/230 VAC

Jumper wire for pre­heat control setting
(JK)

Jumper wire for
changing defrost
setting (JS)

Temperature(°F)

11

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

locking mechanism.

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

Hold the sleeve, and
pull out the terminal
slowly.

Connector

Sleeve

Locking lever

OBH747C

DISASSEMBLY INSTRUCTIONS

<"Terminal with locking mechanism" Detaching points>

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

11-1. MUZ-HM09NA MUZ-HM12NA MUZ-HM09NA2 MUZ-HM12NA
MUZ-HM15NA MUZ-HM18NA MUZ-HM15NA2 MUZ-HM18NA2

NOTE: Turn OFF the power supply before disassembly.

OPERATING PROCEDURE PHOTOS

1. Removing the cabinet

(1) Remove the screw fixing the service panel.
(2) Pull down the service panel and remove it.
(3) Remove the screws fixing the conduit cover.
(4) Remove the conduit cover. (Photo 4)
(5) Remove the screw fixing the conduit plate. (Photo 5)
(6) Remove the conduit plate.
(7) Disconnect the power supply wire and indoor/outdoor

connecting wire.
(8) Remove the screws fixing the top panel.
(9) Remove the top panel.
(

10

) Remove the screws fixing the cabinet.

(

11

) Remove the cabinet.

(

12

) Remove the screws fixing the back panel.

(

13

) Remove the back panel.

Photo 2

Screws of the
top panel

Photo 1

Screws of
the cabinet

Photo 3

Screws of
the top panel

Screw of the
cabinet

Back
panel

Screws
of the
back
panel

Service
panel

Screws of
the terminal block
support and the
back panel

Screws of the
cabinet

Screws of
the cabinet

59

Direction
to remove

Hooks

OPERATING PROCEDURE PHOTOS

OBH747C

Photo 4 Photo 5

Screws of the
conduit cover

Screw of the

conduit plate

2. 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

connectors:

<Inverter P.C. board>

CN721 (R.V. coil)
CN931, 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 heat sink support and the

separator.

(5) Remove the fixing screws of the terminal block support and

the back panel.
(6) Remove the inverter assembly.
(7) Remove the screw of the ground wire and screw of the ter-

minal block support.
(8) Remove the heat sink support from the P.C. board support.
(9) Remove the screw of the inverter P.C. board and remove the

inverter P.C. board from the P.C. board support.

3. Removing R.V. coil

(1) Remove the cabinet and panels. (Refer to 1.)
(2) Disconnect the following connectors:
<Inverter P.C. board>

CN721 (R.V. coil)

(3) Remove the R.V. coil.

Photo 6

Screws of the heat sink
support and the separator

Soundproof
felt

Photo 7

Heat sink

Heat sink support

P.C. board
support

Screws of the terminal block
support and the back panel

Screw of the
Terminal block
support

60

Screw of the
inverter P.C. board

Terminal
block
support

Screw of the
ground wire

OPERATING PROCEDURE PHOTOS

OBH747C

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

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

connectors:
<Inverter P.C. board>

CN641 (Defrost thermistor and discharge temperature ther-

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

(3)

Pull out the discharge temperature thermistor from its holder.
(4) Pull out the defrost thermistor from its holder.
(5) Pull out the outdoor heat exchanger temperature thermistor

from its holder.

(6) Pull out the ambient temperature thermistor from its holder.

Photo 8

Discharge temperature thermistor

Photo 9

Ambient temperature
thermistor

Outdoor heat
exchanger tempera­ture thermistor

Defrost thermistor

61

OPERATING PROCEDURE

OBH747C

5. Removing outdoor fan motor

(1) Remove the cabinet and panels. (Refer to 1.)
(2) Disconnect the following connectors:
<Inverter P.C. board>

CN931, CN932 (Fan motor)
(3) Remove the propeller fan nut.
(4) Remove the propeller fan.
(5) Remove the screws fixing the fan motor.
(6) Remove the fan motor.

NOTE: The propeller fan nut is a revers thread.

PHOTOS

Photo 10

Screws of the outdoor fan motor

6. Removing the compressor and 4-way valve

(1) Remove the cabinet and panels. (Refer to 1.)
(2) Remove the inverter assembly. (Refer to 2.)
(3) Remove the screws fixing the reactor.
(4) Remove the reactor.
(5) Remove the soundproof felt.
(6) Recover gas from the refrigerant circuit.

NOTE: Recover gas from the pipes until the pressure gauge

shows 0 PSIG.

(7) Detach the brazed part of the suction and the discharge pipe

connected with compressor.
(8) Remove the nuts fixing the compressor.
(9) Remove the compressor.
(

10

) Detach the brazed part of pipes connected with 4-way valve.

Photo 12

Propeller fan

Photo 11

Discharge pipe
brazed part

Propeller fan nut

Screws of
the reactor

Suction pipe
brazed part

Brazed parts of
4-way valve

Screw of the
R.V. coil

62

11-2. MUZ-HM24NA MUZ-HM24NA2

OBH747C

OPERATING PROCEDURE PHOTOS

NOTE: Turn OFF the power supply before disassembly.

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 screws fixing the conduit cover.
(6) Remove the conduit cover.
(7) Remove the screw of fixing the conduit plate.
(8) Remove the conduit plate.
(9) Remove the top panel.
(10)

Remove the valve cover.

(11)

Disconnect the power supply and indoor/outdoor connect-

ing wire.

(12)

Remove the screws of the cabinet.

(13)

Remove the cabinet.

(14)

Remove the screws of the back panel.

(15)

Remove the back panel.

Photo 3

Screws of the conduit cover

Photo 1

Screws
of the
cabinet

Screws of the cabinet

Photo 2

Screws of the top panel

Screw of
the valve
cover

Screw of the back panel

Screws of the top panel

Screws of the cabinet

Screws of
the cabinet

Photo 4

Screw of the conduit plate

63

Screws of
the cabinet

Screws of
the back panel

Screws of the service panel

OPERATING PROCEDURE

OBH747C

PHOTOS

2. 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)
CN931, 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.
(4) Remove the screw fixing the heat sink support and the sepa-

rator.

(5) Remove the fixing screws of the terminal block support and

the back panel.
(6) Remove the inverter assembly.
(7) Remove the screw of the ground wire, screw of the P.C.

board cover and screws of the terminal block support.
(8) Remove the heat sink support from the P.C. board support.
(9) Remove the screw of the inverter P.C. board and the inverter

P.C. board from the P.C. board support.

3. Removing R.V. coil

(1) Remove the cabinet and panels. (Refer to 1.)
(2) Disconnect the following connector:
<Inverter P.C. board>

CN721 (R.V. coil)

(3) Remove the R.V. coil.

Photo 7

Screw of
the R.V. coil

Photo 5

Screw of the heat sink
support and the separator

Photo 6

Heat sink

P.C. board
support

Screw of
the inverter
P.C. board

Screw of the
ground wire

Screws of the terminal
block support and the
back panel

Heat sink
support

Screw of the
P.C. board
cover

Screws of the
terminal block
support

Brazed parts of
4-way valve

64

OPERATING PROCEDURE PHOTOS

OBH747C

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

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

connectors:
<Inverter P.C. board>

CN641 (Defrost thermistor and discharge temperature ther-

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

(3)

Pull out the discharge temperature thermistor from its holder.
(4) Pull out the defrost thermistor from its holder.
(5) Pull out the outdoor heat exchanger temperature thermistor

from its holder.

(6) Pull out the ambient temperature thermistor from its holder.

5. Removing outdoor fan motor

(1)

Remove the top panel, cabinet and service panel. (Refer to 1.)

(2) Disconnect the following connectors:

<Inverter P.C. board>

CN931 and CN932 (Fan motor)
(3) Remove the propeller fan nut.
(4) Remove the propeller fan.
(5) Remove the screws fixing the fan motor.
(6) Remove the fan motor.

NOTE: The propeller fan nut is a reverse thread.

Photo 8

Photo 9

Outdoor heat
exchanger tempera­ture thermistor

Defrost thermistor

Propeller fan nut

Ambient tem-

perature

thermistor

6. 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 PSIG.

(5) Detach the brazed part of the suction and the discharge

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

65

Photo 10

Brazed part of the
discharge pipe

Screws of the
outdoor fan motor

Discharge temperature
thermistor

Brazed part of the suction pipe

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

© Copyright 2015 MITSUBISHI ELECTRIC CORPORATION

Issued: Feb. 2017. No. OBH747 REVISED EDITION-C
Issued: Mar. 2016. No. OBH747 REVISED EDITION-B
Issued: Feb. 2016. No. OBH747 REVISED EDITION-A
Published: Dec. 2015. No. OBH747
Made in Japan

Specifications are subject to change without notice.