IVT AY-XP12FR-N, AE-X12FR-N Service Manual

TopPage

AYXP12FRN

SERVICE MANUAL

SPLIT TYPE
ROOM AIR CONDITIONER

MODELS

CONTENTS

CHAPTER 1. SPECIFICATION

[1] SPECIFICATION............................................ 1-1

[2] EXTERNAL DIMENSION............................... 1-2

[3] WIRING DIAGRM .......................................... 1-3

[4] ELECTRICAL PARTS .................................... 1-3

CHAPTER 2. EXPLAMATION OF CIRCUIT AND OP­ERATION

[1] BLOCK DIAGRAMS....................................... 2-1

[2] MICROCOMPUTER CONTROL SYSTEM........ 2-3

[3] FUNCTION..................................................... 2-8

CHAPTER 3. FUNCTION AND OPERATION OF PRO­TECTIVE PROCEDURES

[1] PROTECTION DEVICE FUNCTIONS AND

OPERATIONS................................................ 3-1

[2] AIR CONDITIONER OPERATION IN

THERMISTOR ERROR ................................. 3-3

INDOOR UNIT

AY-XP12FR-N

OUTDOOR UNIT

AE-X12FR-N

In the interests of user-safety (Required by safety regulations in some
countries) the set should be restored to its original condition and only
parts identical to those specified should be used.

[3] THERMISTOR TEMPERATURE CHAR-

ACTERISTICS...............................................3-5

[4] HOW TO OPERATE THE OUTDOOR

UNIT INDEPENDENTLY ...............................3-7

[5] GENERAL TROUBLESHOOTING CHART........3-7

[6] MALFUNCTION (PARTS) CHECK METH-

OD .................................................................3-9

[7] OUTDOOR UNIT CHECK METHOD........... 3-11

[8] TROUBLESHOOTING GUIDE ....................3-14

CHAPTER 4. REFRIGERATION CYCLE

[1] FLOW FOW REFRIGERANT ........................4-1

[2] STANDARD CONDITION ..............................4-1

[3] TEMPERATURE AT EACH PART AND

PRESSURE IN 3-WAY VALVE ......................4-1

[4] PERFORMANCE CURVES...........................4-2

Parts marked with " " are important for maintaining the safety of the set. Be sure to replace these parts with specified ones for maintaining the
safety and performance of the set.

This document has been published to be used for
after sales service only.
The contents are subject to change without notice.

AYXP12FRN

AYXP12FRN

CHAPTER 1. SPECIFICATION

Service Manual

[1] SPECIFICATION

1. AY-XP12FR-N – AE-X12FR-N

MODEL INDOOR UNIT OUTDOOR UNIT

ITEMS AY-XP12FR-N AE-X12FR-N

Cooling capacity(Min. > Max.) kW 3.5 (0.9 - 4.0)
Heating capacity(Min. > Max.) kW 4.2 (0.9 - 6.0)
Moisture removal(at cooling) Liters/h 1.1

Electrical data

Phase Single
Rated frequency Hz 50
Rated voltage V 230
Rated current ✩
(Min - Max.)

Rated input ✩
(Min - Max.)

Power factor ✩ Cool % 91

Compressor Type Hermetically sealed rotary type

Refrigerant system Evaporator Louver Fin and Grooved tube type

Noise level
(at cooling)

Fan system

Drive Direct drive
Air flow quantity
(at cooling)

Fan Cross flow fan Propeller fan

Connections

Refrigerant coupling Flare type
Refrigerant tube size Gas, Liquid 1/2", 1/4"
Drain piping mm O.D φ18

Others

Safety device Compressor: Thermal protector

Air filters Polypropylene net (Washable)
Net dimensions Width mm 790 780

Net weight kg 10 37

NOTE: The condition of star”✩” marked item are ‘ISO5151’ : 1994(E), contition T1.

Cool A 4.3 (0.8 - 6.0)
Heat A 4.5 (0.7 - 7.5)
Cool W 900 (150 - 1300)
Heat W 970 (130 - 1700)

Heat % 94

Model 5RS092XDF
Oil charge 320cc (RB68A or Freil Alphc 68M)

Condenser Corrugate Fin and Grooved tube type
Control Expansion valve
Refrigerant (R410A) 1000g
De-lce system Micro computer controled reversed systems
High dB(A) 43 49
Low dB(A) 39 –
Soft dB(A) 27 –

High m3/min. 10.7 30.2
Low m3/min. 9.3 –
Soft m3/min. 6.0 –

Fan motors: Thermal fuse
Fuse, Micro computer control

Height mm 278 540
Depth mm 198 265

1 – 1

[2] EXTERNAL DIMENSION

1. Indoor unit

AYXP12FRN

198790

278

2. Outdoor unit

58

INVERTERAIRCONDITIONER

540

780

175

12

37.5

58

18.5

22.0

135

4.5

72

299

14

324

265

540

1 – 2

165

81

136

AYXP12FRN

[3] WIRING DIAGRM

1. Indoor unit

2. Outdoor unit

[4] ELECTRICAL PARTS

1. Indoor unit

DESCRIPTION MODEL REMARKS

Indoor fan motor MLB084 DC Motor
Indoor fan motor capacitor – –
Transformer – –
FUSE1 – QFS-GA062JBZZ (250V, 3.15A)
FUSE2 – QFS-GA063JBZZ (250V, 2A)

2. Outdoor Unit

DESCRIPTION MODEL REMARKS

Compressor 5RS092XDF D.C. brush-less motor
Outdoor fan motor ML-A902 DC Motor
Outdoor fan motor capacitor – –
Fu4 – QFS-GA064JBZZ(250V, 1A)
Fu3 – QFS-GA051JBZZ(250V, 2A)
Fu2 – QFS-GA052JBZZ(250V, 3.15A)
Fu1 – QFS-CA001JBZZ(250V, 20A)
Fu5, 6 – QFS-CA002JBZZ(250V, 15A)

1 – 3

AYXP12FRN

CHAPTER 2. EXPLAMATION OF CIRCUIT AND OPERATION

Service Manual

[1] BLOCK DIAGRAMS

1. Indoor unit

AYXP12FRN

CPU

DC power supply circuit

Fan motor PWM control circuit

Rotation pulse input circuit

AC clock circuit

Remote controller signal reception circuit

Buzzer drive circuit

CPU reset circuit

CPU oscillator circuit

Room temp. detect circuit

Heat exchanger pipe thermo circuit

EEPROM

Select circuit

Serial I/O circuit

Power supply relay drive circuit

2A

Rectification circuit

Fuse

Indoor fan motor

Fan motor pulse detect

Wireless remote control operation

Audible operation confirmation

Room temp. thermistor

Heat exchanger pipe thermistor

Louvre angle, fan speed

Wireless, preheat, Model select

Indoor/outdoor control signal I/O

Outdoor unit power supply on/off control

3.15A

AC power

Fuse

Unit-unit wiring
(AC power and
serial signals)

Serial signals

Sub

CPU

Auto restart circuit

Test run circuit

Auxiliary mode

Power on circuit

Cluster generator drive circuit

Louvre motor drive circuit(upper)

Louvre motor drive circuit(lower)

LED drive circuit

Test run (forced operation)

Auxiliary mode button ON/OFF

Self diagnostics, fault diagnosis

Cluster generator

Flow direction control (louver motor upper)

Flow direction control (louver motor lower)

LED display

2 – 1

AYXP12FRN

2. Outdoor unit

CPU

AC clock circuit

Pulse amplitube modulation circuit

Power supply circuit

CPU oscillator circuit

DC overvoltage detection circuit

Outdoor fan drive circuit

4-way valve relay drive circuit

DC overcurrent detection circuit

Power transistor module drive circuit

Serial I/O circuit

CPU reset circuit

Position detection circuit

AC overcurrent detection circuit

Compressor thermo circuit

Heat exchanger pipe thermo circuit

Outdoor temp. thermo. circuit

Smoothing
circuit

15A

protection

IGBT

Power factor
converter circuit

Outdoor fan

4-way valve

Power transistor module

Compressor

Current transformer

Compressor thermistor

Heat exchanger pipe thermistor

Outdoor temperature thermistor

Filter
circuit

20A

protection

3.15A

protection

15A

protection

Unit-unit wiring (AC power
and serial signals)

EEPROM

LED drive circuit

Test mode circuit

Expansion valve drive circuit Expansion valve

Suction temp. thermo. circuit Suction pipe thermistor

2-way valve temp. thermo. circuit 2-way valve thermistor

LED

2 – 2

[2] MICROCOMPUTER CONTROL SYSTEM

1. Indoor unit

1.1. Electronic control circuit diagram

AYXP12FRN

1

12V

CNA

BCN5

FU1

3.15A - 250V

RHRE

C23

275V

0.01μ

1W

R76

100

12V

E

D3

C53~C56

250V4700p

C54C53

C56

C55

R1

3.3

FU2

C35

5

1

D15

D1FL20U

10KF

R22 R3

11KF

ZD1

ST03D - 200

65432

TR1

R13

100K

12V

5V

1

1

1

D1N60

5W

1M

R2

2A - 250V

2KV

C12

9

C43

N

1

3W

3W

R75

C1

33p

D21

D1FL20U

R5

30KF

100V

100pF

D14

25V

R10

2

IN

RY1

3

365

3

11K

11K

SSR

3.3K

200K

R26

1/2W

DB1

D2SBA60

450V 120μ

1/2W1M1/2W

RF

D20

D1FL20U

2

C2

50V

100μ

C5

50V

ZD5

15V

101112

D2S6M

470μ

1.5K

2

1

3

OUT

CLUSTER

GENERATOR

5

6

(CLUSTER)

CONNECTOROF JOINT

910

R20

1/4W

R23

910

1/4W

39K

R24

R25

200K

1/2W

NR1

C14 275V 0.1μ

R19A 1/2W 470K

R19 1/2W 470K

NF1

C45 275V 0.1μ

DC15V

IC7

KIA7815API

Q9

D

KRA106S

1SR139

5V

L2

3

IC3

4

MR1712

R65

1500p

D2

D1FL20U

1

C49

C48

250V

10000p

C7

10V

D1

D1FS4

R6

L1

100K

10μH

1K

R9

C4

PC6

2

1

PC817XP3

R80

1.2K

2.4KFR82.4KF

N

N

S

CONNECTOROF JOINT

100μ
35V
C46

0.1μ
25V
C50

0.1μ
50V
C47

4

1

3.3K

R66

100K

R73

1234

CN80

R7

15KF

4

PC6

470μ

C44

10V

220μ

50V

0.1μ

R11

RA

RG R40RBRC

D8

7

(FANMOTOR)

77

BCN1

Vm

R31

56k

14

PC5

5V

32

PC9

PC817XP3

100μ
50V
C3

5V

3

5V

2W

680

2W

680

2W

680680

2W

2W

680

D1N60

D1N60

D7

DC

5

521

5

10K

R16

R34

6.8k

R57

680

0V

C40

50V

1000p

4

PC7

PC817XP3

1

1K

R81

IC9

PJ431CT

41

FAN

MOTOR

33

312

23

14

23

4.7k

R39

PC1 PC817XP3

C20 250V0.01μ

R38 100k

C19 50V0.047μ

C18 35V100μ

ZD2HZ24-2

2W

2W

11K

11K

R37RD

2.7K

R70

R44

12V

5V

C42

1

2

4

PC3

1

Vs

VccPGGND

C98

C99

6.8k
R33

16V47μ

C21

R32

3

PC817XP3

2

14

3.3k

R29

JPF

32

PC817XP3

R41 56k

32

PC2 PC853HXP

(SERIAL I/O CIRCUIT)

89

BZ

1.8k

1/4W

12V

25V

0.1μ

3

PC81716P

2

C16

50V

0.01μ

C98, C99

1KV 1000p

8.2k

PC4

PC817XP3

R35 10k

680

R30

R27

10K

AC CLOCK

5V

5V

JPS

IC6

16V
C17

10k
R28

R71

4.7K
R36

16V
C22

0.01μ

1k

4.7k

R47

4.7k
R97

KID65004AF

0.01μ

1110

987654321

10

SUB MICRO COMPUTER PWB

7654321

9876

12345

8

123456789

1210 11

1110 12 10 11

987654321

123456789

RECEIVER PWB

7-SEGLED&

BOTTOM

33

LOUVER MOTOR

CIRCUIT DIAGRAM

54 21 54 21

TOP

LOUVER MOTOR

DISPLAY PWB

246

8

10

13579

8765432

POWERSUPPLY OF

SUBMICRO COMPUTER

KRC108S

4.7K
R98

16V

0.01μ

10K

R61

C31

1

CN4

BCN7

10.0KF

16V10μ

RM

49P37
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64

JPH

5V

11 12

4.7K

484746454443424140393837363534

P00

P01

P02

P03

P04

P05

P06

P36
P35
P34
P33
P32
P31
P30
VCC

VR

VSS
P67
P66
P65
P64
P63

HOT KEEP

P07

P53

P54

P55

P56

P57

P60

P61

P62

123

4

R52

10K

R53

10K

JPO

(HA CIRCUIT)

AUTO RESTART

5V

FLASH

P10

P52

98765

HAJP

POWERON

BUSY

P11

IC1

P51

10

R95

P12

P13

P47

P50

R91

4.7K

VPP

DRAIN PAN ASS'Y

P14

P15

P16

P44

P45

P46

1514131211

100k
R93

C90

R90

4

321

100K

R69

4.7K

R68

VCC

SCL

P20

P17 33

P21
P22
P23
P24
P25
P26
P27
VSS
XOU
XIN
P40
P41
RST
VSS
P42

P43

16

R92

CN90

SDAOERESET9VSS

4.7k

R45

32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17

MQ

7654321

8

5V

10k

R48

10K

R94

C27

16V

0.01μ

13

50V

C33

8MHz

AUX.

5V

(TESTRUN)

R87

WIRELESS

1000p

2

47k
R67

SW1

10k
R50

TEST

C37

25V

0.1μ

C26

25V

4.7μ

IC2

RESET

10K

C52

25V

0.1μ

C

50V

0.1μ

OSC1

R85

10K

C57

50V

1000p

R86

10K

JPW

JPP

5V

PREHEAT

(DRAINPAN)

CONNECTOROF JOINT

8

6

43

21

7

5

1

12V

Q11

5V

4.7K

R4

5V

50V

C32

1000p

R17 1K

100μ
10V
C25

5V

0.1μ
25V
C24

1k

R46

4

5

3

6

2

7

1

8

IC10

EEPROM

5V

10.0KF

R96

100

1/4W

R56

100

5V

1/4W

R51

JPT

GND for

KRA101S

1K

R89

R54

10K

12V LINE

Q15

Q19

2.4K
R55

GND for

5V LINE

KRC102S

KRC108S

KRC102S

4.7K

RN

4

TEMP THERMO

SIGNAL

5V

OFSERIAL

SERIALSIGNALS

REMOTECONTROLLER

ERRORSIGNAL

Q3

Q1

5V

C39

C36

16V

0.01μ

R58

R59

10K

10.0KF

R60

16V10μ

C30

3

2

TH1

TH2

PIPE THERMO

2 – 3

AYXP12FRN

1.2. Display circuit diagram

IC105

TOP

5432112345

LOUVER MOTOR

12V

12V LINE

GND for

KID65004AF

IC106

1234567

CN101

12V

12345

CN102

GND for

12V LINE

8

SIGNALS

4.7K

KRC106S

SERIAL SIGNALS

ERROR SIGNAL

REMOTE CONTROLLER

OF SERIAL

M5V

POWER SUPPLY OF

SUB MICRO COMPUTER

9

5V

R108

5V LINE

GND for

12V LINE

GND for

1K5VR119

Q105

CIRCUIT DAIGRAM

LOUVER MOTOR

987654321

10

CN103

12V

KID65004AF

BOTTOM

8

7

4.7K
R115

R116

100K

6

5

M5V

R118

10K

IC101

Q104

KRC106S

R114

KRA106S

Q102Q101

12V

KRA106S

Q103

KRC106S

R110
R113

R109

JP2

1/4W

1.2K*4

KID65783AF

12V

1W180*7

P11 36

M37542

P12

123

R101

P01 28

P02 29

P03 30

P04 31

P05 32

P06 33

P07 34

P10 35

P13

P14

P20

P21

P22

P23

P24

P25

4

98765

IC103

R102

R103

R104

R105

P30 19

P31 20

P32 21

P33 22

P34 23

P35 24

P36 25

P37 26

P00 27

12V

IC104

GND for

KID65004AF

Vss18

Xout17

P26

P27

Vref

RESET

CNVss

Vcc

Xin

16

1514131211

10

R106

R107

13

8MHz

2

OSC101

25V

C101

0.1μ

50V

C105

0.22μ

C102

25V

4.7μ

IC102

RESET

25V

C103

C104

0.1μ

16V

47μ

12V LINE

GND for

M5V

12V LINE

5V LINE

GND for

JP1

4

3

2

1

M5V

FLASH

SUB MICRO COMPUTER PWB

cdefg

123456789

7

6

5

4

3

2

1

LED LED LED LED LED LED LED LED

LEDLED

101 102 103 104 105 106 107 108 109 110

LED

PC

111B

CN105B

BLU

()

10

123

E

12V LINE

GND for

11

CN105A

CN105C

abcdefg

6

5

4

3

2

1

8

7

123456789

SIGNALS

5V LINE

GND for

5V

REMOTE CONTROLLER

9

12

11

1010

11

12

CN104B CN104A

2 (H2)

9(G2)

g

8(F2)

f

3 (E2)

e

1 (D2)

d

4 (C2)

c

6 (B2)

b

7 (A2)

a

2 (H1)

9(G1)

g

8(F1)

f

3 (E1)

e

1 (D1)

d

4 (C1)

c

6 (B1)

b

7 (A1)

a

R201

47

C201

+

16V

47μ

C202

25V

0.1μ

IC201

GP1U261RK

RECEIVER CIRCUIT

DISPLAY PWB

7 - SEG LED & RECEIVER PWB

SG201

B2B1

A2

(COM) 5

F2

A1

(COM) 10

F1

H2

C2

G2G1

D2

E2

H1

C1

D1

E1

2 – 4

1.3. Printed wiring board

AYXP12FRN

2 – 5

AYXP12FRN

2. Outdoor unit

2.1. Electronic control circuit diagram

PS21563 or 21564

IPM

15A

FU5

250V

j

PTC

1μF

275V

275V

1μF

275V

FC1

TERMINAL

BOARD

WP

VP

UP

VPI

EARTH

YELLOW

GREEN/

C

(R)

S

(THERMISTOR)

5V

(C)

R100

R

FC3 FC4

(THERMISTOR CIRCUIT)

T9

T7

T8

V33

U32

W34

N

35

R50

26

CIN

R128

R7

MRY1

2.7kF

R88

13KF

R127

R6

23.7KF

510K

4

2

4

2

T1

0V

1/4W

BROWN

1

13KF

23.7KF

T11

T10

T13

25

CF0

Q7

5V

R107

2

0V

8

6

150

R110

-P
V

Q5

18

FU6

15A

250V

WH

WH

e

d

D12

D13

FU2

3.15A

250V

4700pF
250V

C6A

C6

C7A

C7
4700pF
250V
4700pF
250V

C5A

C5

C4

C4A

4700pF
250V

PC1

SA1

NR1

C13

20A

FU1

250V

T4

YELLOW

GREEN/

31

P

M

C14

630V

0.33μ

R126

1/2W

R125

1/2W

270KD

270KD

R5

R2

1/2W

300KF

255KF

1/2W

C10

750μ

+

C9

420V 420V

750μ

+

DB1

T5

GR

GR

OUT

IN

GR

T6

CT1

R89

C3

1/4W

510K

R43

3

L4

1

C2

3

L3

1

1μF

C1

R1

1M

T12

1/2W

T2

BLUE

N

1

330K

10K x 5 R63 ~ 67

5W

R49

0.02

1.8KF
C59

C58

c

KRC105S

330

PC4

3

R101, 102

1/2W 47K x 2

5V

4

1

PC817XP3

0.1μ

D1

FC2

R51 ~ 53

R111

ZD3

1000P

0.022μ

TLP351

5

2.2K

R103, 104

R74

TH4

TH5

TH3

TH2

65432

798

10

CN8

R68 ~ 72

6.8KF x 5

D11

0V

C70 ~ 74

16V 10μ x 5

0V

0.01μ x 5 C65 ~ 69

1/2W

470KF x 3

R99 100

15K

R112

R57 100

R59 100

R58 100

0V

D24

D23

D22

V

D21

5

11

4

15

3

2

14

13

R114

1M

1.8K

0V - P

R115

5V

1.8K
R60

1.8K
R61

1.8K

DB2

R62

μ
7
9

.01
C

0

6

K

5V

.3

C83

3

R10

220μ

1000P

1

4

1000P

6
Q

0V

2S

μ

2

0V

0V

R41 R42

01

C8

KRC10

0.

5

2K

0

2

1
R

5V5V

3

4

PC3

2

1

PC81716NIP

C81

0.01μ

R146

100K

5
2
R

b

R75

2.7K

R76

56K

D6

2

TR1

3

(SERIAL I/O CIRCUIT)

1K

2W

1K

1K

2W 2W

FB

R11

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0.1μ

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R46

0V

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(DC OVERCURRENT CHECK CIRCUIT)

R133 100

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0.1μ

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R84

9.53KF

10V

47μ

C78

0V

R86

6.8KJ

(FAN MOTOR CIRCUIT)

Q3

0V

C77

15V

0.01μ

6.8K

R85

5V

R83

10K

0V

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400V

0.1μ

1

7

3

2

4

CN3

5

R

270

R77

j

2A

FU3

250V

(FAN MOTOR)

2 – 6

2.2. Printed wiring board

AYXP12FRN

2 – 7

AYXP12FRN

[3] FUNCTION

1. Function

1.1. Startup control

The main relay remains off during the first 45 seconds (first safety
time) immediately after the power cord is plugged into an AC outlet in
order to disable outdoor unit operation and protect outdoor unit electric
components.

1.2. Restart control

Once the compressor stops operating, it will not restart for 180 sec­onds to protect the compressor.

Therefore, if the operating compressor is shut down from the remote
control and then turned back on immediately after, the compressor will
restart after a preset delay time.

(The indoor unit will restart operation immediately after the ON switch
is operated on the remote control.)

Compressor operation

Compressor ON Compressor can

Compressor remains OFF

turn ON

for 180 seconds

OFF operation on
remote control

ON operation on
remote control

Compressor ON

1.3. Cold air prevention control

When the air conditioner starts up in heating mode, the indoor unit fan
will not operate until the temperature of the indoor unit heat exchanger
reaches about 23°C in order to prevent cold air from blowing into the
room.

Also, the indoor unit fan operates at low speed until the temperature of
the indoor unit heat exchanger reaches about 38°C so that people in
the room will not feel chilly air flow.

Indoor unit heat exchanger temperature

38

23

Set fan speed

35

Indoor unit fan at low speed

21

Indoor unit fan in non-operation

1.6. Outdoor unit 2-way valve freeze prevention control

If the temperature of the outdoor unit 2-way valve remains below 0°C
for 10 consecutive minutes during cooling or dehumidifying operation,
the compressor operation stops temporarily in order to prevent freez­ing.

When the temperature of the 2-way valve rises to 10°C or higher after
about 180 seconds, the compressor restarts and resumes normal
operation.

1.7. Indoor unit overheat prevention control

During heating operation, if the temperature of the indoor unit heat
exchanger exceeds the indoor unit heat exchanger overheat preven­tion temperature (about 45 to 54°C) which is determined by the operat­ing frequency and operating status, the operating frequency is
decreased by about 4 to 15 Hz. Then, this operation is repeated every
60 seconds until the temperature of the indoor unit heat exchanger
drops below the overheat protection temperature.

Once the temperature of the indoor unit heat exchanger drops below
the overheat protection temperature, the operating frequency is
increased by about 4 to 10 Hz every 60 seconds until the normal oper­ation condition resumes.

If the temperature of the indoor unit heat exchanger exceeds the over­heat protection temperature for 60 seconds at minimum operating fre­quency, the compressor stops operating and then restarts after about
180 seconds, and the abovementioned control is repeated.

1.8. Outdoor unit overheat prevention control

During cooling operation, if the temperature of the outdoor unit heat
exchanger exceeds the outdoor unit heat exchanger overheat preven­tion temperature (about 55°C), the operating frequency is decreased
by about 4 to 15 Hz. Then, this operation is repeated every 60 sec­onds until the temperature of the outdoor unit heat exchanger drops to
about 54°C or lower.

Once the temperature of the outdoor unit heat exchanger drops to
about 54°C or lower, the operating frequency is increased by about 4
to 10 Hz every 60 seconds until the normal operation condition
resumes.

If the temperature of the outdoor unit heat exchanger exceeds the out­door unit heat exchanger overheat protection temperature for (120 sec
: outdoor temperature ≥ 40°C • 60 sec : outdoor temperature < 40°C)
at minimum operating frequency, the compressor stops operating and
then restarts after about 180 seconds, and the abovementioned con­trol is repeated.

1.4. Odor prevention control

When the air conditioner starts up in cooling mode, the discharged air
temperature is lowered slightly, and for the reduction of unpleasant
odors the operation of the indoor unit fan is delayed 60 seconds if the
automatic fan speed mode in cooling mode is set.

1.5. Indoor unit heat exchanger freeze prevention control

If the temperature of the indoor unit heat exchanger remains below
0°C for 4 consecutive minutes during cooling or dehumidifying opera­tion, the compressor operation stops temporarily in order to prevent
freezing.

When the temperature of the indoor unit heat exchanger rises to 2°C
or higher after about 180 seconds, the compressor restarts and
resumes normal operation.

1.9. Compressor overheat prevention control

If the temperature of the compressor exceeds the compressor over­heat prevention temperature (110°C), the operation frequency is
decreased by about 4 to 10 Hz. Then, this operation is repeated every
60 seconds until the temperature of the compressor drops below the
overheat protection temperature (100°C).

Once the temperature of the compressor drops below the overheat
protection temperature, the operating frequency is increased by about
4 to 10 Hz every 60 seconds until the normal operation condition
resumes.

If the temperature of the compressor exceeds the overheat protection
temperature (for 120 seconds in cooling operation or 60 seconds in
heating operation) at minimum operating frequency, the compressor
stops operating and then restarts after about 180 seconds, and the
abovementioned control is repeated.

2 – 8

1.10. Startup control

Heating operation

Set temperature

Activation of
OFF timer

1hour
later

Max.

1.5 hours
later

Max.
2 hours
later

Timer setting
reached

1hour
later

Max.

1.5 hours
later

Max.
2 hours
later

Timer setting
reached

Activation of
OFF timer

Set temperature

-1

O

C

-1

O

C

-1

O

C

0.3

O

C

0.3

O

C

0.3

O

C

Cooling/dehumidifying operation

When the air conditioner starts in the cooling or heating mode, if the
room temperature is 2°C higher than the set temperature (in cooling
operation) or 3.5°C lower (in heating operation), the air conditioner
operates with the operating frequency at maximum. Then, when the
set temperature is reached, the air conditioner operates at the operat­ing frequency determined by fuzzy logic calculation, then enters the
normal control mode after a while.

1.11. Peak control

If the current flowing in the air conditioner exceeds the peak control
current (see the table below), the operation frequency is decreased
until the current value drops below the peak control current regardless
of the frequency control demand issued from the indoor unit based on
the room temperature.

AY-XP12FR-N Approx. 6.4 A Approx. 7.5 A

1.12. Outdoor unit fan delay control

The compressor stops immediately after cooling, dehumidifying or
heating operation is shut down, but the outdoor unit fan continues
operation for 50 seconds before it stops.

1.13. Defrosting

1.13.1 Reverse defrosting

The defrost operation starts when the compressor operating time
exceeds 20 minutes during heating operation, as shown below, and
the outside air temperature and the outdoor unit heat exchanger tem­perature meet certain conditions. When the defrost operation starts,
the indoor unit fan stops. The defrost operation stops when the out­door unit heat exchanger temperature rises to about 13C or higher or
the defrosting time exceeds 10 minutes.

Start of
heating
operation

1.14. ON timer

The ON timer can be activated by pressing the ON timer button. When
the ON timer is activated, the operation start time is adjusted based on
fuzzy logic calculations 1 hour before the set time so that the room
temperature reaches the set temperature at the set time.

1.15. OFF timer

The OFF timer can be activated by pressing the OFF timer button.
When the OFF timer is set, the operation stops after the set time.

When this timer is set, the compressor operating frequency lowers for
quieter operation, and the room temperature is gradually varied after
one hour (reduced 1°C three times (max. 3°C) in heating, or increased

0.3°C three times (max. 1°C) in cooling or dehumidifying operation) so
that the room temperature remains suitable for comfortable sleeping.

Model Peak control current

Cooling operation Heating operation

20 min or more 20 min or more 20 min or more

Defrosting
Max. 10 min

Defrosting
Max. 10 min

AYXP12FRN

1.16. Power ON start

If a jumper cable is inserted in the location marked with HAJP on the
indoor unit control printed circuit board (control PCB), connecting the
power cord to an AC outlet starts the air conditioner in either cooling or
heating mode, which is determined automatically by the room temper­ature sensor.

When a circuit breaker is used to control the ON/OFF operation,
please insert a jumper as described above.

1.17. Self-diagnostic malfunction code display

1.17.1 Indoor unit

1) When a malfunction is confirmed, all relays turn off and a flashing
malfunction code number is displayed to indicate the type of mal­function.

When the air conditioner is in non-operating condition, holding
down AUX button for more than 5 seconds activates the malfunc­tion code display function.

The operation continues only in the case of a serial open-circuit,
and the main relay turns off after 30 seconds if the open-circuit con­dition remains.

In the case of a serial short-circuit, the air conditioner continues
operating without a malfunction code display, and the main relay
turns off after 30 seconds if the short-circuit condition remains.

The malfunction information is stored in memory, and can be
recalled later and shown on display.

2) The self-diagnostic memory can be recalled and shown on the dis­play by stopping the operation and holding down AUX button for
more than 5 seconds.

3) The content of self-diagnosis (malfunction mode) is indicated by a
flashing number.

(For details, refer to the troubleshooting section.)

1.17.2 Outdoor unit

If a malfunction occurs, LED1 on the outdoor unit flashes in 0.2-sec­ond intervals as shown below.

(Example) Compressor high temperature abnormality

ON

OFF

1 sec 1 sec 0.6 sec

2 – 9

AYXP12FRN

1.18. Information about auto mode

In the AUTO mode, the temperature setting and mode are automati­cally selected according to the room temperature and outdoor temper­ature when the unit is turned on.

1.19. Airflow control

The airflow control holds the two upper and lower louvers at special
positions during operation to prevent discharged air from directly blow­ing onto people in the room.

Modes and Temperature Settings

1.19.1 Cooling/dehumidifying operation

When the airflow button is pressed the upper louver is set at an
upward angle to send the air along the ceiling.

1.19.2 Heating

When the airflow button is pressed the lower louver is set at a down-

the figures in ( ) are temperature settings

During operation, if the outdoor temperature changes, the temperature
settings will automatically slide as shown in the chart.

ward angle to send the air directly toward the floor.

1.20. Difference of operation in Auto and Manual modes

In the Auto mode, the temperature setting is automatically determined based on the outside air temperature. In addition, the air conditioner operation
differs from the operation in the Manual mode as explained below.

1.20.1 Difference relating to set temperature

Auto mode Manual mode

Cooling Heating Dehumidifying Cooling Heating Dehumidifying

Temperature
setting
method

Automatic temperature setting based on outside air tem­perature. Can be changed within ±2°C using remote con­trol.

1.21. Dehumidifying operation control

If the room temperature is 26°C or higher when dehumidifying opera­tion starts, the dehumidifying operation provides a low cooling effect in
accordance with the room temperature setting automatically deter­mined based on the outside air operation. (The setting value is the
same as the set temperature for cooling operation in the auto mode.)

If the room temperature is lower than 26°C when dehumidifying opera­tion starts, the dehumidifying operation minimizes the lowering of the
room temperature.

1.22. Self Clean operation

Heating or Fan operation and Cluster operation are performed simulta­neously.

The judgment of whether Heating or Fan operation is used is based on
the outside air temperature at 3 minutes after the start of internal
cleaning.

The operation stops after 40 minutes. (The air conditioner shows the
remaining minutes: 40 → 39 → 38 ... 3 → 2 → 1)

Heating operation Fan operation

Outside air temperature

24OC

1.23. Plasmacluster Ion function

Operating the Plasmacluster Ion button while the air conditioner is in
operation or in non-operation allows the switching of the operation
mode in the following sequence: “Air Clean operation” → “Stop”.

• “Self Clean operation” generates about equal amounts of (+)ions
and (-)ions from the cluster unit to provide clean air.

If the Plasmacluster Ion generation function is operated together with
the air conditioner operation, the indoor unit fan speed and louver
direction are in accordance with the air conditioner settings.

If the Plasmacluster Ion generation function is used without operating
the air conditioning function, the indoor unit fan operates at a very low
speed and the upper louver is angled upward and the lower louver
remains horizontal. (The airflow volume and direction can be changed
by using the remote control.)

Can be changed
between 18 and 32°C
using remote control.

Can be changed
between 18 and 32°C
using remote control.

1.24. Hot keep

When the room temperature rises above the set temperature by 0.6°C
or more, the ON/OFF operation of the compressor and indoor unit fan
is controlled in order to lower the room temperature.

(The values indicated below, such as "0.6°C" and "1.3°C," vary
depending on the outside air temperature.)

1.3OC

O

0.6

C

Set temperature

1.24.1 Hot keep zone 1

With the compressor frequency at the lowest, if the room temperature
is higher than the set temperature by 0.6°C but no more than 1.3°C,
the following processes will be activated.

1) The compressor stops temporarily, and restarts after 2 minutes.

2) If the room temperature remains in the hot keep zone, the com­pressor is turned OFF and ON in 3-minute intervals.

3) The indoor unit fan turns OFF and ON with a delay of 30 seconds
from the compressor OFF/ON.

4) After the above operation in 3-minute intervals is repeated four
times, the interval extends to 6 minutes.

1.24.2 Hot keep zone 2

If the compressor ON/OFF in hot keep zone 1 fails to bring the room
temperature within 1.3°C above the set temperature, the following pro­cesses will be activated.

1) The compressor repeats a cycle of 8-minute OFF and 6-minute
ON.

2) After the second time, the compressor remains completely OFF
and only the indoor unit fan repeats OFF-ON in set intervals.

3) While the compressor is completely OFF in 2), the louvers are set
horizontally to prevent cold air from blowing.

The zone transition and the end of hot keep operation (room tempera­ture lower than the set temperature) are judged when the compressor
ON period ends.

* This function cannot be repealed.

Automatic setting.
Can be changed
within ±2°C.

2 – 10

AYXP12FRN

1.25. Winter cool

Cooling operation is available during the winter season by the built in
winter cool function.

Lower limit of outdoor temperature range is -10°C DB.

When the outside air temperature is low, the outdoor unit fan operates
at slower speed.

NOTE: Built-in protect device may work when outdoor temperature

falls below 21°C DB., depending on conditions.

1.26. Auto restart

When power failure occures, after power is recovered, the unit will
automatically restart in the same setting which were active before the
power failure.

1.26.1 Operating mode (Cool, Heat, Dry)

• Temperature adjustment (within 2°C range) automatic operation

• Temperature setting

2. Explanation of cluster circuit

The cluster unit generates cluster ions, which are circulated throughout the room by the air flow created by the blower fan (indoor unit fan motor) in
the air conditioner unit.

1) When microcomputer output turns "H," the IC6 output changes to "Lo," turning ON the SSR and applying 230 V to the cluster unit for the genera­tion of cluster ions (positive and negative ions).

• Fan setting

• Air flow direction

• Power ON/OFF

• Automatic operation mode setting

• Swing louvre

• Plasmacluster mode

1.26.2 Setting not memorized

• Timer setting

• Full power setting

• Internal cleaning

1.26.3 Disabling auto restart function

By removing (cutting) jumper J (JPJ) on the printed circuit board
(PCB), the auto restart function can be disabled.

12V

R76

C23

RE RH

Cluster unit

1

1

3

3

5

6

AC230V

Microcomputer output

IC6

R75

R23

SSR

R20

3. Outline of PAM circuit

3.1. PAM (Pulse Amplitude Modulation)

The PAM circuit varies the compressor drive voltage and controls the rotation speed of the compressor.

The IGBT shown in the block diagram charges the energy (electromotive force) generated by the reactor to the electrolytic capacitor for the inverter
by turning ON and OFF.

Reactor L5

DB1

AC

230V

Noise

filter

Reactor L6

+

IPM

Compressor

AC clock
detection

circuit

DB2

IGBT

[PAM drive circuit]

Microcomputer (IC1)

PAM drive circuit block diagram

2 – 11

IGBT

drive

circuit

Overvoltage

detection

circuit

Compressor

position
detector

AYXP12FRN

When the IGBT is ON, an electric current flows to the IGBT via the reactor (L5), (L6) and diode bridge (DB2).

When the IGBT turns OFF, the energy stored while the IGBT was ON is charged to the voltage doubler capacitor via the diode bridge (DB1).

As such, by varying the ON/OFF duty of the IGBT, the output voltage is varied.

DB1

Stored energy

IGBT ON

IGBT OFF

Reactor

L6

L5

DB2

IGBT

3.2. High power factor control circuit

This circuit brings the operating current waveform closer to the waveform of commercial power supply voltage to maintain a high power factor.

Because of the capacitor input, when the PAM circuit is OFF, the phase of the current waveform deviates from the voltage waveform as shown below.

To prevent this deviation, a current is supplied during the periods indicated by "O" in the diagram.

To determine the length of period to supply a current, the zero-cross timing of the AC input voltage is input to the microcomputer via the clock circuit.

The power source frequency is also determined at the same time.

The IGBT turns ON after the time length determined by the zero-cross point to supply a current to the IGBT via the reactor.

This brings the current waveform closer to the voltage waveform in phase.

As described above, the ON/OFF operation of the IGBT controls the increase/decrease of the compressor power supply voltage (DC voltage) to
improve the compressor efficiency and maintain a high power factor by keeping the current phase closer to that of the supply voltage.

AC voltage waveform

AC voltage waveform

AC current waveform

AC voltage and current waveforms when PAM is OFF

AC current waveform

Zero-cross detection

IGBT ON period

AC voltage and current waveform when PAM is ON

3.2.1 Detailed explanation of PAM drive circuit sequence

AC voltage waveform

Clock

IGBT ON

A

BC

50Hz

A

1.2mS

B

1.2mS

C

0.25 2.3mS

3.2.2 AC clock (zero-cross) judgment

• The clock circuit determines the time from one rising point of the clock waveform to the next rising point.

The detected clock waveform is used to judge the power source frequency (50Hz).

• The zero-cross of the AC voltage is judged as the rising of the clock waveform, as shown in the diagram above.

3.2.3 IGBT ON start time (delay time B)

• Based on the zero-cross of the AC voltage, the IGBT turns ON after a delay time set according to the power source frequency.

3.2.4 IGBT ON time (C)

• After the above delay time, the IGBT turns ON to supply a current to the reactor.

• The ON time of the IGBT determines the amount of energy (level of DC voltage rise) supplied to the reactor.

DC voltage level in each operation mode (varies depending on external load conditions)

– Cooling operation --- 220 to 240 V

– Heating operation --- 220 to 280 V

2 – 12

3.3. PAM protection circuit

R2
255K

C10C9

420V
750uF

R5
300K

R7

23.7KR823.7K

0V

0V

0V

IC8

15V

R113

19.1KF

R112
15K

5V
R114
1M

R115

1.8K

R116
1K

5

4

2

(Overvoltage detection)

During abnormal voltage output

IC1

38

To prevent excessive voltage of PAM output from
damaging the IPM and electrolytic capacitor as well
as the control printed circuit board (PCB), this circuit
monitors the PAM output voltage and turns off the
PAM control signal and PAM drive immediately
when an abnormal voltage output is generated. At
the same time, it shuts off the compressor operation.

The PAM output voltage is distributed to pin (4) of
the comparator (IC8). If this voltage exceeds the ref­erence voltage at pin (5) of the IC8, the output of the
comparator (IC8) reverses (from H to L) and it is
input to pin (38) of the microcomputer (IC1) to halt
the PAM drive.

The protection voltage level is as follows.

3.3.1 Details of troubleshooting procedure for PAM

1) PAM shutdown due to error

1) When the DC voltage detection circuit sends a signal exceeding the specified voltage to the microcomputer

DC voltage of 350 V or higher (detection circuit input voltage of about 9.2 V or higher) [IC8 pin (4)]

– When an error is detected

• PAM IGBT turns OFF.

• Compressor turns OFF.

• All units shut down completely when the error occurs four times.

2) When the outdoor unit clock waveform differs from the specified value immediately before the PAM IGBT turns ON

When there is no clock waveform input

When a clock signal of other than specified power source frequency (50/60 Hz) is input

– When an error is detected

• PAM IGBT does not turn ON.

• Compressor operates normally.

• Complete shutdown does not occur.

2) PAM error indication

In case of error “1)”

– An error signal is sent to the indoor unit as soon as an error is generated.

• Malfunction No. 14-0 is indicated when the error code is called out by the indoor unit's self-diagnosis function.

– The LED on the outdoor unit flashes 14 times when an error is generated.

• The LED continues flashing in the 14-time cycle even after the compressor stops operating.

• The LED turns off (data is deleted from the memory) when the outdoor unit power is turned off.

In case of error “2)”

– An error signal is sent to the indoor unit as soon as an error is judged.

• Malfunction No. 14-1 is indicated when the error code is called out by the indoor unit's self-diagnosis function.

– The LED on the outdoor unit flashes 14 times when an error is judged.

• The LED on the outdoor unit flashes in normal pattern when the compressor stops operating.

(Compressor OFF or Thermostat OFF from remote control)

* When a user complains that the air conditioner does not provide sufficient cool air or warm air

In addition to conventional error-generating reasons, there is a possibility that the PAM IGBT does not turn ON even if the compressor is operating.

In that case, the DC voltage does not rise even though the compressor is operating, and lowers to the 180-VDC level.

– Check items

• Clock circuit check

• PAM IGBT check

• Fuse (Fu6) open-circuit check

AYXP12FRN

2 – 13

AYXP12FRN

D

4. Explanation of IPM drive circuit

The IPM for compressor drive is made by Mitsubishi Electric.

The power supply for the IPM drive, the shunt resistance for overcurrent detection, etc., are provided outside the IPM (control PCB).

4.1. IPM drive power supply circuit

The power supply for the upper-phase IGBT (HU, HV, HW) drive employs a bootstrap system, and provides power to the upper-phase IC.

The 15-V power supply for the lower-phase IC is provided by the control printed circuit board (PCB).

4.1.1 Brief explanation of bootstrap system (single power drive system)

To supply power to the upper-phase IC, the microcomputer (IC1) turns ON the lower-phase IGBT (LU, LV, LW).

This results in a charging current that flows to the electrolytic capacitor of each upper-phase IC input and charges the bootstrap capacitor with a 15-V
current.

The power supply for the subsequent stages is charged while the lower-phase IGBT is ON in ordinary compressor drive control.

Initial charge period

VDB

Charging current group

Bootstrap capacitor

(HU,HV,HW)

HVIC

High-voltage-withstanding,
high-speed recovery diode

P(Vcc)

U,V,W,

V

D

VCIN(n)

(LU,LV,LW)

Bootstrapcircuit

LVIC

N-side
IGBT

N(GN

2 – 14

AYXP12FRN

4.1.2 DC overcurrent detection circuit

When a current of about 25 A or higher flows through the shunt resistance (R49) on the control printed circuit board (PCB), the voltage at this resis­tance is input to IPM CIN pin (26). Then, the gate voltage of the lower-phase IGBT (LU, LV, LW) inside the IPM turns OFF to cut off the overcurrent. At
the same time, an L output of about 1.8 ms is generated from IPM Fo pin (24), and this results in an L input to overcurrent detection input pin (34) of
the microcomputer (IC1) and turns OFF the PWM signal output (IC1 pins (51) through (56)) to the IGBT gate.

Protection circuit status

(Lower phase)
Internal IGBT gate

Output current Ic (A)

Sense voltage relative
to shunt resistance

Error output Fo

SET

RESET

(About 22 A)

SC

a1

SC reference voltage

Delay by CR time constant circuit

About 1.8 ms

IPM overcurrent
detection circuit

CiN

26

FO

24

P

Shunt resistance

R49

N

Overcurrent

5V

IC1

34

0V

2 – 15

AYXP12FRN

5. 120° energizing control (digital position detection control)

This control system detects the digital position detection signal and adjusts the rate of acceleration/deceleration accordingly.

The motor's induced voltage waveform is input to the comparator in the form of PWM-switched pulse waveform, and a position detection signal is
generated as a reference voltage equaling 1/2 of 280 VDC. However, since there is no induced voltage waveform when the PWM waveform is OFF,
the microcomputer performs internal processing so that detection is enabled only when it is ON. Based on the detected position signal, actual PWM
waveform output timing is determined. Since it does not use a filter circuit, the detection accuracy is high.

The microcomputer performs internal processing to cancel spike voltage during the regenerative process.

Furthermore, even if the induced voltage is low, position detection is still possible, thus allowing sensor-less operation at low rotation speed in the ini­tial stage of operation. This reduces the starting current and improves the IPM reliability.

Terminal voltage waveform

Reference voltage
(1/2 of DC voltage)

Spike voltage

(cancelled)

Comparator output waveform
(Position signal waveform)

2 – 16

AYXP12FRN

AYXP12FRN

CHAPTER 3. FUNCTION AND OPERATION OF PROTECTIVE PROCEDURES

Service Manual

[1] PROTECTION DEVICE FUNCTIONS AND OPERATIONS

Function Operation Self-diagnosis

result display

Description Detection period Reset condition Indoor

1 Indoor unit fan lock Operation stops if there is no

Indoor unit fan rota­tion speed error

2 Indoor unit freeze

prevention

3 2-way valve freeze

prevention

4 Indoor unit heat

exchanger over­heat shutdown

5 Outdoor unit heat

exchanger over­heat shutdown

6 Compressor dis-

charge overheat
shutdown

7 Dehumidifying oper-

ation temporary
stop

8 DC overcurrent

error

input of rotation pulse signal from
indoor unit fan motor for 1 minute.
Operation stops if rotation pulse
signal from indoor unit fan indi­cates abnormally low speed
(about 300 rpm or slower).
Compressor stops if temperature
remains below 0°C for 4 minutes.

Compressor stops if temperature
of outdoor unit 2-way valve
remains below 0°C for 10 continu­ous minutes during cooling or
dehumidifying operation.

Operating frequency lowers if
indoor unit heat exchanger tem­perature exceeds overheat tem­perature during heating
operation.
Compressor stops if indoor unit
heat exchanger temperature
exceeds overheat temperature for
60 seconds at minimum fre­quency.
Overheat temperature setting
value indoor unit heat exchanger
thermistor temperature: about 45
to 54°C

Operation frequency lowers if out­door unit heat exchanger temper­ature exceeds about 55°C during
cooling operation.
Compressor stops if outdoor unit
heat exchanger temperature
exceeds about 55°C for 120 sec­onds at minimum frequency.

Operating frequency lowers if
temperature of compressor
chamber thermistor (TH1) falls
below about 110°C.
Compressor stops if temperature
of compressor chamber ther­mistor (TH1) remains at about
110 °C (for 120 seconds in cooling
operation, or 60 seconds in heat­ing operation) at minimum fre­quency.

Compressor stops if outside air
temperature thermistor is lower
than about 16°C during dehumidi­fying operation.

Compressor stops if electric cur­rent of about 25 A or higher flows
in IPM.

When indoor unit fan
is in operation

When indoor unit fan
is in operation

When in cooling or
dehumidifying opera­tion

When in cooling or
dehumidifying opera­tion

When in heating
operation

When in cooling or
dehumidifying opera­tion

When compressor is
in operation

When in dehumidify­ing operation

When compressor is
in operation

Indoor

unit

error

display

Operation OFF or ON ✩2 Yes None

Operation OFF or ON ✩2 Yes None

Automatic reset when
heat exchanger tem­perature rises above
freeze prevention
temperature (2°C or
higher)

Automatic reset when
temperature of 2-way
valve rises above
10°C.

Automatic reset after
safety period (180
sec).

Automatic reset after
safety period (180
sec).

Automatic reset after
safety period (180
sec).

Automatic reset when
outside air tempera­ture rises above
16°C.

Operation OFF or ON Yes ✩1Yes Yes

— None None

None Yes Yes

None Yes Yes

None Yes Yes

None Yes Yes

None Yes Yes

unit

Outdoor

unit

3 – 1

AYXP12FRN

Function Operation Self-diagnosis

Description Detection period Reset condition Indoor

9 AC overcurrent

error

10 AC overcurrent

error in compressor
OFF status

11 AC maximum cur-

rent error

12 AC current defi-

ciency error

13 Thermistor installa-

tion error or 4-way
valve error

14 Compressor high

temperature error

15 Outdoor unit heat

exchanger ther­mistor short-circuit
error

16 Outdoor unit outside

air temperature
thermistor short-cir­cuit error

17 Outdoor unit suction

thermistor short-cir­cuit error

18 Outdoor unit 2-way

valve thermistor
short-circuit error

19 Outdoor unit heat

exchanger ther­mistor open-circuit
error

20 Outdoor unit outside

air temperature
thermistor open-cir­cuit error

21 Outdoor unit suction

thermistor open-cir­cuit error

22 Outdoor unit 2-way

valve thermistor
open-circuit error

23 Outdoor unit dis-

charge thermistor
open-circuit error

24 Serial signal error Power relay turns OFF if indoor

Operating frequency lowers if
compressor AC current exceeds
peak control current value. Com­pressor stops if compressor AC
current exceeds peak control cur­rent value at minimum frequency.

Indoor and outdoor units stop if
AC current exceeds about 3 A
while compressor is in non-opera­tion status.
Compressor stops if compressor
AC current exceeds 17 A.
Compressor stops if operating
frequency is 50 Hz or higher and
compressor AC current is about

2.0 A or lower.
Compressor stops if high and low
values of temperatures detected
by outdoor unit heat exchanger

thermistor (TH2) and 2-way valve
thermistor (TH5) do not match
operating cycle.
Compressor stops if compressor
chamber thermistor (TH1)
exceeds about 114°C, or if there
is short-circuit in TH1.
Compressor stops if there is
short-circuit in outdoor unit heat
exchanger thermistor (TH2).

Compressor stops if there is
short-circuit in outdoor unit out­side air temperature thermistor
(TH3).

Compressor stops if there is
short-circuit in outdoor unit suc­tion thermistor (TH4).

Compressor stops if there is
short-circuit in outdoor unit 2-way
valve thermistor (TH5).

Compressor stops if there is
open-circuit in outdoor unit heat
exchanger thermistor (TH2).

Compressor stops if there is
open-circuit in outdoor unit out­side air temperature thermistor
(TH3).

Compressor stops if there is
open-circuit in outdoor unit suc­tion thermistor (TH4).

Compressor stops if there is
open-circuit in outdoor unit 2-way
valve thermistor (TH5).

Compressor stops if there is
open-circuit in outdoor unit dis­charge thermistor (TH1).

unit cannot receive serial signal
from outdoor unit for 8 minutes.

Compressor stops if outdoor unit
cannot receive serial signal from
indoor unit for 30 seconds.

result display

Indoor

unit

error

display

When compressor is
in operation

When compressor is
in non-operation

When compressor is
in operation
When compressor is
in operation

3 minutes after com­pressor startup

When in operation Operation OFF or ON Yes ✩1Yes Yes

At compressor star­tup

At compressor star­tup

At compressor star­tup

At compressor star­tup

At compressor star­tup

At compressor star­tup

At compressor star­tup

At compressor star­tup

At compressor star­tup

When in operation Operation OFF or ON

When in operation Reset after reception

Operation OFF or ON Yes ✩1Yes Yes

Replacement of
defective parts such
as IPM

Operation OFF or ON Yes ✩1Yes Yes

Operation OFF or ON Yes ✩1Yes Yes

Operation OFF or ON Yes ✩1Yes Yes

Operation OFF or ON Yes ✩1Yes Yes

Operation OFF or ON Yes ✩1Yes Yes

Operation OFF or ON Yes ✩1Yes Yes

Operation OFF or ON Yes ✩1Yes Yes

Operation OFF or ON Yes ✩1Yes Yes

Operation OFF or ON Yes ✩1Yes Yes

Operation OFF or ON Yes ✩1Yes Yes

Operation OFF or ON Yes ✩1Yes Yes

Operation OFF or ON Yes ✩1Yes Yes

(Automatic reset
when less than 8 min­utes)

of serial signal

Yes ✩ 2Yes Yes

None None None

unit

Yes None

Outdoor

unit

3 – 2

Function Operation Self-diagnosis

Description Detection period Reset condition Indoor

25 Compressor star-

tup error

26 Compressor rota-

tion error (at 120°
energizing)

27 Outdoor unit DC fan

error

28 PAM overvoltage

error

29 PAM clock error When power source frequency

30 IPM pin level error When Outdoor unit starts to run,

✩1—The outdoor unit restarts four times before the indoor unit error is displayed (complete shutdown).

✩2—A single error judgment results in the display of the indoor unit error (complete shutdown).

✩3—The outdoor unit restarts eight times before the indoor unit error is displayed (complete shutdown).

Compressor stops if compressor
fails to start up.

Compressor stops if there is no
input of position detection signal
from compressor or input is
abnormal.

Operation stops if there is no
input of rotation pulse signal from
outdoor unit fan motor for 30 sec­onds.

Compressor stops if DC voltage is
350 V or higher.

cannot be determined (at startup),
or when power source clock can­not be detected for 1 continuous
second (at startup).

MCU checks 6 control pin levels
of IPM. If MCU detects some pin
levels isn’t different from another
pin level. MCU doesn’t run Com­pressor.

At compressor star­tup

Compressor operat­ing at 120° energizing

When outdoor unit
fan is in operation

When in operation Operation OFF or ON Yes ✩1Yes Yes

At compressor star­tup, when in opera­tion

At compressor star­tup

Operation OFF or ON Yes ✩3Yes Yes

Operation OFF or ON Yes ✩3Yes Yes

Operation OFF or ON Yes ✩1Yes Yes

Compressor contin­ues operation with­out stopping.

Operation OFF or ON Yes ✩1Yes Yes

AYXP12FRN

result display

Indoor

unit

error

display

None Yes Yes

unit

Outdoor

unit

[2] AIR CONDITIONER OPERATION IN THERMISTOR ERROR

1. Indoor unit

Item Mode Control opera-

Room tempera­ture thermistor
(TH1)

Auto Operation mode

judgment

Cooling Frequency control Room becomes

Dehumidifying Room tempera-

ture memory
Frequency control

Heating Frequency control Room does not

tion

When resis­tance is low

(temperature

judged higher

than actual)

Cooling mode is
activated even if
room tempera­ture is low.

too cold.

Normal operation. Room tempera-

become warm.

Short-circuit When resis-

Cooling mode is
activated in most
cases.

Air conditioner
operates in full
power even when
set temperature is
reached.

ture is stored in
memory as

31.0°C, and com­pressor does not
stop.

Hot keep status
results immedi­ately after opera­tion starts.
Frequency does
not increase
above 30 Hz (40
Hz).

Open-circuit
tance is high
(temperature
judged lower

than actual)

Heating mode is
activated even if
room tempera­ture is high.

Room does not
become cool.

Normal operation. Room tempera-

Room becomes
too warm.

Heating mode is
always activated.

Compressor does
not operate.

ture is stored in
memory as

18.5°C, and com­pressor does not
operate.

Air conditioner
operates in full
power even when
set temperature is
reached.

3 – 3

AYXP12FRN

Item Mode Control opera-

Heat exchanger
thermistor (TH2)

Cooling
Dehumidifying

Heating Cold air preven-

2. Outdoor unit

Item Mode Control opera-

Compressor
chamber ther­mistor (TH1)

Heat exchanger
thermistor (TH2)

Outside air tem­perature ther­mistor (TH3)

Suction pipe ther­mistor (TH4)

Cooling
Dehumidifying
Heating

Cooling
Dehumidifying

Heating Expansion valve

Auto Operation mode

Cooling
Dehumidifying

Heating Rating control

Cooling
Dehumidifying

Heating Expansion valve

tion

Freeze preven­tion

tion

tion

Expansion valve
control and com­pressor protection

Outdoor unit heat
exchanger over­heat prevention

control
Defrosting

judgment

Operation not
affected

Defrosting

Expansion valve
control

control

When resis­tance is low

(temperature

judged higher

than actual)

Indoor unit evap­orator may
freeze.
Cold air preven­tion deactivates
too soon and cold
air discharges.

When resis­tance is low

(temperature

judged higher

than actual)

Compressor
operates, but
room does not
become cool or
warm (expansion
valve is open).

Compressor
operates at low
speed or stops.

Defrosting opera­tion is not acti­vated as needed,
and frost accumu­lates on outdoor
unit (expansion
valve is closed).
Cooling mode is
activated even if
room tempera­ture is low.

Normal operation. Outdoor unit ther-

Defrosting opera­tion is activated
unnecessarily.

Compressor
operates, but
room does not
become cool
(expansion valve
is open).

Compressor
operates, but
room does not
become warm
(expansion valve
is open).

Short-circuit When resis-

Indoor unit evap­orator may
freeze.
Compressor
operates at low
speed or stops,
and frequency
does not
increase.

Short-circuit When resis-

Compressor high
temperature error
indication.

Outdoor unit ther­mistor short-cir­cuit error
indication.

Outdoor unit ther­mistor short-cir­cuit error
indication.

Outdoor unit ther­mistor short-cir­cuit error
indication.

mistor short-cir­cuit error
indication.
Outdoor unit ther­mistor short-cir­cuit error
indication.

Outdoor unit ther­mistor short-cir­cuit error
indication.

Outdoor unit ther­mistor short-cir­cuit error
indication.

tance is high
(temperature
judged lower

than actual)

Compressor
stops occasion­ally.
Cold air preven­tion deactivates
too slow.

tance is high
(temperature
judged lower

than actual)

Layer short-cir­cuit or open-cir­cuit may result in
compressor in
normal operation.

Normal operation. Outdoor unit ther-

Defrosting opera­tion is activated
unnecessarily,
and room does
not become warm
(expansion valve
is open).
Heating mode is
activated even if
room tempera­ture is high.

Normal operation. Outdoor unit ther-

Defrosting opera­tion is not acti­vated, and frost
accumulates on
outdoor unit.
Frost accumu­lates on evapora­tor inlet section,
and room does
not become cool
(expansion valve
is closed).
Frost accumu­lates on expan­sion valve outlet
section, and room
does not become
warm (expansion
valve is closed).

Open-circuit

Compressor does
not operate.

Cold air preven­tion does not
deactivate, and
indoor unit fan
does not rotate.

Open-circuit

Outdoor unit ther­mistor open-cir­cuit error
indication.

mistor open-cir­cuit error
indication.
Outdoor unit ther­mistor open-cir­cuit error
indication.

Outdoor unit ther­mistor open-cir­cuit error
indication.

mistor open-cir­cuit error
indication.
Outdoor unit ther­mistor open-cir­cuit error
indication.

Outdoor unit ther­mistor open-cir­cuit error
indication.

Outdoor unit ther­mistor open-cir­cuit error
indication.

3 – 4

AYXP12FRN

Item Mode Control opera-

tion

When resis­tance is low

Short-circuit When resis-

(temperature

judged higher

than actual)

2-way valve ther­mistor (TH5)

Cooling
Dehumidifying

Expansion valve
control

Frost accumu­lates on indoor
unit evaporator
and room does

Outdoor unit ther­mistor short-cir­cuit error

indication.
not become cool
(expansion valve
is closed).

Heating Operation not

affected

Normal operation. Outdoor unit ther-

mistor short-cir-

cuit error

indication.

[3] THERMISTOR TEMPERATURE CHARACTERISTICS

1. Indoor unit thermistor temperature characteristics

TH1 TH2

CN4

43

-

+

Room temperature thermistor TH1 (yellow)

Resistance at 25 : 10 k

Resistance

(K )

K

100

80

60

40

20

Heat exchanger thermistor TH2 (orange)
Resistance at 25 : 15 k

21

-

+

TesterTester

CN4

Open-circuit
tance is high
(temperature
judged lower

than actual)

Compressor
operates, but
room does not
become cool

Outdoor unit ther­mistor open-cir­cuit error

indication.
(expansion valve
is open).

Normal operation. Outdoor unit ther-

mistor open-cir-

cuit error

indication.

0

-10

010203040

TH1 Room temperature thermistor
TH2 Heat exchanger thermistor

Thermistor

Room temperature

Heat exchanger

Symbol

TH1

(CN4)

TH2
(CN4)

Temperature( )

Color

Yellow

Orange

Before measuring resistance,
disconnect connectors as
shown above.

3 – 5

AYXP12FRN

2. Outdoor unit thermistor temperature characteristics

500K

400K

Resistance

(K )

300K

200K

100K

0

-20 0 20 60 80 100 120

TH1 Compressor thermistor

Compressor thermistor

Heat exchanger thermistor

Outdoor air temperature thermistor

Suction thermistor

2-way valve thermistor

Thermistor

Resistance at 25

52.76 k

Temperature( )

Connector
CN8

110

+

-

5.8K

Tester

4.17K

3.06K

2.28K

No.

TH1

TH2

TH3

TH4

TH5

1.72K

Resistance

(K )

Connector

No. (1) - No. (2)

No. (3) - No. (4)

No. (5) - No. (6)

No. (7) - No. (8)

No. (9) - No. (10)

Connector
CN8

110

+

-

40K

Resistance at 0

30K

14.57 k

20K

10K

0

-20 0 20 6040

Tester

(In case of TH2 heat exchanger thermistor)

Resistance at 25

4.431 k
TH2 TH5

Temperature( )

TH2 Heat exchanger thermistor
TH3 Outdoor air temperature thermistor
TH4 Suction thermistor
TH5 2-way valve thermistor

Color

Before measuring resistance,

Red

disconnect connectors from PWB.

Orange

Green

Black

Yellow

3 – 6

AYXP12FRN

Connect with IC clip
Test mode cooling at 40 Hz

[4] HOW TO OPERATE THE OUTDOOR UNIT INDEPENDENTLY

1. Cooling in 40 Hz fixed mode

To operate the outdoor unit independently, short-circuit the sections indicated by arrows in the diagram below with an adapter, and apply 230 VAC
between (1) and (N) on the terminal board of the outdoor unit. This allows the outdoor unit to be operated in cooling mode independently.

(Do not operate the outdoor unit in this condition for an extended period of time.)

Short-circuit negative terminal of

Connect with IC clip
Test mode cooling at 40 Hz

C9C10

(L2)

capacitor (C33) and jumper wire
(JP16) using IC clip, etc.

[5] GENERAL TROUBLESHOOTING CHART

1. Indoor unit does not turn on

Main cause Inspection method Normal value/condition Remedy

Cracked PWB.
(Cracked pattern)

Open-circuit in FU1 (250 V, 3 A),
FU2 (250 V, 3 A)

Check visually. There should be no cracking in

PWB or pattern.

Check melting of FU1, FU2. There should be no open-circuit. Replace PWB.

Replace PWB.

2. Indoor unit fan does not operate

Main cause Inspection method Normal value/condition Remedy

Open-circuit in heat exchanger
thermistor (TH2) (in heating oper­ation)

Disconnected heat exchanger
thermistor (TH2) (in heating oper­ation)

Measure thermistor resistance
(dismount for check).

Inspect connector on PWB.
Check thermistor installation con­dition.

3. Indoor unit fan speed does not change

Main cause Inspection method Normal value/condition Remedy

Remote control not designed to
allow fan speed change.

Check operation mode. Fan speed should change except

4. Remote control signal is not received

Main cause Inspection method Normal value/condition Remedy

Batteries at end of service life. Measure battery voltage. 2.5 V or higher (two batteries in

Batteries installed incorrectly. Check battery direction. As indicated on battery compart-

Lighting fixture is too close, or flu­orescent lamp is burning out.

Use Sevick light (Hitachi). Check if Sevick light (Hitachi) is

Operating position/angle is inap­propriate.
Open-circuit or short-circuit in wir­ing of light receiving section.

Defective light receiving unit. Check signal receiving circuit

Turn off light and check. Signal should be received when

used.

Operate within range specified in
manual.
Check if wires of light receiving
section are caught.

(measure voltage between termi­nals 2 and 3 of connector
BCN3B).

– 1 Replace thermistor.
There should be no open-circuit
or faulty contact.
Thermistor should not be discon­nected.

during dehumidifying operation,
ventilation, light dehumidifying
operation, internally normal oper­ation

series connection)

ment.

light is turned off.
Signal may not be received

sometimes due to effect of Sevick
light.
Signal should be received within
range specified in manual.
Wires of light receiving section
should not have any damage
caused by pinching.
Tester indicator should move
when signal is received.

Replace thermistor.

Install correctly.

Explain to user.

Install new batteries.

Install batteries in indicated direc­tion.

Change light position or install
new fluorescent lamp.

Replace light or change position.

Explain appropriate handling to
user.
Replace wires of light receiving
section.

Replace PWB.

3 – 7

AYXP12FRN

Main cause Inspection method Normal value/condition Remedy

Dew condensation on light receiv­ing unit.

5. Louvers do not move

Main cause Inspection method Normal value/condition Remedy

Caught in sliding section. Operate to see if louvers are

Disconnected connector (DCNC,
DCND on relay PWB, louver
motor side)

Contact of solder on PWB
(connector section on PWB)

6. There is noise in TV/radio

Main cause Inspection method Normal value/condition Remedy

Grounding wires not connected
properly.

TV/radio is placed too close to
outdoor unit.

Other than above. Check for radio wave interfer-

7. Malfunction occurs

Check for water and rust. Signal should be received within

caught in place.
Inspect connectors. Connectors or pins should not be

Check visually. There should not be solder con-

Check grounding wire connec­tions.

Check distance between TV/radio
and outdoor unit.

ence. (See page )

range specified in manual.

Louvers should operate smoothly. Remove or correct catching sec-

disconnected.

tact.

Grounding wires should be con­nected properly.

If TV/radio is placed too close, it
may become affected by noise.

Take moisture-proof measure for
lead wire outlet of light receiving
section.

tion.
Install correctly.

Correct contacting section.

Connect grounding wires prop­erly.

Move TV/radio away from outdoor
unit.

Main cause Inspection method Normal value/condition Remedy

Malfunction caused by noise. Check for radio wave interfer-

ence. (See page )

8. Compressor does not start

Main cause Inspection method Normal value/condition Remedy

Erroneous inter-unit connection. Check wiring between indoor and

outdoor units.

Damaged IPM. Check IPM continuity. See [IPM check method] on page

Dried-up electrolytic capacitor. Check electrolytic capacitor. See [Inverter electrolytic capaci-

Blown outdoor unit fuse. Check 20-A fuse.

Check 15-A fuse.

Power supply voltage is too low. Measure power supply voltage

during startup.

Compressor lock. Supply current and touch com-

pressor cover (sound absorbing
material) to check if operation
starts.

Terminal board 1-N: 230 VAC, 50
Hz
Terminal board 2: serial signal

8-3.

tor (C9, C10) check method] on
page 8-2.
Fuse should not be blown. Replace fuse/diode bridge.

230±10 VAC, 50 Hz Make sure that power supply volt-

Compressor should start nor­mally.

9. Operation stops after a few minutes and restarts, and this process repeats

Correct wiring.

Replace IPM.

Replace electrolytic capacitor.

Replace fuse.
Replace outdoor unit PWB
assembly.

age is 180 V or higher.
Apply external impact to com­pressor.
Replace compressor.

Main cause Inspection method Normal value/condition Remedy

Dried-up electrolytic capacitor. Measure 320-VDC line voltage. 250 V or higher. Replace electrolytic capacitor.
Layer short-circuit in expansion
valve coil.

CAUTION: If fuse FU1/FU4/FU5 (outdoor unit control circuit board) is blown, be careful of charging voltage in inverter electrolytic capacitor C9, C10.

To discharge stored electricity, unplug the power cord and connect the plug of a soldering iron (100VAC, 50W) between the positive and
negative terminals of inverter electrolytic capacitor C9, C10.

Measure resistance. 46±3Ω in each phase (at 20°C) Replace coil.

3 – 8

AYXP12FRN

[6] MALFUNCTION (PARTS) CHECK METHOD

1. Procedure for determining defective outdoor unit IPM/compressor

The following flow chart shows a procedure for locating the cause of a malfunction when the compressor does not start up and a DC overcurrent indi­cation error occurs.

Connect power cord

to AC outlet.

Using remote control,
operate air conditioner
so that compressor
starts.

After about
20 seconds

NO

Is there 230 VAC
between (1) and (N)
on outdoor unit PCB?

YES

Is LED1 on outdoor

unit flashing?

Check inter-unit wiring.
Check indoor unit PWB.

NO

Does LED1 remain lit?

No

(unlit)

Is there 320 VDC between
pins IPM (31) and (35)?

Check posistor (PTC1)
(about 40 at 25 ).
Check IPM.
Check fan motor.
Check outdoor unit PCB.

NO

Check wiring.
Check PAM IGBT (Q5).

YES

Compressor starts up.

Immediately
after startup

Does LED1 indicate
DC overcurrent error?

NO

Does LED1 indicate
rotation error?

NO

Normal

YES

Serial signal error.
Check inter-unit wiring.
Check indoor and
outdoor unit PWBs.

YES

Replace outdoor unit
PWB.
Check compressor.
2/3-way valve closed.
Refrigerant shortage.

Outdoor unit PWB.

YES YES

15/5 V display section.
Voltage OK.

NO

Replace outdoor unit PWB.

YES

+13 V, +15 V on PWB.

YES

Replace outdoor unit PWB.

Replace expansion valve.

Replace outdoor unit

NO

Replace compressor.

NO

Disconnect expansion
valve connector.

YES

OK

+13 V on PWB.

End.

NO

Replace outdoor unit PWB.

3 – 9

AYXP12FRN

2. Procedure for determining defective expansion valve

Measure resistance in expansion valve coil.

6

Checker

5.6K

5

4

Connector

J.S.T. XAP-06V-1

Terminal

SXA-001T-P0.6

LED
(red)

5.6K

5.6K

32

1

5.6K

Replace control PWB.

Normal resistance between red

terminal of expansion valve

lead wire and each terminal:

about 46 (at 20 )

YES

Insert checker shown at left into
connector (CN12) on control PWB, and
operate air conditioner.

NO

Do LEDs on checker light in orderly
sequence
(lighting of 1 LED => lighting of 2 LEDs)

YES

If frost accumulates on 2-way valve after 10 to 20

minutes of cooling operation, then thermistors with

yellow and black lead wires may be defective. Check

these thermistors.

&GHGEVKXGVJGTOKUVQT

NO

6JGTOKUVQTUKP

PQTOCNEQPFKVKQP

4GRNCEGVJGTOKUVQTCUUGODN[

4GRNCEGGZRCPUKQP

XCNXGCUUGODN[

3. Diode bridge check method

Turn off the power and let the inverter electrolytic capacitor (C9, C10) discharge completely. Then use a tester and check continuity.

When using a digital tester, the (+) and (-) tester lead wires in the table must be reversed.

Needle-type tester

45 B

Value in ( ) is for digital tester.

Normal resistance value

(several M )

4. Inverter electrolytic capacitor (C9, C10) check method

Turn off the power, let the inverter electrolytic capacitor (C9, C10) discharge completely, and remove the capacitor from the control printed circuit
board (PWB). First, check the case for cracks, deformation and other damages. Then, using a needle-type tester, check continuity.

Determination of normal condition

The tester needle should move on the scale and slowly returns to the original position. The tester needle should move
in the same way when polarities are reversed. (When measurement is taken with the polarities reversed, the tester
needle exceeds the scale range. Therefore, let the capacitor discharge before measurement.)

3 – 10

AYXP12FRN

0

5. IPM check method

Turn off the power, let the large capacity electrolytic capacitor (C10) discharge completely, and dismount the IPM. Then, using a tester, check leak
current between C and E.

When using a digital tester, the (+) and (-) tester lead wires in the table must be reversed.

Needle-type tester Normal resistance value

(-) (+)

PN∞

U

(several MΩ)

V
W

5.1. IPM internal circuit diagram

Needle-type tester Normal resistance value

(-) (+)

UN∞
V

(several MΩ)

W

Values in ( ) are for digital tester.

2

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8

[7] OUTDOOR UNIT CHECK METHOD

After repairing the outdoor unit, conduct the following inspection procedures to make sure that it has been repaired completely. Then, operate the
compressor for a final operation check.

1. Checking procedures

No

.

1 Preparation Disconnect compressor cords (white,

2 Inverter DC power supply

voltage check

3 IPM circuit check Check that 3 lamps (load) light.

Item Check method Normal value/condition Remedy

orange, red: 3 wires) from compres­sor terminals, and connect simulated
load (lamp used as load).
Operate air conditioner in cooling or
heating test operation mode.
Measure DC voltage between IPM
pins (31) and (35).

Check position detection voltage (+15
V, 5 V) on control PWB.

320 VDC Replace control PWB.

Replace diode bridge.
Correct soldered section of Fas­ten tabs (T1, T2, T5 - T3) on con­trol PWB and IMP (S, C, R).
(Repair solder cracks.)

Each voltage should be normal.

Replace control PWB.
All 3 lamps (load) should light with
same intensity.

3 – 11

AYXP12FRN

No

.

4 Compressor check Measure compressor coil resistance

5 Expansion valve check Measure expansion valve coil resis-

6 Final check Turn off power, and connect compres-

Item Check method Normal value/condition Remedy

(for each phase of U, V and W).
Use multi-meter or digital tester capa­ble of displaying two digits right of the
decimal point (0.01Ω).

tance.

sor cords to compressor.
Operate air conditioner.
Measure DC voltage between IPM
pins (31) and (35).

2. Troubleshooting of outdoor unit electric components

Does LED light?

YES

NO

Is 230 V applied
between 1 and
N on outdoor
unit terminal
board?

Check indoor
unit.

NO

YES NO

Is voltage between
IPM pins (31) and
(35) 320 V or
higher?

Resistance value at 20°C --- 0.65Ω Correct connections at compres-

sor terminals.

Replace compressor.

Each phase 46±3Ω (at 20°C) Replace expansion valve.

Compressor should operate nor­mally.
200 VDC or higher.

5/ Short-circuit in DC fan motor
Short-circuit in IPM
Short-circuit in diode bridge
Blown fuse
Defective electrolytic capacitor

YES

Wire disconnection, PWB pattern damage
Short-circuit in PAM IGBT (Q5)

Replace control PWB.

Replace outdoor unit thermistor.

Replace compressor (in case of

compressor lock).

Does LED flash?

YES

Normal

NO

Is switching power
supply output of
13 VDC, 15 VDC
produced?

YES

Is 5 VDC output
produced?

YES

NO

NO

Defective switching power supply circuit
Malfunction of 3-terminal regulator IC4, IC1
Short-circuit in expansion valve coil
Malfunction of transistor array IC7
Solder contact or other problems

Malfunction of 3-terminal regulator IC4, IC1

Microcomputer oscillator error
Malfunction of microcomputer reset IC
Malfunction of microcomputer

Malfunction of serial signal circuit
Check wiring between indoor and outdoor units.

3 – 12

AYXP12FRN

3. Caution in checking printed circuit boards (PWB)

3.1. Non-insulated control circuit

The GND terminals of the low-voltage circuits (control circuits for microcomputer and thermistors and drive circuits for expansion valve and relays) on
the control printed circuit board (PWB) are connected to the compressor drive power supply (320-VDC negative terminal). Therefore, exercise utmost
caution to prevent electric shock.

If a measuring instrument used for the test is grounded, its chassis (ground) has the same electric potential as the 0-V probe. Since non-insulated cir­cuits have the following voltage potential difference from the ground, connection of the grounding wire results in a short-circuit between the 0-V line
and the ground, thus allowing an excessive current to flow to the tester to cause damage.

If the sheaths of the thermistor lead wires or expansion valve lead wires inside the outdoor unit become damaged due to pinching by the front panel
or other metal parts or contacting a pipe, a high voltage can flow and destroy the circuits. To prevent these problems, carefully conduct assembly
work.

Outdoor unit circuits

Terminal board

Reactor

2

Point (E)

AC230V

320-VDC line

0-V line

+

-

IPM

M

1

Compressor motor

Ground

0-V line

Point (F)

3

Voltage at point (E)

+ 160V

Ground voltage

320V

- 160V

0-V line voltage (point (F))

Do not touch the
cabinet or bring metal
parts into contact with
the cabinet.

Danger!!
Do not connect
the grounding
wire.

Reason

The oscilloscope (chassis ground) has the same electric potential as the 0-V probe. The
entire electronic control section of the outdoor unit has a voltage potential difference from
the ground as shown in the above diagram. When the oscilloscope is set up, the 0-V line
and the ground voltage (ground) will be short-circuited, resulting in an excessive current
flow to cause damage to the oscilloscope or indoor electric circuits.

3 – 13

AYXP12FRN

[8] TROUBLESHOOTING GUIDE

1. Self-Diagnosis Function and Display Mode

To call out the content of the self-diagnosis memory, hold down the emergency operation button for more than 5 seconds when the indoor unit is not
operating.

• The number of indications displayed by the LEDs on the outdoor unit differs from that for the 2001 cooling unit models (for detailed display of mal­function information).

The display of malfunction No. differs from that of the 2001 cooling unit models. To show detailed malfunction information, two types of numbers
flash alternately. (example: "21" ←→ "-0")

1) The content of the self-diagnosis memory can be called out and displayed on the seven-segment display section on the indoor unit. (The error
data cannot be called out for display by the LED on the outdoor unit.)

2) If the power cord is unplugged from the AC outlet or the circuit breaker is turned off, the self-diagnosis memory loses the stored data.

a) The self-diagnosis display function of the indoor unit indicates the content of diagnosis by showing the error main category (number) and the

error sub-category (-number) alternately in 1-second intervals on the seven-segment display section of the indoor unit.

Example of self-diagnosis display on indoor unit: Compressor high-temperature error

'TTQTOCKPECVGIQT[ 'TTQTUWDECVGIQT[

b) The self-diagnosis display function of the outdoor unit indicates the error information by flashing LED1 on the outdoor unit according to the con-

tent of self-diagnosis.

The self-diagnosis display function of the outdoor unit is active only for about 3 to 10 minutes after self-diagnosis is performed during operation,
and the display returns to normal condition after this display period.

The content of self-diagnosis cannot be called out by the self-diagnosis display function of the outdoor unit.

Example of self-diagnosis display on outdoor unit: Compressor high-temperature error

ON
OFF

c) The content of diagnosis is transferred to the indoor unit via serial communication, but it does not trigger a complete shutdown operation.

: Flashes in 2-sec intervals (normal), : On, : Off, : Flashes 3 times in 0.2-sec intervals (When LED1 on the outdoor unit flashes in 2-sec

intervals, the outdoor unit is in normal condition.)

Nor-

mal

flash-

ing

Malfunction

No. dis-

played on

main unit

display sec-

tion *1

Sub-

Main

cate-

cate-

gory

gory

00 Normal – –

Status of

indoor/

outdoor

units

Indoor/
outdoor
units in
operation

Indoor/
outdoor
units in
complete
shutdown

Indication

by LED1

on out-

door unit

*2

1 time 1 -0 Outdoor unit

1 sec 1 sec 1 sec 1 sec 1 sec1 sec0.6 sec 0.6 sec0.6 sec 0.6 sec 1 sec

Content of diagnosis Inspection location/method Remedy

Main category Sub-category

Heat exchanger
thermistor
short-circuit

-1 Outside tempera-

-2 Suction thermistor

-3 2-way valve ther-

thermistor short-cir-

cuit error

ture thermistor

short-circuit error

short-circuit error

mistor short-circuit

error

(1) Measure resistance of the

outdoor unit thermistors.
(TH2 to TH5: Approx. 4.4
kΩ at 25°C)

(2) Check the lead wire of the

outdoor unit thermistor for
torn sheath and short-cir­cuit.

(3) No abnormality found in

above inspections (1) and
(2).

1 sec 1 sec

(1) Replace the outdoor

unit thermistor assem­bly.

(2) Replace the outdoor

unit thermistor assem­bly.

(3) Replace the outdoor

unit control PWB
assembly.

3 – 14

AYXP12FRN

Status of

indoor/

outdoor

units

Indoor/
outdoor
units in
complete
shutdown

Indoor
unit in
operation
Outdoor
unit in
tempo­rary stop

Indoor
unit in
operation
Outdoor
unit in
tempo­rary stop

Indoor/
outdoor
units in
complete
shutdown

Indication

by LED1

on out-

door unit

*2

2 times 2 -0 Cycle tempera-

3 times 3 -0 Dry operation Temporary stop due

5 times 5 -0 Outdoor unit

Malfunction

No. dis-

played on

main unit

display sec-

tion *1

Sub-

Main

cate-

cate-

gory

gory

-1 Temporary stop due

-2 Temporary stop due

-3 Temporary stop due

-4 Temporary stop due

-1 Outside tempera-

-2 Suction thermistor

-3 2-way valve ther-

-4 Discharge ther-

Content of diagnosis Inspection location/method Remedy

Main category Sub-category

ture

thermistor
open-circuit

Compressor high-

temperature error

to compressor dis-

charge overheat *3

to outdoor unit heat

exchanger overheat

*3

to outdoor unit heat

exchanger overheat

*3

to 2-way valve

freeze *3

to dehumidifying

operation *3

Heat exchanger

thermistor open-cir-

cuit error

ture thermistor

open-circuit error

open-circuit error

mistor open-circuit

error

mistor open-circuit

error

(1) Check the outdoor unit air

outlet for blockage.

(2) Check if the power supply

voltage is 90 V or higher at
full power.

(3) Check the pipe connec-

tions for refrigerant leaks.

(4) Measure resistance of the

outdoor unit compressor
thermistor.
(TH1: Approx. 53 kΩ at
25°C)

(5) Check the expansion

valve for proper operation.

(Temporary stop for cycle pro­tection)

(Temporary stop for cycle pro­tection)

(Temporary stop for cycle pro­tection)

(Temporary stop for cycle pro­tection)

(Temporary stop for cycle pro­tection)

(1) Check connector CN8 of

the outdoor unit ther­mistor for secure installa­tion.

(2) Measure resistance of out-

door thermistors TH1 to
TH5.

(3) Check the lead wires of

thermistors TH1 through
TH5 on the outdoor unit
control PWB for open-cir­cuit.

(4) No abnormality found in

above inspections (1)
through (3).

(1) Ensure unobstructed

air flow from the out­door unit air outlet.

(2) Connect power sup-

ply of proper voltage.

(3) Charge the specified

amount of refrigerant.

(4) Replace the outdoor

unit compressor ther­mistor assembly.

(5) Replace the expan-

sion valve coil, expan­sion valve or outdoor
unit control PWB
assembly.

–

–

–

–

–

(1) Correct the installa-

tion.

(2) Replace the outdoor

unit thermistor assem­bly.

(3) Replace the outdoor

unit thermistor assem­bly.

(5) Replace the outdoor

unit control PWB
assembly.

3 – 15

AYXP12FRN

Status of

indoor/

outdoor

units

Indoor/
outdoor
units in
complete
shutdown

Indoor/
outdoor
units in
complete
shutdown

Indoor/
outdoor
units in
complete
shutdown

Indication

by LED1

on out-

door unit

*2

6 times 6 -0 Outdoor unit DC DC overcurrent error (1) IPM continuity check (1) Replace the outdoor

7 times 7 -0 Outdoor unit AC AC overcurrent error (1) Check the outdoor unit air

9 times 9 -0 Outdoor unit

Malfunction

No. dis-

played on

main unit

display sec-

tion *1

Sub-

Main

cate-

cate-

gory

gory

-1 IPM pin level error Check the IPM is attached

-1 AC overcurrent error

-2 AC maximum cur-

-3 AC current defi-

-3 Torque control error (1) Check if the refrigerant

Content of diagnosis Inspection location/method Remedy

Main category Sub-category

(2) Check the IPM and heat

sink for secure installation.

(3) Check the outdoor unit fan

motor for proper rotation.

(4) No abnormality found in

above inspections (1)
through (3).

(5) No abnormality found in

above inspections (1)
through (4).

correctly to the outdoor
unit control PWB.

outlet for blockage.

(2) Check the outdoor unit fan

for proper rotation.

(1) IPM continuity check (1) Replace the outdoor

in OFF status

(1) Check the outdoor unit air

outlet for blockage.

(2) Check the outdoor unit fan

for proper rotation.

(1) Check if there is an open-

circuit in the secondary
winding of the current
transformer of the outdoor
unit control PWB.

(2) Check if the refrigerant

volume is abnormally low.

(3) Check if the refrigerant

flows properly.

(1) Check to make sure out-

door unit thermistor TH2
(heat exchanger) and TH5
(2-way valve) are installed
in correct positions.

(2) Measure resistance of

thermistors TH1 and TH5.

(3) Check the 4-way valve for

proper operation.

(4) No abnormality found in

above inspections (1)
through (3).

volume is abnormally low.

(2) Check the 4-way valve for

proper operation.

(3) check to see compressor

type is correct.

cooling/heating
switchover

rent error

ciency error

Thermistor installa-

tion error or 4-way

valve error

unit control PWB
assembly.

(2) Correct the installa-

tion (tighten the
screws).

(3) Replace the outdoor

unit fan motor.

(4) Replace the outdoor

unit control PWB
assembly.

(5) Replace the compres-

sor.

Replace the outdoor
unit control PWB
assembly.

(1) Ensure unobstructed

air flow from the out­door unit air outlet.

(2) Check the outdoor unit

fan motor.

unit control PWB
assembly.

(1) Ensure unobstructed

air flow from the out­door unit air outlet.

(1) Check the outdoor unit

fan motor.

(1) Replace the outdoor

unit control PWB
assembly.

(2) Charge the specified

amount of refrigerant.

(3) Correct refrigerant

clogs.
(2-way valve, 3-way
valve, pipe, expan­sion valve)

(1) Correct the installa-

tion.

(2) Replace the ther-

mistor assembly.

(3) Replace the 4-way

valve.

(4) Replace the outdoor

unit control PWB
assembly.

(1) Change the specified

amount of refrigerant.

(2) Replace the 4-way

valve.

(3) Replace the compres-

sor with the correct
part.

3 – 16

AYXP12FRN

Status of

indoor/

outdoor

units

Indoor/
outdoor
units in
complete
shutdown

Indoor/
outdoor
units in
complete
shutdown

Indoor/
outdoor
units in
complete
shutdown

Indoor/
outdoor
units in
operation

Indoor
unit in
operation
Outdoor
unit in
complete
shutdown

Indication

by LED1

on out-

door unit

*2

11

times

13

times

14

times

Malfunction

No. dis-

played on

main unit

display sec-

tion *1

Sub-

Main

cate-

cate-

gory

gory

11 -0 Outdoor unit DC

13 -0 DC compressor Compressor startup

-1 Compressor rota-

14 -0 Outdoor unit

-1 PAM clock error (1) Check the PAM clock for

17 -0 Wires between

18 -0 Serial short-circuit (1) Check the wires between

-1 Serial erroneous wir-

Content of diagnosis Inspection location/method Remedy

Main category Sub-category

fan

PAM

units

Outdoor unit DC fan

rotation error

error

tion error

(120° energizing

error)

PAM over voltage

error

Compressor rota-

tion error

Serial open-circuit (1) Check the wires between

Outdoor unit does

not turn on due to

erroneous wiring

ing

(1) Check connector CN3 of

the outdoor unit DC fan
motor for secure installa­tion.

(2) Check the outdoor unit fan

motor for proper rotation.

(3) Check fuse FU3. (3) Replace the outdoor

(4) Outdoor unit control PWB (4) Replace the outdoor

(1) Check the colors (red,

white, orange) of the com­pressor cords for proper
connection. (PWB side,
compressor side)

(2) Check if the IPM terminal

resistance values are uni­form.

(3) No abnormality found in

above inspections (1) and
(2).

(4) No abnormality found in

above inspections (1)
through (3).

(1) Check the AC power sup-

ply voltage for fluctuation.

(2) No abnormality found in

above inspection (1).

proper input.

units.

(2) Check voltage between

Nos. 1 and 2 on the
indoor/outdoor unit termi­nal boards.

(1) Check the wires between

units.

(2) Check the outdoor unit

fuse.

(3) Check 15-V, 13-V and 5-V

voltages on the PWB.
Check resistance between
IPM terminals.

(4) Check pins No. 5 and 7 of

connector CN3 of the out­door unit fan motor for
short-circuit.

(5) Outdoor unit control PCB (5) Replace the outdoor

units.

(1) Check the wires between

units.

(1) Correct the installa-

tion.

(2) Replace the outdoor

unit fan motor.

unit control PWB
assembly.

unit control PWB
assembly.

(1) Correct the installa-

tion.
(U: Red, V: White, W:
Orange)

(2) Replace the outdoor

unit control PWB
assembly.

(3) Replace the outdoor

unit control PWB
assembly.

(4) Replace the compres-

sor.

(1) Connect stable power

supply.

(2) Replace the outdoor

unit control PWB
assembly.

(1) Replace the outdoor

unit control PWB
assembly.

(1) Connect stable power

supply.

(2) Replace the outdoor

unit control PCB
assembly.

(1) Correct the wiring.

(2) Replace the fuse/out-

door unit control PCB
assembly.

(3) Replace the outdoor

unit control PCB
assembly.

(4) Replace the outdoor

unit fan motor.

unit control PCB
board.

(1) Correct the wiring.

(1) Correct the wiring.

3 – 17

AYXP12FRN

Status of

indoor/

outdoor

units

Indoor/
outdoor
units in
complete
shutdown

Indoor/
outdoor
units in
operation

Indoor/
outdoor
units in
operation

Indication

by LED1

on out-

door unit

*2

Malfunction

No. dis-

played on

main unit

display sec-

tion *1

Sub-

Main

cate-

cate-

gory

gory

19 -0 Indoor unit fan Indoor unit fan error (1) Check the indoor fan

20 -0 Indoor unit con-

88 Control and dis-

Content of diagnosis Inspection location/method Remedy

Main category Sub-category

motor for proper rotating
operation.(Check fan
lock.)

(2) Check the lead wire of the

indoor fan motor for open­circuit.

(3) Check CN1 of the indoor

unit fan motor for secure
installation.

(4) No abnormality found in

above inspections (1)
through (3).

EEPROM data error (EEPROM read data
trol PCB

play PCB

Communication

error

error)

(1) Check for disconnected

connector between control
PCB and display PCB,
and open-circuit in lead
wires.

(2) Check that control PCB

outputs signals correctly.

(1) Replace the indoor fan

motor.

(2) Replace the indoor fan

motor.

(3) Correct the installa-

tion of CN1 of the
indoor fan motor.

(4) Replace the indoor

unit control PWB.

Replace the indoor
unit control PWB.

(1) Insert connectors cor-

rectly, or replace con­trol PWB.

(2) Replace control PWB.

3 – 18

Malfunction indications due to erroneous wiring during air conditioner installation

Inter-unit wiring error mode Symptom

1 Indoor unit relay

Malfunction diagnosis display

Indoor

unit

1

N

2

1

N

2

Outdoor

unit

Turns On momentarily, then turns Off.
"18-1"

AYXP12FRN

2 Indoor unit relay

1

Indoor

N

unit

2

3 Indoor unit relay

1

Indoor

N

unit

2

4 Indoor unit relay

1

Indoor

N

unit

2

5 Indoor unit relay

1

Indoor

N

unit

2

1

N

2

1

N

2

1

N

2

1

N

2

Outdoor

unit

Outdoor

unit

Outdoor

unit

Outdoor

unit

Malfunction diagnosis display

Malfunction diagnosis display

Malfunction diagnosis display

Malfunction diagnosis display

Relays turns Off after about 30 minutes.
None
(Displays "18-0" when malfunction code is called out.)

Relays turns Off after about 30 minutes.
None
(Displays "18-0" when malfunction code is called out.)

Turns On momentarily, then turns Off.
"18-1"

Turns On momentarily, then turns Off.
"18-1"

3 – 19

AYXP12FRN

AYXP12FRN

CHAPTER 4. REFRIGERATION CYCLE

[1] FLOW FOW REFRIGERANT

Service Manual

Indoor unit

Flare coupling Flare coupling

Outdoor unit

3-way

valve

Silencer

Accumulator

4

Comp-

ressor

Reverse valve

Evaporator

1

Coil

Condenser

C

3

2-way

valve

Heating Cooling

Strainer

s

Expansion
valve

2

[2] STANDARD CONDITION

Indoor side Outdoor side

Dry-bulb Temp. (°C) Relative Humidity (%) Dry-bulb Temp. (°C) Relative Humidity (%)

Cooling 27 47 35 40
Heating20– 787

* REFRIGERANT PIPE LENGTH 5.0m

[3] TEMPERATURE AT EACH PART AND PRESSURE IN 3-WAY VALVE

Model AY-XP12FR-N

Operation model

Hz

No.

1 76815652
2 401639 7
3 15331525
4 103166

3-way valve pressure (MPaG) 1.08 3.05 1.29 2.15

MAX. TEST RUN

Cool Heat Cool Heat

83 more than 93 42 42

4 – 1

[4] PERFORMANCE CURVES

NOTE: 1) Indoor fan speed: Hi

2) Vertical adjustment louver "45°", Horizontal adjustment louver "front"

3) Indoor air temp. : Cooling 27°C, Heating 20°C

4) Power source : 230V, 50Hz

1. AY-XP9FR-N

1.1. At Cooling 1.2. At Heating

AYXP12FRN

1000

900

800

Input(W)

700

4.0

3.8

3.6

3.4

3.2

Cooling capacity(kW)

25 30 35 40

Outside air temp.(ºC)

1100

1000

900

Input(W)

800

5.0

4.5

4.0

3.5

3.0

Heating capacity(kW)

2.5

-5 0 7510
Outside air temp.(ºC)

4 – 2