Mitsubishi Electronics MUZ-FD12NA, MUZ-FD12NA- U1, MUZ-FD09NA- U1 User Manual

OUTDOOR UNIT

Revision A:

• 3. SPECIFICATION has been corrected.
Please void OBH498.

SERVICE MANUAL

Wireless type
Models

MUZ-FD09NA
MUZ-FD09NA­MUZ-FD12NA

MUZ-FD12NA-

U1

U1

HFC

utilized

R410A

No. OBH498

REVISED EDITION-A

Indoor unit service manual

MSZ-FD•NA Series (OBH497)

NOTE:

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

CONTENTS

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

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

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

4. OUTLINES AND DIMENSIONS ························ 6

5. WIRING DIAGRAM ············································ 7

6. REFRIGERANT SYSTEM DIAGRAM ··············· 8

7. DATA ·································································· 9

8. ACTUA TOR CONTROL ··································· 15

9. SERVICE FUNCTIONS ··································· 16

10. TROUBLESHOOTING ····································· 16

11. DISASSEMBLY INSTRUCTIONS ···················· 32

PARTS CATALOG (OBB498)

TM

Revision A:

• 3. SPECIFICATION has been corrected.

2

1

TECHNICAL CHANGES

MUZ-FD09NA
MUZ-FD09NA ­MUZ-FD12NA
MUZ-FD12NA -

1. New model

2

MUZ-FD09NA MUZ-FD12NA

PART NAMES AND FUNCTIONS

U1

U1

Air inlet

Piping

Drain hose

Air outlet

Drain outlet

33

3

SPECIFICATION

Outdoor unit model MUZ-FD09NA MUZ-FD12NA

Capacity

Rated (Minimum~Maximum)

Capacity Rated

Power consumption

Rated (Minimum~Maximum)

Power consumption Rated

1

EER

[SEER] 3 Cooling 13.8 [23.0] 12.5 [22.0]

Cooling 1

Heating 47 1

Heating 17 2

Cooling 1

Heating 47 1

Heating 17 2

Btu/h 9,000 (2,800~9,000) 12,000 (2,800~12,000)
Btu/h 10,900 (3,000~18,000) 13,600 (3,000~21,000)
Btu/h 12,500 13,600
W
W

650 (160~650) 960 (160~960)

750 (150~2,400)

980

(150~2,400)

W 1,730 1,780

HSPF IV (V) 4 Heating 10.55 (7.4) 10.55 (7.4)
COP Heating

1 4.26 4.07
Power supply V , phase , Hz 208/230 , 1 , 60
Max. fuse size (time delay) A 15
Min. circuit ampacity A 12
Fan motor F.L.A 0.56

Model SNB130FQAH

Compressor

R.L.A 8.6
L.R.A 10.8

Refrigerant control Liner expansion valve

Sound level

1

Cooling dB(A) 48 48
Heating dB(A) 49 49

Defrost method Reverse cycle

W in. 31-1/2

Dimensions

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

Weight Ib. 80
External fi nish Munsell 3Y 7.8/1.1
Remote controller Wireless type
Control voltage

(by built-in transformer)

VDC 12 - 24

Refrigerant piping Not supplied

Refrigerant pipe size
(Min. wall thickness)

Connection method

Between the indoor &
outdoor units

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

Piping length ft. 65
Refrigerant charge (R410A) 2 lb. 9 oz.
Refrigeration oil (Model) NE022

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

1 : Rating conditions (Cooling) — Indoor : 80˚FDB, 67˚FWB, Outdoor : 95˚FDB, (75˚FWB) Rated frequency
(Heating) — Indoor : 70˚FDB, 60˚FWB, Outdoor : 47˚FDB, 43˚FWB Rated frequency
2 : (Heating) — Indoor : 70˚FDB, 60˚FWB, Outdoor : 17˚FDB, 15˚FWB Maximum frequency

44

Test condition

3, 4

Mode Test

ARI

"A" 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

Low ambient Cooling Steady State
at minimum compressor Speed

Intermediate Cooling Steady State
at Intermediate compressor Speed

Standard Rating-Heating
at rated compressor Speed

Low temperature Heating
at rated compressor Speed

Max temperature Heating
at minimum compressor Speed

High temperature Heating
at minimum compressor Speed

Frost Accumulation
at rated compressor Speed

Frost Accumulation
at Intermediate compressor Speed

5

5

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

OPERATING RANGE

(1) POWER SUPPLY

Indoor air condition Outdoor air condition

Dry bulb (°F) Wet bulb (°F) Dry bulb (°F) Wet bulb (°F)

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

70 60 35 33

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 14 13

Rated voltage Guaranteed Voltage

208/230 V

1 phase

60 Hz

Min.187 V

DB WB DB WB

208 V 230 V Max.253 V

Intake air temperature (°F)

Indoor Outdoor

55

4

OUTLINES AND DIMENSIONS

MUZ-FD09NA MUZ-FD12NA

21-5/8

1-3/4

Air in

handle

11-1/32

7/8

13/32

15-3/4

Air in

11-29/32

5-15/16

Drain hole 1-5/8

Air out

2- 3/8 13/16 Oval hole

19-11/16

31-1/2

1-9/16

12 ~ 12-3/4

11/16

2

2-23/32

13-9/16

5-7/8

REQUIRED SPACE

4 in. or more

17/3229/32 11-1/4

Open two sides of left,
right, or rear side.

Liquid pipe :1/4 (flared)
Gas pipe :3/8 (flared)

6-23/32

Unit: inch

Basically open 4 inch or more
without any obstruction in front
and on both sides of the unit.

4 in. or more

14 in. or more

8 in. or more

66

5

MUZ-FD09NA MUZ-FD12NA

WIRING DIAGRAM

77

6

REFRIGERANT SYSTEM DIAGRAM

MUZ-FD09NA MUZ-FD12NA

Refrigerant pipe ø3/8
(with heat insulator)

Stop valve
(with service port)

Flared connection

Flared connection

Stop valve
(with strainer)

Refrigerant pipe 1/4
(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

(ø

3.0

× ø

1.8×600

Expansion
valve

)

Refrigerant flow in cooling
Refrigerant flow in heating

Outdoor
heat
exchanger

Strainer
#100

R.V. coil
heating ON
cooling OFF

Outdoor heat
exchanger
temperature
thermistor
RT68

Ambient
temperature
thermistor
RT65

Unit:inch

MAX. REFRIGERANT PIPING LENGTH and MAX. HEIGHT DIFFERENCE

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

Model

MUZ-FD09NA
MUZ-FD12NA

Max. Length

A

Max. Height difference

B

Gas Liquid

65 40 3/8 1/4

Indoor
unit

Max. Height

difference

B

Max. Length
A

Outdoor unit

ADDITIONAL REFRIGERANT CHARGE (R410A : oz.)

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

Model Outdoor unit precharged

MUZ-FD09NA
MUZ-FD12NA

2 lb. 9 oz. 0 1.62 4.86 8.10 11.34 12.96

25 30 40 50 60 65

Refrigerant piping length (one way) : ft.

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

Calculation : X oz. = 1.62 / 5 oz. / ft. × (Refrigerant piping length (ft.) - 25)

8

DATA7

MUZ-FD09NA MUZ-FD12NA

7-1. PERFORMANCE DATA

1) COOLING CAPACITY

Indoor air Outdoor intake air DB temperature (˚F)

Model

MUZ-FD09NA

MUZ-FD12NA

IWB 75 85 95 105 115

(˚F) TC SHC TPC TC SHC TPC TC SHC TPC TC SHC TPC TC SHC TPC

71 11.0 6.9 0.58 10.3 6.5 0.63 9.7 6.1 0.68 9.0 5.6 0.72 8.3 5.2 0.75
67 10.4 7.9 0.55 9.7 7.4 0.60 9.0 6.8 0.65 8.4 6.4 0.69 7.7 5.8 0.72
63 9.8 8.8 0.52 9.1 8.1 0.58 8.5 7.6 0.62 7.7 6.9 0.66 7.0 6.3 0.69
71 14.7 8.8 0.85 13.7 8.2 0.94 12.9 7.7 1.01 12.0 7.2 1.06 11.0 6.6 1.10
67 13.9 10.2 0.81 13.0 9.5 0.89 12.0 8.8 0.96 11.2 8.1 1.02 10.3 7.5 1.07

63 13.1 11.3 0.77 12.1 10.5 0.85 11.3 9.7 0.92 10.3 8.9 0.98 9.4 8.1 1.02

NOTE : 1. IWB : Intake air wet-bulb temperature

TC : Total Capacity (x10
SHC : Sensible Heat Capacity (x10

3

Btu/h)

3

TPC : Total Power Consumption (kW)

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

2) COOLING CAPACITY CORRECTIONS

Refrigerant piping length (one way : ft.)

25 (std.) 40 65

MUZ-FD09NA
MUY-FD12NA

1.0 0.954 0.878

3) HEATING CAPACITY

Indoor air Outdoor intake air WB temperature (˚F)

Model

IDB 15 25 35 43 45 55
(˚F) TC TPC TC TPC TC TPC TC TPC TC TPC TC TPC

75 6.3 0.56 7.9 0.66 9.4 0.73 10.6 0.77 11.0 0.78 12.4 0.81

MUZ-FD09NA

70 6.7 0.54 8.2 0.64 9.6 0.71 10.9 0.75 11.2 0.77 12.7 0.80
65 6.9 0.52 8.6 0.62 10.0 0.69 11.2 0.73 11.6 0.74 13.0 0.78
75 7.9 0.73 9.9 0.86 11.8 0.96 13.3 1.00 13.7 1.02 15.5 1.06

MUZ-FD12NA

70 8.4 0.71 10.2 0.84 12.0 0.93 13.6 0.98 14.0 1.00 15.8 1.04
65 8.6 0.68 10.7 0.81 12.4 0.91 14.0 0.96 14.4 0.97 16.2 1.02

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

TC : Total Capacity (x10

3

Btu/h)

TPC : Total Power Consumption (kW)

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

Btu/h)

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 twice or once, or press any button on
the remote controller.

9

7-2. PERFORMANCE CURVE
Cooling

MUZ-FD09NA

SHF at rating condition = 0.76

13

Indoor intake air WB te

12
11

Btu/h)

10

3

9
8

Total capacity

(10

7

0.7

Indoor intake air

(kW)

0.6

0.5

Total power consumption

65 75 85 95 105 115

Outdoor intake air DB temperature (°F)

Airflow

WB te

mperature (°F)

mpe

Heating

MUZ-FD09NA

= 381 CFM

Airflow

12

10

Btu/h)

8

3

Total capacity

(10

6

0.8

0.6

(kW)

0.4

Total power consumption

15 25 35 45 55

e air DB temperature

Indoor intak

Indoor intake air DB temperat

Outdoor intake air WB temperature (°F)

= 307 CFM

rature (°F)

)

(°F

ure (°F)

MUZ-FD12NA

SHF at rating condition = 0.73

15
14
13

Btu/h)

12

3

71
67
63

71
67
63

11

10

Total capacity

(10

1.2

1.1

1.0

(kW)

0.9

0.8

0.7

Total power consumption

Indoor

intak

9

oor intake air WB temperature (°F)

Ind

65 75 85 95 105 115

Outdoor intake air DB temperature (°F)

= 350 CFM

Airflow

e air WB temperat

ure

(°F)

71
67
63

71
67
63

MUZ-FD12NA

65

70

75

20
18
16

Btu/h)

14

3

12

Total capacity

(10

Indoor intake air DB temperature (°F)

10

8
6

75
70
65

1.1

1.0

(kW)

0.9

Indoor intake air

0.8

Total power consumption

0.7

0.6
15 25 35 45 55

Outdoor intake air WB temperature (°F)

Airflow

temperature (°F)

DB

= 420 CFM

65
70
75

75
70
65

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.

1010

7-3. CONDENSING PRESSURE
Cooling

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

MUZ-FD09NA

(PSIG)

580
540
500
460
420
380

Condensing pressure

340
300
260

68 70 75 80 85 90 95 100 105(°F)

oor DB temperature (°F)

Ind

Outdoor ambient temperature

86
80
75
70

MUZ-FD12NA

(PSIG)

580
540
500

86

460
420
380

Condensing pressure

340
300
260

68 70 75 80 85 90 95 100 105(°F)

Indoor DB temperature (°F)

Outdoor ambient temperature

80
75
70

(PSIG)

180
175
170
165
160
155
150
145
140

Suction pressure

135
130
125
120

68 70 75 80 85 90 95 100 105(°F)

(PSIG)

180
175
170
165
160
155
150
145
140

Suction pressure

135
130
125
120

68 70 75 80 85 90 95 100 105(°F)

Indoor DB temperature (°F)

Outdoor ambient temperature

Indoor DB temperature (°F)

Outdoor ambient temperature

86

80

75
70

86

80

75
70

1111

Heating

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

MUZ-FD09NA

(PSIG) (PSIG)

400
380
360
340
320
300
280
260
240
220

Condensing pressure

200
180
160
140

oor DB tem

Ind

perat

ure(

°F)

58Hz

75
70

65

Suction pressure

14 20 25 30 35 40 45 50 55 60 6570(°F)

Outdoor ambient temperature

MUZ-FD12NA

170
160
150
140
130
120
110
100

90
80
70
60

14 20 25 30 35 40 45 50 55

DB temperature (°F)

oor

Ind

Outdoor ambient temperature

58Hz

60 65 70(°F)

75
70
65

(PSIG) (PSIG)

400
380
360
340
320
300
280
260
240
220

Condensing pressure

200
180
160
140

Indoor DB temperature(°F)

58Hz

75
70

65

170
160
150
140
130
120
110

Suction pressure

100

14 20 25 30 35 40 45 50 55 60 6570(°F)

Outdoor ambient temperature

Indoor DB temperature

90
80
70
60

14 20 25 30 35 40 45 50 55

Outdoor ambient temperature

(°F)

58Hz

60 65 70(°F)

75
70
65

12

7-4. STANDARD OPERATION DATA

Model MSZ-FD09NA MSZ-FD12NA

Item Unit Cooling Heating Cooling Heating

Capacity Btu/h 9,000 10,900 12,000 13,600

SHF — 0.76 — 0.73 —

Total

Input kW 0.650 0.750 0.960 0.980

Rated frequency Hz 35 43 51 54

Indoor unit MSZ-FD09NA MSZ-FD12NA

Power supply

Input kW 0.018 0.024 0.024 0.030

Fan motor current A 0.19/0.17 0.25/0.23 0.25/0.23 0.32/0.29

Outdoor unit MUZ-FD09NA MUZ-FD12NA

Power supply

Electrical circuit

Input kW 0.632 0.726 0.936 0.950

Comp. current A 2.96/2.68 3.39/3.06 4.40/3.97 4.43/4.01

Fan motor current A 0.35/0.32

Condensing pressure PSIG 376 355 402 392

Suction pressure PSIG 154 108 148 104

Discharge temperature ˚F 143 144 161 159

Condensing temperature ˚F 112 108 117 115

Suction temperature ˚F51465145

Comp. shell bottom temperature ˚F 144 128 146 129

Refrigerant circuit

Ref. pipe length ft. 25

Refrigerant charge (R410A) 2 lb. 9 oz.

Intake air temperature

Discharge air temperature

Indoor unit

Fan speed (High) rpm 1,020 1,120 1,120 1,220

Airfl ow (High) CFM 307 (Wet) 381 350 (Wet) 420

Intake air temperature

Fan speed rpm 810 870 810 870

Airfl ow CFM 1,102 1,187 1,102 1,187

Outdoor unit

DB ˚F80708070

WB ˚F67606760

DB ˚F 59 100 56 105

WB ˚F 56 — 54 —

DB ˚F95479547

WB ˚F — 43 — 43

V,

phase,

Hz

V,

phase,

Hz

208/230 , 1 , 60

208/230 , 1 , 60

1313

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

MUZ-FD09NA

Correction of Cooling capacity

1.5

1.0

Correction of Cooling total input

1.5

1.0

Correction of Heating capacity

2.0

1.5

1.0

Correction of Heating total input

3.0

2.0

0.5

Capacity correction factors

0 50 100 150

The operational frequency of compressor

0.5

Input correction factors

(Hz)

0 50 100 150

The operational frequency of compressor

0.5

Capacity correction factors

(Hz)

0 50 100 150

The operational frequency of compressor

1.0

Input correction factors

(Hz)

0 50 100 150

The operational frequency of compressor

MUZ-FD12NA

Correction of Cooling capacity

1.5

1.0

0.5

Capacity correction factors

0 50 100 150

The operational frequency of compressor

Correction of Cooling total input

1.5

1.0

0.5

Input correction factors

(Hz)

0 50 100 150

The operational frequency of compressor

Correction of Heating capacity

1.5

1.0

0.5

Capacity correction factors

(Hz)

0 50 100 150

The operational frequency of compressor

Correction of Heating total input

2.0

1.0

Input correction factors

(Hz)

0 50 100 150

The operational frequency of compressor

7-6. TEST RUN OPERATION (How to operate fixed-frequency operation)

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

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

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

4. Indoor fan operates at High speed.

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

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

(Hz)

(Hz)

14

8

ACTUATOR CONTROL

MUZ-FD09NA MUZ-FD12NA

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 Protection

Indoor coil temperature thermistor

Defrost thermistor

Fin temperature thermistor Protection

Outdoor heat exchanger temperature thermistor

Ambient temperature thermistor

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

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

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

Compressor

R.V.coil

Outdoor fan
motor

Sensor Purpose

ON
OFF
OFF

<COOL>

5 seconds

ON
OFF

ON
OFF

ON
OFF

Cooling : Coil frost prevention

Heating : High pressure protection

Cooling : High pressure protection

Heating :

Defrosting

High pressure protection

Low ambient temperature operation

Compressor

<HEAT>

5 seconds

Actuator

LEV

Outdoor

fan motor

○○
○
○○
○○
○○○○○
○○
○○○
○○○

R.V. coil

Indoor fan

motor

1515

9

SERVICE FUNCTIONS

MUZ-FD09VA MUZ-FD12VA

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 Defrost fi nish temperature

(Initial setting)

JS

Soldered

None

(Cut)

41°F (5°C)

50°F (10°C)

9-2. PRE-HEAT CONTROL SETTING

PRE-HEAT CONTROL

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

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

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

10

TROUBLESHOOTING

MUZ-FD09NA MUZ-FD12NA

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 to the residual voltage of smoothing capacitor.

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

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

Lead wiring

3. Troubleshooting procedure

1) First, check if the OPERATION INDICATOR lamp on the indoor unit is flashing on and off to indicate an abnormality.

To make sure, check how many times the abnormality indication is flashing on and off before starting service work.

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

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

components for bursting and discoloration.

4) Refer to 10-2. and 10-3.

Housing point

16

10-2. FAILURE MODE RECALL FUNCTION

Outline of the function
This air conditioner can memorize the abnormal condition which has occurred once.
Even though LED indication listed on the troubleshooting check table (10-3.) disappears, the memorized failure details
can be recalled.
This mode is very useful when the unit needs to be repaired for the abnormality which doesn't recur.

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

Operational procedure

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

Setting up the failure mode recall function

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

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

remote controller at the same time, press RESET button.

First, release RESET button.

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

remote controller is displayed after 3 seconds.

1. Regardless of normal or ab­normal condition, a short beep

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

1

is emitted once the signal is
received.

Does POWER lamp on the indoor unit blink at the interval of

0.5 seconds?
Blinks: Either indoor or outdoor unit is abnormal. Beep is emit-

ted at the same timing as the blinking of POWER lamp.

2

Yes

Judgment of indoor/outdoor abnormality

Before blinking, does POWER lamp stay ON for 3 seconds?
Stays ON for 3 seconds (without beep):
The outdoor unit is abnormal.

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

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 defective parts.

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

function" mentioned above.

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

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

mentioned above.

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

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

(Blinks)

No

No
(OFF)

Yes

2

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

The outdoor unit is abnormal.
Check the blinking pattern, and confi rm the abnormal point with the
outdoor unit failure mode table. (Refer to 10-2.3)
Make sure to check at least two consecutive blinking cycles.

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

Beeps

Repeated cycle

3

Beeps

3.Blinking pattern when the outdoor unit is abnormal:

2.5-second OFF 3-second ON

ON

OFF

No beep Beeps

Repeated cycle

Blinking at 0.5­second interval

2.5-second OFF 3-second ON

No beep Beeps

Repeated cycle

17

Blinking at 0.5­second interval

Repeated cycle

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

Operational procedure

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

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

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

1

Does POWER 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 POWER
lamp. 2

Yes

)

(Blinks

The outdoor unit is abnormal.
Check the blinking pattern, and confi rm the abnormal point with the out-
door unit failure mode table (10-2.3.).
Make sure to check at least two 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 defective parts.

Deleting the memorized abnormal condition

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

function" (10-2.1.).

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

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

tioned above.

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

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

No
(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

18

Blinking at 0.5-

second interval

Repeated cycle

3. Outdoor unit failure mode table

POWER 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

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

(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

LED indication

—— ———

Overcurrent protection stop is
continuously performed 3 times within

—

—

1 minute after the compressor gets
started.

Thermistor shorts or opens during
compressor running.

Large current fl ows into intelligent
power module.

Waveform of compressor current is
distorted.

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

Condition Correspondence

Reconnect connectors.

•
Refer to 10-5. "How

•
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. "How

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

•

Reconnect compressor

•
connector.
Refer to 10-5. "How

•
to check inverter/
compressor".

Check refrigerant circuit

•
and refrigerant amount.
Refer to 10-5. "Check

•
of LEV".

Indoor/
outdoor unit
failure mode

recall function

○○

○○

—

—

—

Outdoor unit
failure mode

recall function

○

○

○

6-time fl ash

2.5 seconds
OFF

7-time fl ash

2.5 seconds
OFF

8-time fl ash

2.5 seconds
OFF

9-time fl ash

2.5 seconds
OFF

10-time fl ash

2.5 seconds
OFF

11-time fl ash

2.5 seconds
OFF

12-time fl ash

2.5 seconds
OFF

14-time fl ash

2.5 seconds
OFF

High pressure

—

Fin temperature/ P.C. board
temperature

Outdoor fan motor

Nonvolatile memory data 5-time fl ash

Discharge temperature

DC voltage 8-time fl ash

Each phase current of
compressor

Overcurrent Compressor open­phase

Stop valve (Closed valve) 14-time fl ash

7-time fl ash

2.5 seconds OFF

—

2.5 seconds OFF

—

2.5 seconds OFF

9-time fl ash

2.5 seconds OFF

10-time fl ash

2.5 seconds OFF

2.5 seconds OFF

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

DC voltage of inverter cannot be
detected normally.

Each phase current of compressor
cannot be detected normally.

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

Closed valve is detected by compressor
current.

Check refrigerant circuit

•
and refrigerant amount.
Check stop valve.

•

Check around outdoor

•
unit.
Check outdoor unit air

•
passage.
Refer to 10-5. "Check

•
of outdoor fan motor".

Refer to 10-5. "Check

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

Replace the inverter

•
P.C. board.

Refer to 10-5. "Check

•
of LEV".
Check refrigerant circuit

• —
and refrigerant amount.

Refer to 10-5. "How

•
to check inverter/
compressor".

Reconnect compressor

•
connector.
Refer to 10-5. "How

•
to check inverter/
compressor".

Check stop valve •

NOTE: Blinking patterns of this mode differ from the ones of Troubleshooting check table (10-3.).

19

—

—

—

○

○

○

○○

○

—

—

○

○

○○

10-3. TROUBLESHOOTING CHECK TABLE

No. Symptom LED indication

Outdoor unit
does not oper-

1

ate.

2

3

4

5

6

'Outdoor unit
stops and

7

restarts 3 min­utes later' is
repeated.

8

9

1-time fl ash every

2.5 seconds

6-time fl ash

2.5 seconds OFF
11-time fl ash

2.5 seconds OFF
14-time fl ash

2.5 seconds OFF

2-time fl ash

2.5 seconds OFF

3-time fl ash

2.5 seconds OFF

4-time fl ash

2.5 seconds OFF

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

Outdoor unit
(Other abnormality)

Overcurrent protec­tion

Discharge tempera­ture overheat protec­tion

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

Condition Correspondence

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

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

Nonvolatile memory data cannot be read properly.

(POWER lamp of the indoor unit lights up or fl ashes 7 times.)

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

Outdoor unit is defective. Refer to 10-2.2. "Flow chart of the

Large current fl ows into intelligent power module.

When overcurrent protection occurs within 10 seconds after

compressor starts, compressor restarts after 15 seconds.

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 fi n temperature thermistor on the heat sink
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).

Reconnect connector of compres-

•
sor.
Refer to 10-5. "How to check in-

•
verter/compressor".
Check stop valve.

•
Refer to 10-5. "Check of outdoor

•
thermistors".

Replace inverter P.C. board. •

Refer to 10-5. "How to check

•
miswiring and serial signal error.

•
detailed outdoor unit failure mode
recall function".

Reconnect connector of compres-

•
sor.
Refer to 10-5. "How to check in-

•
verter/compressor".
Check stop valve.

•
Check refrigerant circuit and refrig-

•
erant amount.
Refer to 10-5. "Check of LEV".

•

Check around outdoor unit.

•
Check outdoor unit air passage.

•
Refer to 10-5. "Check of outdoor

•
fan motor".

10

11

12

13

14

Outdoor unit

15

operates.

16

17

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.

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

5-time fl ash

2.5 seconds OFF

8-time fl ash

2.5 seconds OFF

10-time fl ash

2.5 seconds OFF

12-time fl ash

2.5 seconds OFF
13-time fl ash

2.5 seconds OFF
1-time fl ash

2.5 seconds OFF
3-time fl ash

2.5 seconds OFF

4-time fl ash

2.5 seconds OFF

High pressure pro­tection

Compressor syn­chronous abnormal­ity

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

Each phase current
of compressor

DC voltage DC voltage of inverter cannot be detected normally. Refer to 10-5. "How to check in-

Frequency drop by
current protection

Frequency drop by
high pressure pro­tection

Frequency drop by
defrosting in COOL
mode

Frequency drop by
discharge tempera­ture protection

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. Reconnect connector of compres-

after outdoor fan start-up.

Each phase current of compressor cannot be detected nor­mally.

Current from power outlet is nearing Max. fuse size. The unit is normal, but check the

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.

Check refrigerant circuit and refrig-

•
erant amount.
Check stop valve.

•

•
sor.
Refer to 10-5. "How to check in-

•
verter/compressor".

Refer to 10-5. "Check of outdoor

•
fan motor.
Refer to 10-5. "Check of inverter

•
P.C. board.

Refer to 10-5. "How to check in-

•
verter/compressor".

•
verter/compressor".

following.
Check if indoor fi lters are clogged.

•
Check if refrigerant is short.

•
Check if indoor/outdoor unit air cir-

•
culation is short cycled.

Check refrigerant circuit and refrig-

•
erant amount.
Refer to 10-5.

•
Refer to 10-5. "Check of outdoor

•
thermistors".

Inverter P.C. board (Parts side)

Flashing →

"Check of LEV".

LED

ON

OFF

2.5-second OFF

0.5-second ON

2.5-second OFF

0.5-second ON

20

No. Symptom LED indication

Outdoor unit
operates.

18

19

20

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

Low discharge tem­perature protection

PAM protection
PAM: Pulse Ampli­tude Modulation

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

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) or the bus-bar voltage reaches 320 V or more,
PAM stops and restarts.

mode starts.

Condition Correspondence

Refer to 10-5. "Check of LEV".

•
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. "How to check in­verter/compressor".

21

10-4. TROUBLE CRITERION OF MAIN PARTS

MUZ-FD09NA MUZ-FD12NA

Part name Check method and criterion Figure

Defrost thermistor
(RT61)

Ambient temperature
thermistor (RT65)

Outdoor heat ex­changer temperature
thermistor (RT68)

Discharge tem­perature thermistor
(RT62)

Fin temperature
thermistor (RT64)

Measure the resistance with a tester.

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

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

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

Compressor

Outdoor fan motor

R. V. coil (21S4)

Expansion valve coil
(LEV)

Measure the resistance between terminals using a tester.
(Winding temperature : -4 ~ 104°F (-20 ~ 40°C))

Normal

U-V

U-W

1.52 ~ 2.17 Ω

V-W

Measure the resistance between lead wires using a tester.
(Part temperature : 14 ~ 104°F (-10 ~ 40°C))

Color of lead wire Normal

RED – BLK
BLK – WHT

11 ~ 16 Ω

WHT – RED

Measure the resistance using a tester.
(Part temperature : 14 ~ 104°F (-10 ~ 40°C))

Normal

970 ~ 1380 Ω

Measure the resistance using a tester.
(Part temperature : 14 ~ 104°F (-10 ~ 40°C))

Color of lead wire Normal

WHT – RED
RED – ORN

YLW – BRN

37 ~ 54 Ω

BRN – BLU

WHT

WHT

WHT

RED

ORN

RED BLK

23

V

23

V

W

U

RED BLK

1

W

U

LEV

YLW

BRN

1

BLU

22

10-5. TROUBLESHOOTING FLOW

A How to check inverter/compressor

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

Check the voltage between terminals.

Are the voltages balanced?

Yes

Check the compressor.

No

See 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 intelligent power module disconnected,

activate the inverter and check if the inverter is normal by measuring the balance of voltage
between the terminals.

Output voltage 115 V

<< Operation method>>
Start cooling or heating operation by pressing EMERGENCY OPERATION switch on the

indoor unit. (TEST RUN OPERATION : Refer to 7-6.)
<<Measurement point>>
at 3 points
BLK (U) - WHT (V)
BLK (U) - RED (W)
WHT(V) - RED (W)

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

2. Measure the voltage by analog type tester.

3. During this check, LED of the inverter P.C. board fl ashes 9 times. (Refer to 10-6.1.)

Measure AC voltage between the
lead wires at 3 points.

9-time flash

2.5-second OFF

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”.

23

D Check of compressor winding

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

the compressor terminals.
<<Measurement point>>
at 3 points
BLK-WHT
BLK-RED

Measure the resistance between the lead wires at 3 points.
WHT-RED
<<Judgement>>
Refer to 10-4.
0[Ω] ················Abnormal [short]
Infinite[Ω] ·······Abnormal [open]

NOTE: Be sure to zero the ohmmeter before measurement.

E Check of compressor operation time

<<Judgement>>

●Connect the compressor and activate the inverter. Then measure

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

OPERATION switch on the indoor unit.
(TEST RUN OPERATION : Refer to 7-6.)
<<Measurement>>
Measure the time from the start of compressor to the stop of

compressor due to overcurrent.

0 second

1 second

2 seconds

10 seconds

Compressor starts

Abnormal
(IPM failure)
(Compressor winding short)

Abnormal
(Compressor lock out)
(Starting defect)

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

F Check of compressor start failure

Confi rm that 1~4 is normal.

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

1.
Output voltage of inverter P.C. board and balance of them (See 10-5. )

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

3.
Voltage between outdoor terminal block S1-S2

4

.

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

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.

Abnormal
(Refrigerant circuit defect)
(Closed valve)

10 minutes

Normal

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

24

Heating part

G Check of outdoor thermistors

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

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

Yes

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

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

Yes

OK.
(Cause is poor contact.)

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

No

No

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

Replace the inverter P.C. board.

Inverter P.C. board

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.
In case CN721 is not connected or R.V. coil is open, voltage is generated between the terminal pins of the connector

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

Check if CN721 is connected.

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

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

Is there 230 VAC between CN721 and

on the inverter P.C. board 3 minutes

after the power supply is turned ON?

Replace the 4-way valve.

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

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

Is there 230 VAC between CN721 and

on the inverter P.C. board 3 minutes

after the power supply is turned ON?

Replace the 4-way valve.

25

Yes

No

Replace the inverter

No

P.C. board.

Replace the inverter

Yes

P.C. board.

I Check of outdoor fan motor

Disconnect CN932 from the inverter P.C. board, and
measure the resistance of the outdoor fan motor.

Is the outdoor fan motor normal?
(Refer to 10-4.)

Yes

Replace the inverter P.C. board.

J Check of power supply

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

Does POWER lamp on the indoor
unit light up?

Yes

No

No

Rectify indoor/outdoor
connecting wire.

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

Replace the outdoor fan motor.

Yes

Replace the indoor
electronic control P.C.

No

board.

Is there voltage 280 ~ 370 VDC
between DB61 (+) and DB61 (–) on
the inverter P.C. board?
(Refer to 10-6.1.)

No

Check the electric parts in main circuit.

Yes

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

Yes

If light up, OK.
If fl ash, refer to 10-3.

26

Replace the inverter

No

P.C. board.

DB61

Inverter P.C. board
(Solder side)

280 ~ 370 VDC

K Check of LEV (Expansion valve)

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

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

First, release RESET button.

And release the other two buttons after all LCD except

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

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

Expansion valve operates in full-opening direction.

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

No

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 ON it again.

2. Press RESET button on the remote controller.

No

Yes

Properly fi x the LEV coil to the expansion valve.

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

1.Pin (-) — Pin (+)

2.Pin (-) — Pin (+)

3.Pin (-) — Pin (+)

4.Pin (-) — Pin (+)
Is there about 3 ~ 5 VAC between each?

NOTE: Measure the voltage by an analog

tester.

Replace the expansion valve.

Yes

Replace the inverter P.C.

No

board.

27

L Check of inverter P.C. board

Check the outdoor fan motor.
(Refer to10-5. .)

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

No

Check the connection of the connectors
(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

Inverter P.C. board
(Solder side)

CN932

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

28

M How to check miswiring and serial signal error

Turn OFF the power supply.

Is there rated voltage in the
power supply?

Yes

Turn ON the power supply.

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

Press EMERGENCY OPERATION switch once.

Does AREA-L lamp light up? <Confi rmation of
the power to the indoor unit>

Is serial signal error indicated 6 minutes later?

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

B

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

Turn ON the power supply.

Yes

Yes

Yes

A

1

No

No

Check the power supply.

Check the wiring.

No

Is there any miswiring,
poor contact, or wire
disconnection of the

No

indoor/outdoor connect­ing wire?

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

Be sure to confi rm the wiring is correct before the opera-

tion starts.

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

No

Yes

Correct them.

A

Turn OFF inverter-controlled lighting

•
equipment.
Turn OFF the power supply and then

•
turn ON again.
Press EMERGENCY OPERATION

•
switch.

Reinstall

•
either the unit
or the light
each other

No

•

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

Is serial signal
error indicated 6
minutes later?

Yes

B

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

Yes

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

Yes

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

Yes

Replace the indoor electronic control P.C. board.

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

No
(Lighted
or not
lighted)

No

No

29

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

2

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

Is there any error of the in­door/outdoor connecting wire,
such as the damage of the wire,
intermediate connection, poor
contact to the terminal block?

Is there any error of the in­door/outdoor connecting wire,
such as the damage of the wire,
intermediate connection, poor
contact to the terminal block?

No

No

Replace the indoor/
outdoor connecting

Yes

wire.

Replace the indoor/
outdoor connecting

Yes

wire.

N Electromagnetic noise enters into TV sets or radios

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.?

No

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

No

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

No

No

Yes

Yes

Yes

Yes

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 followings 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, grounding wire, antennas, wiring from antennas, receiver

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

6. Presence or absence of amplifi er such as booster

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

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

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

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

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

30

10-6. TEST POINT DIAGRAM AND VOLTAGE

1. Inverter P.C. board

MUZ-FD09NA MUZ-FD12NA

Back side of unit

AC 208/230 V

Fuse (F901)
250 V 3.15 A

Output to
drive com­pressor
(LDU,
LDV,
LDW)

DB61
DC260 ~300 V

(-)

(+)

Smoothing
capacitor
(C63)

Smoothing
capacitor
(C62)

Fuse (F801)
250 V 3.15 A

Smoothing
capacitor
(C61)

Fuse (F701)
250 V 3.15 A

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

AC208/230 V

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

Resistance(kΩ)

20

10

0

-4 14 32 50 68 86 104

Output to drive outdoor

fan motor (CN932)

Temperature(°F)

Fin temperature

thermistor /RT64

(CN642)

Outdoor heat exchanger

temperature thermistor

/RT68(CN644)

Discharge temperature thermistor(RT62)

700

600

500

400

300

200

Resistance(kΩ)

100

0

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

Defrost thermistor

/RT61(CN641)

Ambient temperature

thermistor /RT65

(CN643)

Temperature(°F)

Discharge temperature

thermistor /RT62

LEV
connector
(CN724)

(CN641)

Jumper wire for
changing defrost
setting (JS)

Fin temperature thermistor(RT64)

200

180

160

140

120

100

80

60

Resistance(kΩ)

40

20

0

32 50 68 86 104 122 140 158 176

Temperature(°F)

Jumper wire
for pre-heat
control setting
(JK)

31

11

DISASSEMBLY INSTRUCTIONS

<"Terminal with locking mechanism" Detaching points>

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

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

Sleeve

Slide the sleeve.
Pull the terminal while

Locking lever

pushing the locking
lever.

11-1. MUZ-FD09NA MUZ-FD12NA

OPERATING PROCEDURE PHOTOS

1. Removing the cabinet

(1) Remove the screw fixing the service panel. (See

Photo 1.)

(2) Pull down the service panel and remove it. (See Photo

1.)

(3) Remove the screws fixing the conduit cover. (See

Photo 2.)
(4) Remove the conduit cover. (See Photo 2.)
(5) Disconnect the power supply wire and indoor/outdoor

connecting wire.
(6) Remove the screws fixing the top panel. (See Photo 1.)
(7) Remove the top panel. (See Photo 1.)
(8) Remove the screws fixing the cabinet.
(9) Remove the cabinet.
(10)

Remove the screws fixing the back panel.

(11)

Remove the back panel.

Photo 2

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

Hold the sleeve, and
pull out the terminal
slowly.

Connector

NOTE : Turn OFF power supply before disassembling.

Photo 1

Screws

of the top
panel

Screw of the
cabinet

Screws of
the top panel

Screw of
the service
panel

Back
panel

Hooks

Conduit cover

Screw of the

conduit cover

Conduit plate

32

32

Screws of
the cabinet

Service

panel

OPERATING PROCEDURE

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

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

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

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

T.B.support. (See Photo 4.)

(7) Remove the inverter P.C. board from the inverter assembly.

3. Removing R.V. coil

(1) Remove the cabinet and panels. (Refer to 1.)
(2) Remove the R.V. coil. (See Photo 5.)

Photo 3

Screws of the
relay panel

Photo 4 (Inverter assembly)

Heat sink

Inverter
P.C. board

Screw of the
T.B.support

T.B.support

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

(1) Remove the cabinet and panels. (Refer to 1.)
(2) Pull out the discharge temperature thermistor from its hold-

er. (See Photo 5.)
(3) Pull out the defrost thermistor from its holder. (See Photo 6.)
(4) Pull out the outdoor heat exchanger temperature thermistor

from its holder. (See Photo 6.)

33

Photo 5

Screw of the
ground wire

R.V. coil

Discharge temperature thermistor

OPERATING PROCEDURE

PHOTOS

5. Removing outdoor fan motor

(1) Remove the cabinet and panels. (Refer to 1.)
(2) Disconnect the connectors for outdoor fan motor.
(3) Remove the propeller nut. (See Photo 7.)
(4) Remove the propeller. (See Photo 7.)
(5) Remove the screws fixing the fan motor. (See Photo 7.)
(6) Remove the 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) Recover gas from the refrigerant circuit.

NOTE: Recover gas from the pipes until the pressure

gauge shows 0 PSIG.

(4) Detach the welded part of the suction and the discharge

pipe connected with compressor.
(5) Remove the nuts of compressor legs.
(6) Remove the compressor.
(7) Detach the welded part of pipes connected with 4-way

valve. (See Photo 8.)

Photo 6

Photo 7

Outdoor heat
exchanger tempera­ture thermistor

Defrost thermistor

Screws of the outdoor fan motor

34

Propeller

Photo 8

Propeller nut

Welded parts of 4-way valve

35

TM

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

Copyright 2008 MITSUBISHI ELECTRIC ENGINEERING CO.,LTD
Distributed in Mar. 2008. No. OBH498 REVISED EDITION-A 7
Distributed in Jan. 2008. No. OBH498 7
Made in Japan

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