Mitsubishi Electric Mr.Slim MUZ-FE09NA User manual

SERVICE MANUAL
CONTENTS
1. TECHNICAL CHANGES ··································· 2
2. PART NAMES AND FUNCTIONS····················· 2
3. SPECIFICATION················································ 3
4. OUTLINES AND DIMENSIONS ························ 5
5. WIRING DIAGRAM············································ 6
6. REFRIGERANT SYSTEM DIAGRAM ··············· 7
7. DATA·································································· 9
8. ACTUATOR CONTROL··································· 16
9. SERVICE FUNCTIONS ··································· 17
10. TROUBLESHOOTING····································· 17
11. DISASSEMBLY INSTRUCTIONS···················· 36
Models
MUZ-FE09NA
MUZ-FE12NA
MUZ-FE18NA
SPLIT-TYPE AIR CONDITIONERS
OUTDOOR UNIT
Indoor unit service manual
MSZ-FE•NA Series (OBH542)
NOTE:
RoHS compliant products have <G> mark on the spec name plate.
TM
HFC
utilized
R410A
No. OBH543
REVISED EDITION-A
PARTS CATALOG (OBB543)
Revision A:
• MUZ-FE18NA has been added.
Please void OBH543.
MUZ-FE09NA
MUZ-FE12NA

2
1TECHNICAL CHANGES
MUZ-FE09NA
MUZ-FE12NA
MUZ-FE18NA
1. New model
PART NAMES AND FUNCTIONS
2
MUZ-FE09NA MUZ-FE12NA
Air outlet
Drain outlet
Piping
Drain hose
Air inlet
(back and side)
Revision A:
• MUZ-FE18NA has been added.
MUZ-FE18NA
Piping
Air outlet
Drain outlet
Air inlet
(back and side)
Drain hose

3
3SPECIFICATION
Outdoor unit model MUZ-FE09NA MUZ-FE12NA MUZ-FE18NA
Capacity
Rated (Minimum~Maximum)
Cooling 1 Btu/h 9,000 (2,800~9,000) 12,000 (2,800~12,000) 18,000 (8,200~25,200)
Heating 47 1 Btu/h 10,900 (3,000~18,000) 13,600 (3,000~21,000) 21,600 (7,500~29,700)
Capacity Rated Heating 17 2 Btu/h 12,500 13,600 19,300
Power consumption
Rated (Minimum~Maximum)
Cooling 1 W
580 (160~650) 930 (160~960) 1,270 (570~2,280)
Heating 47 1 W
710 (150~2,250) 950 (150~2,250) 1,540 (520~2,420)
Power consumption Rated Heating 17 2 W 1,730 1,780 2,180
EER 1 [SEER] 3 Cooling 15.5 [26.0] 12.9 [23.0] 14.2 [20.2]
HSPF IV 4Heating 10.0 10.6 10.3
COP Heating 1 4.50 4.20 4.11
Power supply V , phase , Hz 208/230, 1 , 60
Max. fuse size (time delay) A 15 20
Min. circuit ampacity A 12 17.1
Fan motor F.L.A 0.56 0.93
Compressor
Model SNB130FQAH SNB172FQKMT
R.L.A 8.6 12.9
L.R.A 10.8 16.1
Refrigeration oil L (Model) 0.45 (NEO22) 0.40 (FV50S)
Refrigerant control Linear expansion valve
Sound level 1Cooling dB(A) 48 48 55
Heating dB(A) 49 49 55
Defrost method Reverse cycle
Dimensions
W in. 31-1/2 33-1/16
D in. 11-1/4 13
H in. 21-5/8 34-5/8
Weight Ib. 80 119
External finish 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)
Liquid in. 1/4 (0.0315) 3/8 (0.0315)
Gas in. 3/8 (0.0315) 5/8 (0.0315)
Connection method Indoor Flared Flared
Outdoor Flared Flared
Between the indoor
& outdoor units
Height difference ft. 40 50
Piping length ft. 65 100
Refrigerant charge (R410A) 2 lb. 9 oz. 4 lb. 3 oz.
NOTE: Test conditions are based on AHRI 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

4
Test condition
ARI Mode Test Indoor air condition (°F) Outdoor air condition (°F)
Dry bulb Wet bulb Dry bulb Wet bulb
SEER
(Cooling)
"A-2" Cooling Steady State
at rated compressor Speed 80 67 95 (75)
"B-2" Cooling Steady State
at rated compressor Speed 80 67 82 (65)
"B-1" Cooling Steady State
at minimum compressor Speed 80 67 82 (65)
"F-1" Cooling Steady State
at minimum compressor Speed 80 67 67 (53.5)
"E-V" Cooling Steady State
at Intermediate compressor Speed 5 80 67 87 (69)
HSPF
(Heating)
"H1-2" Heating Steady State
at rated compressor Speed 70 60 47 43
"H3-2" Heating
at rated compressor Speed 70 60 17 15
"H0-1" Heating Steady State
at minimum compressor Speed 70 60 62 56.5
"H1-1" Heating Steady State
at minimum compressor Speed 70 60 47 43
"H2-V" Heating
at Intermediate compressor Speed 5 70 60 35 33
5: At Intermediate compressor Speed
= ("Cooling rated compressor speed" - "minimum compressor speed") / 3 + "minimum compressor speed".
3, 4
(2) OPERATION
Mode Condition
Intake air temperature (°F)
Indoor Outdoor
DB WB DB WB
Cooling
Standard temperature 80 67 95 —
Maximum temperature 90 73 115 —
Minimum temperature 67 57 14 —
Maximum humidity 78 % —
Heating
Standard temperature 70 60 47 43
Maximum temperature 80 67 75 65
Minimum temperature 70 60 -13 -15
OPERATING RANGE
(1) POWER SUPPLY
Rated voltage Guaranteed voltage (V)
Outdoor unit
208/230 V
1 phase
60 Hz
Min. 187 208 230 Max. 253

5
OUTLINES AND DIMENSIONS
4
Unit: inch
MUZ-FE09NA MUZ-FE12NA
Liquid pipe :1/4 (flared)
Gas pipe :3/8 (flared)
6-23/32
2
5-7/8
2-23/32
1-3/4
15-3/4
12 ~ 12-3/4
13-9/16
11/16
1-9/16
7/8
21-5/8
11-1/32
13/32
31-1/2
19-11/16
5-15/16
11-29/32
29/32 11-1/4
Air in
handle
Air in
Air out
2- 3/8 13/16 Oval hole
Drain hole 1-5/8
REQUIRED SPACE Basically open 4 inch or more
without any obstruction in front
and on both sides of the unit.
14 in. or more
8 in. or more
4 in. or more
4 in. or more
Open two sides of left,
right, or rear side.
MUZ-FE18NA
16-7/16
1-9/16
1-5/8
Drain hole
6-7/8 19-11/16
13
2
Air in
Air out
2-holes 13/32 13/16
14-3/16
33-1/16
4-5/16
3-3/16
34-5/8
17-25/32
Service panel
3-29/32
6-1/2
7-11/16
35
44
Liquid refrigerant
pipe joint
Refrigerant pipe
(flared) Ø3/8
Gas refrigerant
pipe joint
Refrigerant pipe
(flared) Ø5/8
14 in. or more
4 in. or more
REQUIRED SPACE
20 in. or more
4 in. or more
20 in. or more

6
5WIRING DIAGRAM
MUZ-FE09NA MUZ-FE12NA
MUZ-FE18NA

7
6REFRIGERANT SYSTEM DIAGRAM
Unit: inch
MUZ-FE09NA MUZ-FE12NA
Outdoor
heat
exchanger
Flared connection
Defrost
thermistor
RT61
Discharge
temperature
thermistor
RT62
Service
port
Service
port
Flared connection
Stop valve
(with strainer)
Stop valve
(with service port)
Refrigerant flow in cooling
Compressor
4-way valve
Refrigerant flow in heating
Refrigerant pipe ø 3/8
(with heat insulator)
Refrigerant pipe ø1/4
(with heat insulator)
R.V. coil
heating ON
cooling OFF
Strainer
#100
Capillary tube
Expansion
valve
Ambient
temperature
thermistor
RT65
Muffler
O.D. 0.118 × I.D. 0.071
× 23-5/8
(ø
3.0 × ø 1.8 × 600 )
Capillary tube
O.D. 0.118 ×I.D. 0.079×9-7/16
(ø3.0 × ø2.0 ×240)
Outdoor heat
exchanger
temperature
thermistor
RT68
Muffler
MUZ-FE18NA
Service
port
Service
port
Outdoor
heat
exchanger
Flared connection
Defrost
thermistor
RT61
Discharge
temperature
thermistor
RT62
Flared connection
Stop valve
Stop valve
(with service port)
Capillary tube
O.D. 0.157 ×I.D. 0.094×3-15/16
(ø4.0×ø2.4×100)
Compressor
4-way valve
Refrigerant pipe
ø 5/8
(with heat insulator)
Refrigerant pipe ø 3/8
(with heat insulator)
LEV
R.V. coil
heating ON
cooling OFF
Muffler
#100
Strainer
#100
Outdoor heat
exchanger
temperature
thermistor
RT68
Ambient
temperature
thermistor
RT65
Strainer
#100
Refrigerant flow in cooling
Refrigerant flow in heating

8
Max. Length
A
Max. Height
difference
B
Indoor
unit
Outdoor unit
MAX. REFRIGERANT PIPING LENGTH and MAX. HEIGHT DIFFERENCE
Model
Refrigerant piping: ft. Piping size O.D: in.
Max. Length
A
Max. Height difference
B Gas Liquid
MUZ-FE09NA
MUZ-FE12NA 65 40 3/8 1/4
MUZ-FE18NA 100 50 5/8 3/8
ADDITIONAL REFRIGERANT CHARGE (R410A: oz.)
NOTE: Refrigerant piping exceeding 25 ft. requires additional refrigerant charge according to the calculation.
Model Outdoor unit precharged Refrigerant piping length (one way): ft.
25 30 40 50 60 65
MUZ-FE09NA
MUZ-FE12NA 2 lb. 9 oz. 0 1.62 4.86 8.10 11.34 12.96
Calculation: X oz. = 1.08/5 oz. / ft. × (Refrigerant piping length (ft.) - 25)
NOTE: Refrigerant piping exceeding 33 ft. requires additional refrigerant charge according to the calculation.
Model Outdoor unit
precharged
Refrigerant piping length (one way): ft.
33 40 50 60 70 80 90 100
MUZ-FE18NA 4 lb. 3 oz. 0 4.14 10.06 15.98 21.90 27.82 33.74 39.66
Calculation: X oz. = 2.96/5 oz. / ft. × (Refrigerant piping length (ft.) - 33)

9
DATA7
MUZ-FE09NA MUZ-FE12NA MUZ-FE18NA
7-1. PERFORMANCE DATA
1) COOLING CAPACITY
Model
Indoor air Outdoor intake air DB temperature (˚F)
IWB (˚F) 75 85 95 105 115
TC SHC TPC TC SHC TPC TC SHC TPC TC SHC TPC TC SHC TPC
MUZ-FE09NA
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
MUZ-FE12NA
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
MUZ-FE18NA
71 22.1 15.6 1.13 20.6 14.6 1.24 19.4 13.7 1.33 18.0 12.7 1.40 16.6 11.7 1.46
67 20.9 17.5 1.07 19.4 16.3 1.17 18.0 15.1 1.27 16.7 14.1 1.35 15.4 12.9 1.41
63 19.6 19.1 1.02 18.2 17.7 1.12 16.9 16.5 1.21 15.4 15.0 1.30 14.0 13.7 1.35
NOTE: 1. IWB : Intake air wet-bulb temperature
TC : Total Capacity (x103Btu/h)
SHC : Sensible Heat Capacity (x103Btu/h)
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 65 100
MUZ-FE09NA
MUZ-FE12NA 1.0 0.954 0.878 -
MUZ-FE18NA 1.0 0.954 0.878 0.771
3) HEATING CAPACITY
Model
Indoor air Outdoor intake air WB temperature (˚F)
IDB (˚F) 5 152535434555
TC TPC TC TPC TC TPC TC TPC TC TPC TC TPC TC TPC
MUZ-FE09NA
75 4.8 0.44 6.3 0.56 7.9 0.66 9.4 0.73 10.6 0.77 11.0 0.78 12.4 0.81
70 5.2 0.42 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 5.5 0.41 6.9 0.52 8.6 0.62 10.0 0.69 11.2 0.73 11.6 0.74 13.0 0.78
MUZ-FE12NA
75 6.0 0.58 7.9 0.73 9.9 0.86 11.8 0.96 13.3 1.00 13.7 1.02 15.5 1.06
70 6.5 0.55 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 6.8 0.53 8.6 0.68 10.7 0.81 12.4 0.91 14.0 0.96 14.4 0.97 16.2 1.02
MUZ-FE18NA
75 9.5 0.91 12.5 1.15 15.7 1.35 18.7 1.50 21.1 1.58 21.7 1.60 24.6 1.66
70 10.3 0.87 13.3 1.11 16.2 1.32 19.1 1.46 21.6 1.54 22.2 1.57 25.2 1.63
65 10.8 0.83 13.6 1.06 17.0 1.27 19.8 1.42 22.2 1.50 22.9 1.52 25.7 1.60
NOTE: 1. IDB : Intake air dry-bulb temperature
TC : Total Capacity (x103Btu/h)
TPC : Total Power Consumption (kW)
2. Above data is for heating operation without any frost.
How to operate with fixed operational frequency of the compressor.
1. Press the EMERGENCY OPERATION switch on the front of the indoor unit, and select either EMERGENCY COOL
mode or EMERGENCY HEAT mode before starting to operate the air conditioner.
2. The compressor starts with operational frequency.
3. The fan speed of the indoor unit is High.
4. This operation continues for 30 minutes.
5. In order to release this operation, press the EMERGENCY OPERATION switch twice or once, or press any button on
the remote controller.

10
7-2. PERFORMANCE CURVE
Cooling
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.
71
67
63
Indoor intake air WB temperature (°F)
SHF at rating condition = 0.76
= 307 CFM
Airflow
0.8
0.7
0.6
0.5
65 75 85 95 105 115
Outdoor intake air DB temperature (°F)
Total power consumption
(kW)
71
63
67
1.3
1.2
1.1
1.0
0.9
0.8
0.7
Indoor intake air WB temperature (°F)
SHF at rating condition = 0.73
= 350 CFM
Airflow
65 75 85 95 105 115
Outdoor intake air DB temperature (°F)
Total power consumption
(kW)
MUZ-FE09NA MUZ-FE12NA
MUZ-FE18NA
Cooling capacity ( at Rated frequency)
0.9
1.0
1.1
1.2
1.3
1.4
1.5
14 23 32 41 50 59 68 77 86 95 104 113
Outdoor intake air Dry-bulb temperature(°F)
Capacity correction factors
76
75
68
64
72
Indoor intake air Wet-bulb
temperature( F)
Indoor air Wet-bulb temperature
difference (°F)
71
67
63
65 70 75 80 85 90 95 100 105 110 115
0.9
1.0
1.1
1.2
1.3
1.4
1.5
Indoor intake air WB temperature (°F)
Total power consumption
(kW)
SHF at rating condition = 0.84
= 634 CFM
Airflow
Outdoor intake air DB temperature (°F)

11
75
70
65
Indoor intake air DB temperature (°F)
= 381 CFM
Airflow
1552535455565
Outdoor intake air WB temperature (°F)
0.7
0.5
0.3
0.1
0.9
0.6
0.4
0.2
0.8
Total power consumption
(kW)
-15 -5
0
0.6
0.5
Indoor intake air DB temperature (°F)
= 420 CFM
Airflow
1552535455565
Outdoor intake air WB temperature (°F)
0.7
0.8
0.9
1.0
1.1
Total power consumption
(kW)
75
70
65
-5
-15
0.4
0.3
0.1
0.2
Heating
MUZ-FE09NA MUZ-FE12NA
MUZ-FE18NA
This value of frequency is not the same as the actual frequency in operating. Refer to 7-5 and 7-6 for the relationships
between frequency and capacity.
Indoor air Dry-bulb temperature
difference (°F)
Outdoor intake air Wet-bulb temperature (°F)
-4 5 142332415059
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
Heating capacity ( at Rated frequency)
Capacity correction factor
59
68
79
Indoor intake air Dry-bulb temperature ( F)
70
75
-15 -5 5 15 25 35 45 55 65
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
Outdoor intake air WB temperature (°F)
Total power consumption
(kW)
= 738 CFM
Airflow
Indoor intake air DB temperature (°F)
65

12
7-3. CONDENSING PRESSURE
Cooling
Data is based on the condition of indoor humidity 50 %.
Air flow should be set to High speed.
MUZ-FE12NA
(PSIG)
Condensing pressure
86
80
75
70
68 70 75 80 85 90 95 100 105(°F)
120
125
130
135
140
145
150
155
160
165
170
175
180
Suction pressure
Outdoor ambient temperature
Indoor DB temperature (°F)
(PSIG)
86
80
75
70
68 70 75 80 85 90 95 100 105(°F)
260
300
340
380
420
460
500
540
580
Indoor DB temperature (°F)
Outdoor ambient temperature
MUZ-FE09NA
(PSIG)
Condensing pressure
86
80
75
70
68 70 75 80 85 90 95 100 105(°F)
120
125
130
135
140
145
150
155
160
165
170
175
180
Suction pressure
Outdoor ambient temperature
Indoor DB temperature (°F)
(PSIG)
86
80
75
70
68 70 75 80 85 90 95 100 105(°F)
260
300
340
380
420
460
500
540
580
Indoor DB temperature (°F)
Outdoor ambient temperature
MUZ-FE18NA
(PSIG)
Condensing pressure
86
80
75
70
70 75 80 85 90 95 100 105(°F)
110
120
130
140
150
160
170
180
190
Suction pressure
Outdoor ambient temperature
Indoor DB temperature (°F)
(PSIG)
86
80
75
70
68 70 75 80 85 90 95 100 105(°F)
240
280
320
360
400
440
480
Indoor DB temperature (°F)
Outdoor ambient temperature
68 70 75 80 85 90 95 100 105(°F)
110
120
130
140
150
160
170
180
190

13
75
70
65
(PSIG) (PSIG)
Condensing pressure
Outdoor ambient temperature
155 10 2025303540455055606570(°F)
220
200
180
160
140
240
260
280
320
300
340
360
380
400 75
70
65
Suction pressure
Outdoor ambient temperature
15 205 10 25303540455055606570(°F)
80
70
60
50
90
100
110
120
130
140
150
160
170
-10
-15 -10
-15
40
120
Indoor DB temperature (°F)
Indoor DB temperature (°F)
58Hz
58Hz
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-FE12NA
MUZ-FE09NA
75
70
65
(PSIG) (PSIG)
Condensing pressure
Outdoor ambient temperature
20 25 305 1015 3540455055606570(°F)
220
200
180
160
140
240
260
280
320
300
340
360
380
400 75
70
65
Suction pressure
Outdoor ambient temperature
20 25 305 1015 3540455055606570(°F)
80
70
60
50
90
100
110
120
130
140
150
160
170
120
-10
-15 -15 -10
40
Indoor DB temperature (°F)
Indoor DB temperature (°F)
58Hz 58Hz
MUZ-FE18NA
(PSIG)
Condensing pressure
75
70
65
75
70
65
Suction pressure
Outdoor ambient temperature
(PSIG)
-15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75(°F)
240
260
280
300
320
340
360
380
400
420
440
460
480
-15 -10 -5 0510 15 20 25 30 35 40 45 50 55 60 65 70 75(°F)
0
20
40
60
80
100
120
140
160
180
200
220
240
Indoor DB temperature (°F)
Outdoor ambient temperature
Indoor DB temperature (°F)
58Hz 58Hz

14
7-4. STANDARD OPERATION DATA
Model MSZ-FE09NA MSZ-FE12NA MSZ-FE18NA
Item Unit Cooling Heating Cooling Heating Cooling Heating
Total
Capacity Btu/h 9,000 10,900 12,000 13,600 18,000 21,600
SHF — 0.76 — 0.73 — 0.84 —
Input kW 0.580 0.710 0.930 0.950 1.800 2.200
Rated frequency Hz 34 42 51 52.5 50.5 62.5
Electrical circuit
Indoor unit MSZ-FE09NA MSZ-FE12NA MSZ-FE18NA
Power supply
V,
phase,
Hz
208/230, 1, 60
Input kW 0.018 0.024 0.024 0.030 0.058
Fan motor current A 0.19/0.17 0.25/0.23 0.25/0.23 0.32/0.29 0.56/0.51
Outdoor unit MUZ-FE09NA MUZ-FE12NA MUZ-FE18NA
Power supply
V,
phase,
Hz
208/230, 1, 60
Input kW 0.562 0.686 0.906 0.920 1.212 1.482
Comp. current A 2.38/2.15 2.98/2.70 4.05/3.66 4.12/3.72 4.47/4.04 5.72/5.17
Fan motor current A 0.35/0.32 1.16/1.05 1.13/1.02
Refrigerant circuit
Condensing pressure PSIG 376 355 402 392 373 357
Suction pressure PSIG 154 108 148 104 151 107
Discharge temperature ˚F 142 145 160 158 150 159
Condensing temperature ˚F 112 108 117 115 111 105
Suction temperature ˚F533653345841
Comp. shell bottom temperature ˚F 144 128 146 129 132 136
Ref. pipe length ft. 25
Refrigerant charge (R410A) 2 lb. 9 oz. 4 lb 3 oz.
Indoor unit
Intake air temperature DB ˚F807080708070
WB ˚F676067606760
Discharge air temperature DB ˚F 59 99 58 101 59 102
WB ˚F56—55—56—
Fan speed (High) rpm 1,020 1,120 1,120 1,220 1,300
Airflow (High) CFM 307 (Wet) 381 350 (Wet) 420 634 (Wet) 738
Outdoor unit
Intake air temperature DB ˚F954795479547
WB ˚F — 43 — 43 — 43
Fan speed rpm 810 870 810 870 840 810
Airflow CFM 1,102 1,187 1,102 1,187 1,769 1,701

15
7-5. CAPACITY AND INPUT CORRECTION BY INVERTER OUTPUT FREQUENCY
Capacity correction factors
Input correction factors
Input correction factors
Capacity correction factors
Correction of Cooling capacity
The operational frequency of compressor
Correction of Cooling total input
The operational frequency of compressor
Correction of Heating total input
The operational frequency of compressor
Correction of Heating capacity
The operational frequency of compressor
MUZ-FE09NA
0 50 100 150
0.5
1.0
1.5
(Hz) 0 50 100 150
0.5
1.0
1.5
(Hz) 0 50 100 150
0.5
1.0
2.0
1.5
(Hz) 0 50 100 150
1.0
2.0
3.0
(Hz)
MUZ-FE12NA
Capacity correction factors
Input correction factors
Input correction factors
Capacity correction factors
Correction of Cooling capacity
The operational frequency of compressor
Correction of Cooling total input
The operational frequency of compressor
Correction of Heating total input
The operational frequency of compressor
Correction of Heating capacity
The operational frequency of compressor
0 50 100 150
0.5
1.0
1.5
(Hz) 0 50 100 150
0.5
1.0
1.5
(Hz) 0 50 100 150
0.5
1.0
1.5
(Hz) 0 50 100 150
1.0
0.5
1.5
2.0
2.5
(Hz)
MUZ-FE18NA
Capacity correction factors
Input correction factors
Input correction factors
Capacity correction factors
Correction of Cooling capacity
The operational frequency of compressor
Correction of Cooling total input
The operational frequency of compressor
Correction of Heating total input
The operational frequency of compressor
Correction of Heating capacity
The operational frequency of compressor
0 50 100 150
0.5
1.0
1.5
(Hz) (Hz) 0 50 100 150
0.5
1.0
1.5
(Hz) (Hz)
0 50 100 150
0.5
1.0
1.5
2.0
0 50 100 150
0.5
1.0
1.5
2.0
7-6. HOW TO OPERATE FIXED-FREQUENCY OPERATION (Test run operation)
1. Press EMERGENCY OPERATION switch to start COOL or HEAT mode (COOL: Press once, HEAT: Press twice).
2. Test run operation starts and continues to operate for 30 minutes.
3. Compressor operates at rated frequency in COOL mode or 58 Hz in HEAT mode.
4. Indoor fan operates at High speed.
5. After 30 minutes, test run operation finishes and EMERGENCY OPERATION starts (operation frequency of compressor var-
ies).
6. To cancel test run operation (EMERGENCY OPERATION), press EMERGENCY OPERATION switch or any button on
remote controller.

16
8ACTUATOR CONTROL
MUZ-FE09NA MUZ-FE12NA MUZ-FE18NA
8-2. R.V. COIL CONTROL
Heating . . . . . . . . . . . . . . . . . ON
Cooling . . . . . . . . . . . . . . . . . OFF
Dry . . . . . . . . . . . . . . . . . . . . OFF
NOTE: The 4-way valve reverses for 5 seconds right before start-up of the compressor.
ON
OFF
ON
OFF
Outdoor fan
motor
Compressor
5 seconds 15 seconds
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.
8-3. RELATION BETWEEN MAIN SENSOR AND ACTUATOR
Sensor Purpose
Actuator
Compressor LEV Outdoor
fan motor R.V. coil Indoor fan motor
Discharge temperature thermistor Protection ○○
Indoor coil temperature thermistor
Cooling: Coil frost prevention
○
Heating: High pressure protection ○○
Defrost thermistor
Cooling: High pressure protection
○○
Heating: Defrosting ○○○○○
Fin temperature thermistor Protection ○○
Outdoor heat exchanger temperature thermistor High pressure protection ○○○
Ambient temperature thermistor Low ambient temperature operation
○○○
ON
OFF
Compressor
Outdoor fan
motor
R.V.coil ON
OFF
ON
OFF
<COOL>
5 seconds
<HEAT>
5 seconds

17
SERVICE FUNCTIONS
9
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 finish temperature
MUZ-FE09/12NA MUZ-FE18NA
JS
Soldered
(Initial setting) 41°F (5°C) 50°F (10°C)
None
(Cut) 50°F (10°C) 64°F (18°C)
MUZ-FE09NA MUZ-FE12NA MUZ-FE18NA
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 tempera-
ture. 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
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 con-
firming the horizontal vane is closed, turn off the breaker and/or disconnect the power plug.
2) Be sure to turn OFF the power supply before removing the front panel, the cabinet, the top panel, and the electronic
control P.C. board.
3) When removing the electrical parts, be careful of the residual voltage of smoothing capacitor.
4) When removing the electronic control P.C. board, hold the edge of the board with care NOT to apply stress on the
components.
5) When connecting or disconnecting the connectors, hold the housing of the connector. DO NOT pull the lead wires.
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.
Lead wiring
<Incorrect>
Housing point
<Correct>
MUZ-FE09NA MUZ-FE12NA MUZ-FE18NA

18
10-2. FAILURE MODE RECALL FUNCTION
1. Flow chart of failure mode recall function for the indoor/outdoor unit MSZ-FE09NA
MSZ-FE12NA
MSZ-FE18NA
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.
2. Blinking pattern when the indoor unit is abnormal:
3.Blinking pattern when the outdoor unit is abnormal:
ON
OFF
Beeps
Repeated cycle Repeated cycle
ON
OFF
No beep Beeps
Repeated cycle
2.5-second OFF
Blinking at 0.5-
second interval
2.5-second OFF 3-second ON
Blinking at 0.5-
second interval
Beeps
Repeated cycle
2.5-second OFF
Blinking at 0.5-
second interval
No beep Beeps
Repeated cycle
2.5-second OFF 3-second ON
Blinking at 0.5-
second interval
Repeated cycle
Beeps
Does POWER lamp (MSZ-FE09/12NA)/the upper lamp
of OPERATION INDICATOR lamp (MSZ-FE18NA) on
the indoor unit blink at the interval of 0.5 seconds?
Blinks: Either indoor or outdoor unit is abnormal. Beep
is emitted at the same timing as the blinking
of POWER lamp (MSZ-FE09/12NA)/the upper
lamp of OPERATION INDICATOR lamp (MSZ-
FE18NA). 2
Indoor unit is normal.
But the outdoor unit might be abnormal because there are some abnor-
malities that can not be recalled with this way.
Confirm if outdoor unit is abnormal according to the detailed outdoor
unit failure mode recall function. (Refer to 10-2.2)
No
Yes
The cause of abnormality cannot be found because the abnormality does not recur.
Setting up the failure mode recall function
Turn ON the power supply.
<Preparation of the remote controller>
While pressing both OPERATION SELECT button and TOO COOL button on the
remote controller at the same time, press RESET button.
First, release RESET button.
And release the other two buttons after all LCD in operation display section of the
remote controller is displayed after 3 seconds.
Press OPERATE/STOP (ON/OFF) button of the remote controller (the set temperature is
displayed) with the remote controller headed towards the indoor unit. 1
Judgment of indoor/outdoor abnormality
Before blinking, does POWER lamp (MSZ-FE09/12NA)/the
upper lamp of OPERATION INDICATOR lamp (MSZ-FE18NA)
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 confirm 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. 2
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.
The outdoor unit is abnormal.
Check the blinking pattern, and confirm 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. 3
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" 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.
Operational procedure
Yes
(Blinks)
No
(OFF)
NOTE: 1. Make sure to release the failure mode recall function once it is set up, otherwise the unit cannot operate properly.
2. If the abnormal condition is not deleted from the memory, the last abnormal condition is kept memorized.
1. Regardless of normal or abnormal
condition, a short beep is emitted
once the signal is received.

19
Does POWER lamp(MSZ-FE09/12NA)/the up-
per lamp of OPERATION INDICATOR lamp(MSZ-
FE18NA) 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 (MSZ-FE09/12NA)/the upper lamp of
OPERATION INDICATOR lamp (MSZ-FE-
18NA). 2
Yes
(Blinks)
No
(OFF)
The outdoor unit might be abnormal.
Confirm if outdoor unit is abnormal according to the following procedures.
Operational procedure
Confirm 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
1. Regardless of normal or abnormal condition, 2 short
beeps are emitted as the signal is received.
The outdoor unit is abnormal.
Check the blinking pattern, and confirm the abnormal point with the out-
door unit failure mode table (10-2.3.).
Make sure to check at least two consecutive blinking cycles. 2
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.
The outdoor unit is normal.
Release the failure mode recall function accord-
ing to the left mentioned procedure.
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 is set up, otherwise the unit cannot operate properly.
2. If the abnormal condition is not deleted from the memory, the last abnormal condition is kept memorized.
2. Flow chart of the detailed outdoor unit failure mode recall function
2.Blinking pattern when outdoor unit is abnormal:
ON
OFF
No beep Beeps
Repeated cycle
2.5-second OFF 3-second ON
Blinking at 0.5-
second interval
No beep Beeps
Repeated cycle
2.5-second OFF 3-second ON
Blinking at 0.5-
second interval
Repeated cycle

20
3. Outdoor unit failure mode table
OPERATION
INDICATOR
POWER lamp
Upper lamp
(Indoor unit)
Abnormal point
(Failure mode/protection)
LED indication
(Outdoor P.C. board) Condition Remedy
Indoor/
outdoor unit
failure mode
recall function
Outdoor unit
failure mode
recall function
OFF None (Normal) — — — — —
2-time flash
2.5 seconds
OFF
Outdoor power system
—
Overcurrent protection stop is
continuously performed 3 times within
1 minute after the compressor gets
started.
Reconnect connectors.
Refer to 10-5. "How
to check inverter/
compressor".
Check stop valve.
•
•
•
○○
3-time flash
2.5 seconds
OFF
Discharge temperature
thermistor
1-time flash every
2.5 seconds
Thermistor shorts or opens during
compressor running.
Refer to 10-5. "Check
of outdoor thermistors".
Defective outdoor
thermistors can be
identified by checking
the blinking pattern of
LED.
•
○○
Defrost thermistor
Fin temperature thermistor 3-time flash
2.5 seconds OFF
P.C. board temperature
thermistor
4-time flash
2.5 seconds OFF
Ambient temperature
thermistor
2-time flash
2.5 seconds OFF
4-time flash
2.5 seconds
OFF
Overcurrent 11-time flash
2.5 seconds OFF
Large current flows into intelligent
power module.
Reconnect compressor
connector.
Refer to 10-5. "How
to check inverter/
compressor".
Check stop valve.
•
•
•
—○
Compressor synchronous
abnormality (Compressor start-
up failure protection)
12-time flash
2.5 seconds OFF
Waveform of compressor current is
distorted.
Reconnect compressor
connector.
Refer to 10-5. "How
to check inverter/
compressor".
•
•—○
5-time flash
2.5 seconds
OFF
Discharge temperature
—
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.
Check refrigerant circuit
and refrigerant amount.
Refer to 10-5. "Check
of LEV".
•
•—○
6-time flash
2.5 seconds
OFF
High pressure
—
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.
Check refrigerant circuit
and refrigerant amount.
Check stop valve.
•
•—○
7-time flash
2.5 seconds
OFF
Fin temperature/ P.C. board
temperature
7-time flash
2.5 seconds OFF
Temperature of fin 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).
Check around outdoor
unit.
Check outdoor unit air
passage.
Refer to 10-5. "Check
of outdoor fan motor".
•
•
•
—○
8-time flash
2.5 seconds
OFF
Outdoor fan motor
—
Outdoor fan has stopped 3 times in a
row within 30 seconds after outdoor fan
start-up.
Refer to 10-5. "Check
of outdoor fan motor".
Refer to 10-5. "Check
of inverter P.C. board".
•
—○
9-time flash
2.5 seconds
OFF
Nonvolatile memory data 5-time flash
2.5 seconds OFF
Nonvolatile memory data cannot be
read properly.
Replace the inverter
P.C. board.
•
○○
MUZ-FE18NA
Power module
6-time flash
2.5 seconds OFF
The interphase short circuit occurs
in the output of the intelligent power
module (IPM).
The compressor winding shorts circuit.
Refer to 10-5. "How
to check inverter/
compressor".
•
10-time flash
2.5 seconds
OFF
Discharge temperature
—
Temperature of discharge temperature
thermistor has been 122°F (50°C) or
less for 20 minutes.
Refer to 10-5. "Check
of LEV".
Check refrigerant circuit
and refrigerant amount.
•
•—○
11-time flash
2.5 seconds
OFF
DC voltage 8-time flash
2.5 seconds OFF
DC voltage of inverter cannot be
detected normally.
Refer to 10-5. "How
to check inverter/
compressor".
•
—○
Each phase current of
compressor
9-time flash
2.5 seconds OFF
Each phase current of compressor
cannot be detected normally.
12-time flash
2.5 seconds
OFF
Overcurrent Compressor open-
phase
10-time flash
2.5 seconds OFF
Large current flows into intelligent
power module (IPM).
The open-phase operation of
compressor is detected.
The interphase short circuit occurs
in the output of the intelligent power
module (IPM).
The compressor winding shorts circuit.
Reconnect compressor
connector.
Refer to 10-5. "How
to check inverter/
compressor".
•
•
—○
14-time flash
2.5 seconds
OFF
Stop valve (Closed valve) 14-time flash
2.5 seconds OFF
Closed valve is detected by compressor
current.
Check stop valve• ○○
NOTE: Blinking patterns of this mode differ from the ones of Troubleshooting check table (10-3.).
OPERATION INDICATOR
POWER lamp: MSZ-FE09/12NA
Upper lamp: MSZ-FE18NA