Mitsubishi Electric MUZ-JP09WA-U1 User manual

Models
MUZ-JP09WA -U1
MUZ-JP12WA -U1
HFC
utilized
R410A
MUZ-JP09WA
PARTS CATALOG (OBB821)
SERVICE MANUAL
No. OBH821
REVISED EDITION-A
Indoor unit service manual
MSZ-JP•WA Series (OBH820)
CONTENTS
1. TECHNICAL CHANGES ······························3
2. PART NAMES AND FUNCTIONS··················4
3. SPECIFICATION ········································5
4. OUTLINES AND DIMENSIONS ·····················8
5. WIRING DIAGRAM·····································9
6. REFRIGERANT SYSTEM DIAGRAM ··········· 10
7. DATA······················································ 11
8. ACTUATOR CONTROL ····························· 18
9. SERVICE FUNCTIONS······························ 19
10. TROUBLESHOOTING ······························· 20
11. DISASSEMBLY INSTRUCTIONS················· 39
OUTDOOR UNIT
OBH821 is void.
Revision A:
• 3. SPECIFICATION has been corrected.

2
Use the specified refrigerant only
Never use any refrigerant other than that specified.
Doing so may cause a burst, an explosion, or fire when the unit is being used, serviced, or disposed of.
Correct refrigerant is specified in the manuals and on the spec labels provided with our products.
We will not be held responsible for mechanical failure, system malfunction, unit breakdown or accidents caused by
failure to follow the instructions.
Revision A:
• 3. SPECIFICATION has been corrected.
OBH821A

3
1TECHNICAL CHANGES
MUZ-JP09WA - U1
MUZ-JP12WA - U1
1. New model
OBH821A

4
PART NAMES AND FUNCTIONS
2
MUZ-JP09WA MUZ-JP12WA
Air outlet
Drain outlet
Piping
Drain hose
Air inlet
(back and side)
OBH821A

5
3SPECIFICATION
Outdoor unit model MUZ-JP09WA
Capacity
Rated (Minimum~Maximum)
Cooling 1 Btu/h 9,000 ( 3,800 ~ 10,000 )
Heating 47 1 Btu/h 10,900 ( 4,500 ~ 11,800 )
Capacity
Rated (Maximum) Heating 17 2 Btu/h 6,700 (7,200)
Power consumption
Rated (Minimum~Maximum)
Cooling 1 W 750 (240 - 850)
Heating 47 1 W 900 (240 - 1,000)
Power consumption
Rated (Maximum) Heating 17 2 W 700 (780)
EER 1 [SEER] 3Cooling 12.0 [ 17.0 ]
HSPF IV 4Heating 9.0
COP Heating 13.55
Power factor Cooling % 93
Heating % 94
Power supply V, phase, Hz 115, 1, 60
Max. fuse size (time delay) A 15
Min. circuit ampacity A 12
Fan motor F.L.A A 0.70
Compressor
Model KNB073FRXMC
R.L.A A 8.8
L.R.A A 11.0
Refrigeration oil
floz. (L) (Model) 9.1 (0.27) (FV50S)
Refrigerant control Linear expansion valve
Sound level 1Cooling dB(A) 46
Heating dB(A) 50
Airflow
High - Med. - Low
Cooling CFM 1,105 - 1,105 - 1,063
Heating CFM 1,282 - 1,105 - 1,105
Fan speed
High - Med. - Low
Cooling rpm 770 - 770 - 740
Heating rpm 890 - 770 - 770
Defrost method Reverse cycle
Dimensions
W in. 31-1/2
D in. 11-1/4
H in. 21-5/8
Weight Ib. 73
External finish Munsell 3Y 7.8/1.1
Refrigerant piping Not supplied
Refrigerant pipe size
(Min. wall thickness)
Liquid in. 1/4 (0.0315)
Gas in. 3/8 (0.0315)
Connection method Indoor Flared
Outdoor Flared
Between the indoor &
outdoor units
Height difference ft. 40
Piping length ft. 65
Refrigerant charge (R410A) 1 lb. 12 oz.
NOTE: Test conditions are based on AHRI 210/240.
1: Rating conditions (Cooling) — Indoor: 80˚FDB, 67˚FWB, Outdoor: 95˚FDB, (75˚FWB)
(Heating) — Indoor: 70˚FDB, 60˚FWB, Outdoor: 47˚FDB, 43˚FWB
2: (Heating) — Indoor: 70˚FDB, 60˚FWB, Outdoor: 17˚FDB, 15˚FWB
3: Test condition (Refer to page 7.)
4: Test condition (Refer to page 7.)
OBH821A

6
Outdoor unit model MUZ-JP12WA
Capacity
Rated (Minimum~Maximum)
Cooling 1 Btu/h 12,000 ( 3,800 ~ 12,200 )
Heating 47 1 Btu/h 12,200 ( 4,500 ~ 14,500 )
Capacity
Rated (Maximum) Heating 17 2 Btu/h 7,600 (9,000)
Power consumption
Rated (Minimum~Maximum)
Cooling 1 W 1,210 (240 - 1,300)
Heating 47 1 W 990 (240 - 1,220)
Power consumption
Rated (Maximum) Heating 17 2 W 800 (990)
EER 1 [SEER] 3Cooling 9.9 [ 17.0 ]
HSPF IV 4Heating 9.0
COP Heating 13.61
Power factor Cooling % 93
Heating % 94
Power supply V , phase , Hz 115,1, 60
Max. fuse size (time delay) A 20
Min. circuit ampacity A 14
Fan motor F.L.A A 0.70
Compressor
Model KNB073FRXMC
R.L.A A 10.4
L.R.A A 13.0
Refrigeration oil
floz. (L) (Model) 9.1 (0.27) (FV50S)
Refrigerant control Linear expansion valve
Sound level 1Cooling dB(A) 49
Heating dB(A) 51
Airflow
High - Med. - Low
Cooling CFM 1,105 - 1,105 - 1,063
Heating CFM 1,282 - 1,105 - 1,105
Fan speed
High - Med. - Low
Cooling rpm 770 - 770 - 740
Heating rpm 890 - 770 - 770
Defrost method Reverse cycle
Dimensions
W in. 31-1/2
D in. 11-1/4
H in. 21-5/8
Weight Ib. 73
External finish Munsell 3Y 7.8/1.1
Refrigerant piping Not supplied
Refrigerant pipe size
(Min. wall thickness)
Liquid in. 1/4 (0.0315)
Gas in. 3/8 (0.0315)
Connection method Indoor Flared
Outdoor Flared
Between the indoor &
outdoor units
Height difference ft. 40
Piping length ft. 65
Refrigerant charge (R410A) 1 lb. 12 oz.
NOTE: Test conditions are based on AHRI 210/240.
1: Rating conditions (Cooling) — Indoor: 80˚FDB, 67˚FWB, Outdoor: 95˚FDB, (75˚FWB)
(Heating) — Indoor: 70˚FDB, 60˚FWB, Outdoor: 47˚FDB, 43˚FWB
2: (Heating) — Indoor: 70˚FDB, 60˚FWB, Outdoor: 17˚FDB, 15˚FWB
3: Test condition (Refer to page 7.)
4: Test condition (Refer to page 7.)
OBH821A

7
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
= ("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 -4 -5
OPERATING RANGE
(1) POWER SUPPLY
Rated voltage Guaranteed voltage (V)
Outdoor unit
115 V
1 phase
60 Hz
Min. 103 115 Max. 127
OBH821A

8
OUTLINES AND DIMENSIONS
4
Unit: inch
MUZ-JP09WA MUZ-JP12WA
4 in. (100 mm)
or more
14 in. (350 mm)
or more
8 in. (200 mm)
or more *2
4 in. (100 mm)
or more
Liquid refrigerant pipe joint
Refrigerant pipe (flared) Ø 1/4
Gas refrigerant pipe joint
Refrigerant pipe (flared) Ø 3/8
REQUIRED SPACE
clear *1
*1 4 in. (100 mm) or more when
front and sides of the unit are clear
*2 When any 2 sides of left, right
and rear of the unit are clear
holes
OBH821A

9
5WIRING DIAGRAM
MUZ-JP09WA MUZ-JP12WA
OBH821A

10
6REFRIGERANT SYSTEM DIAGRAM
Unit: Inch (mm)
Flared connection
Discharge
temperature
thermistor
RT62
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 ø3/8 (ø9.52)
(with heat insulator)
Refrigerant pipe ø1/4 (ø6.35)
(with heat insulator)
R.V. coil
heating ON
cooling OFF
Strainer
#100
LEV
Muffler
Capillary tube
O.D. 0.118 × I.D. 0.055
× 10-1/4
(ø3.0 × ø1.4
× 260)
Muffler
Service port
Service port
Outdoor
heat
exchanger
Defrost
thermistor
RT61
Ambient
temperature
thermistor
RT65
Outdoor heat
exchanger
temperature
thermistor
RT68
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-JP09WA
MUZ-JP12WA 65 40 3/8 1/4
ADDITIOWAL 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-JP09WA
MUZ-JP12WA 1 lb. 12 oz. 0 1.08 3.24 5.40 7.56 8.64
Calculation: X oz. = 1.08/5 oz./ft. × (Refrigerant piping length (ft.) - 25)
MUZ-JP09WA MUZ-JP12WA
OBH821A

11
DATA7
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-JP09WA
71 11.0 7.6 0.67 10.3 7.1 0.73 9.7 6.6 0.79 9.0 6.2 0.83 8.3 5.7 0.86
67 10.4 8.6 0.63 9.7 8.0 0.69 9.0 7.4 0.75 8.4 6.9 0.80 7.7 6.3 0.83
63 9.8 9.4 0.60 9.1 8.7 0.66 8.5 8.1 0.72 7.7 7.3 0.77 7.0 6.7 0.80
MUZ-JP12WA
71 14.7 9.4 1.08 13.7 8.7 1.18 12.9 8.2 1.27 12.0 7.6 1.34 11.0 7.0 1.39
67 13.9 10.7 1.02 13.0 10.0 1.12 12.0 9.2 1.21 11.2 8.6 1.28 10.3 7.9 1.34
63 13.1 11.8 0.97 12.1 10.9 1.07 11.3 10.2 1.16 10.3 9.3 1.23 9.4 8.5 1.28
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.
MUZ-JP09WA MUZ-JP12WA
2) COOLING CAPACITY CORRECTIONS
Refrigerant piping length (one way: ft.)
Model 25 (std.) 40 65 100
MUZ-JP09WA
MUZ-JP12WA 1.0 0.988 0.967 —
4) 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-JP09WA
75 4.8 0.53 6.3 0.67 7.9 0.79 9.4 0.88 10.6 0.92 11.0 0.94 12.4 0.97
70 5.2 0.51 6.7 0.65 8.2 0.77 9.6 0.86 10.9 0.90 11.2 0.92 12.7 0.95
65 5.5 0.49 6.9 0.62 8.6 0.74 10.0 0.83 11.2 0.88 11.6 0.89 13.0 0.94
MUZ-JP12WA
75 5.4 0.58 7.1 0.74 8.8 0.87 10.6 0.97 11.9 1.01 12.3 1.03 13.9 1.07
70 5.8 0.56 7.5 0.71 9.2 0.85 10.8 0.94 12.2 0.99 12.6 1.01 14.2 1.05
65 6.1 0.53 7.7 0.68 9.6 0.82 11.2 0.92 12.6 0.97 12.9 0.98 14.5 1.03
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 or press any button on the remote con-
troller.
3) HEATING CAPACITY CORRECTIONS
Refrigerant piping length (one way: ft.)
Model 25 (std.) 40 65 100
MUZ-JP09WA
MUZ-JP12WA 1.0 0.997 0.993 —
OBH821A

12
7-2. PERFORMANCE CURVE
Cooling
Cooling capacity ( at Rated frequency)
0.9
1.0
1.1
1.2
1.3
1.4
1.5
14 23 32 41 50 59 68 77 86 95 104 113
Outdoor intake air DB temperature(°F)
Capacity correction factors
79
75
68
64
72
Indoor intake air Wet-bulb
temperature( F)
Indoor air Wet-bulb temperature
difference (°F)
71
67
63
65 75 85 95 105 115
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Indoor intake air WB temperature (°F)
SHF at rating condition = 0.82
= 399 CFM
Airflow
Outdoor intake air DB temperature (°F)
Total power consumption
(kW)
71
67
63
65 75 85 95 105 115
0.9
1.0
1.1
1.2
1.3
1.4
1.5
Indoor intake air WB temperature (°F)
SHF at rating condition = 0.77
= 399 CFM
Airflow
Outdoor intake air DB temperature (°F)
Total power consumption
(kW)
MUZ-JP09WA MUZ-JP12WA
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.
Heating
Indoor air Dry-bulb temperature
difference (°F)
Outdoor intake air WB 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)
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.
MUZ-JP09WA MUZ-JP12WA
0 10203040506070
0.3
0.5
0.7
0.9
1.1
Indoor intake air DB temperature (°F)
= 406 CFM
Airflow
Outdoor intake air WB temperature (°F)
Total power consumption
(kW)
75
70
65
75
70
65
0 10203040506070
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
Indoor intake air DB temperature (°F)
= 406 CFM
Airflow
Outdoor intake air WB temperature (°F)
Total power consumption
(kW)
OBH821A

13
7-3. CONDENSING PRESSURE
Cooling
Data are based on the condition of indoor humidity 50 %.
Air flow should be set to High speed.
MUZ-JP09WA
68 70 75 80 85 90 95 100 105 (°F)
120
140
160
180
200
(PSIG)(PSIG)
6870 75 80 85 90 95 100 105(°F)
280
320
360
400
440
Condensing pressure
86
80
75
70
Suction pressure
Outdoor ambient temperature
Indoor DB temperature (°F)
Outdoor ambient temperature
Indoor DB temperature (°F)
86
80
75
70
MUZ-JP12WA
70 75 80 85 90 95 100 105
100
120
140
160
180
(PSIG)(PSIG)
70 75 80 85 90 95 100 105
280
335
390
445
500
Condensing pressure
4
86
80
7
5
7
0
Suction pressure
Outdoor ambient temperature
Indoor DB temperature ( F)
u
Indoor DB temperature (°F)
d
e
ur
DB
Outdoor ambient temperature
Indoor DB temperature (°F)
86
80
75
70
OBH821A

14
5 15253545556575(°F) 5 15253545556575(°F)
60
85
110
135
160
185
210
220
245
270
295
320
345
370
Indoor DB temperature (°F)
Condensing pressure
Outdoor ambient temperature
(PSIG) (PSIG)
75
70
65
58Hz
Indoor DB temperature (°F)
Suction pressure
Outdoor ambient temperature
75
70
65
58Hz
MUZ-JP09WA MUZ-JP12WA
Heating
Data are based on the condition of outdoor humidity 75%.
Air flow should be set to High speed.
Data are for heating operation without any frost.
OBH821A

15
7-4. STANDARD OPERATION DATA
Model MSZ-JP09WA
Item Unit Cooling Heating
Total
Capacity Btu/h 9,000 10,900
SHF — 0.82 —
Input kW 0.750 0.900
Rated frequency Hz 61.0 79.0
Electrical circuit
Indoor unit MSZ-JP09WA
Power supply V, phase, Hz 115, 1, 60
Input kW 0.022 0.023
Fan motor current A 0.37 0.38
Outdoor unit MUZ-JP09WA
Power supply V, phase, Hz 115, 1, 60
Input kW 0.728 0.877
Comp. current A 6.15 7.38
Fan motor current A 0.48 0.54
Refrigerant circuit
Condensing pressure PSIG 384 331
Suction pressure PSIG 152 102
Discharge temperature ˚F 151 155
Condensing temperature ˚F 113 101
Suction temperature ˚F58 41
Comp. shell bottom temperature ˚F 146 149
Ref. pipe length ft. 25
Refrigerant charge (R410A) 1 lb. 12 oz.
Indoor unit
Intake air temperature DB ˚F80 70
WB ˚F67 60
Discharge air temperature DB ˚F60 97
WB ˚F58 —
Fan speed (High) rpm 1,020 1,040
Airflow (High) CFM 367 (Wet) 413
Outdoor unit
Intake air temperature DB ˚F 95 47
WB ˚F— 43
Fan speed rpm 770 850
Airflow CFM 1,105 1,225
OBH821A

16
7-4. STANDARD OPERATION DATA
Model MSZ-JP12WA
Item Unit Cooling Heating
Total
Capacity Btu/h 12,000 12,200
SHF — 0.77 —
Input kW 1.210 0.990
Rated frequency Hz 91.0 90.0
Electrical circuit
Indoor unit MSZ-JP12WA
Power supply V, phase, Hz 115, 1, 60
Input kW 0.022 0.023
Fan motor current A 0.37 0.38
Outdoor unit MUZ-JP12WA
Power supply V, phase, Hz 115, 1, 60
Input kW 1.188 0.967
Comp. current A 10.35 8.18
Fan motor current A 0.48 0.54
Refrigerant circuit
Condensing pressure PSIG 429 347
Suction pressure PSIG 135 99
Discharge temperature ˚F 180 165
Condensing temperature ˚F 120 104
Suction temperature ˚F60 41
Comp. shell bottom temperature ˚F 174 157
Ref. pipe length ft. 25
Refrigerant charge (R410A) 1 lb. 12 oz.
Indoor unit
Intake air temperature DB ˚F80 70
WB ˚F67 60
Discharge air temperature DB ˚F 56 108
WB ˚F55 —
Fan speed (High) rpm 1,020 1,040
Airflow (High) CFM 367 (Wet) 413
Outdoor unit
Intake air temperature DB ˚F 95 47
WB ˚F— 43
Fan speed rpm 770 850
Airflow CFM 1,105 1,225
OBH821A

17
7-5. CAPACITY AND INPUT CORRECTION BY INVERTER OUTPUT FREQUENCY
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-JP09WA
050100
0.0
0.5
1.0
1.5
0 50 100
0.0
0.5
1.0
1.5
0 50 100 150
0.0
0.5
1.0
1.5
0 50 100 150
0.0
0.5
1.0
1.5
2.0
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-JP12WA
050100
0.0
0.5
1.0
1.5
0 50 100
0.0
0.5
1.0
1.5
0 50 100 150
0.0
0.5
1.0
1.5
0 50 100 150
0.0
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.
OBH821A

18
8ACTUATOR CONTROL
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 protec-
tion ○○
Defrost thermistor Heating: Defrosting ○○○○○
Fin temperature thermistor Protection ○○
Ambient temperature thermistor
Cooling: Low ambient tempera-
ture operation ○○○
Heating: Defrosting (Heater)
Outdoor heat exchanger temperature
thermistor
Cooling: Low ambient tempera-
ture operation ○○○
Cooling: High pressure protec-
tion ○○○
ON
OFF
Compressor
Outdoor fan
motor
R.V.coil ON
OFF
ON
OFF
<COOL>
5 seconds
<HEAT>
5 seconds
MUZ-JP09WA MUZ-JP12WA
OBH821A

19
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-JP09/12
JS
Soldered
(Initial setting) 50°F (10°C)
None
(Cut) 55.4°F (13°C)
9-2. PRE-HEAT CONTROL SETTING
When moisture gets into the refrigerant cycle, it may interfere with the start-up of the compressor at low outside tempera-
ture. The pre-heat control prevents this interference. The pre-heat control turns ON when the discharge temperature ther-
mistor is 68°F (20°C) or below. When the pre-heat control turns ON, the compressor is energized. (About 50 W)
Pre-heat control setting
<JK>
ON: To activate the pre-heat control, cut JK wire of the inverter P.C. board.
OFF: To deactivate the pre-heat control, solder JK wire of the inverter P.C. board.
(Refer to 10-6.1)
Jumper Pre-heat control setting
JK Soldered Deactivated
(Factory setting)
Cut Activated
NOTE: When the inverter P.C. board is replaced, check the jumper wires, and cut/solder them if necessary.
MUZ-JP09WA MUZ-JP12WA
OBH821A

20
MUZ-JP09WA MUZ-JP12WA
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 connector housing. DO NOT pull the lead wires.
3. Troubleshooting procedure
1)
Check if the OPERATION INDICATOR lamp on the indoor unit is blinking on and off to indicate an abnormality. To make
sure, check how many times the OPERATION INDICATOR lamp is blinking on and off before starting service work. (See
the service manual of the indoor unit for a description of those failure codes.)
2) Before servicing, check that the connector and terminal are connected properly.
3) When the electronic control P.C. board seems to be defective, check the copper foil pattern for disconnection and the
components for bursting and discoloration.
4) Refer to 10-2 and 10-3.
Lead wiring
<Incorrect>
Connector housing
<Correct>
OBH821A