Mitsubishi Electronics Muz Fd12na User Manual

Revision A:  
• 3. SPECIFICATION has been corrected.  
Please void OBH498.  
OUTDOOR UNIT  
No. OBH498  
HFC  
REVISED EDITION-A  
utilized  
SERVICE MANUAL  
R410A  
Wireless type  
Models  
MUZ-FD09NA  
U1  
MUZ-FD09NA-  
MUZ-FD12NA  
MUZ-FD12NA-  
U1  
Indoor unit service manual  
MSZ-FD•NA Series (OBH497)  
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. ACTUATOR CONTROL··································· 15  
9. SERVICE FUNCTIONS ··································· 16  
10. TROUBLESHOOTING····································· 16  
11. DISASSEMBLY INSTRUCTIONS···················· 32  
PARTS CATALOG (OBB498)  
TM  
NOTE:  
RoHS compliant products have <G> mark on the spec name plate.  
1
TECHNICAL CHANGES  
MUZ-FD09NA  
MUZ-FD09NA -  
MUZ-FD12NA  
MUZ-FD12NA -  
1. New model  
U1  
U1  
2
PART NAMES AND FUNCTIONS  
MUZ-FD09NA MUZ-FD12NA  
Air inlet  
Piping  
Drain hose  
Air outlet  
Drain outlet  
3
3
SPECIFICATION  
Outdoor unit model  
MUZ-FD09NA  
MUZ-FD12NA  
Cooling  
1
Btu/h  
Btu/h  
Btu/h  
W
W
W
9,000 (2,800~9,000)  
10,900 (3,000~18,000)  
12,500  
12,000 (2,800~12,000)  
13,600 (3,000~21,000)  
13,600  
Capacity  
Rated (Minimum~Maximum)  
Heating 47  
Heating 17  
1
2
Capacity Rated  
Cooling  
1
650 (160~650)  
750 (150~2,400)  
1,730  
960 (160~960)  
980 (150~2,400)  
1,780  
Power consumption  
Rated (Minimum~Maximum)  
Heating 47  
Heating 17  
Cooling  
1
2
Power consumption Rated  
1
EER  
[SEER]  
3
13.8 [23.0]  
12.5 [22.0]  
HSPF IV (V)  
COP  
4
Heating  
Heating  
10.55 (7.4)  
10.55 (7.4)  
1
4.26  
4.07  
Power supply  
V , phase , Hz  
208/230 , 1 , 60  
Max. fuse size (time delay)  
Min. circuit ampacity  
Fan motor  
A
A
F.L.A  
15  
12  
0.56  
Model  
SNB130FQAH  
8.6  
Compressor  
R.L.A  
L.R.A  
10.8  
Refrigerant control  
Liner expansion valve  
Cooling  
Heating  
dB(A)  
dB(A)  
48  
49  
48  
49  
Sound level  
1
Defrost method  
Dimensions  
Reverse cycle  
31-1/2  
W
D
H
in.  
in.  
in.  
Ib.  
11-1/4  
21-5/8  
80  
Weight  
External nish  
Remote controller  
Control voltage (by built-in transformer)  
Refrigerant piping  
Munsell 3Y 7.8/1.1  
Wireless type  
12 - 24  
VDC  
Not supplied  
1/4 (0.0315)  
3/8 (0.0315)  
Flared  
Liquid  
Gas  
Indoor  
Outdoor  
in.  
in.  
Refrigerant pipe size  
(Min. wall thickness)  
Connection method  
Flared  
Height difference ft.  
40  
65  
Between the indoor &  
outdoor units  
Piping length  
ft.  
Refrigerant charge (R410A)  
Refrigeration oil (Model)  
2 lb. 9 oz.  
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  
(Heating) — Indoor : 70˚FDB, 60˚FWB, Outdoor : 17˚FDB, 15˚FWB Maximum frequency  
2 :  
4
Test condition  
3, 4  
Indoor air condition  
Dry bulb (°F) Wet bulb (°F)  
Outdoor air condition  
Dry bulb (°F) Wet bulb (°F)  
Mode  
ARI  
Test  
"A" Cooling Steady State  
at rated compressor Speed  
80  
67  
95  
(75)  
"B-2" Cooling Steady State  
at rated compressor Speed  
80  
80  
80  
80  
70  
70  
70  
70  
70  
70  
67  
67  
67  
67  
60  
60  
60  
60  
60  
60  
82  
82  
67  
87  
47  
17  
62  
47  
35  
35  
(65)  
(65)  
(53.5)  
(69)  
43  
SEER "B-1" Cooling Steady State  
(Cooling) at minimum compressor Speed  
Low ambient Cooling Steady State  
at minimum compressor Speed  
Intermediate Cooling Steady State  
at Intermediate compressor Speed  
5
Standard Rating-Heating  
at rated compressor Speed  
Low temperature Heating  
at rated compressor Speed  
15  
Max temperature Heating  
at minimum compressor Speed  
56.5  
43  
HSPF  
(Heating)  
High temperature Heating  
at minimum compressor Speed  
Frost Accumulation  
at rated compressor Speed  
33  
Frost Accumulation  
at Intermediate compressor Speed  
33  
5
5 : At Intermediate compressor Speed  
= ("Cooling rated compressor speed" - "minimum compressor speed") / 3 + "minimum compressor speed".  
OPERATING RANGE  
(1) POWER SUPPLY  
Rated voltage  
Guaranteed Voltage  
208/230 V  
1 phase  
60 Hz  
Min.187 V 208 V 230 V Max.253 V  
Outdoor unit  
(2) OPERATION  
Intake air temperature (°F)  
Mode  
Condition  
Standard temperature  
Maximum temperature  
Minimum temperature  
Maximum humidity  
Indoor  
78 %  
Outdoor  
DB  
80  
90  
67  
WB  
67  
73  
DB  
95  
115  
14  
WB  
Cooling  
57  
Standard temperature  
Heating Maximum temperature  
Minimum temperature  
70  
80  
70  
60  
67  
60  
47  
75  
14  
43  
65  
13  
5
4
OUTLINES AND DIMENSIONS  
Unit: inch  
MUZ-FD09NA MUZ-FD12NA  
REQUIRED SPACE  
Basically open 4 inch or more  
without any obstruction in front  
and on both sides of the unit.  
15-3/4  
Drain hole 1-5/8  
Air in  
Air in  
1-9/16  
Air out  
2- 3/8 13/16 Oval hole  
29/32  
11-1/4  
17/32  
7/8  
Open two sides of left,  
right, or rear side.  
handle  
Liquid pipe :1/4 (flared)  
Gas pipe :3/8 (flared)  
11-29/32  
6-23/32  
5-15/16  
19-11/16  
31-1/2  
2-23/32  
6
5
WIRING DIAGRAM  
MUZ-FD09NA MUZ-FD12NA  
7
6
REFRIGERANT SYSTEM DIAGRAM  
Unit:inch  
MUZ-FD09NA MUZ-FD12NA  
4-way valve  
Refrigerant pipe ø3/8  
(with heat insulator)  
Muffler  
Outdoor heat  
exchanger  
temperature  
thermistor  
RT68  
Stop valve  
(with service port)  
Outdoor  
heat  
Muffler  
Discharge  
temperature  
thermistor  
RT62  
Flared connection  
exchanger  
Service  
port  
Ambient  
temperature  
thermistor  
RT65  
Compressor  
Service  
port  
Defrost  
thermistor  
RT61  
Capillary tube  
O.D. 0.118 × I.D. 0.071  
× 23-5/8  
3.0 × ø1.8  
×
600)  
Strainer  
#100  
Expansion  
valve  
Flared connection  
Stop valve  
R.V. coil  
heating ON  
cooling OFF  
(with strainer)  
Capillary tube  
O.D. 0.118 × I.D. 0.079  
× 9-7/16  
(ø3.0 × ø2.0 × 240)  
Refrigerant pipe 1/4  
(with heat insulator)  
Refrigerant flow in cooling  
Refrigerant flow in heating  
MAX. REFRIGERANT PIPING LENGTH and MAX. HEIGHT DIFFERENCE  
Refrigerant piping : ft.  
Piping size O.D : in.  
Model  
Max. Length  
Max. Height difference  
B
Gas  
3/8  
Liquid  
1/4  
A
MUZ-FD09NA  
MUZ-FD12NA  
65  
40  
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.  
Refrigerant piping length (one way) : ft.  
Model  
Outdoor unit precharged  
2 lb. 9 oz.  
25  
0
30  
40  
50  
60  
65  
MUZ-FD09NA  
MUZ-FD12NA  
1.62  
4.86  
8.10  
11.34  
12.96  
Calculation : X oz. = 1.62 / 5 oz. / ft. × (Refrigerant piping length (ft.) - 25)  
NOTE : Refrigerant piping exceeding 25 ft. requires additional refrigerant charge according to the calculation.  
8
7 DATA  
MUZ-FD09NA MUZ-FD12NA  
7-1. PERFORMANCE DATA  
1) COOLING CAPACITY  
Indoor air  
Outdoor intake air DB temperature (˚F)  
85 95 105  
TC SHC TPC TC SHC TPC TC SHC TPC TC SHC TPC TC SHC TPC  
Model  
IWB  
(˚F)  
71  
67  
63  
75  
115  
11.0 6.9 0.58 10.3 6.5 0.63 9.7  
6.1 0.68 9.0  
6.8 0.65 8.4  
7.6 0.62 7.7  
5.6 0.72 8.3  
6.4 0.69 7.7  
6.9 0.66 7.0  
5.2 0.75  
5.8 0.72  
6.3 0.69  
MUZ-FD09NA  
10.4 7.9 0.55 9.7  
9.8 8.8 0.52 9.1  
7.4 0.60 9.0  
8.1 0.58 8.5  
71  
67  
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  
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  
MUZ-FD12NA  
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 (x103 Btu/h)  
SHC : Sensible Heat Capacity (x103 Btu/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  
MUZ-FD09NA  
MUY-FD12NA  
1.0  
0.954  
0.878  
3) HEATING CAPACITY  
Indoor air  
Outdoor intake air WB temperature (˚F)  
35 43  
Model  
IDB  
(˚F)  
75  
70  
65  
75  
70  
65  
15  
25  
45  
55  
TC  
6.3  
6.7  
6.9  
7.9  
8.4  
8.6  
TPC  
0.56  
0.54  
0.52  
0.73  
0.71  
0.68  
TC  
7.9  
8.2  
8.6  
9.9  
TPC  
TC  
9.4  
TPC  
0.73  
0.71  
0.69  
0.96  
0.93  
0.91  
TC  
TPC  
0.77  
0.75  
0.73  
1.00  
0.98  
0.96  
TC  
TPC  
0.78  
0.77  
0.74  
1.02  
1.00  
0.97  
TC  
TPC  
0.66  
0.64  
0.62  
0.86  
0.84  
0.81  
10.6  
10.9  
11.2  
13.3  
13.6  
14.0  
11.0  
11.2  
11.6  
13.7  
14.0  
14.4  
12.4  
12.7  
13.0  
15.5  
15.8  
16.2  
0.81  
0.80  
0.78  
1.06  
1.04  
1.02  
MUZ-FD09NA  
MUZ-FD12NA  
9.6  
10.0  
11.8  
12.0  
12.4  
10.2  
10.7  
NOTE : 1. IDB : Intake air dry-bulb temperature  
TC : Total Capacity (x103 Btu/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.  
9
7-2. PERFORMANCE CURVE  
Cooling  
MUZ-FD12NA  
MUZ-FD09NA  
SHF at rating condition = 0.76  
SHF at rating condition = 0.73  
= 307 CFM  
= 350 CFM  
Airflow  
Airflow  
Indoor  
15  
14  
13  
13  
12  
11  
10  
9
intak  
Indoor intak  
e air WB temperat  
e air WB te  
mperature (°F  
ure  
(°F)  
12  
11  
10  
9
)
71  
67  
63  
71  
67  
63  
8
7
1.2  
1.1  
1.0  
0.9  
0.8  
0.7  
71  
67  
63  
(°F)  
rature (°F)  
mpe  
71  
67  
63  
0.7  
0.6  
0.5  
mperature  
WB te  
e air  
oor intak  
Ind  
oor intake air WB te  
Ind  
65  
75  
85  
95  
105  
115  
65  
75  
85  
95  
105  
115  
Outdoor intake air DB temperature (°F)  
Outdoor intake air DB temperature (°F)  
Heating  
MUZ-FD12NA  
MUZ-FD09NA  
= 381 CFM  
65 70  
75  
Airflow  
= 420 CFM  
Airflow  
20  
18  
12  
10  
65  
70  
75  
16  
14  
12  
8
6
10  
8
6
75  
70  
65  
1.1  
1.0  
0.9  
0.8  
0.6  
0.4  
75  
70  
65  
0.8  
0.7  
0.6  
15  
25  
35  
45  
55  
15  
25  
35  
45  
55  
Outdoor intake air WB temperature (°F)  
Outdoor intake air WB 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.  
10  
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  
(PSIG)  
180  
175  
170  
165  
160  
155  
150  
145  
140  
135  
130  
125  
120  
86  
80  
460  
86  
80  
75  
420  
70  
380  
75  
70  
340  
300  
260  
68 70  
75  
80  
85  
90  
95  
100 105(°F)  
68 70  
75  
80  
85  
90  
95  
100 105(°F)  
Outdoor ambient temperature  
Outdoor ambient temperature  
MUZ-FD12NA  
(PSIG)  
580  
540  
500  
460  
420  
380  
340  
300  
(PSIG)  
180  
175  
170  
165  
160  
155  
150  
145  
140  
135  
130  
125  
120  
86  
80  
75  
70  
86  
80  
75  
70  
260  
68 70  
75  
80  
85  
90  
95  
100 105(°F)  
68 70  
75  
80  
85  
90  
95  
100 105(°F)  
Outdoor ambient temperature  
Outdoor ambient temperature  
11  
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)  
400  
(PSIG)  
380  
360  
340  
320  
300  
280  
260  
240  
220  
200  
180  
160  
140  
170  
160  
150  
140  
130  
120  
110  
100  
90  
75  
70  
65  
75  
70  
65  
58Hz  
58Hz  
80  
70  
60  
14  
20 25 30 35 40 45 50 55 60 65 70(°F)  
Outdoor ambient temperature  
14 20 25 30 35 40 45 50 55 60 6570(°F)  
Outdoor ambient temperature  
MUZ-FD12NA  
(PSIG)  
400  
(PSIG)  
380  
360  
340  
320  
300  
280  
260  
240  
220  
200  
180  
160  
140  
170  
160  
150  
140  
130  
120  
110  
100  
90  
75  
70  
65  
75  
70  
65  
58Hz  
58Hz  
80  
70  
60  
14  
20 25 30 35 40 45 50 55 60 65 70(°F)  
Outdoor ambient temperature  
14 20 25 30 35 40 45 50 55 60 6570(°F)  
Outdoor ambient temperature  
12  
7-4. STANDARD OPERATION DATA  
Model  
MSZ-FD09NA  
MSZ-FD12NA  
Item  
Unit  
Cooling  
Heating  
10,900  
Cooling  
Heating  
13,600  
Capacity  
SHF  
Btu/h  
9,000  
0.76  
0.650  
35  
12,000  
0.73  
Input  
kW  
Hz  
0.750  
43  
0.960  
51  
0.980  
54  
Rated frequency  
Indoor unit  
MSZ-FD09NA  
MSZ-FD12NA  
V,  
phase,  
Hz  
Power supply  
208/230 , 1 , 60  
Input  
kW  
A
0.018  
0.024  
0.024  
0.030  
Fan motor current  
Outdoor unit  
0.19/0.17  
0.25/0.23  
0.25/0.23  
0.32/0.29  
MUZ-FD09NA  
MUZ-FD12NA  
V,  
phase,  
Hz  
Power supply  
208/230 , 1 , 60  
Input  
kW  
A
0.632  
0.726  
0.936  
0.950  
Comp. current  
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  
Suction pressure  
PSIG  
PSIG  
˚F  
376  
154  
143  
112  
51  
355  
108  
144  
108  
46  
402  
148  
161  
117  
51  
392  
104  
159  
115  
45  
Discharge temperature  
Condensing temperature  
Suction temperature  
Comp. shell bottom temperature  
Ref. pipe length  
˚F  
˚F  
˚F  
144  
128  
146  
129  
ft.  
25  
2 lb. 9 oz.  
Refrigerant charge (R410A)  
DB  
Intake air temperature  
WB  
˚F  
˚F  
80  
67  
70  
60  
80  
67  
70  
60  
DB  
Discharge air temperature  
WB  
˚F  
59  
100  
56  
105  
˚F  
56  
54  
Fan speed (High)  
rpm  
CFM  
˚F  
1,020  
307 (Wet)  
95  
1,120  
381  
47  
1,120  
350 (Wet)  
95  
1,220  
420  
47  
Airow (High)  
DB  
Intake air temperature  
WB  
˚F  
43  
43  
Fan speed  
rpm  
CFM  
810  
870  
1,187  
810  
870  
1,187  
Airow  
1,102  
1,102  
13  
7-5. CAPACITY AND INPUT CORRECTION BY INVERTER OUTPUT FREQUENCY  
MUZ-FD09NA  
Correction of Cooling capacity  
Correction of Cooling total input  
Correction of Heating total input  
Correction of Heating capacity  
2.0  
1.5  
1.5  
1.0  
0.5  
1.5  
1.0  
0.5  
3.0  
2.0  
1.0  
1.0  
0.5  
(Hz)  
(Hz)  
150  
(Hz)  
(Hz)  
150  
0
50  
100  
150  
0
50  
100  
0
50  
100  
150  
0
50  
100  
The operational frequency of compressor  
The operational frequency of compressor The operational frequency of compressor  
The operational frequency of compressor  
MUZ-FD12NA  
Correction of Cooling capacity  
1.5  
Correction of Cooling total input  
Correction of Heating capacity  
Correction of Heating total input  
1.5  
1.0  
0.5  
1.5  
1.0  
0.5  
2.0  
1.0  
0.5  
1.0  
(Hz)  
(Hz)  
150  
(Hz)  
(Hz)  
150  
0
50  
100  
150  
0
50  
100  
0
50  
100  
150  
0
50  
100  
The operational frequency of compressor  
The operational frequency of compressor The operational frequency of compressor  
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 var-  
ies).  
6. To cancel test run operation (EMERGENCY OPERATION), press EMERGENCY OPERATION switch or any button on  
remote controller.  
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  
ON  
OFF  
OFF  
. . . . . . . . . . . . . . . . . . . .  
Dry  
NOTE: The 4-way valve reverses for 5 seconds right before start-up of the compressor.  
<COOL>  
<HEAT>  
5 seconds  
5 seconds  
ON  
Compressor  
R.V.coil  
OFF  
ON  
OFF  
ON  
Outdoor fan  
motor  
OFF  
8-3. RELATION BETWEEN MAIN SENSOR AND ACTUATOR  
Actuator  
Sensor  
Purpose  
Outdoor  
fan motor  
Indoor fan  
motor  
Compressor  
LEV  
R.V. coil  
Discharge temperature thermistor  
Indoor coil temperature thermistor  
Protection  
○ ○  
Cooling : Coil frost prevention  
Heating : High pressure protection  
Cooling : High pressure protection  
Heating : Defrosting  
○ ○  
○ ○  
Defrost thermistor  
○ ○ ○ ○ ○  
Fin temperature thermistor  
Protection  
Outdoor heat exchanger temperature thermistor  
Ambient temperature thermistor  
High pressure protection  
Low ambient temperature operation  
○ ○ ○  
○ ○ ○  
15  
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 nish temperature  
41°F (5°C)  
Soldered  
(Initial setting)  
JS  
None  
(Cut)  
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 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  
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 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 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  
Housing point  
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.  
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 ab-  
normal condition, a short beep  
is emitted once the signal is  
received.  
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
Does POWER lamp on the indoor unit blink at the interval of  
Indoor unit is normal.  
0.5 seconds?  
But the outdoor unit might be abnormal because there are some abnor-  
malities that can't be recalled with this way.  
Conrm if outdoor unit is abnormal according to the detailed outdoor  
unit failure mode recall function. (Refer to 10-2.2)  
Blinks: Either indoor or outdoor unit is abnormal. Beep is emit-  
No  
(OFF)  
ted at the same timing as the blinking of POWER lamp.  
2
Yes  
(Blinks)  
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.  
Yes  
No  
The indoor unit is abnormal.  
The outdoor unit is abnormal.  
Check the blinking pattern, and conrm the abnormal point with the indoor unit  
failure mode table. (Refer to indoor unit service manual.)  
Check the blinking pattern, and conrm 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
Make sure to check at least two consecutive blinking cycles.  
3
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" 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.  
2. Blinking pattern when the indoor unit is abnormal:  
Blinking at 0.5-  
second interval  
Blinking at 0.5-  
second interval  
2.5-second OFF  
2.5-second OFF  
ON  
OFF  
Beeps  
Beeps  
Beeps  
Repeated cycle  
Repeated cycle  
Repeated cycle  
3.Blinking pattern when the outdoor unit is abnormal:  
Blinking at 0.5-  
Blinking at 0.5-  
second interval  
2.5-second OFF  
3-second ON  
second interval  
2.5-second OFF  
3-second ON  
ON  
OFF  
No beep  
Beeps  
No beep  
Beeps  
Repeated cycle  
Repeated cycle  
Repeated cycle  
17  
2. Flow chart of the detailed outdoor unit failure mode recall function  
Operational procedure  
The outdoor unit might be abnormal.  
Conrm if outdoor unit is abnormal according to the following procedures.  
Conrm 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.  
Does POWER lamp on the indoor unit blink at the  
interval of 0.5 seconds?  
Blinks: The outdoor unit is abnormal. Beep is emitted  
No  
at the same timing as the blinking of POWER  
(OFF)  
lamp.  
2
Yes  
(Blinks  
)
The outdoor unit is abnormal.  
Check the blinking pattern, and conrm the abnormal point with the out-  
door unit failure mode table (10-2.3.).  
The outdoor unit is normal.  
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.  
Release the failure mode recall function accord-  
ing to the left mentioned procedure.  
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.  
2.Blinking pattern when outdoor unit is abnormal:  
Blinking at 0.5-  
second interval  
Blinking at 0.5-  
second interval  
2.5-second OFF  
3-second ON  
2.5-second OFF  
3-second ON  
ON  
OFF  
No beep  
Beeps  
No beep  
Beeps  
Repeated cycle  
Repeated cycle  
Repeated cycle  
18  
3. Outdoor unit failure mode table  
Indoor/  
Outdoor unit  
failure mode  
recall function  
POWER lamp  
(Indoor unit)  
Abnormal point  
LED indication  
outdoor unit  
failure mode  
recall function  
Condition  
Correspondence  
(Failure mode / protection) (Outdoor P.C. board)  
OFF  
None (Normal)  
2-time ash Outdoor power system  
2.5 seconds  
OFF  
Overcurrent protection stop is  
•Reconnect connectors.  
continuously performed 3 times within •Refer to 10-5. "How  
1 minute after the compressor gets  
started.  
to check inverter/  
compressor".  
•Check stop valve.  
3-time ash Discharge temperature  
1-time ash every  
Thermistor shorts or opens during  
compressor running.  
•Refer to 10-5. "Check  
of outdoor thermistors".  
Defective outdoor  
thermistors can be  
identied by checking  
the blinking pattern of  
LED.  
2.5 seconds thermistor  
2.5 seconds  
OFF  
Defrost thermistor  
Fin temperature thermistor  
3-time ash  
2.5 seconds OFF  
P.C. board temperature  
thermistor  
4-time ash  
2.5 seconds OFF  
Ambient temperature  
thermistor  
2-time ash  
2.5 seconds OFF  
4-time ash Overcurrent  
2.5 seconds  
OFF  
11-time ash  
2.5 seconds OFF  
Large current ows into intelligent  
power module.  
•Reconnect compressor  
connector.  
•Refer to 10-5. "How  
to check inverter/  
compressor".  
•Check stop valve.  
Compressor synchronous  
12-time ash  
Waveform of compressor current is  
distorted.  
•Reconnect compressor  
connector.  
•Refer to 10-5. "How  
to check inverter/  
compressor".  
abnormality (Compressor start- 2.5 seconds OFF  
up failure protection)  
5-time ash Discharge temperature  
Temperature of discharge temperature •Check refrigerant circuit  
2.5 seconds  
OFF  
thermistor exceeds 241°F (116°C),  
compressor stops.  
and refrigerant amount.  
•Refer to 10-5. "Check  
of LEV".  
Compressor can restart if discharge  
temperature thermistor reads 212°F  
(100°C) or less 3 minutes later.  
6-time ash High pressure  
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.  
•Check refrigerant circuit  
and refrigerant amount.  
•Check stop valve.  
7-time ash Fin temperature/ P.C. board  
2.5 seconds temperature  
OFF  
7-time ash  
2.5 seconds OFF  
Temperature of n temperature  
•Check around outdoor  
unit.  
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 outdoor unit air  
passage.  
•Refer to 10-5. "Check  
of outdoor fan motor".  
8-time ash Outdoor fan motor  
2.5 seconds  
OFF  
Outdoor fan has stopped 3 times in a  
•Refer to 10-5. "Check  
row within 30 seconds after outdoor fan of outdoor fan motor".  
start-up.  
Refer to 10-5. "Check  
of inverter P.C. board".  
9-time ash Nonvolatile memory data  
2.5 seconds  
OFF  
5-time ash  
2.5 seconds OFF  
Nonvolatile memory data cannot be  
read properly.  
•Replace the inverter  
P.C. board.  
10-time ash Discharge temperature  
2.5 seconds  
OFF  
Temperature of discharge temperature •Refer to 10-5. "Check  
thermistor has been 122°F (50°C) or  
less for 20 minutes.  
of LEV".  
•Check refrigerant circuit  
and refrigerant amount.  
11-time ash DC voltage  
8-time ash  
DC voltage of inverter cannot be  
detected normally.  
•Refer to 10-5. "How  
to check inverter/  
compressor".  
2.5 seconds  
2.5 seconds OFF  
OFF  
Each phase current of  
9-time ash  
2.5 seconds OFF  
Each phase current of compressor  
cannot be detected normally.  
compressor  
12-time ash Overcurrent Compressor open- 10-time ash  
Large current ows into intelligent  
power module (IPM).  
•Reconnect compressor  
connector.  
•Refer to 10-5. "How  
to check inverter/  
compressor".  
2.5 seconds phase  
OFF  
2.5 seconds OFF  
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.  
14-time ash Stop valve (Closed valve)  
2.5 seconds  
OFF  
14-time ash  
2.5 seconds OFF  
Closed valve is detected by compressor •Check stop valve  
current.  
NOTE: Blinking patterns of this mode differ from the ones of Troubleshooting check table (10-3.).  
19  
10-3. TROUBLESHOOTING CHECK TABLE  
Abnormal point/  
Condition  
No.  
Symptom  
LED indication  
Condition  
Correspondence  
Outdoor unit 1-time ash every Outdoor power sys- Overcurrent protection stop is continuously performed 3 times •Reconnect connector of compres-  
does not oper- 2.5 seconds  
ate.  
tem  
within 1 minute after the compressor gets started, or failure of sor.  
restart of compressor has repeated 24 times.  
1
•Refer to 10-5. "How to check in-  
verter/compressor".  
•Check stop valve.  
Outdoor thermistors Discharge temperature thermistor, n temperature thermistor, •Refer to 10-5. "Check of outdoor  
defrost thermistor, P.C. board temperature thermistor or ambi- thermistors".  
ent temperature thermistor shorts or opens during compressor  
running.  
2
3
Outdoor control sys- Nonvolatile memory data cannot be read properly.  
tem  
•Replace inverter P.C. board.  
(POWER lamp of the indoor unit lights up or ashes 7 times.)  
6-time ash  
Serial signal  
Stop valve/  
The communication fails between the indoor and outdoor unit •Refer to 10-5. "How to check  
4
5
2.5 seconds OFF  
for 3 minutes.  
miswiring and serial signal error.  
11-time ash  
Closed valve is detected by compressor current.  
•Check stop valve.  
2.5 seconds OFF Closed valve  
14-time ash Outdoor unit  
2.5 seconds OFF (Other abnormality)  
Outdoor unit is defective.  
•Refer to 10-2.2. "Flow chart of the  
detailed outdoor unit failure mode  
recall function".  
6
7
'Outdoor unit 2-time ash  
Overcurrent protec- Large current ows into intelligent power module.  
•Reconnect connector of compres-  
When overcurrent protection occurs within 10 seconds after sor.  
stops and  
2.5 seconds OFF tion  
restarts 3 min-  
utes later' is  
repeated.  
compressor starts, compressor restarts after 15 seconds.  
•Refer to 10-5. "How to check in-  
verter/compressor".  
•Check stop valve.  
3-time ash  
Discharge tempera- Temperature of discharge temperature thermistor exceeds 241 •Check refrigerant circuit and refrig-  
2.5 seconds OFF ture overheat protec- °F (116°C), compressor stops. Compressor can restart if dis-  
erant amount.  
8
9
tion  
charge temperature thermistor reads 212°F (100°C) or less 3 •Refer to 10-5. "Check of LEV".  
minutes later.  
4-time ash  
Fin temperature  
Temperature of n temperature thermistor on the heat sink  
•Check around outdoor unit.  
2.5 seconds OFF /P.C. board tem-  
exceeds 167 ~ 176°F (75 ~ 80°C) or temperature of P.C. board •Check outdoor unit air passage.  
perature thermistor temperature thermistor on the inverter P.C. board exceeds 158 •Refer to 10-5. "Check of outdoor  
overheat protection ~ 167°F (70 ~ 75°C).  
fan motor".  
5-time ash  
High pressure pro- Indoor coil thermistor exceeds 158°F (70°C) in HEAT mode.  
•Check refrigerant circuit and refrig-  
erant amount.  
10  
11  
2.5 seconds OFF tection  
Defrost thermistor exceeds 158°F (70°C) in COOL mode.  
•Check stop valve.  
8-time ash  
2.5 seconds OFF chronous abnormal-  
ity  
Compressor syn-  
The waveform of compressor current is distorted.  
•Reconnect connector of compres-  
sor.  
•Refer to 10-5. "How to check in-  
verter/compressor".  
10-time ash  
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.  
12  
12-time ash  
Each phase current Each phase current of compressor cannot be detected nor-  
•Refer to 10-5. "How to check in-  
verter/compressor".  
13  
14  
15  
2.5 seconds OFF of compressor  
mally.  
13-time ash  
2.5 seconds OFF  
DC voltage  
DC voltage of inverter cannot be detected normally.  
•Refer to 10-5. "How to check in-  
verter/compressor".  
Outdoor unit 1-time ash  
operates.  
Frequency drop by Current from power outlet is nearing Max. fuse size.  
The unit is normal, but check the  
following.  
2.5 seconds OFF current protection  
•Check if indoor lters are clogged.  
•Check if refrigerant is short.  
•Check if indoor/outdoor unit air cir-  
culation is short cycled.  
3-time ash  
Frequency drop by Temperature of indoor coil thermistor exceeds 131°F (55°C) in  
2.5 seconds OFF high pressure pro-  
tection  
HEAT mode, compressor frequency lowers.  
16  
17  
Frequency drop by Indoor coil thermistor reads 46°F (8°C) or less in COOL mode,  
defrosting in COOL compressor frequency lowers.  
mode  
4-time ash  
Frequency drop by Temperature of discharge temperature thermistor exceeds 232 •Check refrigerant circuit and refrig-  
2.5 seconds OFF discharge tempera- °F (111°C), compressor frequency lowers.  
ture protection  
erant amount.  
•Refer to 10-5. "Check of LEV".  
•Refer to 10-5. "Check of outdoor  
thermistors".  
NOTE: 1. The location of LED is illustrated at the right gure. Refer to 10-6.1.  
Inverter P.C. board (Parts side)  
2. LED is lighted during normal operation.  
The ashing frequency shows the number of times the LED blinks after every 2.5-second OFF. Flashing  
(Example) When the ashing frequency is “2”.  
LED  
Flashing  
0.5-second ON  
0.5-second ON  
2.5-second OFF  
ON  
2.5-second OFF  
OFF  
20  
Abnormal point/  
Condition  
No.  
18  
Symptom  
LED indication  
Condition  
Correspondence  
Outdoor unit 7-time ash  
Low discharge tem- Temperature of discharge temperature thermistor has been  
operates. 2.5 seconds OFF perature protection 122°F (50°C) or less for 20 minutes.  
•Refer to 10-5. "Check of LEV".  
•Check refrigerant circuit and refrig-  
erant amount.  
8-time ash  
PAM protection  
The overcurrent ows into IGBT (Insulated Gate Bipolar tran- This is not malfunction. PAM protec-  
2.5 seconds OFF PAM: Pulse Ampli-  
tude Modulation  
sistor : TR821) or the bus-bar voltage reaches 320 V or more, tion will be activated in the following  
PAM stops and restarts.  
cases;  
19  
20  
1 Instantaneous power voltage drop  
(Short time power failure)  
2 When the power supply voltage is  
high.  
9-time ash  
2.5 seconds OFF  
Inverter check mode The connector of compressor is disconnected, inverter check •Check if the connector of the com-  
mode starts.  
pressor is correctly connected.  
Refer to 10-5. "How to check in-  
verter/compressor".  
21  
10-4. TROUBLE CRITERION OF MAIN PARTS  
MUZ-FD09NA MUZ-FD12NA  
Part name  
Check method and criterion  
Figure  
Defrost thermistor  
(RT61)  
Measure the resistance with a tester.  
Ambient temperature  
thermistor (RT65)  
Refer to 10-6. “Test point diagram and voltage”, 1. “Inverter P.C.  
board”, the chart of thermistor.  
Outdoor heat ex-  
changer temperature  
thermistor (RT68)  
Discharge tem-  
perature thermistor  
(RT62)  
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.  
Fin temperature  
thermistor (RT64)  
Measure the resistance between terminals using a tester.  
(Winding temperature : -4 ~ 104°F (-20 ~ 40°C))  
WHT  
RED BLK  
2
3
1
W
Normal  
U-V  
U-W  
V-W  
Compressor  
V
1.52 ~ 2.17 Ω  
U
Measure the resistance between lead wires using a tester.  
(Part temperature : 14 ~ 104°F (-10 ~ 40°C))  
WHT  
RED BLK  
2
3
1
W
Color of lead wire  
Normal  
Outdoor fan motor  
R. V. coil (21S4)  
RED – BLK  
BLK – WHT  
WHT – RED  
11 ~ 16 Ω  
V
U
Measure the resistance using a tester.  
(Part temperature : 14 ~ 104°F (-10 ~ 40°C))  
Normal  
970 ~ 1380 Ω  
Measure the resistance using a tester.  
WHT  
RED  
ORN  
(Part temperature : 14 ~ 104°F (-10 ~ 40°C))  
LEV  
Color of lead wire  
WHT – RED  
RED – ORN  
YLW – BRN  
BRN – BLU  
Normal  
Expansion valve coil  
(LEV)  
37 ~ 54 Ω  
22  
10-5. TROUBLESHOOTING FLOW  
A How to check inverter/compressor  
Disconnect the connector (CN61) between  
compressor and the intelligent power module  
(IPM).  
See 10-5. “Check of open phase”.  
Replace the inverter P.C. board.  
See 10-5. “Check of compressor”.  
Check the voltage between terminals.  
Are the voltages balanced?  
Yes  
No  
Check the 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)  
9-time flash  
Measure AC voltage between the  
lead wires at 3 points.  
2.5-second OFF  
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 ashes 9 times. (Refer to 10-6.1.)  
C Check of compressor  
Refer to 10-5. “Check of compressor  
winding”.  
Is the compressor normal?  
Replace the compressor.  
No  
No  
Yes  
Refer to 10-5. “Check of compressor  
operation time”.  
Does the compressor operate continuously?  
Refer to 10-5. “Check of compressor start failure”.  
Yes  
OK.  
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>>  
0 second  
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.  
Compressor starts  
1 second  
Abnormal  
(IPM failure)  
(Compressor winding short)  
2 seconds  
(TEST RUN OPERATION : Refer to 7-6.)  
<<Measurement>>  
Measure the time from the start of compressor to the stop of  
compressor due to overcurrent.  
Abnormal  
(Compressor lock out)  
(Starting defect)  
Abnormal  
(Poor contact,)  
(Outdoor P.C. board defect)  
(Disconnected connector)  
10 seconds  
10 minutes  
Abnormal  
(Refrigerant circuit defect)  
(Closed valve)  
Normal  
F Check of compressor start failure  
Conrm that 1~4 is normal.  
• Electrical circuit check  
1.Contact of the compressor connector (including CN61)  
2.Output voltage of inverter P.C. board and balance of them (See 10-5. )  
3.Direct current voltage between DB61(+) and (-) on the inverter P.C. board  
4.Voltage between outdoor terminal block S1-S2  
Check the refrigerant circuit.  
Check the stop valve.  
Does the compressor run for 10 seconds or  
more after it starts?  
Yes  
No  
No  
After the compressor is heated with a drier,  
Replace the compressor.  
does the compressor start?  
1
Yes  
1
Heat the compressor with  
a drier for about 20 minutes.  
Do not recover refrigerant  
gas while heating.  
Compressor start failure. Activate pre-heat control.  
(Refer to 9-2. "PRE-HEAT CONTROL SETTING")  
Heating part  
24  
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.  
Replace the thermistor except RT64. When RT64 is  
abnormal, replace the inverter P.C. board.  
Is the thermistor normal? (Refer to 10-6.1.)  
No  
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?  
Replace the inverter P.C. board.  
No  
Yes  
OK.  
(Cause is poor contact.)  
Thermistor  
Symbol  
Connector, Pin No.  
Board  
Defrost  
Discharge temperature  
Fin temperature  
RT61 Between CN641 pin1 and pin2  
RT62 Between CN641 pin3 and pin4  
RT64 Between CN642 pin1 and pin2  
RT65 Between CN643 pin1 and pin2  
Inverter P.C. board  
Ambient temperature  
Outdoor heat exchanger temperature RT68 Between CN644 pin1 and pin3  
H Check of R.V. coil  
First of all, measure the resistance of R.V. coil to check if the coil is defective. Refer to 10-4.  
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 inverter  
P.C. board.  
No  
Yes  
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 inverter  
P.C. board.  
Yes  
No  
Replace the 4-way valve.  
25  
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.)  
Replace the outdoor fan motor.  
No  
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.  
Rectify indoor/outdoor  
connecting wire.  
Yes  
Is there voltage 208/230 VAC  
between the indoor terminal  
block S1 and S2?  
Replace the indoor  
electronic control P.C.  
board.  
Does POWER lamp on the indoor  
unit light up?  
No  
No  
No  
Yes  
Is there voltage 280 ~ 370 VDC  
between DB61 (+) and DB61 (–) on  
the inverter P.C. board?  
Dose LED on the inverter P.C.  
board light up or ash? (Refer  
to 10-6.1.)  
Replace the inverter  
P.C. board.  
Yes  
(Refer to 10-6.1.)  
Yes  
No  
280 ~ 370 VDC  
If light up, OK.  
If ash, refer to 10-3.  
Check the electric parts in main circuit.  
DB61  
Inverter P.C. board  
(Solder side)  
26  
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
1. Regardless of normal or abnormal condition, a short beep  
is emitted once the signal is received.  
Expansion valve operates in full-opening direction.  
Do you hear the expansion valve "click,  
click·······"?  
OK.  
Do you feel the expansion valve vibrate  
Yes  
on touching it ?  
No  
Is LEV coil properly xed to  
the expansion valve?  
Properly x the LEV coil to the expansion valve.  
No  
Yes  
Measure each voltage between connector  
pins of CN724 on the inverter P.C. board.  
1.Pin (-) — Pin (+)  
2.Pin (-) — Pin (+)  
Does the resistance of LEV  
coil have the characteristics?  
(Refer to 10-4.)  
Replace the inverter P.C.  
board.  
3.Pin (-) — Pin (+)  
4.Pin (-) — Pin (+)  
Is there about 3 ~ 5 VAC between each?  
NOTE: Measure the voltage by an analog  
tester.  
Yes  
No  
No  
Replace the LEV coil.  
Yes  
Replace the expansion valve.  
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.  
27  
L Check of inverter P.C. board  
Check the outdoor fan motor.  
(Refer to10-5. .)  
Is the fuse (F901) blown on the in-  
verter P.C. board?  
Yes  
No  
Inverter P.C. board  
(Solder side)  
Check the connection of the connectors  
(CN932) of the outdoor fan motor.  
If the connection is poor, make it correct.  
CN932  
Operate the outdoor unit by starting  
EMERGENCY OPERATION.  
Check the corresponding parts  
following LED indication.  
(Refer to 10-3.)  
Check the LED indication on the in-  
verter P.C. board.  
Does the LED ash 10 times?  
No  
Yes  
(10-time ash)  
Replace the inverter P.C. board.  
28  
M How to check miswiring and serial signal error  
Turn OFF the power supply.  
Is there rated voltage in the  
power supply?  
Check the power supply.  
No  
No  
Yes  
Turn ON the power supply.  
Is there rated voltage between  
outdoor terminal block S1 and  
S2?  
Yes  
Check the wiring.  
Press EMERGENCY OPERATION switch once.  
Does AREA-L lamp light up? <Conrmation of  
the power to the indoor unit>  
No  
No  
Yes  
Is there any miswiring,  
poor contact, or wire  
disconnection of the  
indoor/outdoor connect-  
ing wire?  
Is serial signal error indicated 6 minutes later?  
Yes  
Correct them.  
Yes  
No  
A
Turn OFF the power supply.  
Check once more if the indoor/outdoor  
connecting wire is not miswiring.  
B
1. Miswiring may damage indoor electronic control P.C.  
board during the operation.  
Be sure to conrm the wiring is correct before the opera-  
tion starts.  
Short-circuit outdoor terminal block S2  
and S3.  
1
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.  
Turn ON the power supply.  
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-second-  
Replace the inverter P.C. board or the out-  
door electronic control P.C. board.  
2
No  
(Lighted  
or not  
ON quick blinking"?  
3
2. Be careful to the residual  
voltage of smoothing capacitor.  
Yes  
lighted)  
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? <Conrmation of serial signal>  
Yes  
Is there any error of the in-  
Replace the indoor/  
outdoor connecting  
wire.  
door/outdoor connecting wire,  
such as the damage of the wire,  
intermediate connection, poor  
contact to the terminal block?  
No  
A
No  
Yes  
• Turn OFF inverter-controlled lighting  
equipment.  
• Turn OFF the power supply and then  
turn ON again.  
• Press EMERGENCY OPERATION  
switch.  
Is there any error of the in-  
door/outdoor connecting wire,  
such as the damage of the wire,  
intermediate connection, poor  
contact to the terminal block?  
No  
Is there rated voltage between  
indoor terminal block S1 and S2?  
<Conrmation of power voltage>  
Replace the indoor/  
outdoor connecting  
wire.  
• Reinstall  
No  
Yes  
either the unit  
or the light  
each other  
Yes  
away.  
Is serial signal  
error indicated 6  
minutes later?  
• Attach a lter  
on remote  
control receiv-  
ing section  
of the indoor  
unit.  
No  
Yes  
Replace the indoor electronic control P.C. board.  
Be sure to release the failure-mode recall function  
after checking.  
B
29  
N Electromagnetic noise enters into TV sets or radios  
Is the unit grounded?  
Yes  
Ground the unit.  
No  
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.?  
Extend the distance between the antennas and  
the indoor unit, and/or the antennas and the  
outdoor unit.  
Yes  
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.?  
Extend the distance between the TV sets and/or  
radios and the indoor unit, or the TV sets or  
radios and the outdoor unit.  
Yes  
No  
Are the antennas damaged?  
Is the coaxial cable damaged?  
Is there any poor contact in the anten-  
na wiring?  
Replace or repair the antenna.  
Replace or repair the coaxial cable.  
Yes  
Yes  
No  
Is the indoor/outdoor connecting wire  
of the air conditioner and the wiring of  
the antennas close?  
Extend the distance between the indoor/outdoor  
connecting wire of the air conditioner and the wir-  
ing of the antennas.  
No  
Even if all of the above conditions are fullled, the electromagnetic noise may enter, depending on the electric eld strength  
or the installation condition (combination of specic 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 eld intensity of the broadcast station affected by the electromagnetic noise  
6. Presence or absence of amplier 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 elec-  
tromagnetic 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  
Smoothing  
capacitor  
(C62)  
Smoothing  
capacitor  
(C63)  
Smoothing  
capacitor  
(C61)  
Fuse (F701)  
250 V 3.15 A  
DB61  
Back side of unit  
DC260 ~300 V  
(-)  
(+)  
Fuse (F801)  
250 V 3.15 A  
AC 208/230 V  
R.V. coil  
(CN721)  
208/230 VAC  
Fuse (F901)  
250 V 3.15 A  
Output to  
drive com-  
pressor  
(LDU,  
AC208/230 V  
LDV,  
LDW)  
Jumper wire  
for pre-heat  
control setting  
(JK)  
LEV  
connector  
(CN724)  
Jumper wire for  
changing defrost  
setting (JS)  
Front side of unit  
Defrost thermistor(RT61)  
Ambient temperature thermistor(RT65)  
Outdoor heat exchanger temperature thermistor(RT68)  
Fin temperature thermistor(RT64)  
200  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
180  
160  
140  
120  
100  
80  
Discharge temperature thermistor(RT62)  
700  
600  
500  
400  
300  
200  
100  
0
60  
40  
20  
0
32 50 68 86 104 122 140 158 176 194 212 230 248  
32 50 68 86 104 122 140 158 176  
-4  
14 32 50 68 86 104  
Temperature(°F)  
Temperature(°F)  
Temperature(°F)  
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.  
(2) The terminal with this connector has the  
locking mechanism.  
Sleeve  
Slide the sleeve.  
Hold the sleeve, and  
Pull the terminal while  
pushing the locking  
pull out the terminal  
slowly.  
Locking lever  
lever.  
Connector  
11-1. MUZ-FD09NA MUZ-FD12NA  
OPERATING PROCEDURE  
NOTE : Turn OFF power supply before disassembling.  
PHOTOS  
1. Removing the cabinet  
Photo 1  
(1) Remove the screw fixing the service panel. (See  
Photo 1.)  
Screws  
of the top  
panel  
(2) Pull down the service panel and remove it. (See Photo  
1.)  
(3) Remove the screws fixing the conduit cover. (See  
Photo 2.)  
Screw of the  
cabinet  
Screws of  
the top panel  
Back  
panel  
(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.  
Screw of  
the service  
panel  
(10) Remove the screws fixing the back panel.  
(11) Remove the back panel.  
Photo 2  
Hooks  
Screw of the  
conduit cover  
Service  
panel  
Screws of  
the cabinet  
Conduit plate  
Conduit cover  
32  
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;  
Photo 3  
Screws of the  
relay panel  
<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.  
Photo 4 (Inverter assembly)  
Inverter  
P.C. board  
Screw of the  
T.B.support  
Heat sink  
T.B.support  
3. Removing R.V. coil  
(1) Remove the cabinet and panels. (Refer to 1.)  
(2) Remove the R.V. coil. (See Photo 5.)  
Screw of the  
ground wire  
4. Removing the discharge temperature thermistor,  
defrost thermistor and outdoor heat exchanger tem-  
perature thermistor.  
Photo 5  
R.V. coil  
(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.)  
Discharge temperature thermistor  
33  
OPERATING PROCEDURE  
PHOTOS  
Photo 6  
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.)  
Outdoor heat  
exchanger tempera-  
ture thermistor  
(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.  
Defrost thermistor  
Photo 7  
Screws of the outdoor fan motor  
(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.)  
Propeller nut  
Propeller  
Photo 8  
Welded parts of 4-way valve  
34  
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.  

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