Download Mitsubishi Electric MXZ-2B20NA Service manual

Revision A:
• MXZ-2B20NA-
1
has been added.
SPLIT-TYPE AIR CONDITIONERS
OUTDOOR UNIT
SERVICE MANUAL
HFC
utilized
No. OBH560
REVISED EDITION-A
R410A
Models
MXZ-2B20NA
MXZ-2B20NA -
1
Indoor unit service manual
MSZ-A·NA Series (OB450)
MSZ-FD·NA Series (OBH497)
MSZ-FE·NA Series (OBH542)
MSZ-GE·NA Series (OBH548)
SEZ-KD·NA.TH Series
CONTENTS
1. TECHNICAL CHANGES· ·································· 2
2. PART NAMES AND FUNCTIONS ····················· 2
3. SPECIFICATION ················································ 3
4. NOISE CRITERIA CURVES ······························ 4
5. OUTLINES AND DIMENSIONS ························ 5
6. WIRING DIAGRAM············································ 6
7. REFRIGERANT SYSTEM DIAGRAM ··············· 7
8. DATA ·································································· 9
9. ACTUATOR CONTROL··································· 17
10. SERVICE FUNCTIONS···································· 17
11. TROUBLESHOOTING ····································· 18
12. DISASSEMBLY INSTRUCTIONS ···················· 34
INDOOR UNITS COMBINATION SHEETS
MXZ-2B20NA
The Slim Line.
From Mitsubishi Electric.
TM
9700058
33223
Revision A:
• MXZ-2B20NA-
1
1
has been added.
TECHNICAL CHANGES
MXZ-2B20NA
New model.
MXZ-2B20NA
MXZ-2B20NA -
1
1. Outdoor fan motor has been changed.
2. Outdoor electronic control P.C. board has been changed.
3. LEV coil has been changed.
2
PART NAMES AND FUNCTIONS
MXZ-2B20NA MXZ-2B20NA -
1
Air inlet
(Back and side)
Air outlet
Drain outlet
2
3
SPECIFICATION
Outdoor model
Item
Capacity
Power
consumption
Cooling
Heating 47
Heating 17
Cooling
Heating 47
Heating 17
Cooling
Cooling
Heating
Heating
MXZ-2B20NA MXZ-2B20NA -
Indoor type
Btu/h
Btu/h
Btu/h
W
W
W
Wall (09+09)
18,000
22,000
12,500
1,440
1,650
1,350
12.5
18.0
8.9 (7.0)
3.91
EER
SEER
HSPF IV (V)
COP
External finish
V, phase, Hz
Power supply
Max. fuse size (time delay)
A
Min. circuit ampacity
A
Fan motor
F.L.A
Model
Winding resistance (at 68°F) Ω
Compressor
R.L.A
L.R.A
Refrigerant control
dB(A)
Sound level
Defrost method
W
in.
D
in.
Dimensions
H
in.
lb.
Weight
Remote controller
Control voltage (by built-in transformer)
Refrigerant piping
Liquid
in.
Valve size
Gas
in.
Indoor
Connection method
Outdoor
lb.
Refrigerant charge (R410A)
oz.
Refrigeration oil (Model)
1
Duct (09+12)
20,000
22,000
12,500
2,190
1,780
1,430
9.1
15.5
8.5 (6.9)
3.62
Munsell 3.0Y 7.8/1.1
208/230, 1, 60
20
15
0.96
SNB130FQBH1
U-V 0.98 V-W 0.98 W-U 0.98
10.1
15
LEV
49/51
Reverse cycle
33-1/16
13
27-15/16
130
Wireless type
12-24 V DC
Not supplied (optional parts)
1/4
A,B: 3/8
Flared
Flared
5 lb. 15 oz.
23.7 (NEO22)
NOTE : Test conditions are based on ARI 210/240.
Unit: °F
Mode
Cooling
Heating
Indoor air condition Outdoor air condition
Dry bulb Wet bulb Dry bulb Wet bulb
Test
1: "A" Cooling steady state at rated compressor speed
"B-2" Cooling steady state at rated compressor speed
"B-1" Cooling steady state at minimum compressor speed
Low ambient cooling steady state at minimum compressor speed
Intermediate cooling steady state at intermediate compressor speed
1: Standard rating-heating at rated compressor speed
2: Low temperature heating at maximum compressor speed
Maximum temperature heating at minimum compressor speed
High temperature heating at minimum compressor speed
Frost accumulation at rated compressor speed
Frost accumulation at intermediate compressor speed
3
80
80
80
80
80
70
70
70
70
70
70
67
67
67
67
67
60
60
60
60
60
60
95
82
82
67
87
47
17
62
47
35
35
(75)
(65)
(65)
(53.5)
(69)
43
15
56.5
43
33
33
NOISE CRITERIA CURVE
4
MXZ-2B20NA
MXZ-2B20NA -
FAN SPEED FUNCTION SPL(dB(A))
1
High
Cooling
49
High
Heating
51
LINE
OCTAVE BAND SOUND PRESSURE LEVEL, 0dB = 0.0002 MICRO BAR
90
80
70
NC-70
60
NC-60
50
NC-50
40
NC-40
30
NC-30
20
10
APPROXIMATE
THRESHOLD OF
HEARING FOR
CONTINUOUS
NOISE
63
NC-20
125
250
500
1000
2000
4000
8000
BAND CENTER FREQUENCIES, Hz
4
OUTLINES AND DIMENSIONS
9-3/16"
6-21/32"
11-11/32"
Rear Air
Intake
14-3/16"
13/16"
1-7/32"
21/32"
2-1/2"
Unit: inch
1
19-11/16"
17/32"
Side Air Intake
3- (1-5/16") Drain Hole
11/16"
Air
Discharge
15-19/32"
6-9/16"
(Bolt Pitch)
MXZ-2B20NA MXZ-2B20NA -
11/16"
5
4-(13/32"×13/16") Oval Hole
(Foundation Bolt M10)
33-1/16"
1-3/16"
7-7/8"
1-3/16"
13"
1/2"
3- 7/8" Punched holes
(Connecting wire hole)
2-3/8"
2-5/8"
LIQ
14-1/4"
5-5/16"
1-25/32"
14-3/16"
27-15/16"
1-3/16"
9-7/16"
1-5/32"
GAS
LIQ
11-3/4"
1.Installation space
Note : Leave front and both sides
clearance fully.
More than 19-11/16"
29/32"
LIQ 1/4"FLARE
GAS 3/8"FLARE
Unit A
3-5/16"
GAS
Unit B
More than 3-15/16"
Grounding terminal
Conduit
cover
More than 7-7/8"
More than 19-11/16"
2.Service space
More than 3-15/16"
More than13-25/32"
More than 3-15/16"
Note : Leave rear, overhead and
both sides clearance fully.
Lock nut
Connector
More than 19-11/16"
Note : Leave front and overhead
clearance fully.
More than 3-15/16"
More than 13-25/32"
5
SERVICE SPACE
More than 13-25/32"
6
WIRING DIAGRAM
MXZ-2B20NA
MXZ-2B20NA -
1
6
REFRIGERANT SYSTEM DIAGRAM
7
MXZ-2B20NA MXZ-2B20NA -
Unit: mm
1
Service
port
Compressor
R.V. coil
OFF
ON
Refrigerant flow in cooling
Refrigerant flow in heating
Oil separator
Stop valve with
service port
Indoor unit
B
Discharge
temperature
thermistor RT62
Service
port
Capillary tube
O.D.0.10 x I.D.0.02 x 39.37
4-way valve
Muffler
Indoor unit
A
Outdoor heat
exchanger
temperature
thermistor
RT68
HEX-OUT
FAN-OUT
Indoor unit
A
Defrost
thermistor
RT61
Capillary tube
O.D.0.16 x I.D.0.11 x 3.93
Strainer
#100
Capillary tube
O.D.0.14 x I.D.0.09 x 19.68
LEV A
Stop valve
Strainer
#100
LEV E
Power
receiver
Indoor unit
B
Ambient
temperature
thermistor
RT65
Capillary tube
O.D.0.16 x I.D.0.11 x 3.93
Strainer
#100
LEV B
7
Strainer
#100
Distributor
Operating Range
Cooling
Heating
MXZ-2B20NA MXZ-2B20NA -
Maximum
Minimum
Maximum
Minimum
1
Indoor intake air temperature Outdoor intake air temperature
115°FDB
95°FDB, 71°FWB
14°FDB
67°FDB, 57°FWB
75°FDB, 65°FWB
80°FDB, 67°FWB
6°FDB, 5°FWB
70°FDB, 60°FWB
MAX. REFRIGERANT PIPING LENGTH & PIPE SIZE SELECTION
MXZ-2B20NA MXZ-2B20NA -
1
Piping length each indoor unit (a, b)
82 ft. MAX.
Total piping length (a+b)
164 ft. MAX.
Bending point for each unit
25 MAX.
Total bending point
60 MAX.
It does not matter which unit is higher.
Indoor
units
a
Max. height difference
Outdoor
unit
49 ft.
49 ft.
33 ft.
b
Refrigerant pipe diameter is different according to indoor unit to be connected. When using extension pipes, refer to the
tables below.
When diameter of refrigerant pipe is different from that of outdoor unit union, use optional Different-diameter pipe.
For further information on Different-diameter pipe.
Unit: inch
Outdoor unit union diameter
Indoor unit class
Extension pipe diameter
For
Liquid
1/4
Liquid
1/4
09 or less
Indoor unit A
Gas
3/8
Gas
3/8
Liquid
1/4
Liquid
1/4
12
Indoor unit B
Gas
3/8
Gas
3/8
Liquid
1/4
15
Gas
1/2
8
8
DATA
MXZ-2B20NA MXZ-2B20NA -
Model
Indoor type
Item
Total
Electrical
circuit
Wall (09+09)
Capacity
Duct (09+12)
Unit
Cooling
Heating
Cooling
Heating
But/h
18,000
22,000
20,000
22,000
SHF
–
–
–
–
–
Input
kW
1.44
1.65
2.19
1.78
Power supply (V,phase,Hz)
208/230, 1, 60
Input
kW
1.396
1.604
2.06
1.69
Comp. current (208/230V)
A
6.08/5.87
7.25/6.80
9.81/8.87
7.98/7.22
Fan motor current
A
0.43/0.39
0.43/0.39
0.43/0.39
0.43/0.39
PSIG
411
319
417
350
PSIG
141
102
130
101
Discharge temperature
ºF
169
154
174
172
Condensing temperature
ºF
114
100
120
104
Suction temperature
ºF
71
46
65
46
Comp. shell bottom temp.
ºF
163
149
185
167
Ref. pipe length
[Total pipe length for multi-system]
ft
82 [164]
–
5 lb. 15 oz.
Refrigerant Condensing pressure
circuit
Suction pressure
Outdoor
unit
1
Refrigerant charge (R410A)
Intake air temperature
DB
ºF
95
47
95
47
WB
ºF
–
43
–
43
Fan speed
rpm
650
700
650
700
Airflow
CFM
1485
1640
1485
1640
8-1. OPERATING RANGE
(1) POWER SUPPLY
Model
Outdoor unit
MXZ-2B20NA
MXZ-2B20NA-
Rating
1
208/230 V 60 Hz 1
9
Guaranteed Voltage
Min. 198 V 208 V 230 V Max. 253 V
(2) OPERATION
Function
Cooling
Heating
Intake air
temperature
Condition
"A" Cooling steady state
at rated compressor speed
"B-2" Cooling steady state
at rated compressor speed
"B-1" Cooling steady state
at minimum compressor speed
Low ambient cooling steady state
at minimum compressor speed
Intermediate cooling steady state
at intermediate compressor speed
Standard rating-heating
at rated compressor speed
Low temperature heating
at rated compressor speed
Max. temperature heating
at minimum compressor speed
High temperature heating
at minimum compressor speed
Frost accumulation
at rated compressor speed
Frost accumulation
at intermediate compressor speed
Outdoor
Indoor
DB (°F)
WB (°F)
DB (°F)
WB (°F)
80
67
95
(75)
80
67
82
(65)
80
67
82
(65)
80
67
67
(53.5)
80
67
87
(69)
70
60
47
43
70
60
17
15
70
60
62
56.5
70
60
47
43
70
60
35
33
70
60
35
33
10
MXZ-2B20NA MXZ-2B20NA -
1
The standard specifications apply only to the operation of the air conditioner under normal conditions.
Since operating conditions vary according to the areas where these units are installed, the following information has been provided to clarify the operating characteristics of the air conditioner under the conditions indicated by the performance curve.
(1) GUARANTEED VOLTAGE
198 ~ 253 V 60 Hz
(2) AIR FLOW
Air flow should be set at MAX.
(3) MAIN READINGS
(1) Indoor intake air wet-bulb temperature :
(2) Indoor outlet air wet-bulb temperature :
(3) Outdoor intake air dry-bulb temperature :
(4) Total input:
°FWB
°FWB
°FDB
W
}
Cooling
}
(5) Indoor intake air dry-bulb temperature :
°FDB
Heating
(6) Outdoor intake air wet-bulb temperature :
°FWB
(7) Total input :
W
Indoor air wet/dry-bulb temperature difference on the left side of the following chart shows the difference between the
indoor intake air wet/dry-bulb temperature and the indoor outlet air wet/dry-bulb temperature for your reference at service.
How to measure the indoor air wet-bulb/dry-bulb temperature difference
1.
2.
3.
4.
5.
6.
7.
8.
Attach at least 2 sets of wet and dry-bulb thermometers to the indoor air intake as shown in the figure, and at least 2 sets
of wet and dry-bulb thermometers to the indoor air outlet. The thermometers must be attached to the position where air
speed is high.
Attach at least 2 sets of wet and dry-bulb thermometers to the outdoor air intake.
Cover the thermometers to prevent direct rays of the sun.
Check that the air filter is cleaned.
Open windows and doors of room.
Press the EMERGENCY OPERATION switch once (twice) to start the EMERGENCY COOL (HEAT) MODE.
Compressor starts running at 33 Hz (COOL) or 45 Hz (HEAT). The frequency at each operation mode is fixed.
When system stabilizes after more than 15 minutes, measure temperature and take an average temperature.
10 minutes later, measure temperature again and check that the temperature does not change.
INDOOR UNIT
OUTDOOR UNIT
Wet-and dry-bulb
thermometers
11
Wet-and dry-bulb
thermometers
8-2. CAPACITY AND THE INPUT CURVES
MXZ-2B20NA MXZ-2B20NA - 1
13.1
6.1
9.5 13.1
12.1
5.6
8.6 11.9
11.2
5.0
7.9 10.8
10.1
4.7
7.0
9.7
9.0
4.1
6.3
8.6
8.1
Capacity correction factors
10.3 14.2
1.5
Indoor intake air Wet-bulb
temperature(°F)
1.4
1.3
1.2
79
1.1
75
1.0
72
68
64
113
0.9
15 class
(69Hz)
6.7
12 class
(50Hz)
14.2
09 class
(35Hz)
11.2 15.5
06 class
(25Hz)
Indoor unit class
(Inverter output
frequency)
Indoor air WB temperature
difference (degree)
Cooling capacity (at Rated frequency)
7.2
14
23
32
41
50
59
68
77
86
95
104
Outdoor intake air Dry-bulb temperature(°F)
Total input (Cooling : at Rated frequency)
Input correction factors
1.3
1.2
72
68
64
75
79
1.1
1.0
0.9
Indoor intake air Wet-bulb
temperature( F)
0.8
14
23
32
41
50
59
68
77
86
95
104
113
Heating capacity (at Rated frequency)
1.2
era
1.0
lb
bu
ry-
ir D
0.9
°F)
e(
tur
1.1
59
68
79
p
tem
a
ke
ta
0.8
Ind
0.7
oo
r in
0.6
0.5
Total input (Heating : at Rated frequency)
1.3
Input correction factor
1.3
Capacity correction factor
47.3
43.7
40.1
36.5
32.3
29.2
25.6
22.0
18.2
14.6
15 class
(78Hz)
40.9
37.6
34.6
31.3
28.3
25.0
22.0
18.9
15.7
12.6
12 class
(59Hz)
32.9
30.4
27.9
25.4
22.9
20.3
17.8
15.3
12.8
10.1
09 class
(47Hz)
22.1
20.5
18.7
17.1
15.3
13.7
11.9
10.3
8.5
6.8
06 class
(31Hz)
Indoor unit class
(Inverter output
frequency)
Indoor air DB temperature
difference (degree)
Outdoor intake air Dry-bulb temperature (°F)
1.2
F)
re (°
1.1
1.0
inta
oor
79
68
59
lb te
y-bu
ir Dr
ke a
0.9
ratu
mpe
Ind
0.8
0.7
0.6
0.5
0.4
0.4
5
14
23
32
41
50
Outdoor intake air Wet-bulb temperature (°F)
59
5
14
23
32
41
50
Outdoor intake air Wet-bulb temperature (°F)
59
NOTE: The above broken lines are for the heating operation without any frost and defrost operation.
12
8-3. CAPACITY AND INPUT CORRECTION BY MEANS OF INVERTER OUTPUT FREQUENCY
(OUTDOOR UNIT: MXZ-2B20NA MXZ-2B20NA -
1
)
1. 06-class unit in single operation
<COOL>Capacity
2.0
<COOL>Total input
2.0
1.5
1.5
1.0
1.0
0.5
0.5
0
50
0
100 Hz
Frequency
50
Frequency
<HEAT>Capacity
2.5
<HEAT>Total input
2.5
2.0
2.0
1.5
1.5
1.0
1.0
0.5
0.5
100 Hz
0
50
100 Hz
0
Frequency
50
Frequency
100 Hz
2. 09-class unit in single operation
<COOL>Capacity
2.0
<COOL>Total input
2.0
<HEAT>Capacity
2.0
1.5
1.5
1.5
1.5
1.0
1.0
1.0
1.0
0.5
0.5
0.5
0.5
0
50
0
100 Hz
Frequency
50
Frequency
100 Hz
0
50
<HEAT>Total input
2.0
100 Hz
0
Frequency
50
Frequency
100 Hz
3. 12-class unit in single operation
<COOL>Capacity
2.0
<COOL>Total input
2.0
<HEAT>Capacity
2.0
1.5
1.5
1.5
1.5
1.0
1.0
1.0
1.0
0.5
0.5
0.5
0.5
0
50
100 Hz
0
Frequency
50
Frequency
100 Hz
0
50
<HEAT>Total input
2.0
0
100 Hz
Frequency
50
Frequency
100 Hz
4. 15-class unit in single operation
<COOL>Capacity
2.0
<COOL>Total input
2.0
<HEAT>Capacity
2.0
1.5
1.5
1.5
1.5
1.0
1.0
1.0
1.0
0.5
0.5
0.5
0.5
0
50
Frequency
100 Hz
0
50
Frequency
100 Hz
13
0
50
Frequency
<HEAT>Total input
2.0
100 Hz
0
50
Frequency
100 Hz
8-4. OUTDOOR LOW PRESSURE AND OUTDOOR UNIT CURRENT
1. 09-class unit in single operation (OUTDOOR UNIT: MXZ-2B20NA MXZ-2B20NA (1) COOL operation
Data is based on the condition of indoor humidity
50%
Air flow speed: High
Inverter output frequency: 33 Hz
<How to work fixed-frequency operation>
1. Set emergency switch to COOL or HEAT. The switch is located
on indoor unit.
2. Press emergency run ON/OFF button.
3. Compressor starts running at 33 Hz (COOL) or 45 Hz (HEAT).
4. Indoor fan runs at High speed and continues for 30 minutes.
5. To cancel this operation, press emergency run ON/OFF button
or any button on remote controller.
(PSIG)
170
6.0
erature
p
DB tem
Indoor
(°F)
150
140
130
86
80
75
Outdoor unit current (A)
Outdoor low pressure
160
)
1
70
ure
4.0
rat
mpe
(°F)
B te
or D
Indo
3.0
86
80
75
70
33 Hz
2.0
1.0
33 Hz
120
65 70 75 80 85 90 95 100 105 110 115 (°F)
0.0
65 70 75 80 85 90 95 100 105 110 115 (°F)
Ambient temperature (°F)
7.0
Outdoor unit current (A)
Ambient temperature (°F)
(2) HEAT operation
Data is based on the condition of indoor humidity
75%
Set air flow to High speed.
Inverter output frequency is 45 Hz.
5.0
6.0
5.0
4.0
F)
re (°
r DB
o
Indo
te
ratu
mpe
75
70
65
3.0
45 Hz
2.0
15 20 25 30 35 40 45 50 55 60 65 70 75 (°F)
Ambient temperature (°F)
14
2. 12-class unit in single operation (OUTDOOR UNIT: MXZ-2B20NA MXZ-2B20NA (1) COOL operation
Data is based on the condition of indoor humidity
50%
Air flow speed: High
Inverter output frequency: 33 Hz
160
r DB
Indoo
6.0
(˚F)
rature
e
temp
)
<How to work fixed-frequency operation>
1. Set emergency switch to COOL or HEAT. The switch is located
on indoor unit.
2. Press emergency run ON/OFF button.
3. Compressor starts running at 33 Hz (COOL) or 45 Hz (HEAT).
4. Indoor fan runs at High speed and continues for 30 minutes.
5. To cancel this operation, press emergency run ON/OFF button
or any button on remote controller.
86
80
150
75
140
5.0
Outdoor unit current (A)
Outdoor low pressure
(PSIG)
170
1
70
130
ure
rat
mpe
4.0
(˚F)
86
80
75
70
te
r DB
o
Indo
3.0
33 Hz
2.0
1.0
33 Hz
120
0.0
65 70 75 80 85 90 95 100 105 110 115 (˚F) 65 70 75 80 85 90 95 100 105 110 115 (˚F)
Ambient temperature (˚F)
Ambient temperature (˚F)
(2) HEAT operation
Data is based on the condition of indoor humidity
75%
Set air flow to High speed.
Inverter output frequency is 45 Hz.
Outdoor unit current (A)
7.0
6.0
5.0
4.0
F
re (˚
ratu
e
p
m
B te
or D
o
d
n
I
)
75
70
65
3.0
45 Hz
2.0
15 20 25 30 35 40 45 50 55 60 65 70 75 (˚F)
Ambient temperature (˚F)
15
3. 15-class unit in single operation (OUTDOOR UNIT: MXZ-2B20NA MXZ-2B20NA (1) COOL operation
Data is based on the condition of indoor humidity
50%
Air flow speed: High
Inverter output frequency: 33 Hz
160
F
ure (˚
perat
m
e
t
r DB
Indoo
)
<How to work fixed-frequency operation>
1. Set emergency switch to COOL or HEAT. The switch is located
on indoor unit.
2. Press emergency run ON/OFF button.
3. Compressor starts running at 33 Hz (COOL) or 45 Hz (HEAT).
4. Indoor fan runs at High speed and continues for 30 minutes.
5. To cancel this operation, press emergency run ON/OFF button
or any button on remote controller.
6.0
)
86
5.0
80
150
75
140
Outdoor unit current (A)
Outdoor low pressure
(PSIG)
170
1
4.0
3.0
or
Indo
F
re (˚
eratu
p
m
e
DB t
86
80
75
70
)
33 Hz
2.0
70
130
1.0
33 Hz
120
0.0
65 70 75 80 85 90 95 100 105 110 115 (˚F) 65 70 75 80 85 90 95 100 105 110 115 (˚F)
Ambient temperature (˚F)
Ambient temperature (˚F)
(2) HEAT operation
Data is based on the condition of indoor humidity
75%
Set air flow to High speed.
Inverter output frequency is 45 Hz.
Outdoor unit current (A)
7.0
6.0
5.0
4.0
3.0
( ˚F
ture
a
r
e
mp
B te
or D
o
d
In
)
75
70
65
45 Hz
2.0
15 20 25 30 35 40 45 50 55 60 65 70 75 (˚F)
Ambient temperature (˚F)
16
9
ACTUATOR CONTROL
MXZ-2B20NA MXZ-2B20NA -
1
Relation between main sensor and actuator
Sensor
Purpose
Discharge temperature thermistor
Protection
Indoor coil thermistor
Compressor
4-way
valve
Defrosting Protection
Defrost thermistor
Defrosting
Fin temperature thermistor
Protection
Control
Ambient temperature thermistor
Protection
Outdoor heat exchanger temperature
Control
Capacity code
10
Actuator
Outdoor
LEV
fan motor
SERVICE FUNCTIONS
10-1. PRE-HEAT CONTROL
If moisture gets into the refrigerant cycle, or when refrigerant is liquefied and collected in the compressor, it may interfere
the start-up of the compressor.
To improve start-up condition, the compressor is energized even while it is not operating.
This is to generate heat at the winding.
The compressor uses about 50 W when pre-heat control is turned ON.
Pre-heat control is ON at initial setting.
[How to deactivate pre-heat control]
Turn OFF the power supply for the air conditioner before making the setting.
Set the 4th Dip Switch of SW1 on the outdoor electronic control P.C. board to ON to deactivate pre-heat control function.
SW1
ON
1 2 3 4
SW1
MXZ-2B20NA
MXZ-2B20NA -
ON
1 2 3 4
Turn ON the power supply for the air conditioner.
NOTE: Pre-heat control will be turned OFF when the breaker is turned OFF.
17
1
11
TROUBLESHOOTING
MXZ-2B20NA MXZ-2B20NA -
1
11-1. CAUTIONS ON TROUBLESHOOTING
1. Before troubleshooting, check the following:
1) Check the power supply voltage.
2) Check the indoor/outdoor connecting wire for mis-wiring.
2. Take care of the following during servicing.
1) Before servicing the air conditioner, be sure to turn off the unit first with the remote controller, and then after confirming the horizontal vane is closed, turn off the breaker and/or disconnect the power plug.
2) Be sure to turn OFF the power supply before removing the front panel, the cabinet, the top panel, and the electronic
control P.C. board.
3) When removing the electrical parts, be careful 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.
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) If the electronic control P.C. board seems to be defective, check the copper foil pattern for disconnection and the components for bursting and discoloration.
3) When troubleshooting, refer to 11-2, 11-3 and 11-4.
11-2. FAILURE MODE RECALL FUNCTION
This air conditioner can memorize the abnormal condition which has occurred once.
Even though LED indication listed on the troubleshooting check table (11-4.) disappears, the memorized failure details
can be recalled.
This mode is very useful when the unit needs to be repaired for the abnormality which does not recur.
1. Type of failure mode recall function
There are 2 types in failure mode recall function as shown below.
Indoor and outdoor unit failure mode recall function
With this function, failure mode of indoor unit and a part of failure mode of outdoor unit can be recalled.
The details of outdoor unit failure mode recall function
With this function, more detailed failure mode of outdoor unit can be recalled.
Refer to the service manual of indoor unit for how to recall the failure mode and the details of indoor unit failure mode.
The outdoor unit failure mode is indicated by the operation indicator lamp on the indoor unit and the LED of outdoor unit.
See "11-2.2. Outdoor unit failure mode table".
18
2. Outdoor unit failure mode table
The left lamp of
OPERATION INDICATOR
lamp (Indoor unit)
Abnormal point
(Failure mode/protection)
LED indication
Condition
(Outdoor P.C. board)
LED 1 LED 2
Lighting Lighting
Lighting Lighting When overcurrent protection stop is
continuously performed three times
within 1 minute after the compressor
gets started, or when converter
protection stop or bus-bar voltage
protection stop is continuously
performed three times within 3
minutes after start-up.
OFF
2-time flash
None (Normal)
Outdoor power system
3-time flash
Discharge temperature
thermistor
Lighting Once
Defrost thermistor
Ambient temperature thermistor
Fin temperature thermistor
P.C. board temperature
thermistor
Lighting
Lighting
Lighting
Lighting
Outdoor heat exchanger
temperature thermistor
Lighting 9 times
When thermistor shorts or opens
during compressor running.
Once
Twice
3 times
4 times
Remedy
• Check the connection
of the compressor
connecting wire.
• Refer to 11-6.
"How to check
inverter/compressor".
• Check the stop valve.
• Refer to 11-6. "Check
of outdoor thermistors".
• Replace the outdoor
electronic control
P.C. board.
• Refer to 11-6. "Check
of outdoor thermistors".
4-time flash
Overcurrent
5-time flash
Discharge temperature
Lighting Lighting When discharge temperature exceeds •Check refrigerant circuit
240.8°F during operation.
and refrigerant amount.
• Refer to 11-6. "Check
Compressor can restart if discharge
of LEV".
temperature thermistor reads 212°F or
less 3 minutes later.
6-time flash
High pressure
Lighting Lighting When the outdoor heat exchanger
temperature exceeds 158°F
during cooling or the indoor gas
pipe temperature exceeds 158°F
during heating.
•Check refrigerant circuit
and refrigerant amount.
• Check the stop valve.
7-time flash
Fin temperature
3 times
Goes
out
When the fin temperature exceeds
188.6°F during operation.
P.C. board temperature
4 times
Goes
out
When the P.C. board temperature
exceeds 158°F during operation.
• Check around outdoor
unit.
• Check outdoor unit air
passage.
• Refer to 11-6. "Check
of outdoor fan motor".
8-time flash
Outdoor fan motor
Lighting Lighting When failure occurs continuously
three times within 30 seconds after
the fan gets started.
• Refer to 11-6. "Check
of outdoor fan motor".
9-time flash
Nonvolatile memory data
Lighting 5 times When nonvolatile memory data
cannot be read properly.
10-time flash
Discharge temperature
Lighting Lighting When the frequency of the
compressor is kept 80Hz or
more and the discharge
temperature is kept under 102.2°F
for more than 20 minutes.
• Replace the outdoor
electronic control
P.C. board.
•Check refrigerant circuit
and refrigerant amount.
• Refer to 11-6. "Check
of LEV".
Once Goes out When 28A current flows into intelligent
power module.
• Reconnect compressor
connector.
• Refer to 11-6. "How to
check inverter/
compressor".
• Check the stop valve.
NOTE: Blinking patterns of this mode differ from the ones of Troubleshooting check table (11-4.).
19
Indoor/outdoor
unit failure mode
recall function
The left lamp of
OPERATION INDICATOR
lamp(Indoor unit)
11-time flash
15-time flash
LED indication
(Outdoor P.C. board)
LED 1 LED 2
Abnormal point
(Failure mode/protection)
Indoor/outdoor
unit failure mode
recall function
Remedy
Condition
Communication error
between P.C. boards
Lighting 6 times
Communication error occurs
between the electronic control P.C.
board and power board for more
than 10 seconds.
When the communication between
boards protection stop is
continuously performed twice.
Current sensor
Lighting 7 times
• Replace the power
board.
Zero cross detecting circuit
5 times
Goes
out
When a short or open circuit is
detected in the current sensor
during compressor operating.
Current sensor protection stop is
continuously performed twice.
When zero cross signal cannot be
detected while the compressor is
operating.
The protection stop of the zero
cross detecting circuit is
continuously performed 10 times.
Converter
5 times
Goes
out
When a failure is detected in the
operation of the converter during
operation.
• Check the voltage of power
supply.
• Replace the power board.
Bus-bar voltage
(1)
5 times
Goes
out
When the bus-bar voltage exceeds
400V or falls to 200V or below
during compressor operating.
Bus-bar voltage
(2)
Even if this protection stop is
performed continuously three
times, it does not mean the
abnormality in outdoor power
system.
6 times Goes
out
When the bus-bar voltage exceeds
400V or falls to 50V or below during
compressor operating.
• Check the voltage of power
supply.
• Replace the outdoor
electronic control P.C. board.
LEV for drain
Lighting Lighting
When the indoor unit detects any
abnormal in the LEV for drain.
• Refer to 11-6. "Check
of LEV".
• Check the drain pump of
the indoor unit.
• Check the connecting
wire between outdoor
electronic control
P.C. board and power
board.
• Check the connecting
wire among electronic
control P.C. board,
noise filter P.C. board
and power board.
NOTE: Blinking patterns of this mode differ from the ones of Troubleshooting check table (11-4.).
11-3. INSTRUCTION OF TROUBLESHOOTING
• Check the indoor unit with referring to the indoor unit service manual, and confirm that there is any problem in the indoor
unit.
Then, check the outdoor unit with referring to this page.
Operation start
Check the outdoor unit
LED indicator.
LED 1 or LED 2
has blinked.
Both LED 1 and
Both LED1 and LED 2 are lighting.
LED2 are OFF.
Refer to 11-4.
"Troubleshooting check table".
Refer to 11-6.
"Check of power supply".
• Indoor unit
serial signal
error
Refer to 11-6.
"How to
check
mis-wiring and
serial signal
error".
• COOL or
HEAT
operation only
Refer to 11-6.
"Check of
R.V. coil".
• When cooling, heat
exchanger of
non-operating indoor
unit frosts.
•When heating, nonoperating indoor unit
gets warm.
Refer to 11-6.
"Check of LEV".
• When cooling
dew drops in the
non-operating
indoor unit.
Check of
miss-piping.
20
• When heating,
room does not get
warm.
Refer to 11-6.
"How to check
inverter/compressor".
Check mis-piping,
shortage of capacity.
• When cooling,
room is not
cool.
Refer to 11-6.
"How to check
inverter/
compressor".
11-4. TROUBLESHOOTING CHECK TABLE
No. Symptom
1
Outdoor unit
does not
operate.
Indication
LED1(Red) LED2(Yellow)
Lighting
Once
Condition
Abnormal point / Condition
Remedy
LEV for drain
When the indoor unit detects any abnormality in the LEV for drain.
2
Lighting
Twice
Outdoor power system
When over current protection stop is continuously performed three times
within 1 minute after the compressor gets started, or when converter
protection stop or bus-bar voltage protection stop is continuously performed
three times within 3 minutes after start-up.
3
Lighting
3 times
Discharge temperature
thermistor
When a short circuit is detected in the thermistor during operation, or
when an open circuit is detected in the thermistor after 10 minutes
of compressor start-up.
4
Lighting
4 times
5
Lighting
Lighting
7 times
7
Lighting
8 times
8
Lighting
11 times
9
Lighting
12 times
10
11
4 times
12
Defrost thermistor
When a short circuit is detected in the thermistor during operation, or
when an open circuit is detected in the thermistor after 5 minutes of
compressor start-up.
Nonvolatile memory data
When the nonvolatile memory data cannot be read properly.
Goes out
Lock protection
When overcurrent is detected within 30 minutes of compressor
start-up
• Reconnect compressor connector.
• Refer to 11-6. "How to check inverter/compressor".
• Check the stop valve.
• Check the power module (PAM module).
High-pressure
protection
Converter protection
Bus-bar voltage
protection (1)
Bus-bar voltage
protection (2)
13 times
Goes out
Outdoor fan motor
8 times
Current sensor
protection
11 times
19
Lighting
12 times
• Replace the outdoor electronic control P.C. board.
When overcurrent is detected after 30 minutes of compressor start-up.
16
Lighting
Communication between P.C.
boards protection
Zero cross detecting circuit
protection
When discharge temperature exceeds 240.8°F during operation. Compressor • Check the amount of gas and refrigerant circuit.
can restart if discharge temperature thermistor reads 212°F or less 3
• Refer to 11-6. "Check of LEV".
minutes later.
When the fin temperature exceeds 188.6°F during operation.
•Check refrigerant circuit and refrigerant amount.
•Refer to 11-6. "Check of outdoor fan motor".
When the P.C. board temperature exceeds 158°F during operation.
When the outdoor heat exchanger temperature exceeds 158°F
during cooling or when indoor gas pipe temperature exceeds 158°F
during heating.
When a failure is detected in the operation of the converter during
operation.
When the bus-bar voltage exceeds 400V or falls to 200V or below
during compressor operating.
When the bus-bar voltage exceeds 400V or falls to 50V or below
during compressor operating.
When failure occurs continuously three times within 30 seconds after
the fan gets started.
When a short or open circuit is detected in the current sensor during
compressor operating.
Communication error occurs between the outdoor electronic control P.C.
board and power board for more than 10 seconds.
When zero cross signal cannot be detected while the compressor is
operating.
• Check around of gas and the refrigerant circuit.
• Check of stop valve.
• Replace the power board.
• Check the voltage of power supply.
• Replace the power board or the outdoor electronic
control P.C. board.
• Refer to 11-6. "Check of bus-bar voltage".
• Refer to 11-6.
• Check the connecting wire between outdoor electronic control
P.C. board and power board.
• Check the connecting wire among outdoor electronic control
P.C. board, noise filter P.C. board and power board.
Outdoor electronic control P.C. board (Parts side)
MXZ-2B20NA, MXZ-2B20NA-
The flashing frequency shows the number of times the LED blinks after every 2.5-second OFF.
(Example) When the flashing frequency is “2”.
0.5-second ON
ON
2.5-second OFF
"Check of outdoor fan motor".
• Replace the power board.
NOTE 1. The location of LED is illustrated at the right figure. Refer to 11-7.1.
2. LED is lighted during normal operation.
OFF
"Check of outdoor thermistors".
IPM protection
Goes out
18
• Refer to 11-6.
• Replace the power board.
9 times
Lighting
• Replace the outdoor electronic control P.C. board.
• Check the connecting wire between outdoor electronic control
P.C. board and power board.
• Check the connecting wire among outdoor electronic control
P.C. board, noise filter P.C. board and power board.
15
17
"Check of outdoor thermistors".
When the communication protection stop between boards is
continuously performed twice.
The protection stop of the zero cross detecting circuit is continuously
performed 10 times.
Fin temperature
protection
P.C. board temperature
protection
8 times
• Refer to 11-6.
Current sensor protection stop is continuously performed twice.
Goes out
14
"Check of outdoor thermistors".
Current sensor
Discharge temperature
protection
Goes out
• Refer to 11-6.
Communication error
between P.C. boards
Zero cross detecting
circuit
Goes out
5 times
• Check the conncetion of the compressor wire.
• Refer to 11-6. "How ro check inverter/compressor”.
• Check the stop valve.
When a short or open circuit is detected in the thermistor during
operation.
When a short circuit is detected in the thermistor during operation, or
when an open circuit is detected in the thermistor after 5 minutes (in
cooling) and 10 minutes (in heating) of compressor start-up.
Goes out
13
When a short or open circuit is detected in the thermistor during
operation.
Outdoor heat exchanger
temperature thermistor
5 times
6
'Outdoor unit
stops and
Twice
restarts 3
minutes
later' is
repeated.
3 times
Fin temperature
thermistor
P.C board temperature
thermistor
Ambient temperature
thermistor
• Refer to 11-6. "Check of LEV".
• Check the drain pump of the indoor unit.
2.5-second OFF
21
LED2 LED1
Lighting
0.5-second ON
1
No. Symptom
Outdoor unit
21 operates.
Indication
LED1(Red) LED2(Yellow)
Once
Twice
22
Lighting
Lighting
Condition
Abnormal point / Condition
Primary current protection
When the input current exceeds 15A.
Secondary current protection
When the current of the compressor exceeds 15A.
Remedy
High-pressure protection
When the indoor gas pipe temperature exceeds 113°F during heating.
Defrosting in cooling
When the indoor gas pipe temperature falls 37.4°F or below during cooling.
These symptoms do not mean any abnormality of the
product, but check the following points.
• Check if indoor filters are clogged.
• Check if refrigerant is short.
• Check if indoor/outdoor unit air circulation is short cycled.
23
3 times
Lighting
Discharge temperature
protection
When the frequency of the compressor is kept 80Hz or more and
the discharge temperature is kept under 122°F(COOL mode)
/104°F(HEAT mode) for more than 40 minutes.
• Check refrigerant circuit and refrigerant amount.
• Refer t1 11-6. "Check of LEV".
• Refer to 11-6. "Check of outdoor thermistors".
24
4 times
Lighting
Low discharge
temperature protection
When the frequency of the compressor is kept 80Hz or more and
the discharge temperature is kept under 102.2°F for more than 20
minutes.
• Refer to 11-6. "Check of LEV".
• Check refrigerant circuit and refrigerant amount.
When the outdoor heat exchanger temperature exceeds 136.4°F
during operation.
This symptom does not mean any abnormality of the
product, but check the following points.
• Check if indoor filters are clogged.
• Check if refrigerant is short.
• Check if indoor/outdoor unit air circulation is short cycled.
When the unit is operated with emergency operation switch.
25
5 times
Lighting
Cooling high-pressure
protection
Outdoor unit
26 operates
normally.
9 times
Lighting
Inverter check mode
27
Lighting
Lighting
Normal
-
-
-
Outdoor electronic control P.C. board(Parts side)
NOTE 1. The location of LED is illustrated at the right figure. Refer to 11-7.1.
2. LED is lighted during normal operation.
MXZ-2B20NA, MXZ-2B20NA-
The flashing frequency shows the number of times the LED blinks after every 2.5-second OFF.
(Example) When the flashing frequency is “2”.
ON
2.5-second OFF
Lighting
0.5-second ON
0.5-second ON
OFF
LED2 LED1
2.5-second OFF
22
1
11-5. TROUBLE CRITERION OF MAIN PARTS
MXZ-2B20NA MXZ-2B20NA -
1
Part name
Check method and criterion
Defrost thermistor (RT61)
Fin temperature
thermistor (RT64)
Measure the resistance with a tester.
Ambient temperature
thermistor (RT65)
Refer to 11-7. “Test point diagram and voltage”,1. “Outdoor electronic control P. C.
board”, or 3. “Outdoor power board”, for the chart of thermistor.
Outdoor heat exchanger
temperature thermistor
(RT68)
Discharge temperature
thermistor (RT62)
Measure the resistance with a tester.
Before measurement, hold the thermistor with your hands to warm it up.
Refer to 11-7. “Test point diagram and voltage”,1. “Outdoor electronic control P. C.
board”, for the chart of thermistor.
Compressor
W
Measure the resistance between terminals using a tester.
(Winding temperature: 14°F ~ 104°F)
RED
V
WHT
Normal (Each phase)
0.86 Ω ~ 1.06 Ω
U
BLK
Outdoor fan motor
RED
WHT
BLK
Measure the resistance between lead wires using a tester.
(Part temperature: 14°F ~ 104°F)
U (W)
V (V)
Normal (Each phase)
MXZ-2B20NA
MXZ-2B20NA -
W (U)
13.4 Ω ~ 16.4 Ω
1
13 Ω ~ 16 Ω
Measure the resistance using a tester. (Part temperature: 14°F ~ 104°F)
Normal
R.V. coil
1.2 kΩ ~1.56 kΩ
Linear expansion valve
MXZ-2B20NA
WHT
LEV
RED
Measure the resistance using a tester. (Part temperature: 14°F ~ 104°F)
ORN
YLW BRN BLU
MXZ-2B20NA -
1
WHT
LEV
RED
ORN
YLW
Color of lead wire
MXZ-2B20NA
MXZ-2B20NA WHT - RED
WHT - RED
RED - ORN
RED - ORN
YLW - BRN
YLW - RED
BRN - BLU
RED - BLU
BLU
23
1
Normal
37.4 Ω ~ 53.9 Ω
11-6. TROUBLESHOOTING FLOW
MXZ-2B20NA MXZ-2B20NA -
1
Outdoor unit does not operate.
Check of power supply
Check the connecting of parts of main power supply circuit.
Turn ON the power supply.
Is there voltage of 208/230 V AC in the
power supply terminal block?
No
Check the power supply cable.
Yes
Is the output voltage from the noise
filter P.C. board 208/230 V AC?
No
Replace the noise
filter P.C. board.
Yes
Is the input voltage to the power board
208/230 V AC?
No
Replace the reactor.
Yes
No
Is the input voltage to the outdoor
electronic control P.C. board 294/325 V DC?
Replace the power board.
Yes
Replace the outdoor electronic control
P.C. board.
24
• When unit cannot operate neither by the remote controller nor by EMERGENCY OPERATION switch.
Indoor unit does not operate.
• When OPERATION INDICATOR lamp flashes ON and OFF in every 0.5-second.
Outdoor unit does not operate.
How to check mis-wiring and serial signal error
Turn OFF the power supply.
Is there rated voltage in
the power supply ?
No
Check the power
supply.
Yes
LED indication
for communication status
Turn ON the power supply.
Communication status is indicated
by the LED.
Unit status
Blinking: normal communication
Lighting: abnormal communication or
not connected
Pattern 1 and 2 is repeatedly displayed
alternately. Each pattern is displayed for
15 seconds.
NOTE: "Lighting" in the table below does not
indicate abnormal communication.
Is there rated voltage between
outdoor terminal block S1 and
S2 ?
No
Check the wiring.
Yes
Press EMERGENCY OPERATION switch once.
Does the left lamp of OPERATION
INDICATOR lamp light up ?
<Confirmation of the power to the indoor unit>
No
Yes
MXZ-2B20NA
MXZ-2B20NA -
Is serial signal error indicated 6 minutes later ?
1
No
Yes
Outdoor electronic control P.C. board
Is there any mis-wiring,
poor contact, or wire
disconnection of the
indoor/outdoor
connecting wire ?
(Parts side)
Yes
Correct them.
No
LED3 LED2 LED1
A
Blinking
Pattern
LED 3
LED 2
LED 1
1
Lighting
Unit B
status
2
Goes out
Lighting
Unit A
status
Unit C
status
Turn OFF the power supply.
Check once more if the indoor/outdoor
B connecting wire is not mis-wiring.
Short-circuit outdoor terminal block S2 and
S3.
1
1 Mis-wiring may damage indoor electronic control
P.C. board during the operation.
Be sure to confirm the wiring is correct before the
operation starts.
Turn ON the power supply.
Does the LED on the outdoor electronic
control P.C. board repeat "3.6-second-OFF
and 0.8-second-ON quick blinking" ?
No
(Lighted
or
not lighted)
Yes
A
· Turn OFF inverter-controlled lighting
equipment.
· Turn OFF the power supply and then
turn ON again.
· Press EMERGENCY OPERATION
switch.
Is serial signal
error indicated
6 minutes later
?
Yes
B
· Reinstall
either the
unit or the
light away
No from each
other.
· Attach a filter
on remote
control
receiving
section of
the indoor
unit.
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 V DC
between outdoor terminal block S2
and S3 ? <Confirmation of serial
signal>
Replace the outdoor electronic control
P.C. board.
2
2 Be careful of the residual
voltage of smoothing capacitor.
No
Yes
Is there rated voltage between
indoor terminal block S1 and S2 ?
<Confirmation of power voltage>
No
Is there any error of the
indoor/outdoor connecting wire,
such as the damage of the wire,
intermediate connection, poor
contact to the terminal block ?
Yes
No
Replace the indoor electronic control P.C. board.
Be sure to release the failure-mode
recall function after checking.
Refer to indoor unit service manual.
25
Yes Replace the
indoor/outdoor
connecting wire.
The cooling operation or heating operation does not operate.
Check of R.V. coil
CN912
CN781
Noise filter P.C. board
Outdoor electronic control
P.C. board
• When heating operation does not work.
1. Disconnect the lead wire leading to the compressor.
2. 3 minutes after turning ON the power supply, start EMERGENCY
OPERATION in HEAT mode.
Is there voltage of 208/230 V AC between pin1
and pin 2 at connector CN912 ?
No
Yes
1. Turn OFF the power supply of indoor and outdoor unit, and
disconnect the connector CN781.
2. 3 minutes after turning ON the power supply, start
EMERGENCY OPERATION in HEAT mode.
Turn OFF the power supply of indoor and outdoor unit.
Disconnect the connector
CN912. Is there normal
resistance to R.V. coil ?
(Refer to 11-5.)
No
Replace the R.V. coil.
Is there voltage of 12 V DC
No
between the connector
CN781 pin 5 (+) and pin 3 (-) ?
Yes
Replace the outdoor
electronic control P.C.
board.
Yes
Replace the power P.C. board or
the noise filter P.C. board.
Replace the 4-way valve.
• When cooling operation does not work.
1. Disconnect the lead wire leading to the compressor.
2. 3 minutes after turning ON the power supply, start EMERGENCY
OPERATION in COOL mode.
Is there voltage of 208/230 V AC between pin1
and pin 2 at connector CN912 ?
Yes
No
Replace the 4-way valve.
If the connector CN912 is not connected or R.V. coil is open, voltage
occurs between terminals even when the control is OFF.
1. Turn OFF the power supply of the indoor and the outdoor unit,
and disconnect the connector CN781.
2. 3 minutes after turning ON the power supply, start
EMERGENCY OPERATION in COOL mode.
Is there voltage of 12 V DC
between the connector CN781
pin 5 (+) and pin 3 (-) ?
No
Replace the noise filter P.C. board.
Yes
Replace the outdoor electronic control P.C. board.
26
• When cooling, heat exchanger of non-operating indoor unit frosts.
• When heating, non-operating indoor unit get warm.
Check of LEV
Turn ON the power supply to the outdoor unit after checking LEV coil is mounted to
the LEV body securely.
Yes
Is "click - click" sound heard ?
Or, do you feel vibration of LEV coil with your hand ?
Normal
No
Disconnect the connectors.
CN791: LEV A, CN792: LEV B, CN795: LEV E
Is there normal resistance to LEV coil ?
(Refer to 11-5.)
Yes
Replace the outdoor electronic control P.C. board.
No
Replace LEV coil.
27
• When heating, room does not get warm.
• When cooling, room does not get cool.
How to check inverter/compressor
Disconnect the terminal of the compressor. 3 minutes after turning ON the power supply, start
EMERGENCY OPERATION.
Measure the voltage between each
lead wire leading to the compressor.
U (BLK) - V (WHT)
V (WHT) - W (RED)
W (RED) - U (BLK)
Output voltage: 50V-250V
Is proper output voltage detected?
1, 2
Yes
Is output balanced ?
Yes
1 • After the outdoor fan starts running, wait for 1 minute
or more before measuring the voltage.
• The output voltage values have the tolerance of ± 20%.
2 • The output differs depending on the capacity or the
number of indoor units to be operated.
No
No
Is the input voltage to the outdoor electronic
control P.C. board 370 V or more ?
No
Replace the power board.
Yes
Turn OFF the power supply of indoor and
outdoor unit, and measure the compressor
winding resistance between the compressor
terminals.
Is the resistance between each terminal normal ?
(Refer to 11-5.)
Yes
No
Replace the
compressor.
Reconnect the lead wire of compressor, and turn ON
the power supply to indoor and outdoor unit.
3 minutes later, start EMERGENCY OPERATION.
Clarify the causes by counting time until the inverter stops.
0 to 10 seconds: compressor layer short
10 to 60 seconds: compressor lock
60 seconds to 5minutes: refrigerant circuit defective
5 minutes or more: normal
28
• When thermistor is abnormal.
Check of outdoor thermistors
Disconnect the connector in the following table and
measure the resistance of the thermistor to check
whether the thermistor is normal or not. (Refer to 11-7.)
Abnormal
Replace the thermistor except RT64.
In case that RT64 is abnormal, replace the
outdoor power board since RT64 is combined
with the outdoor power board.
Normal
Reconnect the connector in the following table and
disconnect the lead wire leading to the compressor.
3 minutes after turning ON the power supply,
start EMERGENCY OPERATION.
No
Does the unit operate 10 minutes or more without
showing thermistor abnormality ?
Replace the outdoor electronic control
P.C. board or the outdoor power board.
Yes
Normal
Thermistor
Defrost
Discharge temperature
Outdoor heat exchanger temperature
Ambient temperature
Fin temperature
Symbol
RT61
RT62
RT68
RT65
RT64
Connector, Pin No.
Between CN661 pin1 and pin2
Between CN661 pin3 and pin4
Between CN661 pin7 and pin8
Between CN663 pin1 and pin2
Between CN3 pin1 and pin2
Board
Outdoor electronic control P.C. board
Outdoor power board
• Fan motor does not operate or stops operating shortly after starting the operation.
Check of outdoor fan motor
Disconnect CN932 from the outdoor
electronic control P.C. board, and measure
the resistance of the outdoor fan motor.
Is the resistance of outdoor fan motor
normal? (Refer to 11-5.)
Yes
No
Turn ON the power supply.
Rotate the outdoor fan motor manually and measure the voltage of
CN931.
Between (+) and (-)
Between (+) and (-)
Between (+) and (-)
(Fixed to either 5 V or 0 V DC) No
No
Replace the outdoor fan motor.
Does the voltage between each terminal become 5 V DC and 0 V DC
repeatedly ?
Yes
Does the outdoor fan motor rotate smoothly ?
Yes
Replace the outdoor electronic control P.C. board.
29
• When the operation frequency does not go up from the lowest frequency.
The other cases
Indoor unit does not operate. (different operating models in multi system)
• When you try to run two indoor units simultaneously, one for cooling and the other for heating, the unit which
transmits signal to the outdoor units first decides the operation mode.
• When the above situation occurs, set all the indoor units to the same mode, turn OFF the indoor units, and
then turn them back ON.
• Though the top of the indoor unit sometimes gets warm, this does not mean malfunction. The reason is that
the refrigerant gas continuously flows into the indoor unit even while it is not operating.
Check of bus-bar voltage
•Check the voltage of power supply.
•Confirm outdoor unit failure mode
recall function. (Refer to 11-2.2.)
Confirm LED1 indication lamp on
the outdoor electronic control P.C.
board.
Blink 6 times
Blink 5 times
Replace the power board.
Replace the outdoor electronic control P.C. board.
Replace the outdoor electronic control P.C. board.
Turn ON power supply. Start
operation.
Turn ON power supply. Start
operation.
Confirm LED1 indication lamp
on the outdoor electronic control P.C. board.
Blink 9 times
Lighting
Lighting
Normal
Lighting
Replace the outdoor electronic control P.C. board.
Confirm LED1 indication lamp
on the outdoor electronic control P.C. board.
Blink 9 times
Replace the power board.
Turn OFF power supply before removing P.C. board.
30
700
MXZ-2B20NA MXZ-2B20NA -
600
Resistance (kΩ)
90
400
Outdoor heat exchanger
temperature thermistor (RT68)
Ambient temperature
CN663
thermistor (RT65)
CN701
Signal transmission
(To power board)
5 V DC pulse wave
300
CN661
Defrost thermistor (RT61)
Discharge temperature thermistor (RT62)
200
100
80
70
60
50
40
86 104 122 140 158 176 194 212 230 248
30
Temperature (°F)
20
10
0
LEV E
(
CN781
68
12 V
DC
50
-4
14
32
50
68
86
Temperature (°F)
104
(
(
(–)
(
(+)
(–)
(+)
(+)
(–)
(+) (
(
GND (power board)
Rush current relay (–)
(–)R.V. coil
32
CN702
GND Signal reception
(From power board)
15 V 5 V DC pulse wave
15 V
0
CN795
12 V DC
pulse wave
Resistance (kΩ)
100
500
(
(
(
CN931
5 V DC
pulse wave
5V
GND
1
(
(
CN932
20-90 V AC
Defrost thermistor (RT61)
Ambient temperature thermistor (RT65)
Outdoor heat exchanger temperature
thermistor (RT68)
Discharge temperature thermistor (RT62)
(
(
To fan
motor
11-7. TEST POINT DIAGRAM AND VOLTAGE
1. Outdoor electronic control P.C. board
LED 1
LED 2
LED 3
DM06Y765
SW1
Bus-bar
voltage
CN801
294 V DC
~
370 V DC
Input
CN602
Serial signal Room B
12~24 V DC
F801
FUSE
T3.15AL250V
CN601
208/230 V AC
Input
Serial signal
Room A
(
(
(+)
(–)
12 V DC
pulse wave
LEV Room
A
12 V DC
pulse wave
LEV Room
B
31
CN791
(
(–)
(
(
(
(+)
CN792
12~24 V DC
2. Noise filter P.C. board
MXZ-2B20NA
MXZ-2B20NA -
1
CN901
To electronic
control
P.C. board
{
{
CN912
R.V. coil
208/230 V AC
CN903
To power
board
CN902
To power
board
CN61
208/230 V AC
Output
{
208/230 V AC
Output
F65
FUSE
T6.3AL250V
208/230 V AC
Input
F64
FUSE
T2AL250V
32
3. Outdoor Power board
200
180
1
Resistance (kΩ)
MXZ-2B20NA
MXZ-2B20NA -
Fin temperature thermistor (RT64)
DM00N019 or DM00N095
160
140
120
100
80
60
40
20
0
32 50 68 86 104 122 140 158 176
Temperature (°F)
Connect to the compressor
Voltage among phases: 5 V to 180 V
Connect to the earth
294-370 V DC
Output
(Red)
(+) 1
CN2
Connect to the controller board
(+)1-5(–): Signal transmission
(To electronic control P.C. board)
5 V DC pulse wave
(+)2-5(–): Zero cross signal
3-4 : Not used
(+)6-5(–): 15 V
(+)7-5(–): 15 V
(–) 3
(White)
CN3
Fin temperature thermistor RT64
reception (From
) Signal
electronic control P.C. board)
5 V DC pulse wave
CN5
Primary current detection
(Connect to the noise filter)
33
12
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
Locking lever
Slide the sleeve.
Pull the terminal while
pushing the locking
lever.
Hold the sleeve, and
pull out the terminal
slowly.
Connector
12-1. MXZ-2B20NA MXZ-2B20NA -
1
OUTDOOR UNIT
OPERATING PROCEDURE
PHOTOS
1. Removing the compressor
Photo 1
Screws of the
top panel
(1) Remove the screws of the top panel, and remove the top
panel.
(2) Remove the screws of the service panel, and remove the
service panel.
(3) Recover gas from the refrigerant circuit.
NOTE: Recover gas from the pipes until the pressure gauge
shows 0 PSIG.
(4) Remove the screws of the cabinet, and remove the cabinet.
(5) Remove the screws of the back panel, and remove the back
panel (Photo 3).
(6) Disconnect the compressor lead wire from terminal of the
compressor (U, V, W).
(7) Disconnect the outdoor electronic control P.C. board
connectors:
CN661, CN663, CN791, CN792, CN795, CN931, CN932
Disconnect the noise filter P.C. board connector:
CN912
(8) Remove the screws of the electrical parts, and remove the
electrical parts (Photo 4).
(9) Remove the propeller.
(10) Remove the screws of the separator, and remove the
separator (Photo 6).
(11) Remove the sound proof felt (Photo 6).
(12) Detach the welded parts of the compressor suction and discharge pipes (Photo 5).
(13) Remove the compressor nuts and remove the compressor.
Screws of
the cabinet
Screws of
service
panel
Screws of the cabinet
Photo 2
Screws of the
top panel
2. Removing the electronic control P.C. board
(1) Remove the screws of the sub panel.
(2) Remove the sub panel.
(3) Disconnect all connectors and lead wires on the electronic
control P.C. board.
(4) Remove the electronic control P.C. board.
34
Screw of
the cabinet
Screws of the
cabinet
Screws of
the cabinet
Screws of the
sub panel
PHOTOS
OPERATING PROCEDURE
Photo 3
Screw of the rear guard
Screw of the
back panel
Photo 5
R.V. coil
4 way valve
Screws of
the back panel
LEV coil E
Expansion valve E
Suction pipe
welded part
Screws of
the back panel
Photo 4
Discharge
pipe welded part
Screw of the
back panel
Screws of
the electrical
parts
Compressor nuts
3. Removing the fan motor
(1) Remove the top panel, the service panel, and the cabinet
(Photo 1, 2).
(2) Disconnect the connector CN931 and CN932 on the outdoor
electronic control P.C. board.
(3) Remove the propeller.
(4) Remove the fan motor.
Photo 6
Screws of the outdoor fan motor
Propeller nut
Propeller
35
Separator
Sound
proof
felt
OPERATING PROCEDURE
4. Removing the 4-way valve
(1) Remove the top panel (Photo 1).
(2) Remove the service panel, the cabinet, and the back panel
(Photo 1, 2, 3).
(3) Recover gas from the refrigerant circuit.
NOTE: Recover gas from the pipes until the pressure gauge
shows 0 PSIG.
PHOTOS
Photo 7
4 way valve
(4) Remove the electrical parts (Photo 4).
(5) Detach the welded parts of 4-way valve and pipe (Photo 7).
R.V. coil
Welded parts
5. Removing the expansion valve
Photo 8
(1) Remove the top panel (Photo 1).
(2) Remove the service panel, the cabinet, and the back panel
(Photo 1, 2, 3).
(Gas recovery is not required if the unit is pumped down.)
(3) Remove the electrical parts for removing LEV E (Photo 4, 5).
(4) Remove the LEV coils.
(5) Detach the welded parts of expansion valves and pipes.
Expansion
valves
LEV coils
6. Removing the reactor
Photo 9
(1) Remove the top panel (Photo 1).
(2) Remove the service panel, cabinet, back panel, and the
electrical parts (Photo 1, 2, 3, 4).
(3) Disconnect the reactor lead wire from the terminal of the
reactor.
(4) Remove the screws of the reactor, and remove the reactor
(Photo 9).
Screws of the reactor
37
HEAD OFFICE: TOKYO BLDG., 2-7-3, MARUNOUCHI, CHIYODA-KU, TOKYO 100-8310, JAPAN
Copyright 2009 MITSUBISHI ELECTRIC ENGINEERING CO., LTD
Distributed in Dec. 2009. No. OBH560 REVISED EDITION-A 5
Distributed in Sep. 2009. No. OBH560 5
Made in Japan
New publication, effective Dec. 2009
Specifications subject to change without notice.
MXZ-2B20NA MXZ-2B20NA Indoor units
combination
06
Indoor type
A
B
Wall
09
Wall
Duct
12
Wall
Duct
15
Wall
Duct
06+06
06+09
Wall
Wall
Wall
06+12
Wall
Wall
06+15
Wall
Wall
09+09
Wall
Wall
Wall
Wall
Duct
Wall
Duct
Wall
Duct
Wall
Duct
Duct Duct
09+12
Wall
Wall
Wall
Duct
Duct Wall
Duct Duct
09+15
Wall
Wall
Wall
Duct
Duct Wall
Duct Duct
12+12
Wall
Wall
Wall
Duct
Duct Duct
1
Cooling
Cooling capacity(BTU/h)
Unit B
Total
6000
( 5400 - 9000
9000
9000
( 5400 - 9000
9000
9000
( 5400 - 9000
12000
12000
( 5400 - 12000
12000
12000
( 5400 - 12000
15000
15000
( 5400 - 15000
15000
15000
( 5400 - 15000
12000
6000
6000
( 7800 - 15000
6000
9000
15000
( 7800 - 18000
6000
9000
15000
( 7800 - 16500
6000
12000
18000
( 7800 - 20000
6000
12000
18000
( 7800 - 19000
5800
14200
20000
( 7800 - 23000
5800
14200
20000
( 7800 - 21500
9000
9000
18000
( 7800 - 20000
9000
9000
18000
( 7800 - 19000
9000
9000
18000
( 7800 - 18000
8500
11500
20000
( 7800 - 23000
8500
11500
20000
( 7800 - 21500
8500
11500
20000
( 7800 - 21500
8500
11500
20000
( 7800 - 20000
7500
12500
20000
( 7800 - 23000
7500
12500
20000
( 7800 - 21500
7500
12500
20000
( 7800 - 21500
7500
12500
20000
( 7800 - 20000
10000 10000
20000
( 7800 - 23000
10000 10000
20000
( 7800 - 21500
10000 10000
20000
( 7800 - 20000
Unit A
6000
1/2
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
Power consumption
(W)
530
(
490 680 )
680
(
490 680 )
750
(
510 750 )
930
(
490 930 )
1010
(
510 - 1010 )
1330
(
490 - 1330 )
1560
(
510 - 1560 )
800
(
630 - 1820 )
1050
(
630 - 1820 )
1150
(
650 - 1800 )
1440
(
630 - 1820 )
1610
(
650 - 1800 )
1660
(
630 - 2230 )
1930
(
650 - 2210 )
1440
(
630 - 1820 )
1610
(
650 - 1800 )
1780
(
670 - 1780 )
1660
(
630 - 2230 )
1930
(
650 - 2210 )
1930
(
650 - 2210 )
2190
(
670 - 2190 )
1660
(
630 - 2230 )
1930
(
650 - 2210 )
1930
(
650 - 2210 )
2190
(
670 - 2190 )
1630
(
630 - 2230 )
1910
(
650 - 2210 )
2190
(
670 - 2190 )
Current(A)
P/F(%)
208V 230V
2.68
2.43
95
3.44
3.11
95
3.80
3.43
95
4.71
4.26
95
5.11
4.62
95
6.73
6.09
95
7.89
7.14
95
3.97
3.59
97
5.20
4.71
97
5.70
5.15
97
7.14
6.45
97
7.98
7.22
97
8.23
7.44
97
9.57
8.65
97
7.14
6.45
97
7.98
7.22
97
8.82
7.98
97
8.23
7.44
97
9.57
8.65
97
9.57
8.65
97
10.85
9.82
97
8.23
7.44
97
9.57
8.65
97
9.57
8.65
97
10.85
9.82
97
8.08
7.31
97
9.47
8.56
97
10.85
9.82
97
MXZ-2B20NA MXZ-2B20NA Indoor units
combination
06
Indoor type
A
B
Wall
09
Wall
Duct
12
Wall
Duct
15
Wall
Duct
06+06
06+09
Wall
Wall
Wall
06+12
Wall
Wall
06+15
Wall
Wall
09+09
Wall
Wall
Duct
09+12
Wall
Wall
Wall
Wall
Duct
Wall
Duct
Wall
Duct
Wall
Duct
Duct
Wall
Duct
Duct Wall
Duct Duct
09+15
Wall
Wall
Wall
Duct
Duct Wall
Duct Duct
12+12
Wall
Wall
Wall
Duct
Duct Duct
1
Heating
Heating capacity(BTU/h)
Unit B
Total
7400
( 5200 - 14400
11000
11000
( 5200 - 15400
10900
10900
( 5200 - 15400
13600
13600
( 5200 - 16400
13600
13600
( 5200 - 16400
18000
18000
( 5200 - 21100
18000
18000
( 5200 - 21100
7400
7400
14800
( 8500 - 25500
7400
11000
18400
( 8500 - 25500
7400
10900
18300
( 8500 - 25500
7400
13600
21000
( 8500 - 25500
7400
13600
21000
( 8500 - 25500
6400
15600
22000
( 8500 - 25500
6400
15600
22000
( 8500 - 25500
11000 11000
22000
( 8500 - 25500
11000 10900
21900
( 8500 - 25500
10900 10900
21800
( 8500 - 25500
9500
12500
22000
( 8500 - 25500
9500
12500
22000
( 8500 - 25500
9500
12500
22000
( 8500 - 25500
9500
12500
22000
( 8500 - 25500
8250
13750
22000
( 8500 - 25500
8250
13750
22000
( 8500 - 25500
8250
13750
22000
( 8500 - 25500
8250
13750
22000
( 8500 - 25500
11000 11000
22000
( 8500 - 25500
11000 11000
22000
( 8500 - 25500
11000 11000
22000
( 8500 - 25500
Unit A
7400
2/2
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
Power consumption
(W)
610
(
480 - 1400 )
880
(
480 - 1430 )
940
(
480 - 1430 )
1150
(
480 - 1460 )
1180
(
480 - 1460 )
1650
(
480 - 2100 )
1720
(
480 - 2100 )
960
(
520 - 2410 )
1270
(
520 - 2410 )
1400
(
520 - 2520 )
1520
(
520 - 2410 )
1590
(
520 - 2520 )
1650
(
520 - 2410 )
1720
(
520 - 2520 )
1650
(
520 - 2410 )
1740
(
520 - 2520 )
1820
(
520 - 2620 )
1650
(
520 - 2410 )
1720
(
520 - 2520 )
1720
(
520 - 2520 )
1780
(
520 - 2620 )
1650
(
520 - 2410 )
1720
(
520 - 2520 )
1720
(
520 - 2520 )
1780
(
520 - 2620 )
1650
(
520 - 2410 )
1720
(
520 - 2520 )
1780
(
520 - 2620 )
Current(A)
P/F(%)
208V 230V
3.09
2.79
95
4.45
4.03
95
4.76
4.30
95
5.82
5.26
95
5.97
5.40
95
8.35
7.55
95
8.70
7.87
95
4.76
4.30
97
6.29
5.69
97
6.94
6.28
97
7.53
6.81
97
7.88
7.13
97
8.18
7.40
97
8.52
7.71
97
8.18
7.40
97
8.62
7.80
97
9.02
8.16
97
8.18
7.40
97
8.52
7.71
97
8.52
7.71
97
8.82
7.98
97
8.18
7.40
97
8.52
7.71
97
8.52
7.71
97
8.82
7.98
97
8.18
7.40
97
8.52
7.71
97
8.82
7.98
97