Mitsubishi Electric MXZ-18TV User manual

SERVICE MANUAL
SPLIT-TYPE,HEAT PUMP AIR CONDITIONER
CONTENTS
1. TECHNICAL CHANGES ····································2
2. PART NAMES AND FUNCTIONS······················2
3. INDOOR/OUTDOOR
CORRESPONDENCE TABLE ···························3
4. INDOOR UNITS COMBINATION·······················3
5. SPECIFICATION·················································4
6. NOISE CRITERIA CURVES······························ 5
7. OUTLINES AND DIMENSIONS ························ 6
8. WIRING DIAGRAM ············································7
9. REFRIGERANT SYSTEM DIAGRAM················8
10. PERFORMANCE CURVES································9
11. MICROPROCESSOR CONTROL·····················14
12. TROUBLESHOOTING······································19
13. DISASSEMBLY INSTRUCTIONS·····················29
14. PARTS LIST······················································32
15. OPTIONAL PARTS···········································34
Inverter-controlled multi system
Model
MXZ-18TV - E1
No. OB280
This manual describes technical data of outdoor unit.
For the indoor unit refer to the service manuals No. OB229, OB227 REVISED EDITION-B, OB252 REVISED EDI-
TION-A, and OC165 of corresponding models.
Model indication
OB280-1.qxp 01.4.4 2:40 PM Page 1

PART NAMES AND FUNCTIONS
2
OUTDOOR UNIT Air inlet
Air outlet
(back and side)
Model indication
MXZ-18TV- E1
2
TECHNICAL CHANGES
1
MXZ-18RV - ➔MXZ-18TV -
1. The combination pattern of indoor unit has increased.
2. Outside dimension of the outdoor equipment changed.
3. Ball valve has changed to stop valve.
4. Accumulator has been removed.
5. Hight pressure switch has been removed.
6. Compressor has changed.
7. Refrigerant filling capacity has changed. (1.3kg ➝1.55kg)
E1E1
OB280-1.qxp 01.4.4 2:40 PM Page 2

3
3INDOOR / OUTDOOR CORRESPONDENCE TABLE
❈There is no combination other than this table.
MXZ-18TV- E1
OUTDOOR UNIT
Combination of the
connectable indoor units
07+09
07+12
07+SEH-1.6
09+09
09+12
09+SEH-1.6
12+12
INDOOR UNITS COMBINATION
4
07
09
12
07+09
07+12
09+09
09+12
12+12
90
90
90
90
90
90
90
90
3.88
4.17
6.22
8.79
8.85
8.88
9.00
9.07
2.3
(0.9-2.8)
2.5
(0.9-3.0)
3.4
(0.9-3.8)
4.8
(1.49-5.25)
5.0
(1.51-5.45)
5.0
(1.51-5.45)
5.2
(1.53-5.60)
5.3
(1.55-5.70)
0.850
(0.225-1.055)
0.865
(0.225-1.125)
1.29
(0.220-1.550)
1.82
(0.370-2.11)
1.835
(0.365-2.125)
1.840
(0.370-2.130)
1.865
(0.365-2.145)
1.88
(0.370-2.190)
–
–
–
2.5
2.98
2.5
3.0
2.65
2.3
2.5
3.4
2.3
2.02
2.5
2.2
2.65
Indoor units
combination Unit A Unit B
Cooling capacity (kw)
Total Outdoor unit
power consumption
(kw)
Current
(A) Power factor
(%)
230V
NOTE: Electrical data is for outdoor unit only.
MXZ-18TV - E1
NOTE: SEH-1.6AR is equivalent to class 12 (12000BTU).
However, the combination of “12+12” has only the MSC type.
NOTE: Electrical data is for outdoor unit only.
07
09
12
07+09
07+12
09+09
09+12
12+12
90
90
90
90
90
90
90
90
4.85
5.23
6.95
9.27
9.14
9.17
8.81
8.64
3.3
(0.9-4.0)
3.6
(0.9-4.5)
4.0
(0.9-4.7)
6.2
(1.53-6.70)
6.5
(1.55-7.00)
6.5
(1.55-7.0)
6.55
(1.56-7.1)
6.6
(1.58-7.2)
1.005
(0.225-1.115)
1.085
(0.225-1.195)
1.440
(0.220-1.490)
1.92
(0.300-2.030)
1.895
(0.295-2.005)
1.900
(0.300-2.010)
1.825
(0.295-1.925)
1.790
(0.290-1.840)
–
–
–
3.23
3.88
3.25
3.77
3.30
3.3
3.6
4.0
2.97
2.62
3.25
2.78
3.30
Indoor units
combination Unit A Unit B
Heating capacity (kw)
Total Outdoor unit
power consumption
(kw)
Current
(A) Power factor
(%)
230V
OB280-1.qxp 01.4.4 2:40 PM Page 3

4
5SPECIFICATION
Outdoor model
Indoor units number
Indoor units total capacity (Connectable)
indoor units total capacity (Simultaneous operation)
Piping total length
Connecting pipe length
Height difference (Indoor ~ Outdoor)
Height difference (Indoor ~ Indoor)
Function
Capacity
Dehumidification
Outdoor air flow
Power outlet
Running current
Power input
Auxiliary heater
Crankcase heater
Power factor
Starting current
Compressor motor current
Fan motor current
Model
Output
Winding
resistance(at20:)
Model
Winding
resistance(at20:)
Dimensions WOHOD
Weight
Sound level (Hi)
Fan speed (Hi)
Fan speed regulator
Refrigerant filling
capacity(R-22)
Refrigerating oil (Model)
Thermistor RT61
Thermistor RT62
Thermistor RT63
Thermistor RT65,66
Thermistor RT67
m
m
m
m
kW
R/h
K/h
A
A
W
A(kW)
W
%
A
A
A
W
"


"
mm
kg
dB
rpm
kg
cc
k"
k"
k"
k"
k"
Compressor Electrical
data
Fan motor
Special remarks
Capacity System
Coefficient of performance(C.O.P)
Outdoor unit power supply
MXZ-18TV - E1
Single phase
230V,50Hz
2
Total model name 24
Total model name 24
Max. 30 (chargeless 20)
Max. 20
10
10
1,860
20
—
—
90.0
9.08
0.38
SHV-130FEA (ROTARY)
1,400
U-V 0.45
V-W 0.45 W-U 0.45
RA6V35-AA
WHT-BLK 236.2 BLK-YLW 48.1
BLK-RED 224.1
800(+69)o600o300
46
630
2
1.55
350 (MS-56)
13.4 (at 100:)
10.0 (at 25:)
10.0 (at 25:)
10.0 (at 25:)
17.0 (at 50:)
Cooling
5.3 (1.55~5.7)
—
9.08
1,880 (370~2,190)
8.70
2.82
48
Heating
6.6 (1.58~7.2)
—
8.64
1,790 (290~1,840)
8.26
3.69
49
TEST CONDITIONS COOLING INDOOR DB27.0°C WB19.0°C
OUTDOOR DB35.0°C WB24.0°C
HEATING INDOOR DB20.0°C
OUTDOOR DB 7.0°C WB 6.0°C
NOTE: Test conditions are based on ISO 5151 (Refrigerant piping length (one way) :5m
✽1 Electrical data is for only outdoor unit.
OB280-1.qxp 01.4.4 2:40 PM Page 4

5
NOISE CRITERIA CURVES6
90
80
70
60
50
40
30
20
10 63 125 250 500 1000 2000 4000 8000
APPROXIMATE
TERESHOLD OF
HEARING FOR
CONTINUOUS
NOISE
NC-60
NC-50
NC-40
NC-30
NC-20
NC-70
OCTAVE BAND SOUND PRESSURE LEVEL, 0dB = 0.0002 MICRO BAR
BAND CENTER FREQUENCIES, Hz
Test conditions.
Cooling :DB35: WB24:
Heating :DB 7:WB 6:
Cooling
NOTCH
Heating
48
SPL(dB(A))
49
LINE
MXZ-18TV - E1
OB280-1.qxp 01.4.4 2:40 PM Page 5

6
OUTLINES AND DIMENSIONS
7
MXZ-18TV -E1
Unit: mm
OUTDOOR UNIT
23 16 69
800
500
400
45.4 40
165
347.5
Air in
Air out
Air in
Drainage hole {33
Drainage
hole {33
113
300
152
155
43.6
34 17
90 65 65 65
34 17300
330
600
Handle Handle Liquid refrigerant pipe joint
Refrigerant pipe (flared) {6.35
Gas refrigerant pipe joint
Refrigerant pipe (flared) {9.52
Service
port
Bolt pitch for installation
100mm or more
100mm or more
200mm or more
350mm or more
However, either the
left / right sides or
back side should
be unobstructed.
Basically unobstructed
Even if the right / left sides or
back side are vacant, the top
has to be at least 100mm
unobstructed. WA
WA
WB
WA In case of poorly-ventilated place, the front
or the back has to be at least 200mm
unobstructed.
WB The wall may get dirty in case the air is
discharged toward it.
REQUIRED SPACE
OB280-1.qxp 01.4.4 2:40 PM Page 6

7
WIRING DIAGRAM
8
R61
IPM
FUSE(1A)
T801
CT62
WVU
TAB61
TAB65
C65
SSR61
CN664 CN663 CN661
66
MF61
CN912CN911
21S4
CN61
R62
TAB62
V
W
UMC
BLK
WHT
RED RED
WHT
BLK
PE
F911(1A)
BLU
ORN
YLW
TB2
BLK
BREAKER
GRN/YLW
CIRCUIT
POWER
SUPPLY
~/N
230V~
50Hz
TB1
TO INDOOR
UNIT No.B
CONNECTING
12V
TO INDOOR
UNIT No.A
CONNECTING
12V
N
L
N
3
N
3
GROUND
BLK
BLU
BLK BLU
GRN
RED
X62 X61
X64
R64
CT61
TAB2
TAB1
LDE
CN601CN602 CN851
TAB4
CN901
LDS62
DS61
C61 C62
7
ORN
BLU
RED
YLW
YLW
RED
4
FUSE(20A)
ELECTRONIC CONTROL
P.C. BOARD
2 1 2 16 5 4 3 2 1
RT65RT66RT61RT67
LEV ALEV B
CN772 CN771 4 3
RT62RT63
6 5 4 3 2 1 3 2 14
1 2 3
3 2 14567
1234567
123 123
NOISE FILTER
P.C.BOARD
–
++ –
–
+
–
+
NAMESYMBOLNAMESYMBOL
1.About the indoor side electric wiring refer to the indoor unit electric wiring diagram for servicing.
2.Use copper conductors only (For field wiring).
3.Symbols below indicate.
:Terminal block :Connector
NAMESYMBOL
NOTES:
C61
C62
C65
CT61
CT62
DS61,DS62
FUSE
FUSE
F911
IPM
L
POWER-FACTOR CAPACITOR
SMOOTHING CAPACITOR
FAN MOTOR CAPACITOR
CURRENT TRANSFORMER
CURRENT TRANSFORMER
DIODE MODULE
FUSE(20A)
FUSE(1A)
FUSE(1A)
POWER TRANSISTOR MODULE
REACTOR
R64
R61,R62
LEV A
LEV B
21S4
MC
MF61
RT61
RT62
RT63
RT65
RESISTOR
RESISTOR
EXPANSION VALVE A,COIL
EXPANSION VALVE B,COIL
REVERSING VALVE SOLENOID COIL
COMPRESSOR
FAN MOTOR
DISCHARGE TEMP. THERMISTOR
DEFROST TEMP. THERMISTOR
EVAPORATOR TEMP. THERMISTOR
GAS PIPE TEMP. A THERMISTOR
RT66
RT67
SSR61
T801
TB1
TB2
X61
X62
X64
CN61
GAS PIPE TEMP. B THERMISTOR
FIN TEMP. THERMISTOR
SOLENOID COIL RELAY
TRANSFORMER
TERMINAL BLOCK
TERMINAL BLOCK
FAN MOTOR RELAY
FAN MOTOR RELAY
RELAY
CONNECTOR
SG79J191H01
MODELS MXZ-18TV- E1
OUTDOOR UNIT
OB280-1.qxp 01.4.4 2:40 PM Page 7

8
REFRIGERANT SYSTEM DIAGRAM
9
Unit:mm
MXZ-18TV -E1
Compressor
Discharge
temperature
thermistor
R.V. coil
heating ON
cooling OFF
Refrigerant flow in cooling
Refrigerant flow in heating
Muffler
Outdoor
heat
exchanger
Muffler
LEV (A)
Evaporation
temperatuer
thermistor
LEV (B)
Strainer
Strainer
Defrost
thermistor
Capillary tube
{4.0✕{2.4✕300
Capillary tube
{2.4✕{0.6✕750
Capillary tube
{3.0✕{2.0✕400
Capillary tube
{3.0✕{2.0✕400
Stop valve
(with service port) Gas pipe temperature
B thermistor
Gas pipe temperature
A thermistor
Stop valve
Stop valve
Indoor
Unit B
Indoor
Unit B
Indoor
Unit A
Indoor
Unit A
Stop valve
(with service port)
4-way valve
{8
{6
{6
{16
{12
●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, see page BACK COVER.
Indoor unit
Extension pipe diameter
class Pipe diameter
Liquid 6.35(1/4) Liquid 6.35(1/4)
07/09 Gas 9.52(3/8) Gas 9.52(3/8)
Liquid 6.35(1/4) Liquid 6.35(1/4)
12 Gas 12.7(1/2) Gas 12.7(1/2)
Outdoor unit union diameter
For Liquid 6.35(1/4)
Indoor unit A Gas 9.52(3/8)
Liquid 6.35(1/4)
Indoor unit B Gas 9.52(3/8)
Unit : mm (inch)
Piping length each indoor unit (a, b) 20m
Total piping length (a+b) 30m
Height difference between units (H) 10m
Bending point for each unit 15
Total bending point 30
❋It does not matter which unit is higher.
NOTE: SEH-1.6AR is equivalent to class 12.
a
Outdoor
unit
b
H
H
H
MAX REFRIGERANT PIPING LENGTH
MXY-18TV -E1
OB280-1.qxp 01.4.4 2:40 PM Page 8

9
10
The standard data contained in these 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 pro-
vided to clarify the operating characteristics of the air conditioner under the conditions indicated by the performance curve.
(1) GUARANTEED VOLTAGE
198 ~ 264V, 50Hz
(2) AIR FLOW
Air flow should be set at MAX.
(3) MAIN READINGS
(1) Indoor intake air wet-bulb temperature : °CWB
(2) Indoor outlet air wet-bulb temperature : °CWB
(3) Outdoor intake air dry-bulb temperature : °CDB
(4) Total input: W
(5) Indoor intake air dry-bulb temperature : °CDB
(6) Outdoor intake air wet-bulb temperature : °CWB
(7) Total input : W
Indoor air wet/dry-bulb temperature difference on the left side of the chart on page 10 and 11 shows the difference
between the indoor intake air wet/dry-bulb temperature and the indoor outlet air wet/dry-bulb temperature for your refer-
ence at service.
How to measure the indoor air wet-bulb/dry-bulb temperature difference
1. 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.
2. 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.
3. Check that the air filter is cleaned.
4. Open windows and doors of room.
5. Press the EMERGENCY OPERATION switch once(twice) to start the EMERGENCY COOL(HEAT) MODE.
6. When system stabilizes after more than 15 minutes, measure temperature and take an average temperature.
7. 10 minutes later, measure temperature again and check that the temperature does not change.
INDOOR UNIT OUTDOOR UNIT
}
}
Cooling
Heating
PERFORMANCE CURVES
Wet-and dry-bulb
thermometers
Wet-and dry-bulb
thermometers
07 class
7.7
7.2
6.6
6.1
5.5
5.0
9.3
8.6
7.9
7.3
6.6
6.0
8.4
7.8
7.2
6.6
6.0
5.4
12 class 09 class
10-1. CAPACITY AND THE INPUT CURVES
25.9
23.9
21.9
19.9
17.9
15.9
13.9
11.9
23.6
21.8
19.9
18.1
16.3
14.5
12.7
10.9
25.7
23.7
21.8
19.8
17.8
15.8
13.8
11.9
07 class 09 class 12 class
OB280-1.qxp 01.4.4 2:40 PM Page 9

10
10-2. Capacity and input correction by inverter output frequency
(OUTDOOR UNIT:MXZ-18TV)
NOTE 1 : Inverter output frequency : COOL 55Hz,HEAT 80Hz
NOTE 2 : The dotted line on graphs connects the frequency range in normal operation shown by the full line and the frequency
in test run shown by the point.
0 50 100 150
0.5
1.0
1.5
0 50 100 150
0.5
1.0
1.5
0 50 100 150
0.5
1.0
1.5
0 50 100 150
0.5
1.0
1.5
0 50 100 150
0.5
1.0
1.5
0 50 100 150
0.5
1.0
1.5
0 50 100 150
0.5
1.0
1.5
0 50 100 150
0.5
1.0
1.5
0 50 100 150
0.5
1.0
1.5
0 50 100 150
0.5
1.0
1.5
0 50 100 150
0.5
1.0
1.5
<COOL>Capacity
Frequency Hz Frequency
<COOL>Total input
Hz Hz
<HEAT>Capacity
Frequency Frequency
<HEAT>Total input
Hz
<COOL>Capacity
Frequency Hz Frequency
<COOL>Total input
Hz
<HEAT>Capacity
Frequency 0 50 100 150
0.5
1.0
1.5
Frequency
<HEAT>Total input
Hz
<COOL>Capacity
Frequency Hz Frequency
<COOL>Total input
Hz
<HEAT>Capacity
Frequency Hz
Hz
Frequency
<HEAT>Total input
Hz
1. 07-class unit in single operation
2. 09-class unit in single operation
3. 12-class unit in single operation
OB280-1.qxp 01.4.4 2:40 PM Page 10

11
10-3. Outdoor low pressure and outdoor unit current
1. 07-class unit in single operation (OUTDOOR UNIT : MXZ-18TV)
NOTE:The unit of pressure has been changed to MPa on the international system of units(SI unit system).
The converted score against the traditional unit system can be gotten according to the formula below.
1(MPa • G) =10.2(kgf/ff• G)
(1) COOL operation
1Both indoor and outdoor units are under the same
temperature/humidity condition.
Dry-bulb temperature(°C) Relative humidity(%)
20 50
25 60
30 70
<How to work fixed-frequency operation>
1.Set emergency switch to COOL or HEAT.The switch is locat-
ed on indoor unit.
2.Press emergency run ON/OFF button.
3.Compressor starts running at 55Hz (COOL) or 80Hz (HEAT).
4.Indoor fan runs at HI speed and continues for 30 minutes.
5.To cancel this operation,press emergency run ON/OFF button
or any button on remote controller.
①
➁
Indoor Outdoor
Set air flow to Hi speed.
Inverter output frequency is 80Hz.
➂
(2) HEAT operation
DB(°C) 20.0
WB(°C) 14.5 DB(°C) 2 7 15 20.0
WB(°C) 1 6 12 14.5
18 50 60 70
20 25 30 32
0.2
0.3
0.4
0.5
0.6
0.7
0.8
18 50 60 70
20 25 30 32
0.5
1.5
2
2.5
3
3.5
4
Ambient temperature(:)/ Ambient humidity(%)
(:)
(%)
55Hz
(MPa•Gauge)
2 5 10 15 20 25
2
3
4
5
6
7
8
Ambient temperature(:)
80Hz
Outdoor low pressure
Ambient temperature(:)/ Ambient humidity(%)
(:)
(%)
55Hz
Outdoor unit current (A)
Outdoor unit current (A)
(kgf/F• Gauge)
8
7
6
5
4
3
2
2Air flow speed : HI
3Inverter output frequency : 55Hz
OB280-1.qxp 01.4.4 2:40 PM Page 11

12
2. 09-class unit in single operation (OUTDOOR UNIT : MXZ-18TV)
NOTE:The unit of pressure has been changed to MPa on the international system of units(SI unit system).
The converted score against the traditional unit system can be gotten according to the formula below.
1(MPa • G) =10.2(kgf/ff• G)
(1) COOL operation
1Both indoor and outdoor units are under the same
temperature/humidity condition.
Dry-bulb temperature(°C) Relative humidity(%)
20 50
25 60
30 70
<How to work fixed-frequency operation>
1.Set emergency switch to COOL or HEAT.The switch is locat-
ed on indoor unit.
2.Press emergency run ON/OFF button.
3.Compressor starts running at 55Hz (COOL) or 80Hz (HEAT).
4.Indoor fan runs at HI speed and continues for 30 minutes.
5.To cancel this operation,press emergency run ON/OFF button
or any button on remote controller.
2Air flow speed : HI
3Inverter output frequency : 55Hz
①
➁
Indoor Outdoor
Set air flow to Hi speed.
Inverter output frequency is 80Hz.
➂
(2) HEAT operation
DB(°C) 20.0
WB(°C) 14.5 DB(°C) 2 7 15 20.0
WB(°C) 1 6 12 14.5
18 50 60 70
20 25 30 32
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Ambient temperature(:)/ Ambient humidity(%)
(:)
(%)
55Hz
18 20 25 30
50 60 70 32
1.5
2
2.5
3
3.5
4
Ambient temperature(:)/ Ambient humidity(%)
(:)
(%)
55Hz
80Hz
Ambient temperature(:)
(MPa•Gauge)
Outdoor low pressure
Outdoor unit current (A)
Outdoor unit current (A)
(kgf/F• Gauge)
8
7
6
5
4
3
2
2 5 10 15 20 25
2
3
4
5
6
7
8
OB280-1.qxp 01.4.4 2:40 PM Page 12

13
3. 12-class unit in single operation (OUTDOOR UNIT : MXZ-18TV)
NOTE:The unit of pressure has been changed to MPa on the international system of units(SI unit system).
The converted score against the traditional unit system can be gotten according to the formula below.
1(MPa • G) =10.2(kgf/ff• G)
(1) COOL operation
1Both indoor and outdoor units are under the same
temperature/humidity condition.
Dry-bulb temperature(°C) Relative humidity(%)
20 50
25 60
30 70
<How to work fixed-frequency operation>
1.Set emergency switch to COOL or HEAT.The switch is locat-
ed on indoor unit.
2.Press emergency run ON/OFF button.
3.Compressor starts running at 55Hz (COOL) or 80Hz (HEAT).
4.Indoor fan runs at HI speed and continues for 30 minutes.
5.To cancel this operation,press emergency run ON/OFF button
or any button on remote controller.
2Air flow speed : HI
3Inverter output frequency : 55Hz
①
➁
Indoor Outdoor
Set air flow to Hi speed.
Inverter output frequency is 80Hz.
➂
(2) HEAT operation
DB(°C) 20.0
WB(°C) 14.5 DB(°C) 2 7 15 20.0
WB(°C) 1 6 12 14.5
18 50 60 70
20 25 30 32
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Ambient temperature(:)/ Ambient humidity(%)
(:)
(%)
55Hz
Ambient temperature(:)
80Hz
18 20 25 30
50 60 70 32
1
1.5
2
2.5
3
3.5
4
Ambient temperature(:)/ Ambient humidity(%)
(:)
(%)
55Hz
(MPa•Gauge)
Outdoor low pressure
Outdoor unit current (A)
Outdoor unit current (A)
(kgf/F• Gauge)
8
7
6
5
4
3
2
2 5 10 15 20 25
2
3
4
5
6
7
8
OB280-1.qxp 01.4.4 2:40 PM Page 13

MICROPROCESSOR CONTROL
14
11
Compressor
power
factor
Indoor unit
microprocessor
SSR61 Drive
circuit
Transistor
module
Indoor Unit
B
Indoor Unit
B
Comp. Discharge
temperature
thermistor
RT61
Evaporation
temperature
thermistor
RT63
Gas pipe
temperature
thermistor RT66
Gas pipe
temperature
thermistor RT65
Indoor Unit
A
Indoor Unit
A
Outdoor
fan motor
MF61
x 61
x 62
Defrost
thermistor
RT62
LEV (A)
LEV (B)
Outdoor unit control microprocessor
Compressor
primary
current
Compressor
secondary
current
Fin temperature
thermistor RT67
R. V. coil
21S4
Input signal
Output signal
MXZ-18TV -E1
INVERTER MULTI SYSTEM CONTROL
OB280-1.qxp 01.4.4 2:40 PM Page 14

15
Linear expansion valve (LEV) is controlled by "Thermostat ON" commands given from each unit.
• The standard opening is on the straight line, which connects an each standard point in the section where divided
into seven according to the operation frequency of compressor as shown in the figure below.
(LEV opening is controlled in proportion to the operation frequency.)
Note: Opening is adjusted at the standard opening according to the indoor unit conditions.
However, inclination of standard opening in each point of opening does not change with the original curve.
• Add opening provided in Difference in Capacity in the table below to the standard opening from 1 to 8,
when capacity of the indoor unit is excluding code 1.
• Add opening provided in Difference in Operation number in the table below to determined LEV opening for
each indoor unit, when 2, 3 or 4 indoor units are operated at the same time.
Note: Even when the adjusted standard opening exceeds the driving range from 59 to 500 pulse, actual
driving output opening is in a range from 59 to 500 pulse.
< Calculation example of LEV opening >
Cool operation: Compressor frequency 70Hz: 2 unit ON: 18class
(170-150)p(80-60)o(70-60)+150+75-30=205 pulse
Determination of LEV standard opening in each indoor unit
When outdoor unit is operating,
some indoor unit stops and
some operates.
• LEV opening for each indoor unit is determined by adding adjustment in accordance
with the number of operating unit and the capacity class to standard opening, based
on the operation frequency:
Ex.) Opening 130 pulse in standard opening 1 ➝Minimum 80 pulse, Maximum 205
pulse. (Capacity code 4 at 1 unit operation) (Capacity code 1 at 4 unit operation)
• After starting operation, adjustment in accordance with intake super heat, discharge
temperature is included in standard opening. w1
Note: LEV opening in each frequency at DRY operation and COOL operation is the
same. However, velocity and compressor operation frequency controls are
different. See 11-2 Operational frequency range
(As far as the indoor unit velocity control goes, refer to DRY operation in
MICROPROCESSOR CONTROL in the indoor unit service manual.)
• LEV opening for each indoor unit is determined by adding adjustment in accordance
with the number of operating unit and the capacity class to standard opening, based
on the operation frequency:
Ex.) Opening 120 pulse in standard opening 1 ➝Minimum 70 pulse, Maximum 165
pulse. (Capacity code 4 at 1 unit operation) (Capacity code 1 at 4 unit operation)
• After starting operation, opening becomes the one that adjustment in accordance
with discharge temperature was added to basic opening. w1
Thermostat ON in HEAT mode
LEV opening
Thermostat OFF in
COOL or DRY mode
Thermostat OFF in HEAT mode
Stop of all indoor unit
Indoor unit status
COOL : 5 pulse (full closed)
HEAT : 59 pulse (slightly opened)
Thermostat ON in
COOL or DRY mode
Opening before stop ➝ 500 pulse in 15 minutes
When the outdoor unit operation (When the other indoor unit operate): 5 pulse.
When outdoor unit stops. (When the other indoor unit stops or thermo off):
Maintain LEV opening before stop ➝500 pulse in 15 minutes
• When the outdoor unit operates. (When the other indoor unit operates): 59 pulse
• When the outdoor unit stops. (When the other indoor unit stops or thermo off):
Maintain LEV opening before stop ➝500 pulse in 15 minutes.
w1 LEV opening when the outdoor unit operating: Upper limit 500 pulse, Lower limit 59 pulse.
7 20 40 60 80 100 120 140
Operation frequency of compressor (Hz) : F
120
130
140
150
160
170
180
190
200
210
220
LEV opening (Pulse)
Standard opening
1 2 3 4 5 6 7 8
COOL
HEAT
11-1.LEV control
OB280-1.qxp 01.4.4 2:40 PM Page 15

16
(1) LEV opening correction by suction super heat (COOL, DRY)
(Suction super heat) = (Minimum gas pipe temperature) - (Evaporation temperature)
When COOL and DRY , correct the LEV openings corrected from the table below
(2) Separate correction (COOL,DRY)
(When number of operation unit is 2 units)
(a) Correction by the separate super heat
Correct the LEV separately by temperature difference between each gas pipe temperature thermistor and evaporator
temperature thermistor.
1Calculate each super heat of the unit from the expression below;
(Super heat) = (Gas pipe temperature thermistor) - (Evaporation temperature thermistor)
2Select a minimum super heat from among them.
3Correct an each LEV is corrected opening is corrected by difference between each super heat and minimum super
heat.
Suction superheat (S.H.) LEV opening
correction (pulse)
more than 12
10 to12
8 to 10
6 to 8
6 or less
6
4
3
2
0
Difference of
superheat LEV opening correction (pulse)
more than 9
6 to9
3to 6
6 or less
8
6
2
0
1Suction super heat
(MIN gas pipe temperature thermistor - Evaporation temperature thermistor)
2Each correction w1
• (Each gas pipe temperature thermistor - Evaporation temperature thermistor)
• (Main pipe temperature thermistor - sub pipe temperature thermistor)
w1 Perform this, when number of operation units is 2units or more
w2 When the correction opening of suction super heat is 0, correct the LEV opening by dischaege temperature.
3Discharge temperature
COOL DRY HEAT
• •
-
•
w2
•
w2
•
<Correction>
2 Code3Code2
Standard opening Difference in
capacity Difference in operation number
1 2 3 4 5 6 7 8
COOL
HEAT 150 120 160 130 170 140 180 150
Capacity code
Indoor unit 1 07 2 09 3 12 4 18
190
160 190 170 200 180 200 180 25 20 50 40 -60 -60
OB280-1.qxp 01.4.4 2:40 PM Page 16

17
11-2.Operational frequency range
(3) LEV opening correction by discharge temperature
When LEV correction output is 0 pulse by the suction super heat at cool or dry operation, or dry operating, correct LEV is cor-
rected according to the following table.
The target discharge temperature is determined according to frequency zone and number of operation unit of the
compressor.
Correct the LEV opening according to difference between the target discharge temperature and discharge temperature.
Operation frequency
of compressor
Minimum ~ 20
21 ~ 33
34 ~ 46
47 ~ 59
60 ~ 72
73 ~ 85
86 ~ 98
97 ~ 111
111 ~ Maximum
Single
40
40
45
45
50
55
65
70
75
Double
40
40
45
45
50
55
65
70
75
Single
40
45
50
55
60
65
70
75
75
Double
40
45
50
55
60
65
70
73
73
Number of operating unit. Number of operating unit.
COOL, DRY HEAT
Discharge temperature (;)LEV opening
correction (pulse)
more than Target discharge temperature+11
Target discharge temperature+11 to Target discharge temperature+8
Target discharge temperature+8 to Target discharge temperature+5
Target discharge temperature+5 to Target discharge temperature+2
Target discharge temperature+2 to Target discharge temperature-2
Target discharge temperature-2 to Target discharge temperature-5
Target discharge temperature-5 to Target discharge temperature-8
Target discharge temperature-8 to Target discharge temperature-11
Target discharge temperature-11 or less
COOL
10
4
2
1
0
-1
-2
-5
-8
HEAT
8
2
1
1
0
-1
-1
-2
-6
DRY
Min. Max. Rated Min. Max.
Defrost Rated
Note: When the fan speed of indoor unit is total
Lo notch, restrict the maximum frequency is
rated frequency.
COOL HEAT
Number of
operating
unit
1
2
3
2
3
4
5
6
7
30
30
70
80
100
120
55
61
85
108
30
41
53
72
30
30
100
100
120
120
100
100
100
100
80
85
94
120
1
2
capacity
cord
11-3.Heat defrosting control
(1) Conditions to enter defrosting mode
1. When temperature of defrosting thermistor is -3;or less.
2.When specified non-defrosting time, is counted in the control p.c.board is satisfied.
(Total time of compressor operating)
Going to defrosting mode at both condition of 1and 2.
(2) Defrosting operation
1. Compressor stops for 50 seconds, Indoor fan is off, Defrosting lamp lights
2.4-way valve reverses flow, Compressor operates by the frequency in heat defrosting control.
3. After compressor stops for 35 seconds, 4-way valve reverses flow, then defrosting finishes.
(3) Conditions to finish defrosting mode
1. When the defrosting thermistor temperature is 8;or more.
2. When it has spent 10 minutes for defrosting.
Defrosting finishes at condition of 1or 2.
OB280-1.qxp 01.4.4 2:40 PM Page 17

18
This protection controls the compressor ON/OFF and operation frequency according to temperature of the discharge temp.
thermistor.
(1) Compressor ON/OFF
When temperature of the discharge temp. thermistor exceeds 116;, the control stops the compressor.
When temperature of the discharge temp. thermistor is 80;or less, the controls starts the compressor.
(2) Compressor operation frequency
When temperature of the discharge temp. thermistor is expected to be higher than 116;, the control decreases 12Hz from the
current frequency.
When temperature of the discharge temp. thermistor is expected to be higher than 111;and less than 116;, the control
decreases 6Hz from the current frequency.
When temperature of the discharge temp. thermistor is expected to be higher than 104;and less than 111;, the control is set
at the current frequency.
11-5.Discharge temperature protection control
<Control status>
The control performs when the following status are satisfied everything;
• When there is 1 unit or more not operating indoor unit on heat operation. (Excluding thermo OFF)
• When discharge temperature becomes 107;or more.
• When it passed 60 minutes or more since the operation has started or the last refrigerant recovery has controlled.
<Control details>
LEV opening, which adjusts to not operating indoor unit, is considered to be 80 pulse.
<Control finish status>
The control finishes either as follows. However, the LEV opening is considered to be 59 pulse.
• When it passed 60 seconds since the control has started.
• When the discharge temperature is 90;or less.
Fan speed is switched according to a number of operating indoor unit and the compressor frequency.
Note
•When operation, fan speed of Hi/ Low mode changes to VHi/ Hi mode by promoting those fan speeds respectively by
1 step after defrosting is operated. This control is cleared, when the compressor off.
•When overheat protection of P.C. board temperature or fin temperature operates, the outdoor fan speed is fixed to VHi
mode regardless of compressor frequency. Also, when the overheat protection is cleared, the fan speed is
back to normal
•When the indoor coil thermistor is 57;or more on HEAT operation, fan speed is fixed to Low notch .
Or, the indoor coil thermistor is 45;or less on HEAT operation, fan speed is back to normal.
11-6.Refrigerant recovery control on heating
11-7.Outdoor fan control
COOL
Fan speed
Up
Down
Up
Down
Single Double
Mode
HEAT
Indoor unit operation
<Relation between compressor frequency and fan speed.>
60Hz
50Hz
60Hz
50Hz
60Hz
50Hz
60Hz
50Hz
Up
Down
Fan speed
Hi
Low Compressor frequencyMin. Max.
Discharge temperature thermistor
Indoor pipe temperature thermistor
Defrost thermistor
Evaporation temperature thermistor
Gas pipe temperature thermistor
Fin temperature thermistor
Capacity code
Purpose
Protection
Defrosting Protection
Defrosting
Control
Control
Protection
Control
Compressor LEV Outdoor
fan motor Reversing valve
Sensor Actuator
Relation between main sensor and actuator.
11-8.Relation between main sensor and actuator
OB280-1.qxp 01.4.4 2:40 PM Page 18

19
12 TROUBLESHOOTING
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 is supposed to be defective, check the copper foil pattern for disconnection and the
components for bursting and discoloration.
3) When troubleshooting, refer to the flow chart on page 19 and the check table on page 20, 21.
Lead wiring Housing point
12-1. 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 the following during servicing.
1) Before servicing the air conditioner, be sure to first turn off the remote controller to stop the unit, and then after con-
firming the horizontal vane is closed, turn off the breaker and / or disconnect the power plug.
2) Be sure to unplug the power cord before removing the front panel, the cabinet, the top panel, and the electronic con-
trol P.C. board.
3) When removing the electronic control P.C. board, hold the edge of the board with care NOT to apply stress on the
components.
4) When connecting or disconnecting the connectors, hold the housing of the connector. DO NOT pull the lead wires.
12-2. Instruction of troubleshooting
Operation start
Check the outdoor unit
LED indicator
ACheck of power supply
See page 22.
• Indoor unit
serial signal
error
BCheck of
serial signa
See page 22.
• Cool or HEAT
opereation only
CCheck of
R.V.coil
See page 23.
• When cooling,
room does not
cool.
ECheck of
inverter,
compressor
See page 24.
• When cooling, heat
exchanger of
non-operating indoor
unit frosts.
•When heating, non
operating indoor unit
gets warm.
DCheck of LEV
See page 24.
• When cooling,
dew drops in the
non-operating
indoor unit
Check of mis-
piping.
• When heating,
room doed not get
warm.
ECheck of
inverter,compressor
See page 24.
Check mis-piping
Shortage of capacity
Refer to indicator list
See page 20, 21.
OFF Both LED 1 and
LED 2 lighting
• 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.
LED 1 or LED 2
has blinked.
OB280-1.qxp 01.4.4 2:40 PM Page 19