Mitsubishi SEZ-A12AR Operating manual

TECHNICAL & SERVICE MANUAL
CONTENTS
1. PART NAMES AND FUNCTIONS········3
2. SPECIFICATIONS·································5
3. OUTLINES AND DIMENSIONS············8
4. WIRING DIAGRAM·······························9
5. REFRIGERANT SYSTEM DIAGRAM ······10
6. TROUBLESHOOTING························11
7. DISASSEMBLY PROCEDURE···········18
8. PARTS LIST········································21
9. OPTIONAL PARTS·····························23
INDOOR UNIT
Indoor unit
[Model names] [Service Ref.]
SEZ-A12AR SEZ-A12AR.TH
SEZ-A18AR SEZ-A18AR.TH
SEZ-A24AR SEZ-A24AR.TH
SPLIT-TYPE, HEAT PUMP AIR CONDITIONERS
WIRED REMOTE
CONTROLLER
ON/OFF
CENTRALLY CONTROLLED
ERROR CODE
CLOCK
ON OFF
˚C
CHECK
CHECK MODE
FILTER
TEST RUN
FUNCTION
˚C
1Hr.
NOT AVAILABLE
STAND BY
DEFROST
TEMP.
Ceiling Concealed
Series SEZ R410A
Model name
indication
Note :
•This manual does not cover the
following outdoor units. When
servicing them, please refer to
the service manual No.OC304
REVISED EDITION-A and this
manual in a set.
•Please void OC303.
Revision :
•“2. SPECIFICATIONS ” has
been modified.
No.OC303
REVISED EDITION-A
OC303-A-1.qxp 04.9.21 4:08 PM Page 1

2
Revision:
“2. SPECIFICATIONS ” has been modified on page 5 and 6.
Service Ref.
Page
5
5
6
SEZ-A12AR.TH
SEZ-A18AR.TH
SEZ-A24AR.TH
IncorrectRevise point Correct
Electrical date
Power input
Rated frequency
33 48
49 61
64 87
OC303-A-1.qxp 04.9.21 4:08 PM Page 2

3
1PART NAMES AND FUNCTIONS
Indoor Unit
SEZ-A12AR.TH
SEZ-A18AR.TH
SEZ-A24AR.TH
Air outlet duct flange
Air outlet
Air inlet
(Selecting the either back side or bottom side)
● Operation buttons
PAR-20MAA
ON/OFF
CENTRALLY CONTROLLED
ERROR CODE
CLOCK
ON OFF
˚C
CHECK
CHECK MODE
FILTER
TEST RUN
FUNCTION
˚C
1Hr.
NOT AVAILABLE
STAND BY
DEFROST
FILTER
CHECK TEST
TEMP.
TIMER SET
This sets the ventilation fan speed.
VENTILATION button
Press this button to switch the cooling,
electronic dry (dehumidify), automatic
and heating modes.
OPERATION SWITCH button
This sets the room temperature. The
temperature setting can be performed
in 1:units
Setting range
Cooling 19:to 30:
Heating 17:to 28:
TEMP. ADJUSTMENT button
This switches between continuous
operation and the timer operation.
TIMER button
This switches between the operation
and stop modes each time it is pressed.
The lamp on this button lights during
operation.
ON/OFF button
Only press this button to perform an
inspection check or test operation.
Do not use it for normal operation.
CHECK-TEST RUN button
This switch the horizontal fan motion
ON and OFF.
LOUVER button
AIR DIRECTION button
This resets the filter service indication
display
FILTER button
This sets the current time, start time
and stop time.
TIME SETTING button
This sets the ventilation fan speed.
FAN SPEED button
(Not available for this model.) (Not available for this model.)
This adjusts the vertical angle of the
ventilation.
(Not available for this model.)
On the controls are set, the same operation mode can be repeated by simply pressing the ON/OFF button.
Wired remote controller
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4
Caution
●Only the Power display lights when the unit is stopped and power supplied to the unit.
●“NOT AVAILABLE” is displayed when the Air speed button are pressed.This indicates that this room unit is not equipped
with the fan direction adjustment function and the louver function.
●When power is turned ON for the first time, it is normal that “H0” is displayed on the room temperature indication (For max.
2minutes). Please wait until this “H0” indication disappear then start the operation.
CENTRALLY
CONTROLLED display
This indicates when the unit is con-
trolled by optional features such as
central control type remote controller.
TIMER display
This indicates when the continuous
operation and time operation modes
are set.
It also display the time for the timer
operation at the same time as when
it is set.
OPERATION MODE display
This indicates the operation mode.
STANDBY display
The [STANDBY] symbol is only dis-
played from the time the heating
operation starts unit the heated air
begins to blow.
DEFROST display
This indicates when the defrost oper-
ation is performed.
CHECK display
This indicates when a malfunction
has occurred in the unit which should
be checked.
CLOCK display
The current time , start time and stop
time can be displayed in ten second
intervals by pressing the time switch
button. The start time or stop time is
always displayed during the timer
operation.
●Display
In this display example on the bot-
tom left, a condition where all dis-
play lamps light is shown for expla-
nation purposes although this differs
from actual operation.
Operation lamp
This lamp lights during operation,
goes off when the unit stops and
flashes when a malfunction occurs.
POWER display
This lamp lights when electricity is
supplied to the unit.
SET TEMPERATURE display
This displays the selected setting
temperature.
AIR DIRECTION display
This displays the air direction.
ROOM TEMPERATURE display
The temperature of the suction air
is displayed during operation. The
display range is 8°C to 39°C. The
display flashes 8°C when the actual
temperature is less than 8°C and
flashes 39°C when the actual tem-
perature is greater than 39°C.
display
This display lights in the check mode
or when a test operation is per-
formed.
CHECK MODE
TEST RUN
This lamp lights when the filter need
to be cleaned.
AIR SPEED display
The selected fan speed is displayed.
FILTER display
PAR-20MAA
ON/OFF
CENTRALLY CONTROLLED
ERROR CODE
CLOCK
ON OFF
˚C
CHECK
CHECK MODE
FILTER
TEST RUN
FUNCTION
˚C
1Hr.
NOT AVAILABLE
STAND BY
DEFROST
FILTER
CHECK TEST
TEMP.
TIMER SET
(Not available for this model.)
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5
2SPECIFICATIONS
SEZ-A12AR.TH SEZ-A18AR.TH
Indoor model
Function
Power supply Single phase
230V, 50Hz
780/600
10
0.21
48
—
0.21
PK6V19-EF
1100o270o700
33.5
1
35/30
770/630
3
10
10
10
PAR-20MAA
Cooling
94
Heating
95
Single phase
230V, 50Hz
1020/720
20
0.27
61
—
0.27
PK6V32-EF
1100o270o700
33.5
1
39/31
840/640
3
10
10
10
PAR-20MAA
Cooling
97
Heating
98
Air flow (High/Low)
Power outlet
Running current ✽1
Power input Rated frequency
Auxiliary heater
Power factor ✽1
Fan motor current ✽1
Model
Winding
resistance (at20:)
Dimensions WoHoD
Weight
Air direction
Sound level (High/Low)
Fan speed (High/Low)
Fan speed regulator
Thermistor RT11 (at 25:)
Thermistor RT12 (at 25:)
Thermistor RT13 (at 25:)
Remote controller model
K/h
A
A
W
A(kW)
%
A
"
mm
kg
dB(A)
rpm
k"
k"
k"
Electrical data
Fan motor
Special remarks
Capacity
WHT-BLK : 251.4 BLK-BLU : 19.9
BLU-YLW : 26.5 YLW-BRN : 13.2
BRN-RED : 50.0
WHT-BLK : 161.9 BLK-BLU : 50.3
BLU-YLW : 18.7 YLW-BRN : 8.0
BRN-RED : 39.2
NOTE : Test conditions are based on ISO 5151
Cooling : Indoor D.B. 27:W.B. 19:
Outdoor D.B. 35:W.B. 24:
Heating : Indoor D.B. 20:W.B. 5:
Outdoor D.B. 7:W.B. 6:
Refrigerant piping length (one way): 5m
✽1 Measured under rated operating frequency.
SEZ-A12/18AR.TH : 2.5+ 440V SEZ-A24AR.TH : 3.0+ 440V
250V 3.15A
ERZV10D471
POWER SUPPLY : 3P TO OUTDOOR UNIT : 4P
G4A-1A-E-PS 12V DC
145:i2:
INDOOR UNIT
Item Model
Indoor fan capacitor
Fuse
Varistor
Terminal block
Contactor
Indoor fan motor thermal fuse
SEZ-A12AR.TH SEZ-A18AR.TH SEZ-A24AR.TH
(C1)
(FUSE)
(ZNR1)
(TB)
(52C)
Specifications and rating conditions of main electric parts
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6
SEZ-A24AR.TH
Indoor model
Function
Power supply Single phase
230V, 50Hz
1200/720
20
0.34
87
—
0.34
PK6V50-EF
1100o270o700
33.5
1
43/32
890/660
3
10
10
10
PAR-20MAA
Cooling
98
Heating
98
Air flow (High/Low)
Power outlet
Running current ✽1
Power input Rated frequency
Auxiliary heater
Power factor ✽1
Fan motor current ✽1
Model
Winding
resistance (at20:)
Dimensions WoHoD
Weight
Air direction
Sound level(High/Low)
Fan speed(High/Low)
Fan speed regulator
Thermistor RT11 (at 25:)
Thermistor RT12 (at 25:)
Thermistor RT13 (at 25:)
Remote controller model
K/h
A
A
W
A(kW)
%
A
"
mm
kg
dB(A)
rpm
k"
k"
k"
Electrical data
Fan motor
Special remarks
Capacity
WHT-BLK : 101.1 BLK-BLU : 56.1
BLU-YLW : 14.7 YLW-BRN : 6.7
BRN-RED : 28.2
NOTE : Test conditions are based on ISO 5151
Cooling : Indoor D.B. 27:W.B. 19:
Outdoor D.B. 35:W.B. 24:
Heating : Indoor D.B. 20:W.B. 15:
Outdoor D.B. 7:W.B. 6:
Refrigerant piping length (one way): 5m
✽1 Measured under rated operating frequency.
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7
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, dB (0 dB = 0.0002 µbar)
BAND CENTER FREQUENCIES, Hz
SEZ-A18AR.TH Hi
Lo 39
SPL(dB)
31
LINE
<50Hz>
NOTCH
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, dB (0 dB = 0.0002 µbar)
BAND CENTER FREQUENCIES, Hz
SEZ-A12AR.TH Hi
Lo 35
SPL(dB)
30
LINE
<50Hz>
NOTCH
NOISE CRITERION CURVES
UNIT
External static
pressure 30Pa 1.5m
MICROPHONE
90
80
70
60
50
40
30
20
10 63 125 250 500 1000 2000 4000 8000
APPROXIMATE
TERESHOLD OF
HEARING FOR
CONTINUOUS
NOISE
OCTAVE BAND SOUND PRESSURE LEVEL, dB (0 dB = 0.0002 µbar)
BAND CENTER FREQUENCIES, Hz
NC-60
NC-50
NC-40
NC-30
NC-20
NC-70
SEZ-A24AR.TH Hi
Lo 43
SPL(dB)
32
LINE
<50Hz>
NOTCH
NOTE: The sound level is measured in an anechoic room where echoes are few, when compressor stops. The sound
may be bigger than displayed level under actual installation condition by surrounding echoes. The sound level
can be higher by about 2 dB than the displayed level during cooling and heating operation.
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8
OUTLINES AND DIMENSIONS
3
SEZ-A12AR.TH
SEZ-A18AR.TH
SEZ-A24AR.TH
42 930
Terminal
block
3/8F
flared connection
[9.52mm
[6.35mm
flared connection
1/4F
SEZ-A24AR
SEZ-A18AR
Air outlet
duct flange
Air outlet duct flange
51
25
930
(Inlet size)
PLATE (B) o2
After installation, remove the
transportation support PLATE (B). PLATE (A)
In case of bottom side suction,
mount the PLATE (A) on the rear side.
39
955
7o100=700
100
77.5
(Inlet size)
215
Air inlet (bottom side) dimensions
wSelect the either
back side or bottom side.
Air inlet (rear side) dimensions
wSelect the either back side or bottom side.
29 955
7o100=70010077.5
240
120
12.5
25
(Inlet size)
(Inlet size)
Air inlet
(bottom side)
24-[2.9 holes
24-[2.9 holes
215
120
12.5 240
450
1/4F
flared connection
[6.35mm
(It is necessary to
maintain a working
service area from
the ceiling.)
150
(10) 50
Electrical parts box
2o2-[2.9
holes
50 880
7o100=700
100
40
9o2-[2.9 holes
100 32.5
75 170 25
(10) 50
flared connection
[15.88mm
5/8F
flared connection
1/2F
[12.7mm
Refrigerent pipe
(gas)
Refrigerent pipe
(liquid)
1/4F
flared connection
[6.35mm
SEZ-A12AR
Models
1000
50
5027 1016
77
150
600
Air inlet
(rear side) Electrical parts box
700
Access door
Service space
Air outlet
38
60
680
350
Suspension bolt pitch
Suspension bolt pitch
1070
Suspension bolt
M10 or 3/8
(procure locally)
(Suspension bolt pitch)
Electrical parts box
(1070)
1100
20 or more
270
30
Access door
Wiring entry
Refrigerent pipe (liquid)
Refrigerent pipe (gas)
Drain plug R1 male
108 20
94 80
25
350
Unit : mm
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9
4WIRING DIAGRAM
SEZ-A12AR.TH
SEZ-A18AR.TH
SEZ-A24AR.TH
FOR A18/24 (1:1 SYSTEM)
OR MULTI SYSTEM
FOR A12
(1:1 SYSTEM)
X5
X4
X2
REMOTE CONTROLLER
BOARD
R.B
RT12
RT11
I.B
RT13
FUSE
X4
X2
ZNR1
52C
4
3
w
TRANS
DC13.1V
BLK
C1
MF X5
N
wBLU
CIRCUIT BREAKER TB
GRN/YLW
N
wWHT
GRN/YLW
wBLU
TO OUTDOOR
UNIT
CONNECTING
wRED
L
12VDC
220-240V~
2
N
3
wWHT
TB
POWER SUPPLY
~/N
220-240V 220V
50Hz 60Hz
2
TO OUTDOOR
UNIT
CONNECTING
12V DC 3
[LEGEND]
INDOOR CONTROLLER
BOARD
I.B
52C COMPRESSOR CONTACTOR
RELAY(FAN MOTOR)
X2,X4,X5
NAME
SYMBOL NAME SYMBOL
VARISTOR
ZNR1
FUSE(3.15A)
FUSE
MF FAN MOTOR
ROOM TEMPERATURE
THERMISTOR
RT11
RT12 PIPE TEMPERATURE
THERMISTOR / LIQUID
C1 FAN MOTOR CAPACITOR
TERMINAL BLOCK
TB
RT13 CONDENSER / EVAPORATOR
TEMPERATURE THERMISTOR
1.Since the indoor fan motor(MF) is connected with 50Hz power,if 60Hz power is used, change the wiring
connection showing fig: *1
Indoor Fan Motor(MF) for 60Hz
2.About the outdoor side electric wiring refer to the outdoor unit electlic wiring diagram for servicing.
3.Use copper conductors only. (For field wiring)
4.Symbols below indicate.
: Terminal block : Connector
How to remove the terminals shown at " w" mark.
sleeve 1Slide the sleeve.
2Pull the wire while pushing the locking lever.
locking lever
" w" shows the terminals with a lock mechanism, so they cannot be removed when you pull the lead wire.
Be sure to pull the wire by pushing the locking lever (projected part) of the terminal with a finger.
NOTES:
60 BLUE
YELLOW
50
fig: *1
BLUE
BLU
TRANSMISSION WIRE
DC12V
2
1TB
CN2
R.B
1BLU
BLU
2
TB
(REMOCON)
BLU
CN22
21
2
2
1
1
(LIQUID)
(INTAKE)
CN21
CN20
RED
WHT
CN29
BLK 2
1
(2 PHASE)
FAN1
FAN2(FAN)
RED
CND(POWER)
(FAN)
5
3
1
7
5
3
1
WHT
WHT
BLU
YLW
1
3
5WHT
BRN
RED
ORN
★
★
★The 12V DC is NOT always against the ground.
Terminal 3 has 12V DC against terminal N.
However, between 3 and 2, these terminals are
NOT electrically insulated by the transformer or
other device.
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10
REFRIGERANT SYSTEM DIAGRAM
5
Pipe temperature
thermistor/liquid
(RT12)
Distributor
with strainer
#50
Condenser/evaporator
temperature thermistor
(RT13)
Room temperature
thermistor (RT11)
Refrigerant flow in cooling
Refrigerant flow in heating
Strainer
#50
Strainer
#50
Heat exchanger Refrigerant GAS pipe connection
(Flare)
Refrigerant LIQUID pipe connection
(Flare)
SEZ-A12AR.TH
SEZ-A18AR.TH
SEZ-A24AR.TH
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11
6TROUBLESHOOTING
6-1. Cautions on troubleshooting
(1) Before troubleshooting, check the followings:
1Check the power supply voltage.
2Check the indoor/outdoor connecting wire for mis-wiring.
(2) Take care the followings during servicing.
1Before servicing the air conditioner, be sure to first turn off the remote controller to stop the main unit, and then turn
off the breaker.
2When removing the indoor controller board, hold the edge of the board with care NOT to apply stress on the
components.
3When connecting or disconnecting the connectors, hold the housing of the connector. DO NOT pull the lead wires.
PAR-20MAA
ON/OFF
ERROR CODE
CHECK
CHECK MODE
FILTER
CHECK TEST
TEMP.
TIMER SET
A
B
C
ERROR CODE
CHECK
CHECK MODE
CHECK
CHECK MODE
DE
6-2. Self-check function
Wired remote controller
(1) Turn on the power.
(2) Press the [CHECK] button twice.
(3) Set refrigerant address with [TEMP] button
if system control is used.
(4) Press the [ON/OFF] button to stop the
self-check.
AACHECK button
BBRefrigerant address
CCTEMP button
DDIC : Indoor unit
OC : Outdoor unit
EECheck code
• For description of each check code, refer to the following table.
5101
5102
2503
2502
1503
0405, 1501, 4210, 5102
6831~6834
6800
– – – –
F F F F
Room temperature thermistor error
RT12, RT13, Outdoor thermistor error
Drain sensor error
Drain pump error
Freezing safeguard operation
Outdoor unit error
Signal error between remote controller and indoor units
Communication error between indoor and outdoor units
No alarm history
No unit
1Check code Symptom
• On wired remote controller
1Check code displayed in the LCD.
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12
6-3. Trouble shooting
(1) In case of being indicated irregularity on the self diagnoses
Mis-wiring6800
5102
5101
Indoor-outdoor
signal error
Wiring between the indoor and
outdoor is coming off.
Difference of wiring polarity
between the indoor and outdoor.
Trouble of the outdoor inverter
P.C. board.
Check the wiring out between the indoor and
outdoor.
Check the outdoor inverter P.C. board. Refer to the
TECHNICAL & SERVICE MANUAL of outdoor unit.
Trouble of the Indoor controller
board. Exchange the Indoor controller board.
Pipe temperature thermistor
/ Liquid. Mis-connecting of the pipe temperature thermistor / Liquid. Reinsert the connector (CN21).
Trouble of the pipe temperature
thermistor / Liquid.
Trouble of the Indoor controller
board. Exchange the Indoor controller board.
Check the resistance value of the thermistor.
Room temperature
thermistor Mis-connecting of the room temperature thermistor. Reinsert the connector (CN20).
Trouble of the room temperature
thermistor.
Trouble of the Indoor controller
board. Exchange the Indoor controller board.
Check the resistance value of the thermistor.
Condenser / evaporator
temperature thermistor Mis-connecting of the condenser / evaporator temperature thermistor. Reinsert the connector (CN29).
Trouble of the condenser / evaporator
temperature thermistor.
Trouble of the Indoor controller
board. Exchange the Indoor controller board.
Check the resistance value of the thermistor.
Phenomenon
Check
code Cause Countermeasure
1503
0405
1501
4210
Freezing protection is
working. 1) Short cycle of air cycle
2) Dirty air filter
3) Damaged fan
4) Abnormal refrigerant
1) Clear obstructions from air cycle.
2) Clean the air filter
3) Check the fan
4) Check the refrigerant temperature.
Malfunction of outdoor unit Malfunction of outdoor unit Refer to the TECHNICAL & SERVICE MANUAL
of outdoor unit.
Outdoor thermistor Mis-connecting of the outdoor
thermistor. Reinsert the connector.
Trouble of the outdoor thermistor.
Trouble of the outdoor inverter P.C.
board. Exchange the outdoor inverter P.C. board.
Check the resistance value of the thermistor.
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13
(2) Other case
Not working of remote
controller switch ON/OFF
Short circuit the protecting parts in the
Indoor controller board.
Trouble of the Indoor controller board. Check the Indoor controller board out.
Wiring between the indoor and the wired
remote controller is coming off. Check the wiring between the Indoor and the wired remote controller.
Trouble of the remote controller.
Check the varistor (ZNR1) and fuse (FUSE) out in
the Indoor controller board.
Exchange the remote controller.
Wiring between the indoor and outdoor is
coming off.
Working the Indoor units
and not working the outdoor
units.
Check the wiring out between the indoor and
outdoor.
Difference of wiring polarity between the
indoor and outdoor.
Trouble of the outdoor inverter P.C. board.
Trouble of the contactor (52C). Exchange the contactor.
Check the outdoor inverter P.C. board.
Malfunction of outdoor unit. Refer to the TECHNICAL & SERVICE MANUAL of
outdoor unit.
Fan motor connector is coming off.
Not rotating the fan in the
indoor unit.
Trouble of the Indoor controller board.
Check the fan motor output of the Indoor controller
board.
Check the connector out.
Trouble of the fan motor. Check the resistance value between the each tap
of fan motor.
A connector attaching the panel to the body
is not connected.
Horizontal vane doesn't work.
Check if the connector for vane motor is connected.
Connect it.
A connector attaching the panel to the body
is not connected.
Fixing of horizontal vane.
Connect it.
Phenomenon Cause Countermeasure
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14
Yes
No
No
Yes
Yes
No
Yes
No
Yes
No
No
Yes
Check code : 6800
Indoor controller board is defective.
Connection is defective.
Error was found in the signal transmitted or
received between the indoor and outdoor units.
Turn off the power supply and turn it on again to operate the unit in
cooling or heating mode.
Is the connecting wire between
the indoor and outdoor units
connected properly?
Normal
Operation lamp blinks once in a
fixed period.
Remove the devices.
Are there any devices emitting
noise near the power supply or
the connecting wire between the
indoor and outdoor units?
Check code : 5101
Measure the resistance of
room temperature thermistor.
Indoor controller board is defective.
Check the room temperature thermistor.
Turn off the power supply and turn it on again to operate the unit in
cooling mode.
Is the connector CN20 on the
indoor controller board connected?
Connection is defective.
Room temperature
thermistor is defective.
Is the resistance 0 (short circuit) or
∞(open circuit)?
Normal
Operation lamp blinks twice in a
fixed period.
Check of indoor controller board and indoor fan motor
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15
Yes
No
Yes
No
No
Yes
Yes
No
Measure the resistance
of the pipe temperature
thermistor / liquid.
Indoor controller board is defective.
Check the pipe temperature
thermistor / liquid.
Turn off the power supply and turn it on again to operate the unit in
cooling mode.
Connection is defective.
Is the connector CN21 on the
indoor controller board connected?
Pipe temperature
thermistor / liquid
is defective.
Is the resistance 0 (short circuit) or
∞(open circuit)?
No
Yes
Yes
No Measure the resistance of
condenser/evaporator
temperature thermistor.
Check the condenser/evaporator
temperature thermistor.
Is the connector CN29 on the
indoor controller board connected?
Refer to the TECHNICAL &
SERVICE MANUAL of
outdoor unit.
Is the error of indoor unit?
Connection is defective.
Condenser/evaporator
temperature thermistor
is defective.
Is the resistance 0 (short circuit) or
∞(open circuit)?
Normal
Operation lamp blinks twice in a
fixed period.
Check code : 5102
Yes
No
Yes
No
Indoor fan motor does not rotate.
Measure the resistance of connectors FAN1
and 2 on the indoor controller board.
Connection is defective.
Turn off the power supply and check the connectors
FAN1 and 2 on the indoor controller board visually.
Indoor fan motor is defective.
Are the connectors FAN1 and 2
connected?
Indoor controller board is defective.
Is the resistance 0 (short circuit) or
∞(open circuit)?
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16
6-4. Test point of indoor controller board
Indoor controller board
•Room temperature thermistor (RT11)
•Pipe temperature thermistor/liquid (RT12)
•Condenser/evaporator temperature
thermistor (RT13)
0
10
20
30
40
50
-20 -10 0 10 20 30 40 50
< Thermistor for lower temperature >
Temperature (:)
Resistance (K")
Fuse 250V AC 3.15A
Room temperature thermistor (RT11)
Pipe temperature thermistor/liquid (RT12)
Power supply
input 220-240V AC
Drain sensor (DS)
Condenser/evaporator
temperature thermistor
(RT13)
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17
6-5. Trouble criterion of main parts
SEZ-A12AR.TH
SEZ-A18AR.TH
SEZ-A24AR.TH
BLK RED
GRN
YLW
ORNYLW
BLU BRN WHT
P
Room temperature
thermistor
(RT11)
Condenser/evaporator
temperature thermistor
(RT13)
Measure the resistance with a tester.
(Part temperature 10°C ~ 30°C)
Measure the resistance between the terminals with a tester.
(Coil wiring temperature 10°C ~ 30°C)
P: Thermal fuse
145 ±2˚C
Pipe temperature
thermistor/liquid
(RT12)
Indoor fan motor
(MF)
Check method and criterion
Part name
Normal
A12AR Normal
WHT-BLK
BLK-BLU
BLU-YLW
YLW-BRN
BRN-RED
241.4~261.2Ω
19.0~20.6Ω
25.4~27.5Ω
12.6~13.7Ω
47.9~51.9Ω
A18AR
155.5~168.2Ω
48.3~52.3Ω
17.8~19.4Ω
7.6~8.3Ω
37.6~40.7Ω
A24AR
97.0~105Ω
53.8~58.3Ω
14.0~15.3Ω
6.3~6.9Ω
27.0~29.3Ω
8kΩ~20kΩAbnormal
Abnormal
Opened or
short-circuited
Opened or short-circuited
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18
DISASSEMBLY PROCEDURE7
1. Removing the electrical parts
(1) Remove the 2 screws and the electrical parts cover.
(See Photo 1.)
●Indoor controller board (I.B)
●Compressor contactor (52C)
●Fuse (FUSE)
●Varistor (ZNR1)
●Terminal block (TB) (See Photo 2.)
OPERATING PROCEDURE PHOTOS
2. Removing the pipe temperature thermistor (RT12)
(1) Remove the electrical parts cover. (Refer to 1.)
(2) Remove the 2 screws and the service panel.
(See Photo 3.)
(3) Remove the thermistor (RT12) from the holder.
(See Photo 4.)
(4) Remove the connector (CN21) from the indoor
controller board and pull the white wire of thermistor
(RT12) out.
Service panel
(Pipe temperature
thermistor / liquid)
Front panel
Set screws
(for drain pan)
Set screws
Terminal block
Photo 2.
Photo 3.
Photo 1.
SEZ-A12AR.TH
SEZ-A18AR.TH
SEZ-A24AR.TH
Electrical
parts cover
Service panel
(Condenser / evaporator
temperature thermistor)
Drain
pan
Indoor
controller box
Indoor controller board
Varistor
Fuse
Compressor contactor
Condenser / evaporator
temperature thermistor (RT13)
Screws
Screws
Service
panel
Photo 4.
3. Removing the condenser / evaporator temperature
thermistor (RT13)
(1) Remove the electrical parts cover. (Refer to 1.)
(2) Remove the 2 screws and the service panel.
(See Photo 3.)
(3) Remove the thermistor (RT13) from the holder.
(See Photo 4.)
(4) Remove the connector (CN29) from the indoor
controller board and pull the black wire of thermistor
(RT13) out.
Pipe temperature
thermistor / liquid
(RT12)
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19
4. Removing the room temperature thermistor (RT11)
(1) Remove the electrical parts cover. (Refer to 1.)
(2) Remove the front panel at fan side. (12 screws)
(See Photo 1.)
(3) Remove the thermistor (RT11) from the separator (panel).
(See Photo 6.)
(4) Disconnect the connector (CN20)from the indoor
controller board and pull the lead wire of
thermistor (RT11) out.
PHOTOS
OPERATING PROCEDURE
5. Removing the sirocco fan and the fan motor (MF).
(1) Remove the electrical parts cover. (Refer to 1.)
(2) Remove the front panel at fan side.(12 screws)
(See Photo 1.)
(3) Disconnect the fan motor connector (FAN1, FAN2) from
the indoor controller board. (See Photo 2.)
(4) Undo the 4 claws and remove the fan claws.(down side)
<Either left or right> (See Photo 5.)
(5) Remove the motor bands.
<A screw each on left and right.> (See Photo 5.)
(6) Disconnect the earth wire from the fan motor leg.
(See Photo 7.)
(7) Remove the fan motor and the sirocco fan by assembly.
(See Photo 7.)
(8) Unscrew the setting screw and remove the sirocco fan.
<Either left or right> (See Photo 7.)
Set screw
Earth wire
Motor bands
Claws Screws
Fan casing
Fan motor
Claws
Photo 5.
Photo 7.
Fan casing
Fan motor Room temperature
thermistor (RT11)
Photo 6. Separator
(panel)
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20
6. Removing the drain pan
(1) Unscrew each set screw on the right and left, and
remove the drain pan pushing it toward the the back.
(See Photo 1.)
PHOTOS
OPERATING PROCEDURE
7. Removing the heat exchanger
(1) Remove the drain pan. (Refer to 1.)
(2) Remove the Under flange at heat exchanger side.
(16 screws) (See Photo 8.)
(3) Remove the 4 screws of heat exchanger.( 2 screws
each on left and right) (See Photo 9.)
(4) Remove the thermistor (RT12) from the holder.
(Refer to 2.)
(5) Remove the thermistor (RT13) from the holder.
(Refer to 3.)
(6) Remove the service panel.( 3 screws )
(See Photo 9.)
(7) Put the heat exchanger down to the fan motor and
pull it toward you. (See Photo 9.)
Screws
(for heat exchanger) Screws
(for service panel)
Photo 8.
Photo 9.
Heat exchanger
Under flange
Screws
Service
panel
OC303-A-1.qxp 04.9.21 4:08 PM Page 20