Mitsubishi SEZ-A12AR.TH, SEZ-A18AR.TH, SEZ-A24AR.TH Service Manual

SPLIT-TYPE, HEAT PUMP AIR CONDITIONERS

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.

TECHNICAL & SERVICE MANUAL

No. OC303

Series SEZ

Ceiling Concealed

R410A

Indoor unit
[Model names] [Service Ref.]

SEZ-A12AR SEZ-A12AR.TH
SEZ-A18AR SEZ-A18AR.TH
SEZ-A24AR SEZ-A24AR.TH

•This manual does not cover
the following outdoor units.
When servicing them,
please refer to the service
manual No.OC304 and this
manual in a set.

CONTENTS

1. PART NAMES AND FUNCTIONS········2

2. SPECIFICATIONS·································4

3. OUTLINES AND DIMENSIONS············7

Model name
indication

4. WIRING DIAGRAM ·······························8

5.

REFRIGERANT SYSTEM DIAGRAM

········9

6. TROUBLESHOOTING························10

7. DISASSEMBLY PROCEDURE ···········17

INDOOR UNIT

8. PARTS LIST········································20

9. OPTIONAL PARTS·····························22

WIRED REMOTE

CONTROLLER

1

Air outlet duct flange

Air outlet

Air inlet
(Selecting the either back side or bottom side)

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.)

PART NAMES AND FUNCTIONS

Indoor Unit
SEZ-A12AR.TH
SEZ-A18AR.TH
SEZ-A24AR.TH

Wired remote controller

On the controls are set, the same operation mode can be repeated by simply pressing the ON/OFF button.

● Operation buttons

2

● 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

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.

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.

In this display example on the bot­tom left, a condition where all dis­play lamps light is shown for expla­nation purposes although this differs
from actual operation.

AIR DIRECTION display

This displays the air direction.

(Not available for this model.)

AIR SPEED display

The selected fan speed is displayed.

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 tem­perature is greater than 39°C.

Operation lamp

This lamp lights during operation,
goes off when the unit stops and
flashes when a malfunction occurs.

This display lights in the check mode
or when a test operation is per­formed.

CHECK MODE

TEST RUN

display

FILTER display

CHECK display

This indicates when a malfunction

has occurred in the unit which should
be checked.

SET TEMPERATURE display

This displays the selected setting

temperature.

Caution

● Only the Power display lights when the unit is stopped and power supplied to the unit.

● When the central control remote control unit, which is sold separately, is used the ON-OFF button, operation switch button

and TEMP. adjustment button do not operate.

● “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.

POWER display

This lamp lights when electricity is
supplied to the unit.

This lamp lights when the filter need
to be cleaned.

3

2

SEZ-A12AR.TH SEZ-A18AR.TH

Indoor model

Function

Power supply

Single phase

230V, 50Hz

780/600

10

0.21
33
—

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
49
—

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

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

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.

Specifications and rating conditions of main electric parts

4

Indoor model

SEZ-A24AR.TH

Function

Power supply

Capacity

NOTE : Test conditions are based on ISO 5151

Air flow (High/Low)
Power outlet
Running current ✽1
Power input Rated frequency
Auxiliary heater

Electrical

data

Power factor ✽1
Fan motor current ✽1
Model

Winding

Fan

motor

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:)

Special remarks

Thermistor RT13 (at 25:)
Remote controller model

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.

K /h

A
A

W

A(kW)

%

A

"

mm

kg

dB(A)

rpm

k"
k"
k"

WHT-BLK : 101.1 BLK-BLU : 56.1
BLU-YLW : 14.7 YLW-BRN : 6.7
BRN-RED : 28.2

Cooling

98

Heating

Single phase

230V, 50Hz

1200/720

20

0.34
64
—

98

0.34

PK6V50-EF

1100o270o700

33.5

1

43/32

890/660

3
10
10
10

PAR-20MAA

5

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.

6

3

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

7

o100=700

100

77.5

(Inlet size)

215

Air inlet (bottom side) dimensions

w Select the either

back side or bottom side.

Air inlet (rear side) dimensions

w Select the either back side or bottom side.

29

955

7

o100=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

7

o100=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

50

27

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

OUTLINES AND DIMENSIONS

SEZ-A12AR.TH
SEZ-A18AR.TH
SEZ-A24AR.TH

Unit : mm

7

4

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

w BLU

CIRCUIT BREAKER

TB

GRN/YLW

N

w WHT

GRN/YLW

w BLU

TO OUTDOOR
UNIT
CONNECTING

w RED

L

12VDC

220-240V~

2

N

3

w WHT

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

1

TB

CN2

R.B

1

BLU

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

5

WHT

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.

WIRING DIAGRAM

SEZ-A12AR.TH
SEZ-A18AR.TH
SEZ-A24AR.TH

8

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)

REFRIGERANT SYSTEM DIAGRAM

SEZ-A12AR.TH
SEZ-A18AR.TH
SEZ-A24AR.TH

9

6

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

• 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

1 Check code Symptom

• On wired remote controller
1 Check code displayed in the LCD.

TROUBLESHOOTING

6-1. Cautions on troubleshooting

(1) Before troubleshooting, check the followings:

1 Check the power supply voltage.
2 Check the indoor/outdoor connecting wire for mis-wiring.

(2) Take care the followings during servicing.

1 Before servicing the air conditioner, be sure to first turn off the remote controller to stop the main unit, and then turn

off the breaker.

2 When removing the indoor controller board, hold the edge of the board with care NOT to apply stress on the

components.

3 When connecting or disconnecting the connectors, hold the housing of the connector. DO NOT pull the lead wires.

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.

AA

CHECK button

BB

Refrigerant address

CC

TEMP button

DD

IC : Indoor unit
OC : Outdoor unit

EE

Check code

10

6-3. Trouble shooting

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.

(1) In case of being indicated irregularity on the self diagnoses

11

(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

12

Check of indoor controller board and indoor fan motor

Check code : 6800

Error was found in the signal transmitted or
received between the indoor and outdoor units.

Is the connecting wire between
the indoor and outdoor units

No

Connection is defective.

connected properly?

Are there any devices emitting
noise near the power supply or
the connecting wire between the

Yes

Yes

Remove the devices.

Turn off the power supply and turn it on again to operate the unit in
cooling or heating mode.

Operation lamp blinks once in a

No

Normal

fixed period.

Yes

Indoor controller board is defective.

indoor and outdoor units?

No

Check code : 5101

Check the room temperature thermistor.

Is the connector CN20 on the
indoor controller board connected?

No

Connection is defective.

Yes

Room temperature
thermistor is defective.

Turn off the power supply and turn it on again to operate the unit in
cooling mode.

No

Normal

Measure the resistance of
room temperature thermistor.

Is the resistance 0 (short circuit) or
∞ (open circuit)?

Operation lamp blinks twice in a
fixed period.

Indoor controller board is defective.

Yes

No

Yes

13

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)?

14

6-4. Test point of 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")

Indoor controller board

Pipe temperature thermistor/liquid (RT12)
Condenser/evaporator
temperature thermistor
(RT13)

Room temperature thermistor (RT11)

Drain sensor (DS)

Power supply
input 220-240V AC

Fuse 250V AC 3.15A

15

6-5. Trouble criterion of main parts

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~20kΩ

Abnormal

Abnormal

Opened or

short-circuited

Opened or short-circuited

SEZ-A12AR.TH
SEZ-A18AR.TH
SEZ-A24AR.TH

16

DISASSEMBLY PROCEDURE7

SEZ-A12AR.TH
SEZ-A18AR.TH
SEZ-A24AR.TH

OPERATING PROCEDURE PHOTOS

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.)

Photo 1.

Service panel
(Pipe temperature

thermistor / liquid)

Electrical
parts cover

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.

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.

Drain
pan

Service panel
(Condenser / evaporator

temperature thermistor)

Photo 2.

Terminal block

Indoor controller board

Photo 3.

Screws

Service
panel

Set screws
(for drain pan)

Compressor contactor

Photo 4.

Set screws

Front panel

Indoor
controller box

Varistor

Fuse

Pipe temperature
thermistor / liquid
(RT12)

17

Screws

Condenser / evaporator
temperature thermistor (RT13)

OPERATING PROCEDURE

PHOTOS

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.

Photo 5.

Photo 6.

Fan motor

Claws

Claws

Motor bands

Screws

Fan casing

Fan casing

Fan motor

Separator
(panel)

Room temperature
thermistor (RT11)

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.)

Photo 7.

Set screw

Earth wire

18

OPERATING PROCEDURE

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.)

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.)

Photo 8.

PHOTOS

Screws

Under flange

Photo 9.

Screws

(for heat exchanger)

Heat exchanger

Service
panel

Screws
(for service panel)

19

PARTS LIST8

No.

Parts No.

Parts name

Specification

Remarks

Unit

Amount

Wiring

Diagram

Symbol

Recom­mended

Q'ty

Q'ty/set

Price

1
2
3

4

5
6
7
8
9

10

11
12
13
14
15

LEFT SIDE PANEL
SIROCCO FAN
FAN MOTOR RUBBER MOUNT
FAN MOTOR
FAN MOTOR
FAN MOTOR
ROOM TEMPERATURE THERMISTOR
FRONT PANEL
DRAIN PAN

PIPE TEMPERATURE THERMISTOR / LIQUID

INDOOR HEAT EXCHANGER
INDOOR HEAT EXCHANGER
INDOOR HEAT EXCHANGER
RIGHT SIDE PANEL
SEPARATOR ASSY
LEFT LEG
BASE
RIGHT LEG

E07 039 086
E07 039 500
E02 179 505
E07 039 300
E07 040 300
E07 041 300
E07 143 308
E07 039 000
E07 039 700
E07 143 309
E07 136 307
E07 143 620
E07 144 620
E07 145 620
E07 143 085
E07 143 293
E07 039 809
E07 039 290
E07 039 808

(Drawing No.)

MF
MF
MF
RT11

RT13
RT12

PK6V19-EF
PK6V32-EF
PK6V50-EF

SEZ-

A18AR.THA12AR.TH A24AR.TH

<2PCS/SET>

1
2
2
1

1
1
1
1
1
1

1
1
2
1
2

1
2
2

1

1
1
1
1
1

1

1
1
2
1
2

1
2
2

1
1
1
1
1
1

1
1
1
2
1
2

CONDENSER / EVAPORATOR
TEMPERATURE THERMISTOR

INDOOR UNIT
STRUCTURAL PARTS
SEZ-A12AR.TH
SEZ-A18AR.TH
SEZ-A24AR.TH

14

13

12

11

1

10

2
3

Part number that is circled is not shown in the illustration.

9
8

7

4

5

20

6

L

N

3

N

N

3

2

TO OUTDOOR

UNIT

POWER

SUPPLY

TO REMOTE

CONTROLLER

No.

Parts No.

Parts name

Specification

250/3.15A

4P
3P
2P

Remarks

(Drawing No.)

Unit

Amount

Wiring

Diagram

Symbol

Recom­mended

Q'ty

Q'ty/set

Price

1

2
3
4
5
6
7
8
9

10

INDOOR CONTROLLER BOARD
INDOOR CONTROLLER BOARD
INDOOR CONTROLLER BOARD
COMPRESSOR CONTACTOR
FUSE
VARISTOR
TERMINAL BLOCK
TERMINAL BLOCK
TERMINAL BLOCK
REMOTE CONTROLLER
REMOTE CONTROLLER CABLE
CONTROLLER COVER

E07 143 447
E07 144 447
E07 145 447
E07 140 340
E02 127 382
E02 661 385
E02 257 375
E02 367 377
E02 007 375
E07 136 426
E07 018 089
E07 039 449

I.B
I.B
I.B

52C
FUSE
ZNR1

TB
TB
TB

R.B

1

1
1
1
1
1
1
1
1
1

1

1
1
1
1
1
1
1
1
1

1
1
1
1
1
1
1
1
1
1

SEZ-

A18AR.THA12AR.TH A24AR.TH

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.

INDOOR UNIT
ELECTRICAL PARTS
SEZ-A12AR.TH
SEZ-A18AR.TH
SEZ-A24AR.TH

1

7

6

5

8

9

4

Part numbers that is circled is not shown in the illustration.

2

21

3

9

OPTIONAL PARTS

9-1. REFRIGERANT PIPES

The air conditioner has flared connections its indoor and outdoor sides.
Please use the optional extension pipe as follows.

Applied unit

SEZ-A12AR.TH

SEZ-A18AR.TH

SEZ-A24AR.TH

Models Pipe length

MAC-680PI
MAC-681PI
MAC-682PI
MAC-683PI
MAC-684PI

MAC-670PI
MAC-671PI
MAC-672PI
MAC-673PI
MAC-674PI

MAC-860PI
MAC-861PI
MAC-862PI
MAC-863PI
MAC-864PI

3m
5m

7m
10m
15m

3m

5m

7m
10m
15m

3m

5m

7m
10m
15m

Cross-section A-Gas

Pipe size O.D.mm (in.)

B-liquid

{9.52

(3/8)

{12.7

(1/2)

{6.35

(1/4)

{15.88

(5/8)

Insulation

CD

{27

{31

{21

{27

Additional

refrigerant

charge

R410A (g)

0

60
150
300

0

40
100
200

0

40
100
200

9-2. AIR FILTER

Applied unit

SEZ-A12AR.TH
SEZ-A18AR.TH
SEZ-A24AR.TH

Models

PAC - 1000 FT

22

HEAD OFFICE : MITSUBISHI DENKI BLDG., 2-2-3, MARUNOUCHI, CHIYODA-KU, TOKYO 100-8310, JAPAN

CCopyright 2004 MITSUBISHI ELECTRIC ENGINEERING CO., LTD.
Distributed in Mar. 2004 No. OC303 PDF 8
Made in Japan.

New publication, effective Mar. 2004.
Specifications subject to change without notice.