Mitsubishi Electric Mr. Slim MS-A09WA User manual

SERVICE MANUAL
CONTENTS
1. TECHNICAL CHANGES ··································· 2
2. PART NAMES AND FUNCTIONS····················· 3
3. SPECIFICATION················································ 5
4. OUTLINES AND DIMENSIONS ························ 6
5. WIRING DIAGRAM············································ 7
6. REFRIGERANT SYSTEM DIAGRAM ··············· 7
7. SERVICE FUNCTIONS ····································· 8
8. TROUBLESHOOTING······································· 9
9. DISASSEMBLY INSTRUCTIONS···················· 21
10. PARTS LIST····················································· 24
10-1. PARTS LIST············································· 24
10-2. RoHS PARTS LIST ·································· 27
11. MICROPROCESSOR CONTROL···················· 30
Models
MS-A09WA
MS-A09WA - 1
MS-A12WA
MS-A12WA - 1
NOTE:
RoHS compliant products have <G> mark on the spec name plate.
For servicing of RoHS compliant products, refer to the RoHS PARTS
LIST (RoHS compliant).
INDOOR UNIT
Outdoor unit service manual
MU-A•WA Series (OB449)
Revision C:
• TEST POINT DIAGRAM AND VOLTAGE has
been corrected. (8-7)
Please void OB448 REVISED EDITION-B.
No. OB448
REVISED EDITION-C

MS-A09WA MS-A09WA -1
MS-A12WA MS-A12WA -1
1. Remote controller has been changed.
• Temperature indication function (°F/°C) has been added. (Refer to 11-8.)
Models Remote controller Temperature indication
MS-A09/12WA KM06C °F
MS-A09/12WA- 1KM07L °F/°C
• Timer indication has been changed. (AM/PM indication)
2. Conduit plate has been removed.
3. Conduit cover, terminal block cover and terminal block holder have been changed.
2
1TECHNICAL CHANGES
MS09TW MS-A09WA
MS12TN MS-A12WA
1.Indoor fan motor has been changed.
2.Signal of remote controller has been changed. (It is not available for conventional models.)
Revision A :
• MS-A•WA-1have been added.
Remote controller has been changed.
Revision B :
• SPECIFICATION has been corrected.
Powerful has been added. (Airflow ,Sound level)
Revision C:
• TEST POINT DIAGRAM AND VOLTAGE has been corrected. (8-7)

3
PART NAMES AND FUNCTIONS
2
MS-A09WA
MS-A12WA
Line flow fan
Air outlet
Vertical vane
Air inlet
Display section
Front panel
Panel
Heat exchanger
Horizontal vane
Operation section
(When the front panel is opened)
Remote controller
Remote control
receiving section
Catechin air filter
Air cleaning filter
(Anti-Allergy Enzyme
Filter, Blue bellows
type)
Emergency operation switch
Operation Indicator
lamp

4
ACCESSORIES
MS-A09WA
MS-A12WA
MS-A09/12WA MS-A09/12WA- 1
Installation plate 1 1
Installation plate fixing screw 4 × 25 mm 8 5
Remote controller holder 1 1
Fixing screw for 3.5 × 1.6 mm (Black) 2 2
Battery (AAA) for remote controller 2 2
Wireless remote controller 1 1
Felt tape (Used for left or left-rear piping) 1 1
Conduit plate 1 —

5
SPECIFICATION
3
Model MS-A09WA MS-A12WA
Indoor unit model MS-A09WA MS-A12WA
External finish White
Power supply V, phase, Hz 115, 1, 60
Max.-fuse size (time delay) /
Disconnect switch A15
Min. circuit ampacity A 1.2
Fan motor F.L.A 0.95
Airflow
Low–Med.–High–Powerful
COOL
Dry (Wet) CFM 183 - 261 - 335 - 367 (162 - 233 - 300 - 328)
222 - 286 - 406 - 446
(198 - 254 - 363 - 399)
Moisture removal pt./h 2.7 3.2
Sound level
Low–Med.–High–Powerful dB(A) 26 - 32 - 40 - 42 33 - 38 - 45 - 47
Cond. drain connection O.D. in. 5/8
Dimensions
W
in.
30-11/16
D 8-1/4
H 11/-3/4
Weight Ib. 23
Remote controller Wireless type
Control voltage (by built-in transformer) 115 VAC
NOTE : Test conditions are based on ARI 210/240
1 : Rating conditions (cooling) — Indoor : 80˚FDB, 67˚FWB, Outdoor : 95˚FDB, (75˚FWB) Rated frequency : 60Hz
Operating Range
Indoor intake air temperature Outdoor intake air temperature
Cooling Maximum 95˚FDB, 71˚FWB 115˚FDB
Minimum 67˚FDB, 57˚FWB 67˚FDB

6
4OUTLINES AND DIMENSIONS
MS-A12WA
Unit : inch
MS-A09WA
11-3/4
424-9/16
30-11/16
8-1/4 3/16
2-1/8
3/4
6-1/4
2-5/16
Air in
Air out
Installation plate
6-1/8 6-1/8
7/8
1-3/4
13-3/16 12-5/8
1-5/8 8-7/16
10-1/8
1-11/16
8-7/16
1/8 11-5/16
2-3/4
2-3/16
2-3/16 2-3/16
8-7/8 8-7/8
9/1610-3/4
9-3/16
Wall hole 2-9/16
Indoor unit
Installation plate
7/16x13/16 Oblong hole
7/16x1 Oblong hole
7/8
hole
Conduit plate(MS-A•WA- is excluded.)
3/4 I.D
Insulation 1-1/8
Drain hose 5/8
(Connected part O.D)
Liquid line 1/4 19-11/16
Gas line 3/8 16-15/16
Insulation 1-3/8 O.D
{

7
WIRING DIAGRAM
5
REFRIGERANT SYSTEM DIAGRAM
6
MS-A09WA
MS-A12WA
Indoor
heat
exchanger
Flared connection
Room temperature
thermistor
RT11
Flared connection
Refrigerant flow in cooling
Refrigerant pipe 3/8 (MS-A09)
1/2 (MS-A12)
(with heat insulator)
Refrigerant pipe 1/4
(with heat insulator)
Indoor coil
thermistor
RT12
Unit : inch
MS-A09WA
MS-A12WA

8
7SERVICE FUNCTIONS
7-1. TIMER SHORT MODE
For service, set time can be shortened by short circuit of JPG and JPS the electronic control P.C. board.
The time will be shortened as follows. (Refer to 8-7.)
Set time : 1-minute 1-second
Set time : 3-minute 3-second (It takes 3 minutes for the compressor to start operation. However, the starting time is
shortened by short circuit-of JPG and JPS.)
7-2. P.C. BOARD MODIFICATION FOR INDIVIDUAL OPERATION
A maximum of 4 indoor units with wireless remote controllers can be used in a room.
In this case, to operate each indoor unit individually by each remote controller, P.C. boards of remote controller must be
modified according to the number of the indoor unit.
How to modify the remote controller P.C. board
Remove batteries before modification.
The board has a print as shown below :
Table 1
1 unit operation 2 units operation 3 units operation 4 units operation
No. 1 unit No modification Same as at left Same as at left Same as at left
No. 2 unit — Solder J1 Same as at left Same as at left
No. 3 unit — — Solder J2 Same as at left
No. 4 unit — — — Solder both J1 and J2
How to set the remote controller exclusively for particular indoor unit.
After you turn the breaker ON, the first remote controller that sends the signal to the indoor unit will be regarded as the remote
controller for the indoor unit.
The indoor unit will only accept the signal from the remote controller that has been assigned to the indoor unit once they are
set.
The setting will be cancelled if the breaker has turned off, or the power supply has shut down.
Please conduct the above setting once again after the power has restored.
The P.C. board has the print “J1” and “J2”. Solder “J1” and “J2” according to the number of indoor unit as shown in Table 1.
After modification, press the RESET button.
NOTE : For modification, take out
the batteries and press
the OPERATE/STOP(ON/
OFF)button twice or 3
times at first.
After finish modification,
put back the batteries then
press the RESET button.
J2
J1
MS-A09WA
MS-A12WA

9
TROUBLESHOOTING
8
8-1. CAUTIONS ON TROUBLESHOOTING
1. Before troubleshooting, check the following
1) Check the power supply voltage.
2) Check the indoor/outdoor connecting wire for miswiring.
2. Take care of the following during servicing
1) Before servicing the air conditioner, be sure to turn off the 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 electronic control P.C. board, hold the edge of the board with care NOT to apply stress on the com-
ponents.
4) When connecting or disconnecting the connectors, hold the housing of the connector. DO NOT pull the lead wires.
MS-A09WA MS-A12WA
NOTE:
• The operation settings are memorized when 10 seconds have passed after the indoor unit was operated with the
remote controller.
• If main power is turned OFF or a power failure occurs while AUTO START/STOP timer is active, the timer setting is
cancelled.
• If the unit has been off with the remote controller before power failure, the auto restart function does not work as the
power button of the remote controller is off.
• To prevent breaker off due to the rush of starting current, systematize other home appliance not to turn on at the
same time.
• When some air conditioners are connected to the same supply system, if they are operated before power failure, the
starting current of all the compressors may flow simultaneously at restart.
Therefore, the special counter-measures are required to prevent the main voltage-drop or the rush of the starting
current by adding to the system that allows the units to start one by one.
JR07
CN151 CN211CN112 CN1R1
BZ
7-3. AUTO RESTART FUNCTION
When the indoor unit is controlled with the remote controller, the operation mode, the set temperature, and the fan speed
are memorized by the indoor electronic control P.C. board. The “AUTO RESTART FUNCTION” sets to work the moment
power has restored after power failure. Then, the unit will restart automatically.
Operation
If the main power has been cut, the operation settings remain.
After the power is restored, the unit restarts automatically according to the memory.
(However, it takes at least 3 minutes for the compressor to start running.)
How to release “AUTO RESTART FUNCTION”
Turn off the main power for the unit.
Solder the Jumper wire JR07 on the indoor electronic control P.C. board. (Refer to 8-7.)
Lead wiring Housing point

10
3. Troubleshooting procedure
1) First, check if the OPERATION INDICATOR lamp on the indoor unit is flashing on and off to indicate an abnormality.
To make sure, check how many times the abnormality indication is flashing on and off before starting service work.
2) Before servicing check that the connector and terminal are connected properly.
3) When the electronic control P.C. board seems to be defective, check the copper foil pattern for disconnection and the
components for bursting and discoloration.
4) When troubleshooting, refer to 8-2., 8-3. and 8-4.
4. How to replace batteries
Weak batteries may cause the remote controller malfunction.
In this case, replace the batteries to operate the remote controller normally.
RESET button
Insert the negative pole of the
batteries first. Check if the polarity
of the batteries is correct.
NOTE : 1. If RESET button is not pressed, the remote controller may not operate correctly.
2. This remote controller has a circuit to automatically reset the microcomputer when batteries are replaced.
This function is equipped to prevent the microcomputer from malfunctioning due to the voltage drop caused by the
battery replacement.
Press RESET button with tip end of ball point pen
or the like, and then use the remote controller.
Remove the front lid and insert batteries.
Then reattach the front lid.

11
Outline of the function
This air conditioner can memorize the abnormal condition which has occurred once.
Even though LED indication listed on the troubleshooting check table (8-4.) disappears, the memorized failure details can
be recalled.
8-2. FAILURE MODE RECALL FUNCTION
1. Flow chart of failure mode recall function for the indoor/outdoor unit
ON
OFF Beeps
Repeated cycle Repeated cycle
2.5-second OFF Blinking at 0.5-
second interval
Beeps Repeated cycle
2.5-second OFF Blinking at 0.5-
second interval
Beeps
2. Blinking pattern when the indoor unit is abnormal:
Does the left lamp of OPERATION INDICATOR lamp on the
indoor unit blink at the interval of 0.5 seconds?
Blinks: Either indoor or outdoor unit is abnormal. Beep is emit-
ted at the same timing as the blinking of the left lamp
of OPERATION INDICATOR lamp. 2
Indoor unit is normal.
But the outdoor unit might be abnormal because there are some abnor-
malities that can't be recalled with this way.
The cause of abnormality cannot be found because the abnormality doesn't recur.
Setting up the failure mode recall function
Turn ON the power supply.
<Preparation of the remote controller>
While pressing both OPERATION SELECT button and TOO COOL button on the
remote controller at the same time, press RESET button.
First, release RESET button.
And release the other two buttons after all LCD except the set temperature in opera-
tion display section of the remote controller is displayed after 3 seconds.
Press OPERATE/STOP (ON/OFF) button of the remote controller (the set temperature
is displayed) with the remote controller headed towards the indoor unit. 1
The indoor unit is abnormal.
Check the blinking pattern, and confirm the abnormal point with the indoor unit
failure mode table. (8-2.2.)
Make sure to check at least two consecutive blinking cycles. 2
Releasing the failure mode recall function
Release the failure mode recall function by the following procedures.
• Turn OFF the power supply and turn it ON again.
• Press RESET button of the remote controller.
Repair the defective parts.
Deleting the memorized abnormal condition
After repairing the unit, recall the failure mode again according to "Setting up the failure mode recall
function" mentioned above.
Press OPERATE/STOP (ON/OFF) button of the remote controller (the set temperature is displayed)
with the remote controller headed towards the indoor unit.
Press EMERGENCY OPERATION switch so that the memorized abnormal condition is deleted.
Release the failure mode recall function according to "Releasing the failure mode recall function"
mentioned above.
Operational procedure
Yes
(Blinks)
No
(OFF)
NOTE: 1. Make sure to release the failure mode recall function once it's set up, otherwise the unit cannot operate properly.
2. If the abnormal condition is not deleted from the memory, the last abnormal condition is kept memorized.
1. Regardless of normal or abnormal condition, a short
beep is emitted once the signal is received.

12
2. Indoor unit failure mode table
Left lamp of OPERATION
INDICATOR lamp
Abnormal point
(Failure mode) Condition Correspondence
Not lighted Normal — —
1-time flash every
0.5-second
Room temperature
thermistor
The room temperature thermistor short or
open circuit is detected every 8 seconds dur-
ing operation.
Refer to the characteristics of the room temperature
thermistor (8-7.).
2-time flash
2.5-second OFF
Indoor coil ther-
mistor
The indoor coil thermistor short or open circuit
is detected every 8 seconds during operation.
Refer to the characteristics of the main indoor coil ther-
mistor, the sub indoor coil thermistor (8-7.).
11-time flash
2.5-second OFF Indoor fan motor
The rotational frequency feedback signal is
not emit during the 12 seconds the indoor fan
operation.
Refer to 8-6. "Check of indoor fan motor".
12-time flash
2.5-second OFF
Indoor control
system
It cannot properly read data in the nonvolatile
memory of the indoor electronic control P.C.
board.
Replace the indoor electronic control P.C. board.
NOTE : Blinking patterns of this mode differ from the ones of TROUBLESHOOTING CHECK TABLE (8-4.).

13
8-3. INSTRUCTION OF TROUBLESHOOTING
Indoor unit oper-
ates.
Outdoor unit
doesn't operate.
If blinking of OPERATION INDI-
CATOR lamp cannot be checked,
it can be checked with failure
mode recall function.
Indoor unit
doesn't receive
the signal from
remote controller.
OPERATION INDICATOR
lamp on the indoor unit is
flashing on and off.
Outdoor unit
operates only
in Test Run
operation.
Outdoor
unit doesn't
operate even
in Test Run
operation.
Indoor unit
operates, when
EMERGENCY
OPERATION
switch is pressed.
Indoor unit
doesn't operate,
when EMER-
GENCY OPERA-
TION switch is
pressed.
Check room
temperature
thermistor.
Refer to 8-7.
"Test point
diagram and
voltage".
• Check the
wiring diagram
of the outdoor
unit.
• Check
outdoor fuse.
Refer to 8-6.
"Check of remote
controller and
receiver P.C.
board".
1. Check indoor/outdoor
connecting wire.
2. Refer to 8-6. "Check
of indoor electronic
control P.C. board and
indoor fan motor".
Left lamp
2-time flash
Cause:
Indoor unit
• Trouble of room
temperature /
indoor coil ther-
mistor
Left lamp
3-time flash
Cause:
Indoor unit
• Trouble of in-
door fan motor
Left lamp
4-time flash
Cause:
Indoor unit
• Trouble of
indoor unit con-
trol system
Start
Check room
temperature
thermistor and
indoor coil ther-
mistor. Refer to
8-7. "Test point
diagram and
voltage".
Refer to 8-6.
"Check of indoor
fan motor".
Replace the
indoor electronic
control P.C.
board.
"Test Run operation" means
the operation within 30 minutes
after EMERGENCY OPERA-
TION switch is pressed.

14
8-4. TROUBLESHOOTING CHECK TABLE
Before taking measures, make sure that the symptom reappears for accurate troubleshooting.
When the indoor unit has started operation and detected an abnormality of the following condition (the first detection after the
power ON), the indoor fan motor turns OFF and OPERATION INDICATOR lamp flashes.
OPERATION INDICATOR
Lighted
Blinking
Not lighted
No. Abnormal
point Operation indicator lamp Symptom Condition Correspondence
1
Indoor coil
thermistor
Left lamp flashes.
2-time flash
2.5-second OFF
Indoor unit and
outdoor unit do
not operate.
The indoor coil or the room temperature ther-
mistor is short or open circuit.
Refer to the characteristics of
indoor coil thermistor, and the
room temperature thermistor
(8-7).
•
Room tem-
perature
thermistor
2Indoor fan
motor
Left lamp flashes.
3-time flash
2.5-second OFF
The rotational frequency feedback signal is
not emitted during the indoor fan operation.
Refer to 8-6. "Check of in-
door fan motor".
•
3Indoor con-
trol system
Left lamp flashes.
4-time flash
2.5-second OFF
It cannot properly read data in the nonvolatile
memory of the indoor electronic control P.C.
board.
Replace the indoor electronic
control P.C. board.
•

8-5. TROUBLE CRITERION OF MAIN PARTS
MS-A09WA MS-A12WA
Part name Check method and criterion Figure
Room temperature
thermistor
(RT11) Measure the resistance with a tester. (Part temperature 50 ~ 86°F)
Refer to 8-7. "Test point diagram and voltage", the chart of thermistor.
Indoor coil thermistor
(RT12)
Indoor fan motor
(MF) Check 8-6. .
Horizontal vane motor
(MV)
Measure the resistance between the terminals with a tester.
(Part temperature 50 ~ 86°F)
Color of the lead wire Normal
BRN - other one 235 ~ 255 Ω
15
RED
YLW
BRN
ORN GRN
ROTOR

16
8-6. TROUBLESHOOTING FLOW
A Check of indoor fan motor
The indoor fan motor error has occurred, and the indoor fan doesn't operate.
Turn OFF the power supply.
Is there any foreign matter that interferes
the rotation of the line flow fan?
Yes
No
Remove the foreign matter and
adjust the line flow fan.
Pay careful attention to the high voltage on the fan motor connector CN211.
Turn ON the power supply, wait 5 seconds or more, and then press
EMERGENCY OPERATION switch.
Measure the supply voltage as follows within 12 seconds after EMER-
GENCY OPERATION switch is pressed.
If more than 12 seconds passes by, turn OFF the power supply and
turn ON it again, then measure the voltage.
1. Measure the voltage between CN211 (+) and (-).
2. Measure the voltage between CN211 (+) and (-).
If more than 12 seconds passes after EMERGENCY OPERATION switch
is pressed, the voltage mentioned above 2 goes 0 VDC although the
indoor electronic control P.C. board is normal
Is there 162 VDC between CN211
(+) and (-), and does the voltage
between CN211 (+) and (-) rise
to the range of 3 to 6 VDC within 12
seconds after EMERGENCY OPERA-
TION switch is pressed?
Replace the indoor fan motor.
CN211
Indoor electronic
control P.C. board
Yes
No
The indoor fan motor error has occurred, and the indoor fan repeats "12-second ON and 30-second OFF" 3 times, and then stops.
Measure the voltage between CN211
(+) and (-) while the fan motor is
rotating.
Replace the indoor electronic control P.C. board.
Is it unchanged holding
0 or 15 VDC? No
(Changed)
Yes
(Unchanged)
Replace the indoor electronic control P.C. board.
Replace the indoor fan motor.

17
B Check of remote controller and indoor electronic control P.C. board
Check if the remote controller is exclusive for this air conditioner.
Does the unit operate with the remote
controller?
OK
Yes
No
(Not clear)
Replace the batteries. (Refer to 8-1.4.)
Press OPERATE/STOP (ON/OFF)
button on the remote controller.
Is LCD display on the remote controller
visible?
Remove the batteries, then set them back
and press RESET button. (Refer to 8-1.4.)
Check if the unit operates with the remote
controller.
Yes
No
Turn ON a radio to AM and press OP-
ERATE/STOP (ON/OFF) button on the
remote controller.
Is noise heard from radio?
Yes
No Replace the remote controller.
Are there any fluorescent lights of
inverter or rapid-start type within the
range of 3.28 ft.? Yes
No
Reinstall the unit away from lights.
Attach a filter on receiving part.
•
•
Replace the indoor electronic control
P.C. board. (Including the receiver)

18
CN211
Fuse(F11)
Varistor(NR11)
Indoor electronic
control P.C.Board
C Check of indoor electronic control P.C. board and indoor fan motor
Turn OFF the power supply.
Remove indoor fan motor connector CN211
and vane motor connector CN151 from the
indoor electronic control P.C. board and turn
ON the power supply.
Does the unit operate with the remote
controller? Does OPERATION INDICATOR
lamp light up by pressing EMERGENCY
OPERATION switch?
Yes
No
Measure the resistance between
CN211 and of the indoor fan motor
connector.
Short/open circuit:
Replace the indoor fan motor.
Turn OFF the power supply.
Check both “parts side” and “pattern
side” of the indoor electronic control
P.C. board visually.
Replace the indoor
electronic control P.C. board.
Are the varistor (NR11)
burnt and the fuse (F11)
blown? No
No
Yes
Yes
Be sure to check both the fuse
and the varistor in any case.
Is the fuse (F11) blown
only?
Measure the resistance between
(+) and (-) of the indoor fan motor
connector (to CN211 on the indoor
electronic control P.C. board). 1, 2
1. The fan motor connector's lead wire is red, whereas is
black.
2. Connect "+" of the tester to fan motor connector's lead
wire, and "-" to lead wire, otherwise the resistance can-
not be measured properly.
Yes
Is the resistance 1 MΩ
or more?
Replace indoor electronic control P.C. board
and the indoor fan motor.
No
Replace indoor electronic control
P.C. board.
Measure the resistance of
resistor (R111) on the indoor
electronic control P.C. board.
Yes
Is the resistance approx.
2 Ω?No
Replace the indoor electronic control P.C.
board and the indoor fan motor.
Replace the indoor electronic control P.C. board.
Measure the resistance of the horizon-
tal vane motor coil.
(Refer to 8-5.)
Short/open circuit:
Replace the horizontal vane motor and the
indoor electronic control P.C. board.

19
D Electromagnetic noise enters into TV sets or radios
Yes
Is the unit grounded? No Ground the unit.
Yes
Is the distance between the antennas
and the indoor unit within 9.91 ft., or is
the distance between the antennas and
the outdoor unit within 9.91 ft.?
No
Extend the distance between the antennas and
the indoor unit, and/or the antennas and the
outdoor unit.
Is the distance between the TV sets or
radios and the indoor unit within 3.28
ft., or is the distance between the TV
sets or radios and the outdoor unit
within 9.91 ft.?
Yes
Extend the distance between the TV sets and/or
radios and the indoor unit, or the TV sets or
radios and the outdoor unit.
Are the antennas damaged?
Is the coaxial cable damaged?
Is there any poor contact in the anten-
na wiring? Yes
No
No
Replace or repair the antenna.
Replace or repair the coaxial cable.
Is the indoor/outdoor connecting wire of
the air conditioner and the wiring of the
antennas close? Yes
Extend the distance between the indoor/outdoor
connecting wire of the air conditioner and the wir-
ing of the antennas.
No
Even if all of the above conditions are fulfilled, the electromagnetic noise may enter, depending on the electric field strength
or the installation condition (combination of specific conditions such as antennas or wiring).
Check the followings before asking for service.
1. Devices affected by the electromagnetic noise
TV sets, radios (FM/AM broadcast, shortwave)
2. Channel, frequency, broadcast station affected by the electromagnetic noise
3. Channel, frequency, broadcast station unaffected by the electromagnetic noise
4. Layout of ;
indoor/outdoor unit of the air conditioner, indoor/outdoor wiring, grounding wire, antennas, wiring from antennas, receiver
5. Electric field intensity of the broadcast station affected by the electromagnetic noise
6. Presence or absence of amplifier such as booster
7. Operation condition of air conditioner when the electromagnetic noise enters in
1) Turn OFF the power supply once, and then turn ON the power supply. In this situation, check for the electromagnetic
noise.
2) Within 3 minutes after turning ON the power supply, press OPERATE/STOP (ON/OFF) button on the remote controller for
power ON, and check for the electromagnetic noise.
3) After a short time (3 minutes later after turning ON), the outdoor unit starts running. During operation, check for the elec-
tromagnetic noise.
4) Press OPERATE/STOP (ON/OFF) button on the remote controller for power OFF, when the outdoor unit stops but the
indoor/outdoor communication still runs on. In this situation, check for the electromagnetic noise.

20
Indoor coil thermistor [RT12]
Room temperature thermistor (RT11)
Temperature (°F)
32 50 68 86
104 122 140
Resistance (k )
MS-A09WA MS-A12WA
Indoor electronic control P.C. board
Release of Auto restart
function
Solder the Jumper wire
to JR07
(Refer to 7-3.)
115 VAC Fuse (F11)
250 V 3.15 A
Indoor coil thermistor
RT12
(CN112)
Horizontal vane
motor (CN151)
8-7. TEST POINT DIAGRAM AND VOLTAGE
SW P.C. board
Power monitor
receiver P.C.
board 12 VDC
5 VDC
Power supply input
Indoor fan motor
(CN211)
}
Varistor (NR11)
Room temperature
thermistor (RT11)
}
Timer short mode
point JPG, JPS
(Refer to 7-1.)
(+)3-6 VDC
15 VDC
(-) Fiducial terminal of
cathode side on measur-
ing high-voltage DC
162 VDC
(+)0 or 15 VDC
Emergency
operation switch
Resistor
(R111)