Mitsubishi Electric MSZ-A09NA Series User manual

SERVICE MANUAL
CONTENTS
1. TECHNICAL CHANGES ··································· 3
2. PART NAMES AND FUNCTIONS····················· 4
3. SPECIFICATION················································ 5
4. OUTLINES AND DIMENSIONS ························ 7
5. WIRING DIAGRAM············································ 8
6. REFRIGERANT SYSTEM DIAGRAM··············· 9
7. SERVICE FUNCTIONS ··································· 10
8. TROUBLESHOOTING······································11
9. DISASSEMBLY INSTRUCTIONS···················· 25
10. PARTS LIST····················································· 30
10-1. PARTS LIST············································ 30
10-2. RoHS PARTS LIST································· 36
11. MICROPROCESSOR CONTROL···················· 42
No. OB450
REVISED EDITION-D
SPLIT-TYPE AIR CONDITIONERS
MSZ-A09/12/15/17NA
MSY-A15/17NA
INDOOR UNIT
Outdoor unit service manual
MUZ-A·NA, GA·NA Series (OB451)
MUY-A·NA, GA·NA Series (OB451)
MXZ-A·NA Series (OB444)
NOTE:
RoHS compliant products have <G> mark on the spec name plate.
For servicing of RoHS compliant products, refer to the PARTS
LIST (RoHS compliant).
Revision D:
• MSZ-GA•NA and MSY-GA•NA have been added.
Please void OB450 REVISED EDITION-C.
Models
MSZ-A09NA, - 1
MSZ-A12NA, - 1
MSZ-A15NA, - 1
MSZ-A17NA, - 1
MSZ-A24NA, - 1
MSY-A15NA, - 1
MSY-A17NA, - 1
MSY-A24NA, - 1
MSZ-GA24NA
MSY-GA24NA

2
Revision A:
• PARTS LIST has been revised. (10-1.8, 10-2.8)
Revision B:
• MSZ-A•NA-1and MSY-A•NA-1
Remote controller has been changed.
Revision C:
• SPECIFICATION has been corrected.
Powerful has been added. (Airflow , Sound level)
Revision D:
• MSZ-GA•NA and MSY-GA•NA have been added.

3
1. Remote controller has been changed.
• Temperature indication function (°F/°C) has been added. (Refer to 11-10.)
• Timer indication has been changed. (AM/PM indication)
2. Conduit plate has been removed. (MSZ-A09/12/15/17, MSY-A15/17)
3. Conduit cover, terminal block cover and terminal block holder have been changed. (MSZ-A09/12/15/17, MSY-A15/17)
MSZ09UN ĺMSZ-A09NA
MSZ12UN ĺMSZ-A12NA
MSH15TN ĺMSZ-A15NA
MSH17TN ĺMSZ-A17NA
1. Control method between indoor and outdoor has been changed.
2. Indoor fan motor has been changed.
3. Signal of remote controller has been changed. (It is not available for conventional models.)
MSZ-A09NA ĺMSZ-A09NA-1
MSZ-A12NA ĺMSZ-A12NA-1
MSZ-A15NA ĺMSZ-A15NA-1
MSZ-A17NA ĺMSZ-A17NA-1
MSH24WN ĺMSZ-A24NA
MS15TN ĺMSY-A15NA
MS17TN ĺMSY-A17NA
MS24WN ĺMSY-A24NA
MSZ-A24NA ĺMSZ-A24NA-1
MSY-A15NA ĺMSY-A15NA-1
MSY-A17NA ĺMSY-A17NA-1
MSY-A24NA ĺMSY-A24NA-1
Models Remote controller Temperature indication
MSZ-A09/12/15/17NA KM06A °F
MSZ-A09/12/15/17NA- 1KM07J °F/°C
MSZ-A24NA KM06B °F
MSZ-A24NA - 1KM07K °F/°C
MSY-A15/17NA KM06C °F
MSY-A15/17NA - 1KM07L °F/°C
MSY-A24NA KM06D °F
MSY-A24NA - 1KM07M °F/°C
TECHNICAL CHANGES
1
MSZ-A24NA-1ĺMSZ-GA24NA
MSY-A24NA-1ĺMSY-GA24NA
1. Indoor electronic control P.C. board has been changed.

4
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
Emergency operation switch
Operation indicator lamp
Remote control
receiving section
Operation Indicator
lamp
PART NAMES AND FUNCTIONS
2
MSZ-A09NA MSY-A15NA
MSZ-A12NA MSY-A17NA
MSZ-A15NA
MSZ-A17NA
MSZ-A24NA MSY-A24NA
MSZ-GA24NA MSY-GA24NA
MSZ-A09NA
MSZ-A12NA
MSZ-A15NA
MSZ-A17NA
MSY-A15NA
MSY-A17NA
MSZ-A24NA MSY-A24NA
MSZ-GA24NA MSY-GA24NA
ACCESSORIES
MSZ-A09/12/15/17NA
MSY-A15/17NA MSZ-A09/12/15/17NA- 1
MSY-A15/17NA- 1MSZ-A24NA MSY-A24NA
MSZ-GA24NA MSY-GA24NA
Installation plate 1 1 1
Installation plate ¿xing screw 4 × 25 mm 8 5 7
Remote controller holder 1 1 1
Fixing screw for 3.5 × 1.6 mm (Black) 2 2 2
Battery (AAA) for remote controller 2 2 2
Wireless remote controller 1 1 1
Felt tape (Used for left or left-rear piping) 1 1 1
Conduit plate 1 – –

5
3SPECIFICATION
Indoor unit model MSZ-A09NA MSZ-A12NA
External ¿nish White
Power supply V, phase, Hz 208/230, 1, 60
Max.-fuse size (time delay) / Disconnect switch A 15
Min. circuit ampacity A 1.0
Fan motor F.L.A 0.76
AirÀow
Low–Med.–High–Powerful COOL Dry (Wet) CFM 152-229-307-338
(134-205-275-303) 152-240-353-388 (134-215-318-349)
HEAT 159-222-307-321 159-240-353-353
Moisture removal pt./h 2.3 3.2
Sound level
Low–Med.–High–Powerful COOL dB(A) 22-33-38-41 22-34-42-44
HEAT 22-33-38-39 22-34-42-42
Cond. drain connection O.D. in. 5/8
Dimensions Win. 30-11/16 D8-1/4
H11-3/4
Weight Ib. 23
Remote controller Wireless type
Control voltage (by built-in transformer) 12-24 VDC
Indoor unit model MSZ-A15NA MSY-A15NA MSZ-A17NA MSY-A17NA
External ¿nish White
Power supply V, phase, Hz 208/230, 1, 60
Max.-fuse size (time delay) / Disconnect switch A 15
Min. circuit ampacity A 1.0
Fan motor F.L.A 0.76
AirÀow
Low–Med.–High–Powerful COOL Dry (Wet) CFM 268-328-381-419 (240-293-342-376)
HEAT 254-314-381-381 — 254-314-381-381 —
Moisture removal pt./h 4.7 5.2
Sound level
Low–Med.–High–Powerful COOL dB(A) 34-40-45-47 34-40-46-48
HEAT 34-38-44-44 — 34-38-44-44 —
Cond. drain connection O.D. in. 5/8
Dimensions Win. 30-11/16 D8-1/4
H11-3/4
Weight Ib. 23
Remote controller Wireless type
Control voltage (by built-in transformer) 12-24 VDC
Indoor unit model MSZ-A24NA MSZ-GA24NA MSY-A24NA MSY-GA24NA
External ¿nish White
Power supply V, phase, Hz 208/230, 1, 60
Max.-fuse size (time delay) / Disconnect switch A 15
Min. circuit ampacity A 1.0
Fan motor F.L.A 0.76
AirÀow
Low–Med.–High–Powerful COOL Dry (Wet) CFM 296-431-568-624 (265-385-508-558)
HEAT 296-486-568-590 350-486-568-590 —
Moisture removal pt./h 7.3
Sound level
Low–Med.–High–Powerful COOL dB(A) 34-40-49-51
HEAT 34-40-48-49 —
Cond. drain connection O.D. in. 5/8
Dimensions Win. 43-5/16 D10-1/4
H12-13/16
Weight Ib. 37
Remote controller Wireless type
Control voltage (by built-in transformer) 12-24 VDC
NOTE: Test conditions are based on ARI 210/240.
Rating conditions (Cooling) — Indoor: 80ÛFDB, 67ÛFWB, Outdoor: 95ÛFDB, (75ÛFWB) Rated frequency
(Heating) — Indoor: 70ÛFDB, 60ÛFWB, Outdoor: 47ÛFDB, 43ÛFWB Rated frequency
(Heating) — Indoor: 70ÛFDB, 60ÛFWB, Outdoor: 17ÛFDB, 15ÛFWB Maximum frequency

6
3-1. OPERATING RANGE
(1) POWER SUPPLY
Rated voltage Guaranteed Voltage (V)
Indoor unit 208/230 V 1 phase
60 Hz
Min.187 208 230 Max.253
3-2. OUTLET AIR SPEED AND COVERAGE RANGE
Model Mode Function Air Àow (CFM) Air speed
(ft./sec.) Coverage range (ft.)
MSZ-A09NA HEAT Dry 307 16.8 23.4
COOL Dry 307 16.8 23.4
Wet 275 15.1 21.0
MSZ-A12NA HEAT Dry 353 19.3 26.7
COOL Dry 353 19.3 26.7
Wet 318 17.4 24.1
MSZ-A15NA HEAT Dry 381 20.9 28.8
MSZ-A15NA
MSY-A15NA COOL Dry 381 20.9 28.8
Wet 342 18.8 26.0
MSZ-A17NA HEAT Dry 381 20.9 28.8
MSZ-A17NA
MSY-A17NA COOL Dry 381 20.9 28.8
Wet 342 18.8 26.0
MSZ-A24NA
MSZ-GA24NA HEAT Dry 568 20.2 34.4
MSZ-A24NA
MSY-A24NA
MSZ-GA24NA
MSY-GA24NA COOL Dry 568 20.2 34.4
Wet 508 18.1 30.9
ƔThe air coverage range is the ¿g-
ure up to the position where the
air speed is 1 ft./sec., when air is
blown out horizontally from the
unit properly at the High speed
position.
The coverage range should be
used only as a general guideline
since it varies according to the
size of the room and furniture ar-
ranged inside the room.
(2) OPERATION
Mode Condition Intake air temperature (°F) Indoor Outdoor
DB WB DB WB
Cooling
Standard temperature 80 67 95 —
Maximum temperature 90 73 115 —
Minimum temperature 67 57 14 —
Maximum humidity 78% —
Heating
Standard temperature 70 60 47 43
Maximum temperature 80 67 75 65
Minimum temperature 70 60 14
5 (MUZ-GA24)13 4 (MUZ-GA24)
Except - Umodel

7
4OUTLINES AND DIMENSIONS
Unit: inch
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
Insulation ø1-1/8
Drain hose ø5/8
(Connected part O.D)
Liquid line ø1/4 19-11/16
Gas line ø3/8 16-15/16
Insulation ø1-3/8 O.D
ø3/4 I.D
{
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 ø 2-9/16
Indoor unit
Installation plate
7/16x13/16 Oblong hole
7/16x1 Oblong hole
7/8
hole
Conduit plate(MSZ-A•NA- and MSY-A•NA- are excluded.)
MSZ-A09NA MSY-A15NA MSZ-A12NA MSY-A17NA MSZ-A15NA MSZ-A17NA
10-1/4
6-1/4
3/4
2-5/16
1-7/8
5/16
12-3/8
10-1/161-7/8
1/8
3-7/8
6-13/16
3-7/8 6-13/16 16-5/16 16-5/16
3/16
9-15/16
31-1/8
2-3/16
42-1/16
43-5/16
12-13/16
Air out
Air in
Insulation ø1-1/8
Drain hose ø5/8
(Connected part O.D)
Installation plate
Wall hole ø3
Wireless remote controller
Installation plate Indoor unit
{
Liquid line ø1/4 19-11/16
Gas line ø5/8 16-15/16
Insulation ø1-15/16 O.D
ø1-1/4 I.D
MSZ-A24NA MSY-A24NA MSZ-GA24NA MSY-GA24NA

8
5WIRING DIAGRAM
MSZ-A09NA MSY-A15NA MSZ-A12NA MSY-A17NA MSZ-A15NA MSZ-A17NA
MSZ-A24NA MSY-A24NA
MSZ-GA24NA MSY-GA24NA

9
REFRIGERANT SYSTEM DIAGRAM
6
MSZ-A09NA
MSZ-A12NA
Refrigerant flow in cooling
Refrigerant flow in heating
MSZ-A15NA MSY-A15NA
MSZ-A17NA MSY-A17NA
MSZ-A24NA MSY-A24NA
MSZ-GA24NA MSY-GA24NA
Unit: inch
Indoor
heat
exchanger
Room temperature
thermistor
RT11
Refrigerant pipe ø1/2
(with heat insulator)
Flared connection
Flared connection
Indoor coil
thermistor
RT12(main)
Refrigerant pipe ø1/4
(with heat insulator)
Distributor
Indoor coil
thermistor
RT13(sub)
Indoor
heat
exchanger
Room temperature
thermistor
RT11
Refrigerant pipe ø5/8
(with heat insulator)
Flared connection
Flared connection
Indoor coil
thermistor
RT12(main)
Refrigerant pipe ø1/4
(with heat insulator)
Distributor
Indoor coil
thermistor
RT13(sub)
Indoor
heat
exchanger
Room temperature
thermistor
RT11
Indoor coil
thermistor
RT13(sub)
Indoor coil
thermistor
RT12(main)
Refrigerant pipe ø3/8
(with heat insulator)
Flared connection
Flared connection
Refrigerant pipe ø1/4
(with heat insulator)

10
7SERVICE FUNCTIONS
7-1. TIMER SHORT MODE
For service, set time can be shortened by short circuit of JPG and JPS on the indoor electronic control P.C. board.
The time will be shortened as follows. (Refer to 8-7.)
Set time: 1-minute ĺ1-second
Set time: 3-minute ĺ3-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:
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
MSZ-A09NA MSZ-A12NA MSZ-A15NA MSZ-A17NA MSZ-A24NA MSY-A15NA
MSY-A17NA MSY-A24NA MSZ-GA24NA MSY-GA24NA
Table 1 1 unit operation 2 units operation 3 units operation 4 units operation
No. 1 unit No modi¿cation 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

11
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 confirm-
ing 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
components.
4) When connecting or disconnecting the connectors, hold the housing of the connector. DO NOT pull the lead wires.
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
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 of the unit.
Solder the Jumper wire JR07 on the indoor electronic control P.C. board. (Refer to 8-7.)
JR07
CN151
CN152
CN101
CN211CN112
BZ
MSZ-A24NA MSY-A24NA
MSZ-GA24NA MSY-GA24NA
MSZ-A09/12/15/17NA
MSY-A15/17NA
8TROUBLESHOOTING
MSZ-A09NA MSZ-A12NA MSZ-A15NA MSZ-A17NA MSZ-A24NA MSY-A15NA
MSY-A17NA MSY-A24NA MSZ-GA24NA MSY-GA24NA
Lead wiring Housing point

12
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 microprocessor control when batteries are replaced.
This function is equipped to prevent the microprocessor control 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.
INFORMATION FOR MULTI SYSTEM AIR CONDITIONER
OUTDOOR UNIT: MXZ series
Multi system air conditioner can connect two or more indoor units with one outdoor unit.
• When you try to operate two or more indoor units with one outdoor unit simultaneously, one for the cooling and the
other for heating, the operation mode of the indoor unit that operates earlier is selected. Other indoor units cannot
operate, and operation indicator lamp flashes as shown in the figure below. In this case, please set all the indoor
units to the same operation mode.
• When indoor unit starts the operation while the defrosting of outdoor unit is being done, it takes a few minutes (max.
10 minutes) to blow out the warm air.
• In the heating operation, though indoor unit that does not operate may get warm or the sound of refrigerant flowing
may be heard, they are not malfunction. The reason is that the refrigerant continuously flows into it.
OPERATION INDICATOR
Lighted
Blinking
Not lighted

13
Those figures show about MSZ-A09/12/15/17.
2. Blinking pattern when the indoor unit is abnormal:
3.Blinking pattern when the outdoor unit is abnormal:
ON
OFF Beeps
Repeated cycle Repeated cycle
ON
OFF No beep Beeps
Repeated cycle
2.5-second OFF Blinking at 0.5-
second interval
2.5-second OFF 3-second ON Blinking at 0.5-
second interval
Beeps Repeated cycle
2.5-second OFF Blinking at 0.5-
second interval
No beep Beeps
Repeated cycle
2.5-second OFF 3-second ON Blinking at 0.5-
second interval
Repeated cycle
Beeps
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
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 cannot be recalled with this way.
Con¿rm if outdoor unit is abnormal according to the detailed outdoor
unit failure mode recall function.
No
Yes
The cause of abnormality cannot be found because the abnormality does not 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 in operation 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
Judgment of indoor/outdoor abnormality
Before blinking, does the left lamp of OPERATION INDICA-
TOR lamp stay ON for 3 seconds?
Stays ON for 3 seconds (without beep):
The outdoor unit is abnormal.
The indoor unit is abnormal.
Check the blinking pattern, and con¿rm 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.
The outdoor unit is abnormal.
Check the blinking pattern, and con¿rm the abnormal point with the
outdoor unit failure mode table. (Refer to outdoor unit service manual.)
Make sure to check at least two consecutive blinking cycles. 3
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.

14
2. Indoor unit failure mode table
Left lamp of OPERATION
INDICATOR lamp
Abnormal point
(Failure mode) Condition Correspondence
Not lighted Normal — —
1-time Àash 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 Àash
2.5-second OFF Indoor coil
thermistor 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.).
3-time Àash
2.5-second OFF Serial signal The serial signal from outdoor unit is not re-
ceived for a maximum of 6 minutes. Refer to 8-6. "How to check miswiring and serial signal error".
11-time Àash
2.5-second OFF Indoor fan motor The rotational frequency feedback signal is not
emitted during the 12 seconds the indoor fan
operation. Refer to 8-6. "Check of indoor fan motor".
12-time Àash
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.).

15
8-3. INSTRUCTION OF TROUBLESHOOTING
Indoor unit oper-
ates.
Outdoor unit
does not operate.
If blinking of OPERATION INDI-
CATOR lamp cannot be checked,
it can be checked with failure
mode recall function.
Indoor unit operates.
Outdoor unit does
not operate normally.
Indoor unit does
not receive the
signal from re-
mote controller.
OPERATION INDICATOR
lamp on the indoor unit is
Àashing ON and OFF.
Outdoor unit
operates only
in Test Run
operation.
Outdoor unit
does not
operate even
in Test Run
operation.
Unit does not
operate nor-
mal operation
in COOL or
HEAT mode.
Indoor unit
operates, when
EMERGENCY
OPERATION
switch is pressed.
Indoor unit does
not operate, when
EMERGENCY
OPERATION
switch is pressed.
Check room
temperature
thermistor.
Refer to 8-7.
"Test point
diagram and
voltage".
Refer to "How
to check
inverter/com-
pressor".
Refer to
"Check of R.V.
coil".
Refer to 8-6.
"Check of remote
controller and
receiver P.C.
board".
1. Check indoor/out-
door connecting wire.
(Check if the power is
supplied to the indoor
unit.)
2. Refer to 8-6. "Check
of indoor electronic
control P.C. board and
indoor fan motor".
Left lamp
Flash on
and OFF at
0.5-second
intervals
Cause:
Indoor/Outdoor
unit
• Miswiring or
trouble of
serial signal
Left lamp
2-time Àash
Cause:
Indoor unit
• Trouble
of room
temperature
/ indoor coil
thermistor
Left lamp
3-time Àash
Cause:
Indoor unit
• Trouble of
indoor fan
motor
Left lamp
4-time Àash
Cause:
Indoor unit
• Trouble
of indoor
unit control
system
Left lamp
5-time Àash
Cause:
Outdoor unit
• Outdoor
power
system
abnormality
Left lamp
6-time Àash
Cause:
Outdoor unit
• Trouble of
thermistor in
outdoor unit
Left lamp
7-time Àash
Cause:
Outdoor unit
• Trouble of
outdoor con-
trol system
Left lamp
14-time Àash
Cause:
Outdoor unit
• Other ab-
normality
Start
Refer to 8-6.
"How to
check mis-
wiring and
serial signal
error".
Check room
temperature
thermistor
and indoor
coil thermis-
tor. Refer
to 8-7."Test
point diagram
and voltage".
Refer to 8-6.
"Check of
indoor fan
motor".
Replace the
indoor elec-
tronic control
P.C. board.
Refer to
"How to
check
inverter/com-
pressor".
Refer to
"Check of
outdoor ther-
mistors".
Replace the
inverter P.C.
board or
the outdoor
electronic
control P.C.
board.
Check "Flow
chart of the
detailed
outdoor unit
failure mode
recall func-
tion."
"Test Run operation" means
the operation within 30 minutes
after EMERGENCY OPERA-
TION switch is pressed.
Refer to outdoor unit service manual.

16
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
1Miswiring or serial
signal
Left lamp Àashes.
0.5-second ON
0.5-second OFF
Indoor unit and
outdoor unit do
not operate.
The serial signal from the outdoor unit is not
received for 6 minutes. Refer to 8-6. "How to check
miswiring and serial signal er-
ror".
•
2
Indoor coil
thermistor Left lamp Àashes.
2-time Àash
2.5-second OFF
The indoor coil or the room temperature ther-
mistor is short or open circuit.
Refer to 8-7. the characteristics
of indoor coil thermistor, and
the room temperature thermis-
tor.
•
Room tem-
perature
thermistor
3Indoor fan
motor
Left lamp Àashes.
3-time Àash
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".
•
4Indoor con-
trol system
Left lamp Àashes.
4-time Àash
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.
•
5Outdoor power sys-
tem
Left lamp Àashes.
5-time Àash
2.5-second OFF
It consecutively occurs 3 times that the com-
pressor stops for overcurrent protection or
start-up failure protection within 1 minute after
start-up.
Refer to "How to check of in-
verter/compressor".
Refer to outdoor unit service
manual
Check the stop valve.
•
•
6Outdoor
thermistors
Left lamp Àashes.
6-time Àash
2.5-second OFF
The outdoor thermistors short or open circuit
during the compressor operation.
Refer to "Check of outdoor
thermistor".
Refer to outdoor unit service
manual.
•
7Outdoor control sys-
tem
Left lamp Àashes.
7-time Àash
2.5-second OFF
It cannot properly read data in the nonvolatile
memory of the inverter P.C. board or the out-
door electronic control P.C. board.
Replace the inverter P.C. board
or the outdoor electronic con-
trol P.C. board.
Refer to outdoor unit service
manual.
•
8Other ab-
normality
Left lamp Àashes.
14-time Àash
2.5-second OFF
An abnormality other than above mentioned
is detected.
Check the stop valve.
Con¿rm the abnormality in
detail using the failure mode
recall function for outdoor unit.
•
•
9
Outdoor
control
system
MSZ-A09/12
/15/17
MSY-A15/17
Left lamp lights up Outdoor unit does not oper-
ate
It cannot properly read data in the nonvolatile
memory of the inverter P.C. board or the out-
door electronic control P.C. board.
Check the blinking pattern of
the LED on the inverter P.C.
board or the outdoor electronic
control P.C. board.
•

8-5. TROUBLE CRITERION OF MAIN PARTS
MSZ-A09NA MSZ-A12NA MSZ-A15NA MSZ-A17NA MSZ-A24NA MSY-A15NA
MSY-A17NA MSY-A24NA MSZ-GA24NA MSY-GA24NA
Part name Check method and criterion Figure
Room temperature
thermistor(RT11) Measure the resistance with a tester.
Refer to 8-7. "Test point diagram and voltage",
"Indoor electronic control P.C. board", for the chart of thermistor..
Indoor coil thermistor
(RT12(MAIN),RT13(SUB))
Indoor fan motor(MF) Check 8-6. .
Horizontal vane
motor(MV)
MSZ-A09/12/15/17NA
MSY-A15/17NA
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 
Horizontal vane
motor(MV1)
Vertical vane
motor(MV2)
A24NA, GA24NA
Measure the resistance between the terminals with a tester.
(Part temperature 50 ~ 86°F)
Color of the lead wire Normal
BRN-other one 282 ~ 306 
OPERATION INDICATOR
No. Abnormal
point Operation indicator lamp Symptom Condition Correspondence
1
MXZ type
Operation
mode
setting
Left lamp lights and lower lamp Àashes.
2.5-second OFF
Outdoor unit
operates but
indoor unit does
not operate.
The operation mode of the each indoor unit
is differently set to COOL (includes DRY) and
HEAT at the same time, the operation mode
of the indoor unit that has operated at ¿rst has
the priority.
Unify the operation mode.
Refer to outdoor unit service
manual.
•
17
RED
YLW
BRN
ORN GRN
ROTOR
RED
YLW
BRN
ORN GRN
ROTOR

18
A Check of indoor fan motor
8-6. TROUBLESHOOTING FLOW
The indoor fan motor error has occurred, and the indoor fan does not operate.
Turn OFF the power supply.
Is there any foreign matter that interferes
the rotation of the line Àow fan?
Yes
No
Remove the foreign matter and
adjust the line Àow 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 294/325 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
OPERATION 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.

19
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 Àuorescent lights of
inverter or rapid-start type within the
range of 3.28 ft.? Yes
No
Reinstall the unit away from lights.
Attach a ¿lter on receiving part.
•
•
Replace the indoor electronic control
P.C. board.
Measure the voltage between receiver
P.C. board connector CN301 No.2(+) and
No.3(-) when the remote controller button
is pressed.
Is the voltage approx. 4 VDC?
Replace the receiver P.C. board.
MSZ-A24NA MSY-A24NA
MSZ-GA24NA MSY-GA24NA MSZ-A09/12/15/17NA
MSY-A15/17NA
Yes
No (5 or 0 VDC)

20
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 M
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 resis-
tor (R111) on the indoor electronic
control P.C. board. Yes
Is the resistance approx.
4 ?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.