Mitsubishi Electric MU-A WA Series Service Manual Download Page 22

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OPERATING PROCEDURE

PHOTOS

2. Removing the electronic control P.C. board, the

power monitor receiver P.C. board, SW P.C. board
and the terminal block

(1) Remove the horizontal vane, the panel (refer to 1.) and the

corner box.

(2) Remove the screw of the conduit cover, and conduit cover.

(Photo 2 or Photo 3)

(3) Remove the indoor/outdoor connecting wire.
(4) Remove the switch holder from the electrical cover. (Photo

(5) Remove the screw of the electrical cover, and then the

electrical cover. (Photo 4)

(6) Remove the ground wire connected to the indoor electronic

control P.C. board from the electrical box. (Photo 5)

(7) Unhook the power monitor receiver P.C. board holder from

the catch. (Photo 4)

(8) Open the rear cover of the power monitor receiver P.C.

board holder and pull out the power monitor receiver P.C.
board.

(9) Open the switch holder and pull out SW P.C. board.
(10) Pull the electronic control P.C. board slightly toward you

from the electrical box, and disconnect TAB3, TAB4 and all
the connectors on the electronic control P.C. board. (LD101
and LD105 are direct-mounted to the electronic control P.C.
board.)

(11) Pull out the electronic control P.C. board from the electrical

box.

(12) Remove the ground wire connected to the heat exchanger

from the electrical box. (Photo 5)

(13) Unhook the catches of the electrical box, and pull out the

electrical box.

(14) Remove the screw of the terminal block cover, and then

remove the terminal block cover and the terminal block
holder. (Photo 6)

(15) Remove the terminal block by sliding it.

Photo 4

Photo 5

Photo 6

3. Removing the electrical box

(1) Remove the horizontal vane, the panel (refer to 1.) and the

corner box.

(2) Remove the screw of Conduit cover, and then the indoor/

outdoor connecting wire. (Photo 2 or Photo 3)

(3) Remove the switch holder and the electrical cover. (Photo 4)
(4) Remove the ground wire connected to the heat exchanger

from the electrical box. (Photo 5)

(5) Disconnect the following connectors on the electronic

control P.C. board; the fan motor connector <CN211>, the
indoor coil thermistor connector <CN112>, the vane motor
connector <CN151>. (Photo 5)

(6) Unhook the catches of the electrical box, and pull out the

electrical box.

Indoor coil thermistor

connector (CN112)

Indoor fan motor
connector (CN211)

Vane motor

connector (CN151)

Ground wire

Screw of the
electrical cover.

Switch holder

Power monitor
receiver
P.C. board holder

Screw

Summary of Contents for MU-A WA Series

Page 1: ...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 Ple...

Page 2: ...has been removed 3 Conduit cover terminal block cover and terminal block holder have been changed 2 1 TECHNICAL 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 1 have been added Remote controller has been changed Revision B SPECIFICATION has been corrected Power...

Page 3: ...splay 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 ...

Page 4: ...tallation 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 ...

Page 5: ...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 O...

Page 6: ...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 16 10 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 ...

Page 7: ...oor 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 ...

Page 8: ...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 control...

Page 9: ...e 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 restar...

Page 10: ...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 automat...

Page 11: ...emperature 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 ...

Page 12: ...istor 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 contro...

Page 13: ...est 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 I...

Page 14: ...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 2 Indoor fan motor Left lamp flashes 3 time flash 2 5 second OFF The rotational frequency feedback signal is not emitte...

Page 15: ...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 ...

Page 16: ...asure 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 TIO...

Page 17: ...oller 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...

Page 18: ...wn 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 ...

Page 19: ...ength 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 ...

Page 20: ...AC 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...

Page 21: ...lide the sleeve Pull the terminal while pushing the locking lever Hold the sleeve and pull out the terminal slowly Connector Sleeve Locking lever MS A09 12WA 1 MS A09 12WA Screws of the panel Horizontal vane Conduit cover Screw of the conduit cover Conduit plate Terminal block cover Terminal block cover Conduit cover Screw of the conduit cover Terminal with locking mechanism Detaching points The t...

Page 22: ...ontrol P C board 11 Pull out the electronic control P C board from the electrical box 12 Remove the ground wire connected to the heat exchanger from the electrical box Photo 5 13 Unhook the catches of the electrical box and pull out the electrical box 14 Remove the screw of the terminal block cover and then remove the terminal block cover and the terminal block holder Photo 6 15 Remove the termina...

Page 23: ...fer to 3 3 Pull out the drain hose from the nozzle assembly and remove the nozzle assembly 4 Remove the screws fixing the motor bed Photo 8 5 Loosen the screw fixing the line flow fan Photo 9 6 Remove the motor bed together with fan motor and motor band 7 Release the hooks of the motor band and remove the motor band then pull out the indoor fan motor 8 Remove the screws fixing the left side of the...

Page 24: ... E02 A32 234 BOX 1 1 2 E02 A49 000 PANEL ASSEMBLY 1 1 Including No 3 4 3 E02 913 067 SCREW CAP 2 2 2 PC SET 4 E02 915 010 FRONT PANEL 1 1 5 E02 915 100 CATECHIN AIR FILTER LEFT 1 1 6 E02 916 100 CATECHIN AIR FILTER RIGHT 1 1 7 AIR CLEANING FILTER 1 1 MAC 415FT E 8 E02 A32 975 CORNER BOX RIGHT 1 1 9 E02 913 970 INSTALLATION PLATE 1 1 10 E02 A49 978 CONDUIT PLATE 1 1 2 ACCESSORY AND REMOTE CONTROLLE...

Page 25: ... 7 E02 913 095 POWER MONITOR RECEIVER P C BOARD HOLDER 1 1 8 E02 A49 979 CONDUIT COVER 1 1 9 E02 A49 780 TERMINAL BLOCK COVER 1 1 10 E02 A49 779 TERMINAL BLOCK HOLDER 1 1 11 E02 A49 375 TERMINAL BLOCK TB 1 1 12 E02 A49 452 ELECTRONIC CONTROL P C BOARD 1 1 E02 A50 452 1 13 E02 897 308 ROOM TEMPERATURE THERMISTOR RT11 1 1 14 E02 897 307 INDOOR COIL THERMISTOR RT12 1 1 15 E02 915 782 SWITCH HOLDER 1 ...

Page 26: ...LEANING FILTER is to be washed soak AIR CLEANING FILTER in water when showing dirt in lukewarm water and rinse it delicately without removing the filter from the frame about once every 3 months Clogged AIR CLEANING FILTER may reduce the air conditioner capacity or cause frost on the air outlet Do not remove or attach AIR CLEANING FILTER during unit operation 1 4 INDOOR UNIT HEAT EXCHANGER 3 2 MS A...

Page 27: ...EL ASSEMBLY 1 1 1 1 Including No 3 4 3 G E12 913 067 SCREW CAP 2 2 2 2 2 PC SET 4 G E12 915 010 FRONT PANEL 1 1 1 1 5 G E12 915 100 CATECHIN AIR FILTER LEFT 1 1 1 1 6 G E12 916 100 CATECHIN AIR FILTER RIGHT 1 1 1 1 7 G AIR CLEANING FILTER 1 1 1 1 MAC 415FT E 8 G E12 A32 975 CORNER BOX RIGHT 1 1 1 1 9 G E12 913 970 INSTALLATION PLATE 1 1 1 1 10 G E12 A49 978 CONDUIT PLATE 1 1 2 ACCESSORY AND REMOTE...

Page 28: ...C BOARD HOLDER 1 1 1 1 8 G E12 A49 979 CONDUIT COVER 1 1 9 G E12 C30 979 CONDUIT COVER 1 1 10 G E12 A49 780 TERMINAL BLOCK COVER 1 1 G E12 C30 780 1 1 11 G E12 A49 779 TERMINAL BLOCK HOLDER 1 1 G E12 C30 779 1 1 12 G E12 A49 375 TERMINAL BLOCK TB 1 1 1 1 13 G E12 A49 452 ELECTRONIC CONTROL P C BOARD 1 1 1 G E12 A50 452 1 1 14 G E12 897 308 ROOM TEMPERATURE THERMISTOR RT11 1 1 1 1 15 G E12 897 307 ...

Page 29: ...is to be washed soak AIR CLEANING FILTER in water when showing dirt in lukewarm water and rinse it delicately without removing the filter from the frame about once every 3 months Clogged AIR CLEANING FILTER may reduce the air conditioner capacity or cause frost on the air outlet Do not remove or attach AIR CLEANING FILTER during unit operation 1 4 INDOOR UNIT HEAT EXCHANGER 3 2 MS A09WA MS A12WA M...

Page 30: ...ontroller model is on back Fan speed control button Operation select button ECONO COOL button On timer button CLOCK set button TIME set buttons Forward button Backward button Off timer button RESET button POWERFUL button VANE button Horizontal vane button MS A09WA MS A12WA Operation Indicator lamp The operation indicator at the right side of the indoor unit indicates the operation state The follow...

Page 31: ...RATION SELECT button 3 Press TEMPERATURE buttons TOO WARM or TOO COOL button to select the desired temperature The setting range is 61 88 F 11 3 FAN OPERATION 1 Press OPERATE STOP ON OFF button OPERATION INDICATOR lamp of the indoor unit turns ON with a beep tone 2 Select FAN mode with OPERATION SELECT button 3 Select the desired fan speed When AUTO it becomes Low Only indoor fan operates Outdoor ...

Page 32: ...FF button is pressed POWER OFF b When the operation is stopped by the emergency operation c When ON TIMER is ON standby 6 Dew prevention During COOL or DRY operation with the vane angle at Angle 2 4 when the compressor cumulative operation time exceeds 1 hour the vane angle automatically changes to Angle 1 for dew prevention 7 SWING MODE By selecting SWING mode with VANE CONTROL button the horizon...

Page 33: ...ANE CONTROL button the compressor stops for 3 minutes even during the operation of the air conditioner The air conditioner operates with Very Low speed until the compressor turns on again Horizontal position 9 ECONO COOL operation ECONOmical operation When ECONO COOL button is pressed in COOL mode set temperature is automatically set 3 6 F higher than that in COOL mode Also the horizontal vane swi...

Page 34: ...thout setting the current time Initially 0 00 blinks at the current time display of TIME MONITOR so set the current time correctly with CLOCK SET button How to set the current time 1 Press the CLOCK set button 2 Press the TIME SET buttons and to set the current time Each time FORWARD button is press the set time increases by 1 minute and each time BACKWARD button is press the set time decreases by...

Page 35: ... 75 F The fan speed shifts to Med All protective operations such as the coil frost prevention works even in emergency operation In the test run or emergency operation the horizontal vane operates in VANE AUTO mode Emergency operation continues until EMERGENCY OPERATION switch is pressed once or twice or the unit receives any signal from the remote controller In case of latter normal operation will...

Page 36: ...GINEERING CO LTD Distributed in Oct 2008 No OB448 REVISED EDITION C 5 Distributed in Jun 2008 No OB448 REVISED EDITION B 6 Distributed in May 2007 No OB448 REVISED EDITION A 7 Distributed in Mar 2006 No OB448 7 Made in Japan New publication effective Oct 2008 Specifications subject to change without notice TM ...

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