Mitsubishi Electric MSZ-BT20VG Service Manual Download Page 27

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10-7. TEST POINT DIAGRAM AND VOLTAGE

MSZ-BT20VG MSZ-BT25VG MSZ-BT35VG MSZ-BT50VG

1. Indoor electronic control P.C. board,

indoor terminal P.C. board and power monitor receiver SW P.C. board

Indoor electronic control P.C. board

Room temperature thermistor (RT11)

Indoor coil thermistor (RT12, RT13)

Temperature (°C)

Resistance (kΩ)

Connector to Indoor

fan motor (CN211)

Resistor (R111)

Room temperature

thermistor RT11

(CN111)

Connector to Indoor

coil thermistor (CN112)

RT12, RT13

Vane motor(CN151)

12 V DC

5 V DC

GND

To disable "Auto restart

function",cut the Jumper

wire to JR77. (Refer to 8-3.)

Fuse (F11)

T3.15AL250V

Varistor (NR11)

Emergency operation

switch (E.O. SW) (SW1)

Indoor terminal P.C. board

ower monitor receiver SW P.C. board

OBH849A

Summary of Contents for MSZ-BT20VG

Page 1: ...CONTENTS 1 TECHNICAL CHANGES 2 2 PART NAMES AND FUNCTIONS 3 3 SPECIFICATION 4 4 NOISE CRITERIA CURVES 5 5 OUTLINES AND DIMENSIONS 6 6 WIRING DIAGRAM 7 7 REFRIGERANT SYSTEM DIAGRAM 8 8 SERVICE FUNCTIONS 9 9 MICROPROCESSOR CONTROL 11 10 TROUBLESHOOTING 15 11 DISASSEMBLY INSTRUCTIONS 28 SERVICE MANUAL MSZ BT25VG No OBH849 REVISED EDITION A OBH849 is void Revision A MSZ BT20 25 35 50VG ER1 have been a...

Page 2: ...del Preparation before the repair service Prepare the proper tools Prepare the proper protectors Provide adequate ventilation After stopping the operation of the air conditioner turn off the power supply breaker and remove the power plug Discharge the capacitor before the work involving the electric parts Precautions during the repair service Do not perform the work involving the electric parts wi...

Page 3: ...5 mm 5 Wireless remote controller 1 Felt tape For left or left rear piping 1 Battery AAA for remote controller 2 Remote controller Operation indicator lamp Remote control receiving section Spec name plate Horizontal vane Air inlet Air ﬁlter Air purifying ﬁlter Air cleaning ﬁlter Silver ionized air puriﬁer ﬁlter option Front panel Air outlet Heat exchanger Emergency operation switch OBH849A ...

Page 4: ...w 19 29 Heating Super High 43 44 48 High 37 43 Med 30 38 Low 23 33 Super Low 20 29 Fan speed Cooling Super High rpm 990 1 150 High 840 1 000 Med 700 860 Low 580 760 Super Low 500 660 Heating Super High 1 060 1 210 High 860 1 060 Med 700 920 Low 560 770 Super Low 500 640 Fan speed regulator 5 Remote controller model ZH19A NOTE Test conditions are based on IS 1391 Cooling Indoor Dry bulb temperature...

Page 5: ...NCTION SPL dB A LINE 46 HEATING 48 10 20 30 40 50 60 70 80 90 63 125 250 500 1000 2000 4000 8000 NC 60 NC 50 NC 40 NC 30 NC 20 NC 70 OCTAVE BAND SOUND PRESSURE LEVEL dB re 0 0002 MICRO BAR BAND CENTER FREQUENCIES Hz COOLING FUNCTION SPL dB A LINE 43 HEATING 43 Test conditions Cooling Dry bulb temperature 27 C Wet bulb temperature 19 C Heating Dry bulb temperature 20 C Wet bulb temperature 15 C IND...

Page 6: ... SPACER MIN 125mm MIN 20mm MIN 7mm MIN 30mm INSTALLATION PLATE 11 20 OBLONG HOLE 11 26 OBLONG HOLE INDOOR UNIT WALL HOLE ø65 AIR OUT AIR IN INSTALLATION PLATE PIPING DRAIN HOSE MSZ BT20 25 35VG PIPING INSULATION ø37 O D LIQUID LINE ø6 35 0 39m FLARED CONNECTION ø6 35 GAS LINE ø9 52 0 34m FLARED CONNECTION ø9 52 DRAIN HOSE INSULATION ø29 CONNECTED PART ø16 O D MSZ BT50VG PIPING INSULATION ø37 O D L...

Page 7: ...YE VARİSTÖR TERMİNAL BLOĞU RESİSTÖR İÇ ÜNİTE ELEKTRONİK KONTROL KARTI Konektör Terminal bloğu NOTLAR 1 Dış ünite elektronik kablolaması için dış ünite elektronik kablo devre şemasını referans alınız 2 Sadece bakır besleme kablosu kullanın 3 Sembolleri gösterir ODA SICAKLIK TERMİSTÖRÜ BORU SICAKLIK TERMİSTÖRÜ ANA BORU SICAKLIK TERMİSTÖRÜ YARDIMCI SİGORTA T3 15AL250V FAN MOTORU KANAT MOTORU YATAY RÖ...

Page 8: ...l thermistor RT12 Indoor coil thermistor RT13 Refrigerant flow in cooling Refrigerant flow in heating MSZ BT35VG MSZ BT50VG Indoor heat exchanger Flared connection Room temperature thermistor RT11 Flared connection Refrigerant pipe ø6 35 with heat insulator Indoor coil thermistor RT12 Refrigerant pipe ø 9 52 MSZ BT35VG ø12 7 MSZ BT50VG with heat insulator Indoor coil thermistor RT13 Refrigerant fl...

Page 9: ...er to each remote controller according to the number of the indoor unit Set according to the following procedure 1 Turn the breaker OFF for the unit 2 With the remote controller powered OFF hold down UNIT button on the remote controller for 2 seconds to enter the pairing mode Setting number is displayed in the remote controller 3 Press UNIT button again and assign a number to each remote controlle...

Page 10: ...ds 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 can celled If the unit has been turned 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 the breaker from...

Page 11: ...s OFF ON stop operate FAN speed control button Operation select button ECONO COOL button UNIT button TIME TIMER set buttons forward button backward button RESET button CLOCK button NIGHT MODE button Distance of signal About 6 m Beep s is are heard from the indoor unit when the signal is received ON timer button OFF timer button i save button VANE control button Battery replacement indicator MICROP...

Page 12: ...top operate 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 unit does not operate 9 4 HEAT OPERATION 1 Press OFF ON stop operate button OPERATION INDICATOR lamp of the indoor unit turns on with a beep tone 2 Select HEAT mode with Opera...

Page 13: ...t As a result energy can be saved To cancel this operation select a different mode or press one of the following buttons in ECONO COOL operation ECONO COOL VANE control button 5 STOP operation OFF and ON TIMER standby In the following cases the horizontal vane returns to the closed position a When OFF ON stop operate button is pressed POWER OFF b When the operation is stopped by the emergency oper...

Page 14: ...test run operation the system shifts to EMERGENCY COOL HEAT MODE with a set temperature of 24 C The fan speed shifts to Medium The coil frost prevention works even in the test run or the emergency opera tion 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 receiv...

Page 15: ... OFF before starting ser vice work 2 Before servicing check that the connector and terminal are connected properly 3 When the electric 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 10 2 10 3 and 10 4 NOTE 1 If RESET button is not pressed the remote controller may not operate ...

Page 16: ...p the failure mode recall function mentioned above Press OFF ON stop operate 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 Ye...

Page 17: ...stics of the main indoor coil thermistor the sub indoor coil thermistor 10 7 3 time blink 2 5 sec ond OFF Serial signal The serial signal from outdoor unit is not re ceived for a maximum of 6 minutes Refer to 10 6 How to check miswiring and serial signal error 11 time blink 2 5 second OFF Indoor fan motor The rotational frequency feedback signal is not emitted for the 12 seconds after the indoor f...

Page 18: ...ted refer to outdoor unit service manual Left lamp blink on and off at 0 5 second intervals Cause Indoor Outdoor unit Miswiring or trouble of serial signal Left lamp 2 time blink Cause Indoor unit Trouble of room temperature indoor coil thermistor Left lamp 3 time blink Cause Indoor unit Trouble of indoor fan motor Left lamp 4 time blink Cause Indoor unit Trouble of indoor unit control system Left...

Page 19: ...mpressor Refer to outdoor unit service manual Check the stop valve 6 Outdoor thermistors Left lamp blinks 6 time blink 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 7 Outdoor control sys tem Left lamp blinks 7 time blink 2 5 second OFF It cannot properly read data in the nonvola...

Page 20: ...a tester Temperature 10 30 C Color of the lead wire Normal RED SKY 262 328 Ω SKY SKY RED SKY SKY ROTOR OPERATION INDICATOR No Abnormal point Operation indicator lamp Symptom Condition Remedy 1 MXZ type Operation mode setting Left lamp lights and right lamp blinks 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 C...

Page 21: ...ronic control P C board 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 measured at 2 above goes 0 V DC although the indoor P C board is normal Does the voltage between CN211 and on the power P C board rise to the range of 3 to 6 V DC within 12 seconds after EMERGENCY OPERATION sw...

Page 22: ...ble to operate with it if the inverter fluorescent light is turned on when the room is warm the unit may be able to operate with the remote controller Replace the indoor electronic control P C board Including the receiver Does the unit operate with the remote controller OK Yes No Not clear Replace the batteries Refer to 10 1 4 Press OFF ON stop operate button on the remote controller Is LCD displa...

Page 23: ...n only Measure the resistance between CN211 and of indoor fan motor connector 2 3 Yes Is the resistance 1MΩ or more Replace the fuse F11 and the indoor fan motor 3 No Replace the fuse F11 1 Measure the resistance of resistor R111 on the indoor power P C board No Replace the indoor electronic control P C board and the indoor fan motor Replace the indoor electronic control P C board Measure the resi...

Page 24: ...t is OFF and wiring is not loose No Does DC 6 V or more occur between indoor terminal block S2 and S3 Yes Replace the outdoor inverter P C board 1 No Replace the indoor electronic control P C board 1 Electric charge may remain immediately after the power supply is turned OFF Perform the procedure after 3 minutes Replace the outdoor inverter P C board 1 Yes No Was the indoor unit ever connected to ...

Page 25: ...ny error of the indoor outdoor connecting wire such as the damage of the wire intermediate connection poor contact to the terminal block Replace the indoor outdoor connecting wire Is serial signal error indicated 6 minutes later Yes No Turn OFF inverter controlled lighting equipment Turn OFF the power supply and then turn ON again Press EMERGENCY OPERATION switch Reinstall either the unit or the l...

Page 26: ...he installation condition combination of specific conditions such as antennas or wiring Check the following 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 outd...

Page 27: ...1 Indoor coil thermistor RT12 RT13 Temperature C Resistance kΩ Connector to Indoor fan motor CN211 Resistor R111 Room temperature thermistor RT11 CN111 Connector to Indoor coil thermistor CN112 RT12 RT13 Vane motor CN151 12 V DC 5 V DC GND To disable Auto restart function cut the Jumper wire to JR77 Refer to 8 3 Fuse F11 T3 15AL250V Varistor NR11 Emergency operation switch E O SW SW1 Indoor termin...

Page 28: ...minal slowly Connector Sleeve Locking lever Detaching method of the terminal with locking mechanism The terminal which has the locking mechanism can be detached as shown below There are following 2 types of the terminal with locking mechanism The terminal without locking mechanism can be detached by pulling it out Check the shape of the terminal before detaching DISASSEMBLY INSTRUCTIONS 11 11 1 MS...

Page 29: ...r through B as shown in the Photo 3 Removing the indoor terminal P C board indoor elec tronic control P C board and power monitor receiver SW P C board 8 Remove the screw of the terminal block and remove the earth wire connected to the electrical box from the indoor electronic control P C board 9 Remove the power monitor receiver SW P C board holder from the electrical box 10 Unhook the hooks of t...

Page 30: ... cover Refer to section 2 4 Disconnect the following connectors on the electronic control P C board CN151 Vane motor 5 Pull out the drain hose from the nozzle assembly and remove the nozzle assembly Removing the vane motor 6 Cut the fixing band of the vane motor wire Photo 5 7 Remove the screws of the vane motor and remove the vane motor Photo 6 8 Disconnect the connector from the vane motor 30 Ph...

Page 31: ...otor band and remove the motor band Pull out the indoor fan motor 8 Remove the indoor coil thermistor from the heat exchanger Install the indoor coil thermistor in its former position when assembling it 9 Remove the screws fixing the left side of the heat exchanger 10 Lift the heat exchanger and pull out the line flow fan to the lower left When attaching the line flow fan screw the line flow fan s...

Page 32: ...l thermistor to the clip shape holder shape part the lead wire should point down 1 Set the indoor coil thermistor in the center of the clip shape part 2 Check the marked mounting position 3 Mount the clip shape part Position and procedure for mounting the clip shape part About the same length 32 Copyright 2019 MITSUBISHI ELECTRIC CORPORATION Issued Dec 2019 No OBH849 REVISED EDITION A Published Oc...

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