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11

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) If the electronic control P.C. board seems to be defective, check the copper foil pattern for disconnection and the com-

ponents for bursting and discoloration.

3) When troubleshooting, refer to 11-2, 11-3 and 11-4.

Lead wiring

Housing point

11-1. CAUTIONS ON TROUBLESHOOTING

1. Before troubleshooting, check the following:

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

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 electrical parts, be careful of the residual voltage of smoothing capacitor.
4) When removing the electronic control P.C. board, hold the edge of the board with care NOT to apply stress on the 

components.

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

MXZ-2B20NA  MXZ-2B20NA -

1

11-2. FAILURE MODE RECALL FUNCTION

This air conditioner can memorize the abnormal condition which has occurred once.
Even though LED indication listed on the troubleshooting check table (11-4.) disappears, the memorized failure details
can be recalled.
This mode is very useful when the unit needs to be repaired for the abnormality which does not recur.

1. Type of failure mode recall function

There are 2 types in failure mode recall function as shown below.

Indoor and outdoor unit failure mode recall function

  With this function, failure mode of indoor unit and a part of failure mode of outdoor unit can be recalled. 

The details of outdoor unit failure mode recall function

  With this function, more detailed failure mode of outdoor unit can be recalled.

Refer to the service manual of indoor unit for how to recall the failure mode and the details of indoor unit failure mode.
The outdoor unit failure mode is indicated by the operation indicator lamp on the indoor unit and the LED of outdoor unit.
See "11-2.2. Outdoor unit failure mode table".

TROUBLESHOOTING

Содержание Mr.Slim MXZ-2B20NA

Страница 1: ...TIONS 17 11 TROUBLESHOOTING 18 12 DISASSEMBLY INSTRUCTIONS 34 INDOOR UNITS COMBINATION SHEETS No OBH560 REVISED EDITION A The Slim Line From Mitsubishi Electric TM OUTDOOR UNIT MXZ 2B20NA MXZ 2B20NA 1 MXZ 2B20NA Indoor unit service manual MSZ A NA Series OB450 MSZ FD NA Series OBH497 MSZ FE NA Series OBH542 MSZ GE NA Series OBH548 SEZ KD NA TH Series SPLIT TYPE AIR CONDITIONERS HFC utilized R410A ...

Страница 2: ...Z 2B20NA 1 Air outlet Drain outlet Air inlet Back and side Revision A MXZ 2B20NA 1 has been added MXZ 2B20NA New model MXZ 2B20NA MXZ 2B20NA 1 1 Outdoor fan motor has been changed 2 Outdoor electronic control P C board has been changed 3 LEV coil has been changed ...

Страница 3: ...ied optional parts 1 4 A B 3 8 Flared Flared 5 lb 15 oz 23 7 NEO22 18 000 22 000 12 500 1 440 1 650 1 350 12 5 18 0 8 9 7 0 3 91 20 000 22 000 12 500 2 190 1 780 1 430 9 1 15 5 8 5 6 9 3 62 1 Cooling Heating Mode 1 A Cooling steady state at rated compressor speed B 2 Cooling steady state at rated compressor speed B 1 Cooling steady state at minimum compressor speed Low ambient cooling steady state...

Страница 4: ...ATE THRESHOLD OF HEARING FOR CONTINUOUS NOISE NC 60 NC 50 NC 40 NC 30 NC 20 NC 70 OCTAVE BAND SOUND PRESSURE LEVEL 0dB 0 0002 MICRO BAR BAND CENTER FREQUENCIES Hz Cooling High FUNCTION FAN SPEED Heating High 49 SPL dB A 51 LINE NOISE CRITERIA CURVE 4 MXZ 2B20NA MXZ 2B20NA 1 ...

Страница 5: ... 3 16 2 1 2 15 19 32 11 16 11 16 3 7 8 Punched holes Connecting wire hole 2 3 8 1 3 16 14 1 4 5 5 16 3 5 16 1 25 32 29 32 1 5 32 More than 3 15 16 More than 19 11 16 More than 7 7 8 More than13 25 32 More than 3 15 16 More than 19 11 16 More than 13 25 32 More than 13 25 32 More than 3 15 16 SERVICE SPACE More than 3 15 16 More than 19 11 16 Note Leave front and both sides clearance fully Note Lea...

Страница 6: ...6 WIRING DIAGRAM 6 MXZ 2B20NA MXZ 2B20NA 1 ...

Страница 7: ...8 Capillary tube O D 0 10 x I D 0 02 x 39 37 Capillary tube O D 0 16 x I D 0 11 x 3 93 Capillary tube O D 0 16 x I D 0 11 x 3 93 Discharge temperature thermistor RT62 Strainer 100 Strainer 100 R V coil OFF ON Refrigerant flow in cooling Refrigerant flow in heating Ambient temperature thermistor RT65 Outdoor heat exchanger temperature thermistor RT68 FAN OUT HEX OUT Service port Service port Strain...

Страница 8: ...20NA MXZ 2B20NA 1 Cooling Heating Maximum Minimum Maximum Minimum Indoor intake air temperature 95 FDB 71 FWB 67 FDB 57 FWB 80 FDB 67 FWB 70 FDB 60 FWB Outdoor intake air temperature 115 FDB 14 FDB 75 FDB 65 FWB 6 FDB 5 FWB a b Outdoor unit Indoor units 49 ft 33 ft 49 ft Max height difference Indoor unit class Extension pipe diameter 09 or less Liquid 1 4 Gas 3 8 12 Liquid 1 4 Gas 3 8 15 Liquid 1 ...

Страница 9: ...rcuit Condensing pressure PSIG 411 319 417 350 Suction pressure PSIG 141 102 130 101 Discharge temperature ºF 169 154 174 172 Condensing temperature ºF 114 100 120 104 Suction temperature ºF 71 46 65 46 Comp shell bottom temp ºF 163 149 185 167 Ref pipe length Total pipe length for multi system ft 82 164 Refrigerant charge R410A 5 lb 15 oz Outdoor unit Intake air temperature DB ºF 95 47 95 47 WB º...

Страница 10: ...or speed Standard rating heating at rated compressor speed Low temperature heating at rated compressor speed Max temperature heating at minimum compressor speed High temperature heating at minimum compressor speed Frost accumulation at rated compressor speed Frost accumulation at intermediate compressor speed DB F 80 80 80 80 80 70 70 70 70 70 70 WB F 67 67 67 67 67 60 60 60 60 60 60 Indoor DB F 9...

Страница 11: ...he indoor outlet air wet dry bulb temperature for your reference at service Cooling Heating How to measure the indoor air wet bulb dry bulb temperature difference 1 Attach at least 2 sets of wet and dry bulb thermometers to the indoor air intake as shown in the figure and at least 2 sets of wet and dry bulb thermometers to the indoor air outlet The thermometers must be attached to the position whe...

Страница 12: ...erature F Indoor intake air Dry bulb temperature F NOTE The above broken lines are for the heating operation without any frost and defrost operation 0 8 0 9 1 0 1 1 1 2 1 3 14 23 32 41 50 59 68 77 86 95 104 113 Outdoor intake air Dry bulb temperature F Input correction factors 79 75 72 68 64 Indoor intake air Wet bulb temperature F Total input Cooling at Rated frequency 09 class 35Hz 15 class 69Hz...

Страница 13: ...Total input Hz HEAT Capacity Frequency Hz Frequency HEAT Total input Hz COOL Capacity Frequency Hz Frequency COOL Total input Hz HEAT Capacity Frequency Hz Frequency HEAT Total input Hz 2 09 class unit in single operation 3 12 class unit in single operation 4 15 class unit in single operation 0 50 100 0 5 1 0 1 5 2 0 0 50 100 0 5 1 0 1 5 2 0 0 50 100 0 50 100 1 0 1 5 2 0 2 5 COOL Capacity Frequenc...

Страница 14: ...50 55 60 65 70 75 2 0 3 0 4 0 5 0 6 0 7 0 Ambient temperature F Outdoor low pressure Outdoor unit current A Outdoor unit current A 45 Hz PSIG 33 Hz 33 Hz 65 75 70 86 80 75 70 Indoor DB temperature F Indoor DB temperature F How to work fixed frequency operation 1 Set emergency switch to COOL or HEAT The switch is located on indoor unit 2 Press emergency run ON OFF button 3 Compressor starts running...

Страница 15: ... 75 Indoor DB temperature F Indoor DB temperature F Indoor DB temperature F Data is based on the condition of indoor humidity 50 Air flow speed High Inverter output frequency 33 Hz How to work fixed frequency operation 1 Set emergency switch to COOL or HEAT The switch is located on indoor unit 2 Press emergency run ON OFF button 3 Compressor starts running at 33 Hz COOL or 45 Hz HEAT 4 Indoor fan ...

Страница 16: ... 75 Indoor DB temperature F Indoor DB temperature F Indoor DB temperature F Data is based on the condition of indoor humidity 50 Air flow speed High Inverter output frequency 33 Hz How to work fixed frequency operation 1 Set emergency switch to COOL or HEAT The switch is located on indoor unit 2 Press emergency run ON OFF button 3 Compressor starts running at 33 Hz COOL or 45 Hz HEAT 4 Indoor fan ...

Страница 17: ...liquefied and collected in the compressor it may interfere the start up of the compressor To improve start up condition the compressor is energized even while it is not operating This is to generate heat at the winding The compressor uses about 50 W when pre heat control is turned ON Pre heat control is ON at initial setting How to deactivate pre heat control Turn OFF the power supply for the air ...

Страница 18: ...e of smoothing capacitor 4 When removing the electronic control P C board hold the edge of the board with care NOT to apply stress on the components 5 When connecting or disconnecting the connectors hold the housing of the connector DO NOT pull the lead wires MXZ 2B20NA MXZ 2B20NA 1 11 2 FAILURE MODE RECALL FUNCTION This air conditioner can memorize the abnormal condition which has occurred once E...

Страница 19: ...on stop or bus bar voltage protection stop is continuously performed three times within 3 minutes after start up When thermistor shorts or opens during compressor running When 28A current flows into intelligent power module When discharge temperature exceeds 240 8 F during operation Compressor can restart if discharge temperature thermistor reads 212 F or less 3 minutes later When the outdoor heat...

Страница 20: ... Refer to 11 6 Check of LEV Check the drain pump of the indoor unit When the communication between boards protection stop is continuously performed twice Communication error occurs between the electronic control P C board and power board for more than 10 seconds Current sensor protection stop is continuously performed twice When a short or open circuit is detected in the current sensor during comp...

Страница 21: ...e protection 2 13 times Goes out Outdoor fan motor Refer to 11 6 Check of outdoor fan motor Lighting 8 times Current sensor protection Replace the power board Lighting 11 times Communication between P C boards protection Check the connecting wire between outdoor electronic control P C board and power board Lighting 12 times Zero cross detecting circuit protection Check the connecting wire among ou...

Страница 22: ...erature is kept under 122 F COOL mode 104 F HEAT mode for more than 40 minutes When the frequency of the compressor is kept 80Hz or more and the discharge temperature is kept under 102 2 F for more than 20 minutes When the outdoor heat exchanger temperature exceeds 136 4 F during operation 9 times Lighting Inverter check mode Lighting Lighting Normal When the unit is operated with emergency operat...

Страница 23: ...frost thermistor RT61 Ambient temperature thermistor RT65 Outdoor heat exchanger temperature thermistor RT68 Measure the resistance with a tester Refer to 11 7 Test point diagram and voltage 1 Outdoor electronic control P C board or 3 Outdoor power board for the chart of thermistor Measure the resistance with a tester Before measurement hold the thermistor with your hands to warm it up Refer to 11...

Страница 24: ...V AC in the power supply terminal block Is the output voltage from the noise filter P C board 208 230 V AC Is the input voltage to the outdoor electronic control P C board 294 325 V DC Check the power supply cable Replace the outdoor electronic control P C board Replace the noise filter P C board Is the input voltage to the power board 208 230 V AC Replace the reactor 11 6 TROUBLESHOOTING FLOW MXZ...

Страница 25: ...ltage of smoothing capacitor Replace the outdoor electronic control P C board 2 Is there any 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 ...

Страница 26: ...s there normal resistance to R V coil Refer to 11 5 1 Disconnect the lead wire leading to the compressor 2 3 minutes after turning ON the power supply start EMERGENCY OPERATION in COOL mode Is there voltage of 208 230 V AC between pin1 and pin 2 at connector CN912 1 Turn OFF the power supply of the indoor and the outdoor unit and disconnect the connector CN781 2 3 minutes after turning ON the powe...

Страница 27: ...heard Or do you feel vibration of LEV coil with your hand Disconnect the connectors CN791 LEV A CN792 LEV B CN795 LEV E Is there normal resistance to LEV coil Refer to 11 5 Normal Replace the outdoor electronic control P C board Replace LEV coil When cooling heat exchanger of non operating indoor unit frosts When heating non operating indoor unit get warm ...

Страница 28: ...esistance between the compressor terminals Is the resistance between each terminal normal Refer to 11 5 Is the input voltage to the outdoor electronic control P C board 370 V or more Reconnect the lead wire of compressor and turn ON the power supply to indoor and outdoor unit 3 minutes later start EMERGENCY OPERATION Replace the compressor Replace the power board 1 After the outdoor fan starts run...

Страница 29: ... between each terminal become 5 V DC and 0 V DC repeatedly Replace the outdoor fan motor Replace the outdoor electronic control P C board Disconnect CN932 from the outdoor electronic control P C board and measure the resistance of the outdoor fan motor Is the resistance of outdoor fan motor normal Refer to 11 5 Normal Yes No Abnormal Disconnect the connector in the following table and measure the ...

Страница 30: ...ion frequency does not go up from the lowest frequency Check of bus bar voltage Check the voltage of power supply Confirm outdoor unit failure mode recall function Refer to 11 2 2 Blink 5 times Confirm LED1 indication lamp on the outdoor electronic control P C board Replace the power board Blink 9 times Replace the outdoor elec tronic control P C board Turn OFF power supply before removing P C boa...

Страница 31: ...294 V DC 370 V DC Input LEV Room A 12 V DC pulse wave LEV Room B 12 V DC pulse wave CN932 20 90 V AC GND 5 V 5 V DC pulse wave To fan motor Defrost thermistor RT61 Discharge temperature thermistor RT62 Outdoor heat exchanger temperature thermistor RT68 Rush current relay R V coil 1 2 V DC 15 V 15 V CN931 CN661 CN701 Signal transmission To power board 5 V DC pulse wave GND CN702 Signal reception Fr...

Страница 32: ...8 230 V AC Output F64 FUSE T2AL250V CN901 To electronic control P C board CN912 R V coil 208 230 V AC CN902 To power board CN903 To power board F65 FUSE T6 3AL250V MXZ 2B20NA MXZ 2B20NA 1 208 230 V AC Input CN61 208 230 V AC Output ...

Страница 33: ...ntroller board 1 5 Signal transmission To electronic control P C board 5 V DC pulse wave 2 5 Zero cross signal 3 4 Not used 6 5 15 V 7 5 15 V Signal reception From electronic control P C board 5 V DC pulse wave CN3 Fin temperature thermistor RT64 294 370 V DC Output 1 3 200 180 160 140 120 100 80 60 40 20 0 Resistance kΩ Temperature F 32 50 68 86 104 122 140 158 176 Fin temperature thermistor RT64...

Страница 34: ...ove the cabinet 5 Remove the screws of the back panel and remove the back panel Photo 3 6 Disconnect the compressor lead wire from terminal of the compressor U V W 7 Disconnect the outdoor electronic control P C board connectors CN661 CN663 CN791 CN792 CN795 CN931 CN932 Disconnect the noise filter P C board connector CN912 8 Remove the screws of the electrical parts and remove the electrical parts...

Страница 35: ...he propeller 4 Remove the fan motor Photo 6 Screws of the outdoor fan motor Propeller Propeller nut Separator Sound proof felt Photo 3 Photo 4 R V coil 4 way valve LEV coil E Expansion valve E Suction pipe welded part Discharge pipe welded part Photo 5 Compressor nuts Screw of the rear guard Screw of the back panel Screw of the back panel Screws of the back panel Screws of the back panel Screws of...

Страница 36: ... back panel Photo 1 2 3 3 Recover gas from the refrigerant circuit NOTE Recover gas from the pipes until the pressure gauge shows 0 PSIG 4 Remove the electrical parts Photo 4 5 Detach the welded parts of 4 way valve and pipe Photo 7 5 Removing the expansion valve 1 Remove the top panel Photo 1 2 Remove the service panel the cabinet and the back panel Photo 1 2 3 Gas recovery is not required if the...

Страница 37: ...37 ...

Страница 38: ...O 100 8310 JAPAN Copyright 2009 MITSUBISHI ELECTRIC ENGINEERING CO LTD Distributed in Dec 2009 No OBH560 REVISED EDITION A 5 Distributed in Sep 2009 No OBH560 5 Made in Japan New publication effective Dec 2009 Specifications subject to change without notice ...

Страница 39: ...all Wall 5800 14200 20000 1660 8 23 7 44 97 7800 23000 630 2230 Wall Duct 5800 14200 20000 1930 9 57 8 65 97 7800 21500 650 2210 Wall Wall 9000 9000 18000 1440 7 14 6 45 97 7800 20000 630 1820 Wall Duct 9000 9000 18000 1610 7 98 7 22 97 7800 19000 650 1800 Duct Duct 9000 9000 18000 1780 8 82 7 98 97 7800 18000 670 1780 Wall Wall 8500 11500 20000 1660 8 23 7 44 97 7800 23000 630 2230 Wall Duct 8500...

Страница 40: ...000 1650 8 18 7 40 97 8500 25500 520 2410 Wall Duct 6400 15600 22000 1720 8 52 7 71 97 8500 25500 520 2520 09 09 Wall Wall 11000 11000 22000 1650 8 18 7 40 97 8500 25500 520 2410 Wall Duct 11000 10900 21900 1740 8 62 7 80 97 8500 25500 520 2520 D uct Duct 10900 10900 21800 1820 9 02 8 16 97 8500 25500 520 2620 09 12 Wall Wall 9500 12500 22000 1650 8 18 7 40 97 8500 25500 520 2410 Wall Duct 9500 12...

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