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Mitsubishi Electric MXZ-3C24NA Service Manual
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Mitsubishi Electric MXZ-3C24NA Service Manual

Split-type air conditioners outdoor unit
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OUTDOOR UNIT
INDOOR UNIT

SERVICE MANUAL

Models
MXZ-3C24NA
MXZ-3C30NA
MXZ-4C36NA
Revision A:
• MXZ-3C24NA, MXZ-3C30NA and MXZ-
4C36NA have been added.
Please void OBH702.
HFC
utilized
R410A
Indoor unit service manual
MSZ-FE·NA Series (OBH542)
MSZ-GE·NA Series (OBH548)
MFZ-KA·NA Series (OBH568)
SEZ-KD·NA Series
PLA-A·BA Series (OCH420)
PCA-A·KA Series (OCH455)
PEAD-A·AA Series
SLZ-KA·NA Series (OCH487)
MSZ-FH·NA Series (OBH683)
MVZ-A·AA Series
CONTENTS
1. TECHNICAL CHANGES ··································· 2
2. PART NAMES AND FUNCTIONS ····················· 3
3. SPECIFICATION ················································ 4
4. NOISE CRITERIA CURVES ·····························11
5. OUTLINES AND DIMENSIONS ······················ 13
6. WIRING DIAGRAM ·········································· 18
7. REFRIGERANT SYSTEM DIAGRAM ············· 23
8. DATA ································································ 34
9. ACTUATOR CONTROL ··································· 56
10. SERVICE FUNCTIONS ···································· 57
11. TROUBLESHOOTING ····································· 59
12. DISASSEMBLY INSTRUCTIONS ···················· 77
INDOOR UNITS COMBINATION TABLES
PARTS CATALOG (OBB702)
No. OBH702
REVISED EDITION-A
TM

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Summary of Contents for Mitsubishi Electric MXZ-3C24NA

  • Page 1: Table Of Contents

    Revision A: • MXZ-3C24NA, MXZ-3C30NA and MXZ- 4C36NA have been added. Please void OBH702. INDOOR UNIT OUTDOOR UNIT No. OBH702 utilized REVISED EDITION-A SERVICE MANUAL R410A Models MXZ-3C24NA MXZ-3C30NA Indoor unit service manual MSZ-FE·NA Series (OBH542) MXZ-4C36NA MSZ-GE·NA Series (OBH548) MFZ-KA·NA Series (OBH568)

  • Page 2: Mxz-3C24Na

    Revision A: • MXZ-3C24NA, MXZ-3C30NA and MXZ-4C36NA have been added. Use the specifi ed refrigerant only Never use any refrigerant other than that specified. Doing so may cause a burst, an explosion, or fire when the unit is being used, serviced, or disposed of.

  • Page 3: Part Names And Functions

    PART NAMES AND FUNCTIONS MXZ-3C24NA MXZ-3C30NA MXZ-4C36NA Air inlet (Back and side) Air outlet Drain outlet MXZ-5C42NA MXZ-2C20NAHZ MXZ-3C24NAHZ MXZ-3C30NAHZ Air inlet (Back and side) Air outlet Drain outlet OBH702A...

  • Page 4: Specification

    SPECIFICATION Outdoor model MXZ-3C24NA Item Indoor type Non-Duct (06+09+09 ) Duct ( 09+09+09) Cooling Btu/h 22,000 23,600 Capacity Heating 47 Btu/h 25,000 24,600 19,600 19,600 Heating 17 Btu/h 1,620 2,100 Cooling Power Heating 47 1,750 1,900 consumption Heating 17 2,120...
  • Page 5 Outdoor model MXZ-3C30NA Item Indoor type Non-Duct (09+09+12 ) Duct ( 09+09+12) Cooling Btu/h 28,400 27,400 Capacity Heating 47 Btu/h 28,600 27,600 21,000 21,000 Heating 17 Btu/h 2,680 2,860 Cooling Power Heating 47 2,150 2,220 consumption Heating 17 2,120 2,140 Cooling 10.6 19.0...
  • Page 6 Outdoor model MXZ-4C36NA Item Indoor type Non-Duct (09+09+09+09 ) Duct ( 09+09+09+09) Cooling Btu/h 35,400 34,400 Capacity Heating 47 Btu/h 36,000 34,400 26,600 26,600 Heating 17 Btu/h 3,760 3,940 Cooling Power Heating 47 3,020 3,100 consumption Heating 17 3,340 3,450 Cooling 19.2 16.0...
  • Page 7 Outdoor model MXZ-5C42NA Item Indoor type Non-Duct (06+09+09+09+09) Duct (09+09+09+09+09) Cooling Btu/h 40,500 37,500 Capacity Heating 47 Btu/h 45,000 41,000 24,400 23,000 Heating 17 Btu/h 4,403 4,112 Cooling Power Heating 47 3,575 3,463 consumption Heating 17 2,943 2,869 Cooling 19.7 15.2 SEER Cooling...
  • Page 8 Outdoor model MXZ-2C20NAHZ Item Indoor type Non-Duct (09+09) Duct (09+12) Cooling Btu/h 18,000 20,000 Capacity Heating 47 Btu/h 22,000 22,000 13,700 13,700 Heating 17 Btu/h 1,334 1,819 Cooling Power Heating 47 1,612 1,748 consumption Heating 17 1,450 1,588 Cooling 13.5 11.0 17.0 15.0...
  • Page 9 Outdoor model MXZ-3C24NAHZ Item Indoor type Non-Duct (06+06+09) Duct (09+09+09) Cooling Btu/h 22,000 23,600 Capacity Heating 47 Btu/h 25,000 24,600 14,000 14,000 Heating 17 Btu/h 1,630 2,360 Cooling Power Heating 47 1,725 1,871 consumption Heating 17 1,622 1,635 Cooling 13.5 10.0 19.0 15.5...
  • Page 10 Outdoor model MXZ-3C30NAHZ Item Indoor type Non-Duct (09+09+12) Duct (09+09+12) Cooling Btu/h 28,400 27,400 Capacity Heating 47 Btu/h 28,600 27,600 18,000 17,000 Heating 17 Btu/h 2,272 2,661 Cooling Power Heating 47 2,096 2,187 consumption Heating 17 1,991 1,993 Cooling 12.5 10.3 18.0 16.0...

  • Page 11: Noise Criteria Curves

    NOISE CRITERIA CURVES MXZ-3C24NA MXZ-3C30NA FAN SPEED FUNCTION SPL(dB LINE FAN SPEED FUNCTION SPL(dB LINE High Cooling High Cooling High Heating High Heating NC-70 NC-70 NC-60 NC-60 NC-50 NC-50 NC-40 NC-40 NC-30 NC-30 APPROXIMATE APPROXIMATE THRESHOLD OF THRESHOLD OF HEARING FOR...
  • Page 12 MXZ-5C42NA MXZ-2C20NAHZ FAN SPEED FUNCTION SPL(dB LINE FAN SPEED FUNCTION SPL(dB LINE High Cooling High Cooling High Heating High Heating NC-70 NC-70 NC-60 NC-60 NC-50 NC-50 NC-40 NC-40 NC-30 NC-30 APPROXIMATE APPROXIMATE THRESHOLD OF THRESHOLD OF HEARING FOR HEARING FOR NC-20 NC-20 CONTINUOUS...

  • Page 13: Outlines And Dimensions

    OUTLINES AND DIMENSIONS MXZ-3C24NA Unit: inch (mm) MXZ-3C30NA Conduit plates Conduit connector Lock nut OBH702A...
  • Page 14 Unit: inch (mm) MXZ-4C36NA Conduit plates Conduit connector Lock nut OBH702A...
  • Page 15 Unit: inch (mm) MXZ-5C42NA Conduit plate Top Conduit connector Lock nut Conduit plate Under OBH702A...
  • Page 16 MXZ-2C20NAHZ Unit: inch (mm) Lock nut Conduit plate Conduit connector OBH702A...
  • Page 17 MXZ-3C24NAHZ Unit: inch (mm) MXZ-3C30NAHZ Lock nut Conduit plate Top Conduit connector Conduit plate Under OBH702A...

  • Page 18: Wiring Diagram

    WIRING DIAGRAM MXZ-3C24NA MXZ-3C30NA OBH702A...
  • Page 19 MXZ-4C36NA OBH702A...
  • Page 20 MXZ-5C42NA CIRCUIT BREAKER TAB5 TAB3 TAB6 TAB4 X52CA TAB1 POWER SUPPLY 208/230V IC411 IC501 IC401 X52CB 1 phase 60Hz GRN/YLW TAB2 X65A PTC1 PTC2 PTC3 12-24V TO INDOOR ~208/230V UNIT No. E OUTDOOR CNAC1 POWER P.C. BOARD 12-24V TO INDOOR CNDC CN151 CN152...
  • Page 21 MXZ-2C20NAHZ OBH702A...
  • Page 22 MXZ-3C24NAHZ MXZ-3C30NAHZ OBH702A...

  • Page 23: Refrigerant System Diagram

    REFRIGERANT SYSTEM DIAGRAM MXZ-3C24NA Unit: inch (mm) MXZ-3C30NA R.V.coil Refrigerant flow in heating Refrigerant flow in cooling Accumulator Compressor Service port High pressure switch Compressor shell Muffler temperature thermistor Service port RT62 Union Header(Gas) Stop valve Indoor unit A 4-way valve...
  • Page 24 Operating Range MXZ-3C24NA MXZ-3C30NA Indoor intake air temperature Outdoor intake air temperature Maximum 95°FDB, 71°FWB 115°FDB Cooling Minimum 67°FDB, 57°FWB 14°FDB Maximum 80°FDB, 67°FWB 75°FDB, 65°FWB Heating Minimum 70°FDB, 60°FWB 6°FDB, 5°FWB MAX. REFRIGERANT PIPING LENGTH & PIPE SIZE SELECTION...
  • Page 25 MXZ-4C36NA Unit: inch (mm) R.V.coil Refrigerant flow in heating Refrigerant flow in cooling Accumulator Compressor Service port High pressure switch Compressor shell Muffler temperature thermistor Service port RT62 Union Header(Gas) Stop valve 4-way valve Indoor unit A (with service port) Indoor unit B Header (Evaporator) muffler...
  • Page 26 Operating Range MXZ-4C36NA Indoor intake air temperature Outdoor intake air temperature Maximum 95°FDB, 71°FWB 115°FDB Cooling Minimum 67°FDB, 57°FWB 14°FDB Maximum 80°FDB, 67°FWB 75°FDB, 65°FWB Heating Minimum 70°FDB, 60°FWB 6°FDB, 5°FWB MAX. REFRIGERANT PIPING LENGTH & PIPE SIZE SELECTION MXZ-4C36NA Piping length each indoor unit (a, b, c, d) 82 ft.
  • Page 27 Unit: inch (mm) MXZ-5C42NA R.V.coil Refrigerant flow in heating Refrigerant flow in cooling Accumulator Compressor Compressor shell Service port temperature Oil separator thermistor RT62 High pressure switch Union Service port Header(Gas) Indoor unit A 4-way valve Indoor unit B Stop valve Header(Evaporator) (with service port) Indoor unit C...
  • Page 28 Operating Range MXZ-5C42NA Indoor intake air temperature Outdoor intake air temperature Maximum 95°FDB, 71°FWB 115°FDB Cooling Minimum 67°FDB, 57°FWB 14°FDB Maximum 80°FDB, 67°FWB 75°FDB, 65°FWB Heating Minimum 70°FDB, 60°FWB 6°FDB, 5°FWB MAX. REFRIGERANT PIPING LENGTH & PIPE SIZE SELECTION MXZ-5C42NA Piping length each indoor unit (a, b, c, d, e) 82 ft.
  • Page 29 Unit: inch (mm) MXZ-2C20NAHZ R.V.coil Refrigerant flow in heating Refrigerant flow in cooling Accumulator Compressor Compressor shell Service port temperature Oil separator thermistor RT62 High pressure switch Union Header(Gas) Service port 4-way valve Indoor unit A Stop valve Header(Evaporator) (with service port) Outdoor Capillary tube 2-way...
  • Page 30 Operating Range MXZ-2C20NAHZ Indoor intake air temperature Outdoor intake air temperature Maximum 95°FDB, 71°FWB 115°FDB Cooling Minimum 67°FDB, 57°FWB 14°FDB Maximum 80°FDB, 67°FWB 75°FDB, 65°FWB Heating Minimum 70°FDB, 60°FWB -12°FDB, -13°FWB MAX. REFRIGERANT PIPING LENGTH & PIPE SIZE SELECTION MXZ-2C20NAHZ Piping length each indoor unit (a, b) 82 ft.
  • Page 31 MXZ-3C24NAHZ Unit: inch (mm) MXZ-3C30NAHZ R. V. coil Refrigerant flow in heating Refrigerant flow in cooling Accumulator Compressor Compressor shell Service port temperature Oil separator thermistor RT62 High pressure switch Union Header(Gas) Service port Indoor unit A 4-way valve Stop valve Header(Evaporator) (with service port) Indoor unit B...
  • Page 32 Operating Range MXZ-3C24NAHZ MXZ-3C30NAHZ Indoor intake air temperature Outdoor intake air temperature Maximum 95°FDB, 71°FWB 115°FDB Cooling Minimum 67°FDB, 57°FWB 14°FDB Maximum 80°FDB, 67°FWB 75°FDB, 65°FWB Heating Minimum 70°FDB, 60°FWB -12°FDB, -13°FWB MAX. REFRIGERANT PIPING LENGTH & PIPE SIZE SELECTION MXZ-3C24NAHZ MXZ-3C30NAHZ Piping length each indoor unit (a, b, c) 82 ft.

  • Page 33: Pumping Down

    PUMPING DOWN When relocating or disposing of the air conditioner, pump down the system following the procedure below so that no refriger- ant is released into the atmosphere. 1) Turn off the breaker. 2) Connect the gauge manifold valve to the service port of the stop valve on the gas pipe side of the outdoor unit. 3) Fully close the stop valve on the liquid pipe side of the outdoor unit.

  • Page 34: Data

    DATA Model MXZ-3C24NA Indoor type Non-Duct (06+06+09) Duct (09+09+09) Item Unit Cooling Heating Cooling Heating Total Capacity Btu/h 22,000 25,000 23,600 24,600 – – – – – Input 1.62 1.75 2.10 1.90 Electrical Power supply (V, phase, Hz) 208/230, 1, 60...
  • Page 35 Model MXZ-4C36NA Indoor type Non-Duct (09+09+09+09) Duct (09+09+09+09) Item Unit Cooling Heating Cooling Heating Total Capacity Btu/h 35,400 36,000 34,400 34,400 – – – – – Input 3.76 3.02 3.94 3.10 Electrical Power supply (V, phase, Hz) 208/230, 1, 60 circuit Input 3.672...
  • Page 36 Model MXZ-5C42NA Indoor type Non-Duct (06+09+09+09+09) Duct (09+09+09+09+09) Item Unit Cooling Heating Cooling Heating Capacity Btu/h 40,500 45,000 37,500 41,000 Total Input 4.41 3.58 4.17 3.47 Power supply (V, phase, Hz) 208/230, 1, 60 Input 4.300 3.465 3.870 3.270 Electrical circuit Comp.
  • Page 37 Model MXZ-3C24NAHZ Indoor type Non-Duct (06+06+09) Duct (09+09+09) Item Unit Cooling Heating Cooling Heating Capacity Btu/h 22,000 25,000 23,600 24,600 Total Input 1.63 1.73 2.36 1.88 Power supply (V, phase, Hz) 208/230, 1, 60 Input 1.564 1.661 2.180 1.760 Electrical circuit Comp.
  • Page 38 8-1. OPERATING RANGE (1) POWER SUPPLY Guaranteed Voltage Model Rating MXZ-3C24NA MXZ-2C20NAHZ MXZ-3C30NA MXZ-3C24NAHZ Min. 198 V 208 V 230 V Max. 253 V 208/230 V 60 Hz 1 Outdoor unit MXZ-4C36NA MXZ-3C30NAHZ MXZ-5C42NA (2) OPERATION Intake air Indoor Outdoor...
  • Page 39 MXZ-3C24NA MXZ-3C30NA MXZ-4C36NA MXZ-5C42NA MXZ-2C20NAHZ MXZ-3C24NAHZ MXZ-3C30NAHZ The standard specifications apply only to the operation of the air conditioner under normal conditions. Since operating conditions vary according to the areas where these units are installed, the following information has been pro- vided to clarify the operating characteristics of the air conditioner under the conditions indicated by the performance curve.
  • Page 40 8-2. CAPACITY AND THE INPUT CURVES MXZ-3C24NA MXZ-3C30NA MXZ-4C36NA Cooling capacity (at Rated frequency) 11.3 13.8 13.5 17.1 15.6 Indoor intake air Wet-bulb 10.5 12.7 12.4 15.8 14.4 temperature(°F) 11.7 11.4 14.5 13.2 10.7 10.5 13.2 12.1 12.0 10.9 10.7 Outdoor intake air Dry-bulb temperature(°F)
  • Page 41 MXZ-5C42NA MXZ-2C20NAHZ MXZ-3C24NAHZ MXZ-3C30NAHZ Cooling capacity (at Rated frequency) 11.3 13.8 13.5 17.1 15.6 Indoor intake air Wet-bulb 10.5 12.7 12.4 15.8 14.4 temperature(°F) 11.7 11.4 14.5 13.2 10.7 10.5 13.2 12.1 12.0 10.9 10.7 Outdoor intake air Dry-bulb temperature(°F) Total input (Cooling : at Rated frequency Indoor intake air Wet-bulb...
  • Page 42 8-3. CAPACITY AND INPUT CORRECTION BY MEANS OF INVERTER OUTPUT FREQUENCY (OUTDOOR UNIT: MXZ-3C24NA MXZ-3C30NA MXZ-4C36NA) 1. 06-class unit in single operation <HEAT>Total input <COOL>Total input <HEAT>Capacity <COOL>Capacity Frequency Frequency Frequency Frequency 2. 09-class unit in single operation <HEAT>Capacity <HEAT>Total input <COOL>Total input...
  • Page 43 (OUTDOOR UNIT: MXZ-5C42NA MXZ-2C20NAHZ MXZ-3C24NAHZ MXZ-3C30NAHZ) 1. 06-class unit in single operation <HEAT>Total input <COOL>Total input <HEAT>Capacity <COOL>Capacity Frequency Frequency Frequency Frequency 2. 09-class unit in single operation <HEAT>Capacity <HEAT>Total input <COOL>Capacity <COOL>Total input Frequency Frequency Frequency Frequency 3. 12-class unit in single operation <HEAT>Total input <COOL>Total input <HEAT>Capacity...
  • Page 44 8-4. OUTDOOR LOW PRESSURE AND OUTDOOR UNIT CURRENT 1. 06-class unit in single operation (OUTDOOR UNIT : MXZ-3C24NA MXZ-3C30NA MXZ-4C36NA) (1) COOL operation Data is based on the condition of indoor <How to work fixed-frequency operation> humidity 50% 1. Set emergency switch to COOL or HEAT. The switch is located Air flow speed : High on indoor unit.
  • Page 45 2. 09-class unit in single operation (OUTDOOR UNIT : MXZ-3C24NA MXZ-3C30NA MXZ-4C36NA) (1) COOL operation Data is based on the condition of indoor <How to work fixed-frequency operation> humidity 50% 1. Set emergency switch to COOL or HEAT. The switch is located Air flow speed : High on indoor unit.
  • Page 46 3. 12-class unit in single operation (OUTDOOR UNIT : MXZ-3C24NA MXZ-3C30NA MXZ-4C36NA) (1) COOL operation Data is based on the condition of indoor <How to work fixed-frequency operation> humidity 50% 1. Set emergency switch to COOL or HEAT. The switch is located Air flow speed : High on indoor unit.
  • Page 47 4. 15-class unit in single operation (OUTDOOR UNIT : MXZ-3C24NA MXZ-3C30NA MXZ-4C36NA) (1) COOL operation Data is based on the condition of indoor <How to work fixed-frequency operation> humidity 50% 1. Set emergency switch to COOL or HEAT. The switch is located Air flow speed : High on indoor unit.
  • Page 48 5. 18-class unit in single operation (OUTDOOR UNIT : MXZ-3C24NA MXZ-3C30NA MXZ-4C36NA) (1) COOL operation Data is based on the condition of indoor <How to work fixed-frequency operation> humidity 50% 1. Set emergency switch to COOL or HEAT. The switch is located Air flow speed : High on indoor unit.
  • Page 49 6. 24-class unit in single operation (OUTDOOR UNIT : MXZ-3C30NA MXZ-4C36NA) (1) COOL operation Data is based on the condition of indoor <How to work fixed-frequency operation> humidity 50% 1. Set emergency switch to COOL or HEAT. The switch is located Air flow speed : High on indoor unit.
  • Page 50 7. 06-class unit in single operation (OUTDOOR UNIT : MXZ-5C42NA MXZ-2C20NAHZ MXZ-3C24NAHZ MXZ-3C30NAHZ) (1) COOL operation Data is based on the condition of indoor <How to work fixed-frequency operation> humidity 50% 1. Set emergency switch to COOL or HEAT. The switch is located Air flow speed : High on indoor unit.
  • Page 51 8. 09-class unit in single operation (OUTDOOR UNIT : MXZ-5C42NA MXZ-2C20NAHZ MXZ-3C24NAHZ MXZ-3C30NAHZ) (1) COOL operation Data is based on the condition of indoor <How to work fixed-frequency operation> humidity 50% 1. Set emergency switch to COOL or HEAT. The switch is located Air flow speed : High on indoor unit.
  • Page 52 9. 12-class unit in single operation (OUTDOOR UNIT : MXZ-5C42NA MXZ-2C20NAHZ MXZ-3C24NAHZ MXZ-3C30NAHZ) (1) COOL operation Data is based on the condition of indoor <How to work fixed-frequency operation> humidity 50% 1. Set emergency switch to COOL or HEAT. The switch is located Air flow speed : High on indoor unit.
  • Page 53 10. 15-class unit in single operation (OUTDOOR UNIT : MXZ-5C42NA MXZ-2C20NAHZ MXZ-3C24NAHZ MXZ-3C30NAHZ) (1) COOL operation Data is based on the condition of indoor <How to work fixed-frequency operation> humidity 50% 1. Set emergency switch to COOL or HEAT. The switch is located Air flow speed : High on indoor unit.
  • Page 54 11. 18-class unit in single operation (OUTDOOR UNIT : MXZ-5C42NA MXZ-3C24NAHZ MXZ-3C30NAHZ) (1) COOL operation Data is based on the condition of indoor <How to work fixed-frequency operation> humidity 50% 1. Set emergency switch to COOL or HEAT. The switch is located Air flow speed : High on indoor unit.
  • Page 55 12. 24-class unit in single operation (OUTDOOR UNIT : MXZ-5C42NA MXZ-3C30NAHZ) (1) COOL operation Data is based on the condition of indoor <How to work fixed-frequency operation> humidity 50% 1. Set emergency switch to COOL or HEAT. The switch is located Air flow speed : High on indoor unit.

  • Page 56: Actuator Control

    ACTUATOR CONTROL MXZ-3C24NA MXZ-3C30NA MXZ-4C36NA MXZ-5C42NA MXZ-2C20NAHZ MXZ-3C24NAHZ MXZ-3C30NAHZ Relation between main sensor and actuator Actuator 2-way solenoid Defrost valve heater Sensor Purpose Outdoor (MXZ-5C42VA Compressor 4-way valve (MXZ-2C20NAHZ fan motor MXZ-2C20NAHZ MXZ-3C24NAHZ MXZ-3C24NAHZ MXZ-3C30NAHZ) MXZ-3C30NAHZ) ○ ○ ○ Discharge temperature...

  • Page 57: Service Functions

    SERVICE FUNCTIONS MXZ-3C24NA MXZ-3C30NA MXZ-4C36NA MXZ-5C42NA MXZ-2C20NAHZ MXZ-3C24NAHZ MXZ-3C30NAHZ 10-1. PRE-HEAT CONTROL If moisture gets into the refrigerant cycle, or when refrigerant is 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.
  • Page 58 10-2. AUTO LINE CORRECTING Outdoor unit has an auto line correcting function which automatically detects and corrects improper wiring or piping. Improper wiring or piping can be automatically detected by pressing the piping/wiring correction switch (SW871). When improper wiring or piping is detected, wiring lines are corrected. This will be completed in about 10 to 20 minutes.

  • Page 59: Troubleshooting

    TROUBLESHOOTING MXZ-3C24NA MXZ-3C30NA MXZ-4C36NA MXZ-5C42NA MXZ-2C20NAHZ MXZ-3C24NAHZ MXZ-3C30NAHZ 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 miswiring. 2. Take care of the following during servicing.
  • Page 60 2. Flow chart of the detailed outdoor unit failure mode recall function Operational procedure The outdoor unit might be abnormal. Check if outdoor unit is abnormal according to the following procedures. Make sure that the remote controller is set to the failure mode recall function. 1 Regardless of normal or abnormal condition, 2 short beeps are emitted as the signal is received.
  • Page 61 3. Outdoor unit failure mode table LED indication The left lamp of Indoor/ (Outdoor P.C. OPERATION IN- Abnormal point outdoor unit Condition Remedy board) DICATOR lamp (Failure mode/protection) failure mode (Indoor unit) recall function LED 1 LED 2 None (Normal) Lighted Lighted 2-time fl...
  • Page 62 11-3. INSTRUCTION OF TROUBLESHOOTING • Check the indoor unit with referring to the indoor unit service manual, and confirm that there is any problem in the indoor unit. Then, check the outdoor unit with referring to this page. Operation start Check the outdoor unit LED indicator.

  • Page 63: Troubleshooting Check Table

    P.C. board. • Refer to 11-6. "Check of bus-bar voltage". Low out side tempera- The ambient became 10.4°F or less. ture protection(cooling) The ambient became 1.4°F or less. (MXZ-3C24NA, 11 times Not lighted — Low out side tempera- MXZ-3C30NA, MXZ-4C36NA, MXZ-5C42NA) ture protection(Heating) The ambient became -18°F or less.
  • Page 64 Indication Abnormal point / Con- Symptom Condition Remedy dition LED1(Red) LED2(Yellow) 21 'Outdoor unit A failure occurs 3 consecutive times within 30 13 times Not lighted Outdoor fan motor • Refer to 11-6. "Check of outdoor fan motor". stops and seconds after the fan gets started.
  • Page 65 Compressor Measure the resistance between terminals using a tester. (Winding temperature: 14°F ~ 104°F) Normal (Each phase) MXZ-3C24NA MXZ-3C30NA MXZ-4C36NA Measure the resistance between terminals using a tester. (Winding temperature: 14°F ~ 104°F) Normal (Each phase) MXZ-5C42NA MXZ-2C20NAHZ MXZ-3C24NAHZ MXZ-3C30NAHZ Outdoor fan motor Measure the resistance using a tester.
  • Page 66 11-6. TROUBLESHOOTING FLOW Outdoor unit does not operate. Check of power supply Check the main power supply circuit for proper connections. Turn ON the power supply. Is there voltage of 208/230 VAC in the Check the power supply cable. power supply terminal block? Is the output voltage from the outdoor Replace the outdoor control P.C.
  • Page 67 • When unit cannot operate neither by the remote controller nor by EMERGENCY OPERATION switch. Indoor unit does not operate. • When OPERATION INDICATOR lamp flashes ON and OFF in every 0.5-second. Outdoor unit does not operate. How to check miswiring and serial signal error (when outdoor unit does not work) Turn OFF the power supply.
  • Page 68 The cooling operation or heating operation does not operate. Check of R.V. coil CNAC Outdoor control CN712 P.C. board 1. Disconnect the lead wire leading to the compressor. Outdoor power 2. 3 minutes after turning ON the power supply, start EMERGENCY CNAC2 P.C.
  • Page 69 • When cooling, heat exchanger of non-operating indoor unit frosts. • When heating, non-operating indoor unit gets warm. Check of LEV CN791 Turn ON the power supply to the outdoor unit after checking LEV coil is CN792 Outdoor mounted to the LEV body securely. CN793 control CN794...
  • Page 70 • When heating, room does not get warm. • When cooling, room does not get cool. How to check inverter/compressor Disconnect the terminal of the compressor or the connector (CNMC) between the compressor and the outdoor power P.C. board. 3 minutes after the power supply is turned ON, start EMERGENCY OPERATION.
  • Page 71 • When thermistor is abnormal. Check of outdoor thermistors Replace the thermistor except RT64. Disconnect the connector in the following table and Abnormal In case that RT64 is abnormal, replace the measure the resistance of the thermistor to check outdoor power P.C. board since RT64 is combined whether the thermistor is normal or not.
  • Page 72 • Fan motor does not operate or stops operating shortly after starting the operation. Check of outdoor fan motor Disconnect CNF1 and measure the CNF1 Outdoor control resistance of the outdoor fan motor. P.C. board Is the resistance of outdoor fan motor Measuring points Resistance Replace the outdoor fan motor.
  • Page 73 • When the operation frequency does not go up from the lowest frequency. Check of HPS Outdoor control CN63H P.C. board 1. Disconnect the connector CN63H in the outdoor control P.C. board. 2. Check the resistance of HPS after 1 minute has passed since the outdoor unit power supply was turned OFF. Infinity Replace HPS.
  • Page 74 Defrost thermistor (RT61) 11-7. TEST POINT DIAGRAM AND VOLTAGE Ambient temperature thermistor (RT65) Outdoor heat exchanger temperature 1. Outdoor control P.C. board thermistor (RT68) MXZ-3C24NA MXZ-3C30NA Serial signal 12 ~ 24 V 230 VDC Room A MXZ-4C36NA MXZ-5C42NA Room B Room C Room D Room E...
  • Page 75 2. Outdoor power P.C. board MXZ-3C24NA MXZ-3C30NA MXZ-4C36NA Output to drive compressor CN171 Fin temperature thermistor CN152 (RT64) Signal Transmission (From Outdoor Control P.C. board) 5 VDC pulse wave Connect to earth CNAC2 208/230 VAC Output F1 FUSE T6.3AL250V 208/230 VAC...
  • Page 76 2. Outdoor power P.C. board MXZ-5C42NA MXZ-2C20NAHZ MXZ-3C24NAHZ MXZ-3C30NAHZ CNDC Bus-bur voltage 290 - 370 VDC CN171 Output to drive compressor CNAC1 Connect to earth Fin temperature thermistor 208/230 V Output (RT64) F1 FUSE T6.3AL250V CN152 F2 FUSE Signal T6.3AL250V Transmission (From Outdoor Control P.C.

  • Page 77: Disassembly Instructions

    Pull the terminal while pull out the terminal pushing the locking slowly. Locking lever lever. Connector 12-1. MXZ-3C24NA MXZ-3C30NA MXZ-4C36NA Photos : MXZ-4C36NA NOTE: Turn OFF the power supply before disassembly. OPERATING PROCEDURE PHOTOS 1. Removing the panels Photo 1...
  • Page 78 OPERATING PROCEDURE PHOTOS 2. Removing the outdoor control P.C. board, the reac- Photo 4 tor and the outdoor power P.C. board Catches of the PB cover (1) Remove the top panel and the service panel (Refer to 1). (2) Disconnect the power supply and indoor/outdoor connect- ing wire.
  • Page 79 OPERATING PROCEDURE PHOTOS 3. Removing the fan motor Photo 7 (1) Remove the top panel, the service panel, and the front panel (Refer to 1). Propeller fan (2) Disconnect the power supply and indoor/outdoor connect- ing wire. (3) Disconnect the connector CNF1 on the outdoor control P.C. board.
  • Page 80 OPERATING PROCEDURE PHOTOS 5. Removing the expansion valve Photo 9 (1) Remove the top panel, and the service panel (Refer to 1). (2) Disconnect the power supply and indoor/outdoor connect- ing wire. (Gas recovery is not required if the unit is pumped down.) (3) Remove the LEV coils.
  • Page 81 12-2. MXZ-5C42NA MXZ-2C20NAHZ MXZ-3C24NAHZ MXZ-3C30NAHZ Photos : MXZ-3C30NAHZ NOTE: Turn OFF the power supply before disassembly. OPERATING PROCEDURE PHOTOS Photo 1 1. Removing the panels Screws of the top panel (1) Remove the screws fixing the top panel, and remove the top panel.
  • Page 82 OPERATING PROCEDURE PHOTOS Screw 2. Removing the outdoor control P.C. board, the reac- Photo 4 of the tor and the outdoor power P.C. board electrical (1) Remove the top panel, the service panel and the front parts panel (Refer to 1). (2) Disconnect the power supply and indoor/outdoor connect- Screws ing wire.
  • Page 83 OPERATING PROCEDURE PHOTOS 3. Removing the fan motor Photo 9 (1) Remove the top panel, the service panel, and the front Screw of the panel (Refer to 1). Screws of the outdoor fan motor VB fixture (2) Disconnect the power supply and indoor/outdoor connect- ing wire.
  • Page 84 Compressor nuts LEV coils valves HEAD OFFICE: TOKYO BLDG., 2-7-3, MARUNOUCHI, CHIYODA-KU, TOKYO 100-8310, JAPAN © Copyright 2014 MITSUBISHI ELECTRIC CORPORATION Distributed in Oct. 2014. No. OBH702 REVISED EDITION-A New publication, effective Oct. 2014 Distributed in Sep. 2014. No. OBH702 Specifications are subject to change without notice.

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