Mitsubishi Electric MUZ-HX09NL-U1 Service Manual
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Mitsubishi Electric MUZ-HX09NL-U1 Service Manual

Mitsubishi Electric MUZ-HX09NL-U1 Service Manual

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OUTDOOR UNIT
SERVICE MANUAL
Models
MUZ-HX09NL
MUZ-HX12NL
MUZ-HX18NL
MUZ-HX24NL
MUZ-HX18NL
-
U1
-
U1
-
U1
-
U1
Indoor unit service manual
MSZ-HX•NL Series (OBH952)
CONTENTS
1. TECHNICAL CHANGES ······························ 2
USING REFRIGERANT R454B ····················· 3
3. PART NAMES AND FUNCTIONS ·················· 8
4. SPECIFICATION ········································· 9
5. OUTLINES AND DIMENSIONS ····················12
6. WIRING DIAGRAM ····································15
7. REFRIGERANT SYSTEM DIAGRAM ············18
8. DATA ·······················································21
9. ACTUATOR CONTROL ······························32
10. SERVICE FUNCTIONS ·······························33
11. TROUBLESHOOTING ································34
12. DISASSEMBLY INSTRUCTIONS ··················60
PARTS CATALOG (OBB953)
Revision A:
• MUZ-HX09/12NL -
added.
OBH953 is void.
No. OBH953
HFC
utilized
REVISED EDITION-A
R454B
have been
U1

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Summary of Contents for Mitsubishi Electric MUZ-HX09NL-U1

  • Page 1: Table Of Contents

    Revision A: • MUZ-HX09/12NL - have been added. OBH953 is void. OUTDOOR UNIT No. OBH953 utilized REVISED EDITION-A SERVICE MANUAL R454B Models MUZ-HX09NL MUZ-HX12NL MUZ-HX18NL MUZ-HX24NL Indoor unit service manual MSZ-HX•NL Series (OBH952) CONTENTS 1. TECHNICAL CHANGES ······························ 2 2. SERVICING PRECAUTIONS FOR UNITS USING REFRIGERANT R454B ·····················...

  • Page 2: Technical Changes

    Use the specified 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. Correct refrigerant is specified in the manuals and on the spec labels provided with our products. We will not be held responsible for mechanical failure, system malfunction, unit breakdown or accidents caused by failure to follow the instructions.

  • Page 3: Servicing Precautions For Units Using Refrigerant R454B

    SERVICING PRECAUTIONS FOR UNITS USING REFRIGERANT R454B Servicing precautions for units using refrigerant R454B Refrigerant WARNING Safety Group This unit uses a flammable refrigerant. If refrigerant leaks and comes in contact with fire or heating part, it will create harmful gas and there is risk of fire. Do not use means to accelerate the defrosting process or to clean, other than those recommended by the manufacturer.

  • Page 4: Additional Refrigerant Charge

    2. Additional refrigerant charge Additional refrigerant charge Refrigerant for the indoor units and the extended piping is not included in the outdoor unit when the unit is shipped from the factory. Therefore, charge each refrigerant piping system with additional refrigerant at the installation site. In addition, in order to carry out service, enter the size and length of each liquid pipe and additional refrigerant charge amounts in the spaces pro- vided on the “Refrigerant amount”...
  • Page 5 3. Cautions for the unit using R454B refrigerant Basic work procedures are the same as those for conventional units using refrigerant R410A. However, pay careful attention to the following points. ■ Information on servicing 1. Checks to the area Prior to beginning work on systems containing FLAMMABLE REFRIGERANTS, safety checks are necessary to ensure that the risk of ignition is minimized.
  • Page 6 ■ Repairs to sealed components Sealed electrical components shall be replaced. ■ Repair to intrinsically safe components Intrinsically safe components must be replaced. ■ Cabling Check that cabling will not be subject to wear, corrosion, excessive pressure, vibration, sharp edges or any other adverse environmental effects.
  • Page 7 ■ Decommissioning Before carrying out this procedure, it is essential that the technician is completely familiar with the equipment and all its detail. It is recommended good practice that all refrigerants are recovered safely. Prior to the task being carried out, an oil and refrigerant sample shall be taken in case analysis is required prior to re-use of recovered refrigerant.

  • Page 8: Part Names And Functions

    PART NAMES AND FUNCTIONS MUZ-HX09NL MUZ-HX12NL Air inlet (Back and side) Piping Air outlet Drain hose Drain outlet MUZ-HX18NL Air inlet (Back and side) Piping Air outlet Drain hose Drain outlet MUZ-HX24NL Air inlet (Back and side) Piping Air outlet Drain hose Drain outlet OBH953A...

  • Page 9: Specification

    SPECIFICATION Outdoor unit model MUZ-HX09NL MUZ-HX12NL MUZ-HX18NL Cooling * Btu/h 9,000 (3,600 – 11,000) 12,000 (3,600 – 13,400) 17,200 (5,800 – 18,000) Capacity Rated (Minimum – Maximum) Heating 47 * Btu/h 10,900 (4,000 – 13,000) 12,200 (4,500 – 15,500) 18,000 (5,400 – 20,800) Capacity Heating 17 * Btu/h...
  • Page 10 Outdoor unit model MUZ-HX24NL Cooling * Btu/h 22,400 (5,800 – 22,400) Capacity Rated (Minimum – Maximum) Heating 47 * Btu/h 26,000 (6,200 – 26,000) Capacity Heating 17 * Btu/h 17,200 (18,500) Rated (Maximum) Cooling * 1,910 (380 – 2,200) Power consumption Rated (Minimum –...

  • Page 11: Test Condition

    Test condition *3, *4 AHRI Indoor air condition (°F) Outdoor air condition (°F) Mode Test 210/240 Dry bulb Wet bulb Dry bulb Wet bulb “A-Full” Cooling Steady State at rated compressor speed “B-Full” Cooling Steady State at rated compressor speed SEER “B-Low”...

  • Page 12: Outlines And Dimensions

    OUTLINES AND DIMENSIONS MUZ-HX09NL MUZ-HX12NL Unit: inch REQUIRED SPACE 4 in. (100 mm) or more when front and sides of the unit are clear When any 2 sides of left, right and rear of the unit are clear holes Liquid refrigerant pipe joint Refrigerant pipe (flared) ø1/4 Gas refrigerant pipe joint Refrigerant pipe (flared) ø3/8...
  • Page 13 MUZ-HX18NL Unit: inch LIQUID REFRIGERANT PIPE FLARED 1/4ʺ REFRIGERANT PIPE JOINT GAS REFRIGERANT PIPE FLARED 1/2ʺ OBH953A...
  • Page 14 MUZ-HX24NL Unit: inch REQUIRED SPACE 4 in OR MORE 14 in OR MORE 16-7/16 AIR IN ↓ DRAIN HOLE ø1-21/32 → 20 in OR MORE AIR IN OPEN TWO SIDES OF RIGHT, 4 in OR MORE LEFT OR REAR SIDE ↓...

  • Page 15: Wiring Diagram

    WIRING DIAGRAM MUZ-HX09NL MUZ-HX12NL OBH953A...
  • Page 16 MUZ-HX18NL OBH953A...
  • Page 17 MUZ-HX24NL OBH953A...

  • Page 18: Refrigerant System Diagram

    REFRIGERANT SYSTEM DIAGRAM MUZ-HX09NL Unit: Inch (mm) Refrigerant pipe ø3/8 (ø9.52) 4-way valve (with heat insulator) Muffler Outdoor heat exchanger Stop valve temperature (with service port) Outdoor thermistor Muffler heat Discharge Flared connection RT68 Service port exchanger temperature Service port thermistor (high pressure) (low pressure)
  • Page 19 MUZ-HX18NL Unit: Inch (mm) Refrigerant pipe 1/2 (ø12.7) 4-way valve (with heat insulator) Muffler Outdoor heat exchanger Stop valve Muffler Defrost temperature Outdoor thermistor Capillary tube thermistor Discharge Flared connection RT61 heat O.D. 0.118 × RT68 temperature exchanger I.D. 0.079 × 8-9/32 thermistor (ø3.0 ×...
  • Page 20 MAX. REFRIGERANT PIPING LENGTH and MAX. HEIGHT DIFFERENCE Refrigerant piping: ft. Piping size O.D: in. Model Max. Length Max. Height difference Liquid MUZ-HX09NL MUZ-HX12NL MUZ-HX18NL MUZ-HX24NL Indoor unit Max. Height difference Max. Length Outdoor unit OBH953A...

  • Page 21: Data

    DATA MUZ-HX09NL MUZ-HX12NL MUZ-HX18NL MUZ-HX24NL 8-1. PERFORMANCE DATA 1) COOLING CAPACITY Indoor air Outdoor intake air DB temperature (˚F) Model IWB (˚F) 11.0 0.67 0.64 10.3 0.67 0.70 0.67 0.76 MUZ-HX09NL 10.4 0.80 0.60 0.80 0.67 0.80 0.72 0.93 0.58 0.93 0.64 0.93...

  • Page 22: Heating Capacity

    4) HEATING CAPACITY Indoor air Outdoor intake air WB temperature (˚F) Model IDB (˚F) 0.53 0.67 0.79 0.88 10.6 0.92 11.0 0.94 12.4 0.97 MUZ-HX09NL 0.51 0.65 0.77 0.86 10.9 0.90 11.2 0.92 12.7 0.95 0.49 0.62 0.74 10.0 0.83 11.2 0.88 11.6...

  • Page 23: Performance Curve

    8-2. PERFORMANCE CURVE Cooling (at Rated frequency) Cooling capacity (at Rated frequency) Indoor intake air Wet-bulb temperature( F) Outdoor intake air DB temperature(°F) MUZ-HX09NL MUZ-HX12NL SHF at rating condition = 0.80 SHF at rating condition = 0.76 = 342 CFM = 428 CFM Airflow Airflow...
  • Page 24 Heating (at Rated frequency) Heating capacity (at Rated frequency) Outdoor intake air WB temperature (°F) MUZ-HX09NL MUZ-HX12NL = 390 CFM = 401 CFM Airflow Airflow Outdoor intake air WB temperature (°F) Outdoor intake air WB temperature (°F) MUZ-HX18NL MUZ-HX24NL Airflow = 621 CFM Airflow = 720 CFM...
  • Page 25 8-3. CONDENSING PRESSURE Cooling Data are based on the condition of indoor humidity 50 %. Air flow should be set to High speed. MUZ-HX09NL (psig) (psig) 95 100 105 110 115 (°F) 95 100 105 110 115 (°F) Outdoor ambient temperature Outdoor ambient temperature MUZ-HX12NL (psig)
  • Page 26 MUZ-HX24NL (psig) (psig) 95 100 105 110 115 95 100 105 110 115 (°F) (°F) Outdoor ambient temperature Outdoor ambient temperature NOTE: Data shown are estimated value. Performance may vary depending on operating conditions. Heating Data are based on the condition of outdoor humidity 75%. Air flow should be set to High speed.
  • Page 27 MUZ-HX18NL (psig) (psig) (°F) (°F) Outdoor ambient temperature Outdoor ambient temperature MUZ-HX24NL (psig) (psig) (°F) (°F) Outdoor ambient temperature Outdoor ambient temperature NOTE: 1. Press the emergency operation switch on the front of the indoor unit, and select either EMERGENCY COOL mode or EMERGENCY HEAT mode before starting to operate the air conditioner.

  • Page 28: Standard Operation Data

    8-4. STANDARD OPERATION DATA Model MSZ-HX09NL MSZ-HX12NL Item Unit COOL HEAT COOL HEAT Capacity Btu/h 9,000 10,900 12,000 12,200 — — 0.76 — Input 0.72 0.96 0.99 Rated frequency Indoor unit MSZ-HX09NL MSZ-HX12NL Power supply V, phase, Hz 208/230, 1, 60 208/230, 1, 60 Input 0.018...
  • Page 29 Model MSZ-HX18NL MSZ-HX24NL Item Unit COOL HEAT COOL HEAT Capacity Btu/h 17,200 18,000 22,400 26,000 — 0.78 — 0.73 — Input 1.37 1.59 1.91 2.50 Rated frequency Indoor unit MSZ-HX18NL MSZ-HX24NL Power supply V, phase, Hz 208/230, 1, 60 208/230, 1, 60 Input 0.038 0.038...
  • Page 30 8-5. CAPACITY AND INPUT CORRECTION BY INVERTER OUTPUT FREQUENCY MUZ-HX09NL Correction of Cooling capacity Correction of Cooling total input Correction of Heating capacity Correction of Heating total input (Hz) (Hz) (Hz) (Hz) The operational frequency of compressor The operational frequency of compressor The operational frequency of compressor The operational frequency of compressor MUZ-HX12NL...
  • Page 31 8-6. HOW TO OPERATE FIXED-FREQUENCY OPERATION (Test run operation) 1. Press the emergency operation switch to start COOL or HEAT mode (COOL: Press once, HEAT: Press twice). 2. Test run operation starts and continues to operate for 30 minutes. 3. Compressor operates at rated frequency in COOL mode or 58 Hz (HX09/12/24)/55Hz (HX18) in HEAT mode. 4.

  • Page 32: Actuator Control

    ACTUATOR CONTROL MUZ-HX09NL MUZ-HX12NL MUZ-HX18NL MUZ-HX24NL 9-1. OUTDOOR FAN MOTOR CONTROL The fan motor turns ON/OFF, interlocking with the compressor. [ON] The fan motor turns ON 5 seconds before the compressor starts up. [OFF] The fan motor turns OFF 15 seconds after the compressor has stopped running. 5 seconds 15 seconds Compressor...

  • Page 33: Service Functions

    SERVICE FUNCTIONS MUZ-HX09NL MUZ-HX12NL MUZ-HX18NL MUZ-HX24NL 10-1. CHANGE IN DEFROST SETTING Changing defrost finish temperature <JS> To change the defrost finish temperature, cut/solder the JS wire of the outdoor inverter P.C. board (Refer to 11-6.1.). Defrost finish temperature Jumper MUZ-HX09/12/18NL MUZ-HX24NL Soldered 46°F (8°C)

  • Page 34: Troubleshooting

    TROUBLESHOOTING MUZ-HX09NL MUZ-HX12NL MUZ-HX18NL MUZ-HX24NL 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 1) Before servicing the air conditioner, be sure to turn OFF the main unit first with the remote controller, then after confirm- ing the horizontal vane is closed, turn off the breaker and/or disconnect the power plug.
  • Page 35 11-2. FAILURE MODE RECALL FUNCTION AND ERROR CODE DISPLAY MODE Outline of the function This air conditioner can memorize the failure which has occurred last time. Even though LED indication listed on the troubleshooting check table (11-3.) disappears, the memorized failure can be recalled.
  • Page 36 A (From previous page) Press OFF/ON (stop/operate) button of the remote controller with the remote controller headed towards the indoor unit. *1. The indoor unit is normal, but the outdoor unit might be abnormal. Does the left/upper OPERATION INDICATOR lamp There are some abnormalities that cannot be recalled with this way.
  • Page 37 2. Flow chart of the outdoor unit failure mode recall function Operational procedure The outdoor unit might be abnormal. Check if the outdoor unit is abnormal according to the following procedures. Make sure that the remote controller is set to the failure mode recall function. Get close to the front of the indoor unit.
  • Page 38 A (From previous page) 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. Repair the failure parts. Deleting the memorized abnormal condition After repairing the unit, recall the failure mode again according to “Setting up the failure mode recall function”...
  • Page 39 3. Flow chart of error code display mode This explains how customers can check the error code on their own. This is included in OPERATING INSTRUCTIONS. Operational procedure The remote controller is powered OFF. Get close to the front of the indoor unit. Point the remote controller at the receiving section of the indoor unit, and keep pressing CHECK with a Figure 1 fine-tipped object unil the beeps.
  • Page 40 4. Table of outdoor unit failure mode recall function OPERATION Indoor/outdoor Outdoor unit Error INDICATOR Abnormal point LED indication unit failure Condition Remedy failure mode lamp code (Failure mode/protection) (Outdoor P.C. board) mode recall recall function (Indoor unit) function Not blink None (Normal) —...
  • Page 41 NOTE: Blinking patterns of this mode differ from the ones of TROUBLESHOOTING CHECK TABLE (11-3.). OPERATION Indoor/outdoor Outdoor unit Error INDICATOR Abnormal point LED indication unit failure Condition Remedy failure mode lamp code (Failure mode/protection) (Outdoor P.C. board) mode recall recall function (Indoor unit) function...
  • Page 42 11-3. TROUBLESHOOTING CHECK TABLE Abnormal point/ Symptom LED indication Condition Remedy Condition Outdoor unit 1-time blink every Outdoor power Overcurrent protection cut-out operates 3 consecutive times • Reconnect connector of does not 2.5 seconds system within 1 minute after the compressor gets started. compressor.
  • Page 43 Abnormal point/ Symptom LED indication Condition Remedy Condition Outdoor unit 1-time blink Deceleration of the When the input current exceeds approximately 10A, compres- The unit is normal, but check the operates. 2.5 seconds OFF operational sor frequency lowers. following. frequency of the •...
  • Page 44 11-4. TROUBLESHOOTING CRITERION OF MAIN PARTS MUZ-HX09NL MUZ-HX12NL MUZ-HX18NL MUZ-HX24NL Part name Check method and criterion Figure Defrost thermistor (RT61) Measure the resistance with a multimeter. Fin temperature Refer to 11-6. “Test point diagram and voltage”, 1. “Inverter P.C. board”, for the thermistor (RT64) chart of thermistor.

  • Page 45: Troubleshooting Flow

    11-5. TROUBLESHOOTING FLOW A How to check inverter/compressor Disconnect the connector between the compressor and the power module (IC700). Check the voltage between terminals. See 11-5. “Check of open phase”. Are the voltages balanced? Replace the inverter P.C. board. Check the compressor. See 11-5.
  • Page 46 D Check of compressor winding ●Disconnect the connector between the compressor and the power module (IC700), and measure the resistance between the compressor terminals. <<Measurement point>> At 3 points *Measure the resistance between the lead wires at 3 points. BLK-WHT BLK-RED WHT-RED <<Judgement>>...
  • Page 47 G Check of outdoor thermistors Disconnect the connector of thermistor in the inverter P.C. board (see below table), and measure the resistance of thermistor. Replace the thermistor except RT64. Is the resistance of thermistor normal? When RT64 is abnormal, replace the inverter P.C. (Refer to 11-6.1.) board.
  • Page 48 H Check of R.V. coil MUZ-HX09/12/18 * First of all, measure the resistance of R.V. coil to check if the coil is defective. Refer to 11-4. * In case CN721 is disconnected or R.V. coil is open, voltage is generated between the terminal pins of the connector although no signal is being transmitted to R.V.
  • Page 49 I Check of outdoor fan motor Disconnect the connectors CN931 and CN932 from the inverter P.C. board. Check the connection between the connector CN931 and CN932. Is the resistance between each terminal of outdoor fan motor normal? (Refer to 11-4.) Disconnect CN932 from the inverter P.C.
  • Page 50 J Check of power supply Disconnect the connector between the compressor and the power module (IC700). Rectify indoor/outdoor Turn ON power supply and press connecting wire. the emergency operation switch. Does the left/upper lamp of the Is there voltage 208/230 V AC Replace the indoor OPERATION INDICATOR lamp on between the indoor terminal...
  • Page 51 K Check of LEV (Expansion valve) Turn ON the power supply. <Preparation of the remote controller> While pressing both Operation select button and TEMP button on the remote controller at the same time, press RESET button. First, release RESET button. Hold down the other 2 buttons for another 3 seconds.

  • Page 52: Emergency Operation

    L Check of inverter P.C. board Check the outdoor fan motor. (Refer to 11-5. .) Is the fuse (F901) blown on the inverter P.C. board? Check the connection of the connectors (CN931, CN932) of the outdoor fan motor. If the connection is poor, make it correct. Operate the outdoor unit by starting EMERGENCY OPERATION.
  • Page 53 M How to check miswiring and serial signal error Turn ON the power supply. Is there rated voltage in the power supply? Check the power supply. Is there rated voltage between outdoor terminal block S1 and S2? Check the wiring. Press the emergency operation switch once.
  • Page 54 N Check of defrost heater Check the following points before checking electric continuity. 1. Does the resistance of ambient temperature thermistor have the characteristics? Refer to 11-6.1. 2. Is the resistance of defrost heater normal? Refer to 11-4. 3. Does the heater protector remain conducted (not open)? 4.
  • Page 55 P Check of compressor protector Disconnect the connector of compressor protector in the inverter P.C. board, and check the conduc- tion of compressor protector. Operate the unit Is the discharge temperature Is the compressor and re-confirm if thermistor normal? Refer to 11-5. protector conductive? the abnormality “Check of outdoor thermistors”.
  • Page 56 Q Electromagnetic noise enters into TV sets or radios Is the unit grounded? Ground the unit. Is the distance between the antennas Extend the distance between the antennas and and the indoor unit within 9.91 ft. (3m), the indoor unit, and/or the antennas and the out- or is the distance between the antennas door unit.

  • Page 57: Inverter P.c. Board

    11-6. TEST POINT DIAGRAM AND VOLTAGE 1. Inverter P.C. board MUZ-HX09NL MUZ-HX12NL MUZ-HX18NL Smoothing Smoothing R.V.coil Back side of unit Heater (CN722) capacitor capacitor (CN721) DB61 208/230 V AC (C61) (C62) 208/230 V AC 260 – 370 V DC Fuse (F801) Fuse (F701) Fuse (F62) 208/230 V AC...
  • Page 58 MUZ-HX24NL Smoothing Smoothing Smoothing Output to drive Back side of unit Capacitor Capacitor Capacitor Fuse (F880) outdoor fan motor Heater (CN601) Fuse (F601) T3.15AL250V 230 V AC T3.15AL250V (CB1) (CB2) (CB3) (CN932) R.V. coil/ 21S4 208/230 V AC (CN602) 208/230 V AC Fuse (F62) 15 A 250 V Jumper wire...
  • Page 59 2. Fuse P.C. board MUZ-HX24NL FUSE (F66) FUSE (F65) T6.3AL250V T6.3AL250V OBH953A...

  • Page 60: Disassembly Instructions

    DISASSEMBLY INSTRUCTIONS <Detaching method of the terminal with locking mechanism> The terminal which has the locking mechanism can be detached as shown below. There are 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.
  • Page 61 OPERATING PROCEDURE PHOTOS/FIGURES Screws of Screw of the Photo 4 Screws of the Photo 5 the back panel conduit plate conduit cover 2. Removing the inverter assembly, inverter P.C. Photo 6 board Screw of the heat sink (1) Remove the top panel, cabinet and service panel. support and the separator (Refer to section 1.) (2) Disconnect the lead wire to the reactor and the following...
  • Page 62 OPERATING PROCEDURE PHOTOS/FIGURES * Connection procedure when attaching the inverter Photo 8 P.C. board (Photo 8) MUZ-HX09NL 1. Connect the lead wires of the fan motor (Power) to the Lead wires of Lead wires of Lead wires of the outdoor connector on the inverter P.C.
  • Page 63 OPERATING PROCEDURE PHOTOS/FIGURES 3. Removing R.V. coil Photo 9 (1) Remove the cabinet and panels. (Refer to section 1.) (2) Disconnect the following connectors: <Inverter P.C. board> CN721 (R.V. coil) Screw of (3) Remove the R.V. coil. the R.V. coil Discharge temperature thermistor...
  • Page 64 OPERATING PROCEDURE PHOTOS/FIGURES 5. Removing outdoor fan motor Photo 11 Screws of the outdoor fan motor (1) Remove the top panel, cabinet and service panel. (Refer to section 1.) (2) Disconnect the following connectors: <Inverter P.C. board> CN931, CN932 (Fan motor) (3) Remove the propeller fan nut.
  • Page 65 12-2. MUZ-HX18NL NOTE: Turn OFF the power supply before disassembly. OPERATING PROCEDURE PHOTOS/FIGURES 1. Removing the cabinet Photo 1 (1) Remove the screws of the service panel. (2) Remove the screws of the top panel. (3) Remove the screw of the valve cover. Screws of (4) Remove the service panel.
  • Page 66 OPERATING PROCEDURE PHOTOS/FIGURES Photo 5 Photo 6 Screws of the conduit cover Screw of the conduit plate (These screws are different shape from the other (This screw is different in shape from the other screws. Do not mix them with the other screws.) screws.
  • Page 67 OPERATING PROCEDURE PHOTOS/FIGURES * Connection procedure when attaching the inverter Photo 10 Lead wires of the heat exchanger P.C. board (Photo 9) temperature, the discharge tem- Lead wires of the 1. Connect the lead wires of the heat exchanger tempera- perature and the defrost thermistor ambient temperature ture thermistor, the defrost thermistor and discharge...
  • Page 68 OPERATING PROCEDURE PHOTOS/FIGURES 3. Removing the discharge temperature thermistor, Photo 11 defrost thermistor, outdoor heat exchanger tem- Outdoor heat exchanger Ambient temperature perature thermistor and ambient temperature temperature thermistor thermistor thermistor (1) Remove the cabinet and panels (refer to section 1). (2) Disconnect the lead wire to the reactor and the following connectors: <Inverter P.C.
  • Page 69 OPERATING PROCEDURE PHOTOS/FIGURES 5. Removing R. V. coil Photo 13 (1) Remove the cabinet and panels (refer to section 1). Screw of the R.V. coil (2) Disconnect the following connectors: <Inverter P.C. board> CN721 (R.V. coil) Discharge (3) Remove the R.V. coil. temperature thermistor Compressor...
  • Page 70 12-3. MUZ-HX24NL NOTE: Turn OFF the power supply before disassembly. OPERATING PROCEDURE PHOTOS/FIGURES 1. Removing the cabinet Photo 2 (1) Remove the screws of the service panel. Screws of (2) Remove the screws of the top panel. the top panel (3) Remove the screw of the valve cover.
  • Page 71 OPERATING PROCEDURE PHOTOS/FIGURES Photo 5 Photo 6 Screws of the conduit cover Screw of the conduit plate 2. Removing the inverter assembly, inverter P.C. Photo 7 board and fuse P.C. board 2-1. Removing the inverter assembly and inverter P.C. board (1) Remove the top panel, cabinet and service panel.
  • Page 72 OPERATING PROCEDURE PHOTOS/FIGURES Photo 10 * Connection procedure when attaching the inverter P.C. board (Photo 8, 9, 10, 11) Hook of the lead wires of the Hook of the lead 1. Attach the heat sink support to the P.C. board support. P.C.
  • Page 73 OPERATING PROCEDURE PHOTOS/FIGURES 2-2. Removing the fuse P.C. board Photo 12 Support Fuse P.C. board (1) Remove the top panel, cabinet and service panel. (Refer to section 1.) (2) Disconnect the lead wire to the reactor and the inverter P.C. board connectors. (Refer to section 2-1. (2)) (3) Remove the compressor connector (CN61).

  • Page 74: Removing Outdoor Fan Motor

    OPERATING PROCEDURE PHOTOS/FIGURES Photo 14 4. Removing outdoor fan motor (1) Remove the top panel, cabinet and service panel. Propeller fan nut (Refer to section 1.) (2) Disconnect the following connectors: <Inverter P.C. board> Propeller fan CN931, CN932 (Fan motor) (3) Remove the propeller fan nut.
  • Page 75 OPERATING PROCEDURE PHOTOS/FIGURES 6. Removing the compressor and 4-way valve Photo 16 (1) Remove the cabinet and panels. (Refer to section 1.) (2) Remove the inverter assembly. (Refer to section 2.) (3) Remove the screws fixing the reactor. (4) Remove the reactor. (5) Remove the soundproof felt.
  • Page 76 HEAD OFFICE: TOKYO BUILDING, 2-7-3, MARUNOUCHI, CHIYODA-KU, TOKYO 100-8310, JAPAN © Copyright 2024 MITSUBISHI ELECTRIC CORPORATION Issued: Nov. 2024. No.OBH953 REVISED EDITION-A Published: Sep. 2024. No. OBH953 Made in Japan Specifications are subject to change without notice.

This manual is also suitable for:

Muz-hx12nl-u1Muz-hx18nl-u1Muz-hx24nl-u1

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