MITSUBISHI ELECTRIC NTXWMT09A112AA Indoor Unit Split Type Air Conditioners Instruction Manual

MITSUBISHI ELECTRIC NTXWMT09A112AA Indoor Unit Split Type Air

Conditioners

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.

< 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 pull 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 with wet hands.
• Do not pour water into the electric parts.
• Do not touch the refrigerant.
• Do not touch the hot or cold areas in the refrigeration cycle.
• When the repair or the inspection of the circuit needs to be done without turning off the power, exercise great caution not to touch the live parts.

WARNING

• When the refrigeration circuit has a leak, do not execute pump down with the compressor.
• When pumping down the refrigerant, stop the compressor before disconnecting the refrigerant pipes. The compressor may burst if air etc. get into it.
• When opening or closing the valve below freezing temperatures, refrigerant may spurt out from the gap between the valve stem and the valve body, resulting in injuries.

Revision A:

• 9-7. TEST POINT DIAGRAM AND VOLTAGE has been modified

Revision B:

• NTXWMT09/12/15A112AB have been added.

Revision C:

• Remote controller P.C. board has been added. (7-2.)

TECHNICAL CHANGES

• NTXWMT09A112AA
• NTXWMT12A112AA
• NTXWMT15A112AA
• NTXWMT18A112AA
• NTXWMT24A112AA

1. New model

• NTXWMT09A112AA NTXWMT09A112AB
• NTXWMT12A112AA NTXWMT12A112AB
• NTXWMT15A112AA NTXWMT15A112AB

1.  The indoor electronic control P.C. board and indoor power P.C. board have been changed.

PART NAMES AND FUNCTIONS

NTXWMT09A112AA NTXWMT09A112AB NTXWMT12A112AA NTXWMT12A112AB NTXWMT15A112AA NTXWMT15A112AB

ACCESSORIES

NTXWMT18A112AA NTXWMT24A112AA

ACCESSORIES

SPECIFICATION

OPERATING RANGE

OUTLET AIR SPEED AND COVERAGE

• The air coverage is the figure up to the position where the air speed is 1 ft./s., when air is blown out horizontally from the unit properly at the High speed position.
• The coverage should be used only as a general guideline since it varies according to the size of the room and furniture arranged inside the room.

OUTLINES AND DIMENSIONS

NTXWMT09A112AA NTXWMT09A112AB NTXWMT12A112AA NTXWMT12A112AB NTXWMT15A112AA NTXWMT15A112AB

NTXWMT18A112AA NTXWMT24A112AA

WIRING DIAGRAM

NTXWMT09A112AA NTXWMT12A112AA NTXWMT15A112A

NTXWMT09A112AB NTXWMT12A112AB NTXWMT15A112AB

REFRIGERANT SYSTEM DIAGRAM

NTXWMT09A112AA NTXWMT09A112AB NTXWMT12A112AA NTXWMT12A112AB NTXWMT15A112AA NTXWMT15A112AB

NTXWMT18A112AA NTXWMT24A112AA

SERVICE FUNCTIONS

NTXWMT09A112AA NTXWMT09A112AB NTXWMT12A112AA NTXWMT12A112AB NTXWMT15A112AA NTXWMT15A112AB NTXWMT18A112AA NTXWMT24A112AA

TIMER SHORT MODE

For service, the set time can be shortened by bridging of the timer short point on the indoor electronic control P.C. board. The time will be shortened as follows. (Refer to 9-7.)

• The set time for the ON/OFF timer can be reduced to 1 second for each minute.
• After the breaker is turned on, the time for starting the compressor, which normally takes 3 minutes, can be reduced to 3 seconds. Restarting the compressor, which takes 3 minutes, cannot be reduced.

REMOTE CONTROLLER P.C. BOARD MODIFICATION FOR INDIVIDUAL OPERATION

• A maximum of 4 indoor units with wireless remote controllers can be used in a room.
• In this case, to operate each indoor unit individually by each remote controller, the remote controller P.C. boards must be modified according to the number of the indoor unit.
• NOTE: For modification, take out the batteries and press the STOP/OPERATE (OFF/ON) button 2 or 3 times at first.

How to modify the remote controller P.C. board Remove batteries before modification.
The board has one of the following prints:

The remote controller P.C. board has the print “J1” and “J2”. Solder “J1” and “J2” according to the number of indoor unit as shown in Table 1.
After modification, press the RESET button.

Table 1

• 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 controller for the indoor unit.
• The indoor unit will only accept the signal from the remote controller that has been assigned to the indoor unit once they are set.
• The setting will be cancelled if the breaker is turned OFF, or the power supply is shut down.
• Please conduct the above setting once again after the power has been restored.

AUTO RESTART FUNCTION

When the indoor unit is controlled with the remote controller, the operation mode, the set temperature, and the fan speed are memorized by the indoor electronic control P.C. board. “AUTO RESTART FUNCTION” automatically starts operation in
the same mode just before the shut-off of the main power.
Operation

1. If the main power has been cut, the operation settings remain.
2. After the power is restored, the unit restarts automatically according to the memory.
   (However, it takes at least 3 minutes for the compressor to start running.)

How to disable “AUTO RESTART FUNCTION”

1. Turn OFF the main power of the unit.
2. Solder the Jumper wire JR07 on the indoor electronic control P.C. board. (NTXWMT09/12/15A112AA, NTXWMT09/12/15A112AB)
   Cut the Jumper wire JR77 on the indoor electronic control P.C. board. (NTXWMT18/24A112AA) (Refer to 9-7.)

NOTE

• The operation settings are memorized when 10 seconds 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 cancelled.
• 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 tripping 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 restart.
  Therefore, the special counter-measures are required to prevent the main voltage-drop or the rush of the starting current by adding to the system that allows the units to start one by one.

MICROPROCESSOR CONTROL

NTXWMT09A112AA NTXWMT09A112AB NTXWMT12A112AA NTXWMT12A112AB NTXWMT15A112AA NTXWMT15A112AB NTXWMT18A112AA NTXWMT24A112AA

NOTE : Last setting will be stored after the unit is turned OFF with the remote controller. Indoor unit receives the signal of the remote controller with beeps.

INDOOR UNIT DISPLAY SECTION

Operation Indicator lamp
The operation indicator at the right side of the indoor unit indicates the operation state.
•The following indication applies regardless of shape of the indication.

COOL ( ) OPERATION

1. Press STOP/OPERATE (OFF/ON) button.
   OPERATION INDICATOR lamp of the indoor unit turns on with a beep tone.

2. Select COOL mode with OPERATION SELECT button.

3.  Press TEMPERATURE buttons (TOO WARM or TOO COOL button) to select the desired temperature. The setting range is 61 – 88°F (16 – 31°C).

Coil frost prevention

The compressor operational frequency is controlled by the temperature of the indoor heat exchanger to prevent the coil from frosting.
When the temperature of indoor heat exchanger becomes too low, the coil frost prevention mode works. The indoor fan operates at the set speed and the compressor stops. This mode continues until the temperature of indoor heat exchanger rises.

. DRY ( ) OPERATION

1. Press STOP/OPERATE (OFF/ON) button.
   OPERATION INDICATOR lamp of the indoor unit turns on with a beep tone.

2. Select DRY mode with OPERATION SELECT button.

3. The set temperature is determined from the initial room temperature.

Coil frost prevention

Coil frost prevention works the same way as that in COOL mode. (8-1.1.)

HEAT  OPERATION

1. Press STOP/OPERATE (OFF/ON) button.
   OPERATION INDICATOR lamp of the indoor unit turns on with a beep tone.

2. Select HEAT mode with OPERATION SELECT button.

3. Press the TEMPERATURE buttons (TOO WARM or TOO COOL button) to select the desired temperature.

The setting range is 61 – 88°F (16 – 31°C).

1. Cold air prevention control
   When the compressor is not operating or is starting, and the temperature of indoor heat exchanger and/or the room temperature is low or when defrosting is being done, the indoor fan will stop or rotate in Very Low speed.

2. High-pressure protection

   • The compressor operational frequency is controlled by the temperature of the indoor heat exchanger to prevent the condensing
     pressure from increasing excessively.

   • When the temperature of indoor heat exchanger becomes too high, the high pressure protection works.

   • The indoor fan operates following the cold air prevention control. This mode continues until the temperature of indoor heat exchanger falls.

3. Defrosting

   • Defrosting starts when the temperature of outdoor heat exchanger becomes too low.
   • The compressor stops once, the indoor/outdoor fans stop, the 4-way valve reverses, and the compressor re-starts.
   • This mode continues until the temperature of outdoor heat exchanger rises or the fixed time passes.

AUTO VANE OPERATION

1. Horizontal vane

2. Vane motor drive
   These models are equipped with a stepping motor for the horizontal vane. The rotating direction, speed, and angle of the motor are controlled by pulse signals (approximately 12 V) transmitted from indoor microprocessor.

3. The horizontal vane angle and mode change as follows by pressing VANE CONTROL button.

4. Positioning
   To confirm the standard position, the vane moves until it touches the vane stopper. Then the vane is set to the selected angle. Confirmation of standard position is performed in the following cases:

   • When the operation starts or finishes (including timer operation).
   • When the test run starts.
   • When standby mode (only during multi-system operation) starts or finishes.

5. VANE AUTO ( ) mode
   In VANE AUTO mode, the microprocessor automatically determines the vane angle to make the optimum room temperature distribution.

6. STOP (operation OFF) and ON TIMER standby

   • In the following cases, the horizontal vane returns to the closed position.
   • When STOP/OPERATE (OFF/ON) button is pressed (POWER OFF).
   • When the operation is stopped by the emergency operation.
   • When ON TIMER is ON standby.
   • Dew prevention
     During COOL or DRY operation with the vane angle at Angle 4 or 5 when the compressor cumulative operation time exceeds 0.5 – 1 hour, the vane angle automatically changes to Angle 2 for dew prevention.

7. SWING  mode
   By selecting SWING mode with VANE CONTROL button, the horizontal vane swings vertically.

8. Cold air prevention in HEAT operation.
   The horizontal vane position is set to Upward.
   NOTE: When 2 or more indoor units are operated with multi outdoor unit, even if any indoor unit turns thermostat off, this control does not work in the indoor unit.

9. ECONO COOL ( ) operation (ECONOmical operation)

• When ECONO COOL button is pressed in COOL mode, set temperature is automatically set 4°F (2°C) higher.
• Also the horizontal vane swings in various cycle.
• SWING operation makes you feel cooler than set temperature. So, even though the set temperature is higher, the air conditioner can keep comfort. As a result, energy can be saved.
• ECONO COOL operation is cancelled when ECONO COOL button is pressed once again or VANE CONTROL button is pressed or change to other operation mode.

TIMER OPERATION (ON/OFF TIMER)

1. How to set the timer

2. Press STOP/OPERATE (OFF/ON) button to start the air conditioner.

3. Select the timer mode by pressing the button during operation.
   Each time this button is pressed, the timer mode is changed in sequence:
   (OFF TIMER) → (ON TIMER) → TIMER RELEASE

4. Set the time of the timer using the button.

5. Each time this button is pressed, the set time increase or decrease by 1 hour to 12 hours.

To release the timer

Press the button until (OFF TIMER) and (ON TIMER) are not displayed.

NOTE

• The OFF TIMER and the ON TIMER cannot be set at the same time.
• The displayed time is the time remaining and will decrease in 1-hour increments as time passes.

EMERGENCY/TEST OPERATION

• In the case of test run operation or emergency operation, use the emergency operation switch on the right side of the indoor unit. Emergency operation is available when the remote controller is missing or has
• failed, or when the batteries in the remote controller are running down. The unit will start and OPERATION INDICATOR lamp will light up.
• The first 30 minutes of operation is the test run operation. This operation is for servicing. The indoor fan runs at High speed and the temperature control does not work.
• After 30 minutes of test run operation, the system shifts to EMERGENCY COOL/HEAT MODE with a set temperature of 75°F (24°C). The fan speed shifts to Med.
• The coil frost prevention works even in the test run or the emergency operation.
• In the test run or emergency operation, the horizontal vane operates in VANE AUTO ( ) mode.
• Emergency operation continues until the emergency operation switch is pressed once or twice or the unit receives any signal from the remote controller. In the latter case, normal operation will start.
• NOTE: Do not press the emergency operation switch during normal operation.

MINUTE TIME DELAY OPERATION

When the system turns OFF, compressor will not restart for 3 minutes as 3-minute time delay function operates to protect compressor from overload.

Changing temperature indication (°F/°C)

• The preset unit is °F.
• °F → °C: Press RESET button while the TEMPERATURE buttons are pressed.
• °C → °F: Press RESET button while the TEMPERATURE buttons are pressed.

TROUBLESHOOTING

NTXWMT09A112AA NTXWMT09A112AB NTXWMT12A112AA
NTXWMT12A112AB NTXWMT15A112AA NTXWMT15A112AB NTXWMT18A112AA NTXWMT24A112AA

CAUTIONS ON TROUBLESHOOTING

1. Before troubleshooting, check the following

2. Check the power supply voltage.

3. Check the indoor/outdoor connecting wire for miswiring.

4. Take care of the following during servicing

5. Before servicing the air conditioner, be sure to turn OFF the unit first with the remote controller, and then after confirming the horizontal vane is closed, turn OFF the breaker and/or disconnect the power plug.

6. Be sure to turn OFF the power supply before removing the front panel, the cabinet, the top panel, and the P.C. board.

7. When removing the P.C. board, hold the edge of the board with care NOT to apply stress on the components.

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

9. Troubleshooting procedure

10. First, check if the OPERATION INDICATOR lamp on the indoor unit is blinking ON and OFF to indicate an abnormality. To make sure, check how many times the OPERATION INDICATOR lamp is blinking ON and OFF before starting ser-vice work.

11. Before servicing, verify that all connectors and terminals are connected properly.

12. When the electronic control P.C. board seems to be defective, check for disconnection of the copper foil pattern and burnt or discolored components.

13. When troubleshooting, refer to 9-2, 9-3 and 9-4.

14. How to replace batteries
    Weak batteries may cause the remote controller malfunction.

In this case, replace the batteries to operate the remote controller normally.

1. Remove the back lid and insert batteries. Then reattach the back lid.

2. Press RESET button with a fine-tipped object, and then use the remote controller.

3. NOTE: 1. If RESET button is not pressed, the remote controller may not operate correctly.

4. This remote controller has a circuit to automatically reset the microprocessor when batteries are replaced.
   This function is equipped to prevent the microprocessor from malfunctioning due to the voltage drop caused by the battery replacement.

5. Do not use the leaking batteries.

FAILURE MODE RECALL FUNCTION
Outline of the function
This air conditioner can memorize the abnormal condition which has occurred once.
Even though LED indication listed on the troubleshooting check table (9-4.) disappears, the memorized failure details can be recalled.

1. Flow chart of failure mode recall function for the indoor/outdoor unit

Table of indoor unit failure mode recall function

NOTE: Blinking patterns of this mode differ from the ones of TROUBLESHOOTING CHECK TABLE (9-4.).

INSTRUCTION OF TROUBLESHOOTING

TROUBLESHOOTING CHECK TABLE
Before taking measures, make sure that the symptom reappears for accurate troubleshooting.
When the indoor unit has started operation and detected an abnormality of the following condition (the first detection after the power ON), the indoor fan motor turns OFF and OPERATION INDICATOR lamp blinks.

TROUBLESHOOTING CRITERION OF MAIN PARTS
NTXWMT09A112AA NTXWMT09A112AB NTXWMT12A112AA NTXWMT12A112AB NTXWMT15A112AA NTXWMT15A112AB NTXWMT18A112AA NTXWMT24A112AA

TROUBLESHOOTING FLOW

B Check of remote controller and indoor electronic control P.C. board

Check of indoor P.C. board and indoor fan motor How to check miswiring and serial signal error

Electromagnetic noise enters into TV sets or radios

Even if all of the above conditions are fulfilled, the electromagnetic noise may enter, depending on the electric field strength 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:
   indoor/outdoor unit of the air conditioner, indoor/outdoor wiring, grounding wire, antennas, wiring from antennas, receiv-er

5. Electric field intensity of the broadcast station affected by the electromagnetic noise

6. Presence or absence of amplifier such as booster

7. Operation condition of air conditioner when the electromagnetic noise enters in

8. Turn OFF the power supply once, and then turn ON the power supply. In this situation, check for the electromagnetic noise.

9. Within 3 minutes after turning ON the power supply, press STOP/OPERATE (OFF/ON) button on the remote controller for power ON, and check for the electromagnetic noise.

10. After a short time (3 minutes later after turning ON), the outdoor unit starts running. During operation, check for the electromagnetic noise.

11. Press STOP/OPERATE (OFF/ON) button on the remote controller for power OFF, when the outdoor unit stops but the indoor/outdoor communication still runs on. In this situation, check for the electromagnetic noise.

TEST POINT DIAGRAM AND VOLTAGE NTXWMT09A112AA NTXWMT12A112AA NTXWMT15A112AA

1. Indoor power P.C. board, Indoor terminal P.C. board

NTXWMT09A112AB NTXWMT12A112AB NTXWMT15A112AB

1. Indoor power P.C. board, Indoor terminal P.C. board

NTXWMT18A112AA NTXWMT24A112AA

1. Indoor power P.C. board

DISASSEMBLY INSTRUCTIONS

• 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.

1. Slide the sleeve and check if there is a locking lever or not. (2) The terminal with the connector shown below

NTXWMT09A112AA NTXWMT09A112AB NTXWMT12A112AA NTXWMT12A112AB NTXWMT15A112AA NTXWMT15A112AB

OPERATING PROCEDURE

1. Removing the panel
2. Remove the horizontal vanes.
3. Remove the screw caps of the panel. Remove the screws of the panel.
4. Unhook the lower part ( ) of the panel.
5. Hold the lower part of both ends of the panel and pull it slightly toward you, and then remove the panel by pushing it upward.
   **PHOTOS/FIGURES

**

2. Removing the indoor electronic control P.C. board and the room temperature thermistor
3. Remove the panel (Refer to section 1.) and the corner box.
4. Remove the screw of the V.A. clamp and the V.A. clamp.
5. Loosen the screw of the indoor/outdoor connecting wire and remove the indoor/outdoor connecting wire.
6. Remove the screw of the electrical cover and the electrical cover.
7. Open the indoor electronic control P.C. board holder (to right side)
8. Disconnect the following connectors:

  * <Indoor electronic control P.C. board>
  * CN112 (Indoor coil thermistor)
  * CN151 (Vane motor)
  * CN10A (To the indoor power P.C. board)
7. Unhook the catches of the indoor electronic control P.C. board holder from the nozzle and the electrical box (right side).
8. Remove the indoor electronic control P.C. board hold-er from the conduit cover.
9. Remove the room temperature thermistor from the hook of the indoor electronic control P.C. board holder.
10. Open the back side of the indoor electronic control P.C. board holder, and remove the indoor electronic control P. C. board.
11. Remove the room temperature thermistor from the indoor electronic control P.C. board.

3. Removing the indoor power P.C. board, the indoor terminal P.C. board, and the electrical box

4. Remove the panel (Refer to section 1.) and the corner box.

5. Remove the indoor/outdoor connecting wire and the indoor electric control P.C. board holder. (Refer to section 2 (2)-(8).).

6. Remove the screw of the conduit cover and the con-duit cover.

7. Remove the screw of the conduit plate and the con-duit plate.

8. Remove the ground wire connected to the indoor heat exchanger from the electrical box.

9. Remove the screw fixing the electrical box.

10. Unhook first the lower, then the upper catches of the electrical box, and pull out the electrical box.

11. Disconnect all the connectors on the indoor power P.C. board and unhook all lead wires.

12. Remove the screw of terminal block on the indoor ter-minal P.C. board.

13. Remove the indoor power P.C. board and the indoor terminal P.C. board.

14. Removing the nozzle assembly

15. Remove the panel (Refer to section 1.) and the corner box.

16. Remove the indoor/outdoor connecting wire (Refer to section 2 (2)-(7).).

17. Remove the indoor electronic control P.C. board holder.

18. Pull out the drain hose from the nozzle assembly and remove the nozzle assembly.

19. Removing the horizontal vane motor

20. Remove the nozzle assembly. (Refer to section 4.)

21. Remove the screws of the horizontal vane motor unit.

22. Disconnect the connector from the horizontal vane motor.

23. Remove the screws of the horizontal vane motor.

24. Remove the horizontal vane motor from the horizontal vane motor unit.

25. Removing the indoor fan motor, the indoor coil thermistor, and the line flow fan

26. Remove the panel (Refer to section 1.) and the corner box.

27. Remove the indoor electronic control P.C. board hold-er, the electrical box and the nozzle assembly.

28. Remove the screws fixing the motor bed.

29. Loosen the screw fixing the line flow fan.

30. Remove the motor bed together with fan motor and motor band.

31. Release the hooks of the motor band. Remove the motor band. Pull out the indoor fan motor.

NTXWMT18A112AA NTXWMT24A112AA
NOTE: Turn OFF the power supply before disassembly.

1. Removing the panel

2. Remove the screw caps on the panel and remove the screws of the panel.

3. Pull the panel slightly toward you, and then remove the panel by pushing it upward.

4. Removing the indoor power P.C. board and the electrical box

5. Remove the panel. (Refer to section 1.) Remove the right corner box.

6. Disconnect the following connectors:

  * <Indoor electronic control P.C. board>
  * CN151 (Vane motor)
  * CN112 (Indoor coil thermistor)
  * CN10A (To the indoor power P.C. board)
3. Unhook the catch on the left side of the control P.C. board holder. Pull the control P.C. board holder as if opening the door at 90 degrees. Remove the control P.C. board holder from the axial rod on the electrical box.
4. Remove the screw of the V.A. clamp.
5. Remove the V.A. clamp and the indoor/outdoor con-necting wire.
6. Remove the screw of the conduit cover and the conduit cover.
7. Remove the screw of the conduit plate and the conduit plate.
8. Remove the screw fixing the electrical box.
9. Remove the screws of the ground plate. (Photo 2)
10. Remove the indoor coil thermistor from the water cover.
11. Disengage the hooks of the water cover and remove the water cover.
12. Remove the screw of the electrical cover and remove the electrical cover.
13. Disconnect the CN211 (Indoor fan motor) from the indoor power P.C. board.
14. Remove the upper catch of the electrical box, and pull out the electrical box.  

• To attach the electrical box, pass the wires connect-ing the indoor power P.C. board and the indoor elec-tronic control P.C. board through . Pass the lead wires of the fan motor through as shown in the Photo3. 15. Disconnect the following connectors.

  • CN201 (Terminal block)
  • CN20A (To the indoor electronic control P.C. board)
  3. Removing the indoor electronic control P.C.board
  4. Remove the panel. (Refer to section 1.) Remove the right corner box.
  5. Disconnect the following connectors:

  * <Indoor electronic control P.C. board>
  * CN151 (Vane motor)
  * CN112 (Indoor coil thermistor)
  * CN10A (To the indoor power P.C. board)  

  3. Unhook the catch on the left side of the control P.C. board holder. Pull the control P.C. board holder as if opening the door at 90 degrees. Remove the control P.C. board holder from the axial rod on the electrical box.

  4. Remove the room temperature thermistor from the back side of the control P.C. board holder.

  5. Unhook the catches of the control P.C. board holder, and open the control P.C. board holder.

  6. Remove the indoor electronic control P.C. board from the control P.C. board holder.

  7. Removing the vane motor

  8. Remove the panel. (Refer to section 1.) Remove the corner box.

  9. Remove the control P.C. board holder, water cover and the electrical box. (Refer to section 2.)

  10.  Pull out the drain hose from the nozzle assembly and remove the nozzle assembly.

  11. Remove the screws of the vane motor and remove the vane motor.

  12. Disconnect the connector from the vane motor.

  13. Removing the indoor fan motor, the indoor coil thermistor and the line flow fan

  14. Remove the panel. (Refer to section 1.) Remove the right corner box.

  15. Remove the control P.C. board holder, the water cover, the electrical box and the nozzle assembly. (Refer to section 2.)

  16. Remove the screws fixing the motor bed.

  17. Loosen the screw fixing the line flow fan.

  18. Remove the motor bed together with the indoor fan motor and the motor band.

  19. Disconnect the lead wire of the fan motor from the motor band.

  20. Disengage the hooks of the motor band and remove the motor band. Pull out the indoor fan motor.

  21. 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 and upper right side of the heat exchanger. 10. Lift the heat exchanger, and pull out the line flow.

Fixing the indoor coil thermistor

• There are 2 forms of parts for fixing the indoor coil thermistor.

Position and procedure for mounting the clip-shape par t

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.

NOTE

• Take care to avoid loss and accidental falling of the clip-shape part inside the unit.
• Mount the clip-shape part on the marked position.
• Do not pull the lead wire when removing the indoor coil thermistor.

MITSUBISHI ELECTRIC TRANE HVAC US LLC
HEAD OFFICE: 1340 SATELLITE BOULEVARD, SUWANEE, GA 30024, USA

© Copyright 2018 MITSUBISHI ELECTRIC CORPORATION Issued: Sep. 2023. No. OBHT746 REVISED EDITION-C Issued: Feb. 2022. No. OBHT746 REVISED EDITION-B Issued: Nov. 2021. No. OBHT746 REVISED EDITION-A Published: Dec. 2018. No. OBHT746
Made in Japan

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