Mitsubishi Electric TRANE NTXSST A112AA Series User manual

CONTENTS
1. TECHNICAL CHANGES······································· 2
2. PART NAMES AND FUNCTIONS····················· 3
3. SPECIFICATION················································ 6
4. OUTLINES AND DIMENSIONS ························ 8
5. WIRING DIAGRAM·········································· 10
6. REFRIGERANT SYSTEM DIAGRAM ············· 12
7. SERVICE FUNCTIONS ··································· 13
8. MICROPROCESSOR CONTROL ··················· 15
9. TROUBLESHOOTING····································· 23
10. DISASSEMBLY INSTRUCTIONS···················· 41
Outdoor unit service manual
NTXSST•A112AA, NTYSST•A112AA Series (OBHT733)
NTXMMX•A•AA, NTXMPH•A•AA Series (OCHT573)
PARTS CATALOG (OBBT732)
NTXWST18A112AA
NTYWST18A112AA
INDOOR UNIT
SERVICE MANUAL
INDOOR UNIT
Models
NTXWST06A112AA
NTXWST09A112AA NTYWST09A112AA
NTXWST12A112AA NTYWST12A112AA
NTXWST15A112AA NTYWST15A112AA
NTXWST18A112AA NTYWST18A112AA
NTXWST24A112AA NTYWST24A112AA
No. OBHT732

2
1TECHNICAL CHANGES
Use the speci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.
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.
NTXWST06A112AA
NTXWST09A112AA
NTXWST12A112AA
NTXWST15A112AA
NTXWST18A112AA
NTXWST24A112AA
NTYWST09A112AA
NTYWST12A112AA
NTYWST15A112AA
NTYWST18A112AA
NTYWST24A112AA
1. New model
OBHT732

3
2PART NAMES AND FUNCTIONS
NTXWST06A112AA NTXWST09A112AA NTXWST12A112AA NTXWST15A112AA
NTYWST09A112AA NTYWST12A112AA NTYWST15A112AA
Remote controller
Operation indicator lamp
Remote control receiving section
Emergency operation switch
Horizontal vane
Air outlet
Air filter
Air inlet
Heat exchanger
Front panel
Air cleaning filter
(Anti-Allergy Enzyme
Filter)
(Nano platinum filter )
Display section
ACCESSORIES
Installation plate 1
Attachment screws for the installation plate
4 × 25 mm 5
Remote controller holder 1
Screws for 3.5 × 16 mm (Black) 2
Battery (AAA) for remote controller 2
Wireless remote controller 1
Felt tape (For left or left-rear piping) 1
Air cleaning lter 2
OBHT732

4
NTXWST18A112AA
NTYWST18A112AA
ACCESSORIES
Installation plate 1
Installation plate xing screw 4 × 25 mm 5
Remote controller holder 1
Fixing screw for 3.5 × 16 mm (Black) 2
Battery (AAA) for remote controller 2
Wireless remote controller 1
Felt tape (Used for left or left-rear piping) 1
Air cleaning lter 2
Remote controller
Operation indicator lamp
Remote control receiving section
Emergency operation switch
Horizontal vane
Air outlet
Air filter
Air inlet
Heat exchanger
Front panel
Air cleaning filter
(Anti-Allergy Enzyme
Filter)
(Nano platinum filter )
Display section
OBHT732

5
Remote controller
Display section
Front panel
Air filter
(Nano platinum filter)
Air inlet
Air cleaning filter
(Electrostatic anti-allergy
enzyme filter)
Air outlet
Horizontal vane
Heat exchanger
Operation indicator lamp
Remote control receiving section
Emergency operation switch
NTXWST24A112AA
NTYWST24A112AA
ACCESSORIES
Installation plate 1
Installation plate xing screw 4 × 25 mm 7
Remote controller holder 1
Fixing screw for 3.5 × 16 mm (Black) 2
Battery (AAA) for remote controller 2
Wireless remote controller 1
Felt tape (Used for left or left-rear piping) 1
Air cleaning lter 2
OBHT732

6
3SPECIFICATION
Indoor model NTXWST15A112AA
NTYWST15A112AA
NTXWST18A112AA
NTYWST18A112AA
NTXWST24A112AA
NTYWST24A112AA
Power supply V, phase, Hz 208/230, 1, 60
Max. fuse size (time delay)/ Disconnect switch A 15 20/15
Min. circuit ampacity A 1.0
Fan motor F.L.A 0.76 0.67 0.76
Airow
Super High - High - Med. -
Low - Quiet (15/18)
Powerful - Super High -
High - Med. - Low (24)
COOL Dry
(Wet) CFM
533 - 420 - 335 - 272 - 205
(498 - 385 - 300 - 237 - 170)
646 - 522 - 417 - 332 - 258
(581 - 470 - 375 - 299 - 232)
738 - 628 - 544 - 469 - 388
(661 - 562 - 487 - 420 - 347)
HEAT Dry
(NTXWST)CFM
463 - 367 - 304 - 247 - 205 646 - 565 - 469 - 385 - 297 738 - 628 - 544 - 469 - 388
Moisture removal pt./h 2.7 2.1 5.1
Sound level
Super High - High - Med. -
Low - Quiet (15/18)
Powerful - Super High -
High - Med. - Low (24)
Cooling dB(A) 49 - 44 - 38 - 32 - 26 49 - 44 - 38 - 33 - 28 53 - 49 - 45 - 41 - 34
Heating
(NTXWST)dB(A) 46 - 40 - 35 - 30 - 26 48 - 43 - 38 - 33 - 28 52 - 49 - 45 - 41 - 32
Fan speed
Super High - High - Med. -
Low - Quiet (15/18)
Powerful - Super High -
High - Med. - Low (24)
Cooling rpm
1,280 - 1,060 - 880 - 740 - 600 1,170 - 990 - 830 - 700 - 580 1,300 - 1,140 - 1,010 - 900 - 770
Heating
(NTXWST)rpm
1,140 - 950 - 810 - 690 - 600 1,170 - 1,050 - 910 - 780 - 640 1,300 - 1,140 - 1,010 - 900 - 730
Cond. drain connection O.D. in. 5/8
Dimensions
W
in.
31-7/16 36-5/16 43-5/16
D 9-1/8 9-13/16 9-3/8
H 11-5/8 12 12-13/16
Weight Ib. 22 28 37
External nish Munsell 1.0Y 9.2/0.2
Control voltage (by built-in transformer) 12 - 24 V DC
NOTE: Test conditions are based on AHRI 210/240.
Indoor model NTXWST06A112AA NTXWST09A112AA
NTYWST09A112AA
NTXWST12A112AA
NTYWST12A112AA
Power supply V, phase, Hz 208/230, 1, 60
Max. fuse size (time delay)/ Disconnect switch A 15
Min. circuit ampacity A 1.0
Fan motor F.L.A 0.76
Airow
Super High - High - Med. -
Low - Quiet
COOL Dry
(Wet) CFM 399 - 321 - 237 - 170 - 145
(364 - 286 - 201 - 134 - 109)
HEAT Dry CFM 406 - 321 - 237 - 170 - 145
Moisture removal pt./h – 1.5 2.5
Sound level
Super High - High - Med. -
Low - Quiet
Cooling dB(A)
43 - 37 - 30 - 22 - 19
45 - 37 - 30 - 22 - 19
Heating
(NTXWST)dB(A) 43 - 37 - 30 - 22 - 19
Fan speed
Super High - High - Med. -
Low - Quiet
Cooling rpm 1,020 - 860 - 670 - 530 - 470
Heating
(NTXWST)rpm 1,040 - 860 - 670 - 530 - 470
Cond. drain connection O.D. in. 5/8
Dimensions
W
in.
31-7/16
D 9-1/8
H 11-5/8
Weight Ib. 22
External nish Munsell 1.0Y 9.2/0.2
Control voltage (by built-in transformer) 12 - 24 V DC
OBHT732

7
(2) OPERATION
Mode Condition
Intake air temperature (°F)
Indoor Outdoor
DB WB DB WB
Cooling
Standard temperature 80 67 95 —
Maximum temperature 90 73 115 —
Minimum temperature 67 57 14 —
Maximum humidity 78% —
Heating
Standard temperature 70 60 47 43
Maximum temperature 80 67 75 65
Minimum temperature 70 60 -4 -5
3-1. OPERATING RANGE
(1) POWER SUPPLY
Rated voltage Guaranteed voltage (V)
Indoor unit
208/230 V
1 phase
60 Hz
Min. 187 208 230 Max. 253
3-2. 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.
Model Mode Function Airow
(CFM)
Air speed
(ft./s.)
Coverage
(ft.)
NTXWST06A112AA
HEAT Dry 406 20.6 29.5
COOL Dry 321 16.3 23.5
Wet 286 14.5 21.0
NTXWST09A112AA
NTYWST09A112AA
HEAT(NTX) Dry 406 20.6 29.5
COOL Dry 321 16.3 23.5
Wet 286 14.5 21.0
NTXWST12A112AA
NTYWST12A112AA
HEAT(NTX) Dry 406 20.6 29.5
COOL Dry 321 16.3 23.5
Wet 286 14.5 21.0
NTXWST15A112AA
NTYWST15A112AA
HEAT(NTX) Dry 463 23.4 33.5
COOL Dry 420 21.3 30.5
Wet 385 19.5 28.0
NTXWST18A112AA
NTYWST18A112AA
HEAT(NTX) Dry 646 29.5 44.0
COOL Dry 646 29.5 44.0
Wet 581 26.5 39.7
NTXWST24A112AA
NTYWST24A112AA
HEAT(NTX) Dry 738 18.0 36.9
COOL Dry 738 18.0 36.9
Wet 661 16.1 33.2
OBHT732

8
Unit: inch
NTXWST18A112AA
NTYWST18A112AA
4OUTLINES AND DIMENSIONS
Piping
Insulation Ø2 O.D
Liquid line Ø5/16 15-3/8 (Flared connection Ø1/4)
Gas line Ø15/32 13-3/8 (Flared connection Ø1/2)
Drain hose
Insulation Ø1-1/8 Connected part Ø5/8 O.D
3/4
6-1/4
2-5/16
2-1/4
2-1/2
9-13/16
3/16
35-13/16
36-5/16
1/4
27-15/16 6-5/16
2-1/16
12
2-9/16
2-13/16
2-1/2
2-9/16
3-11/16
2-1/16
9-7/16
10-5/16
1/8
8-7/8 8-7/8 3-11/16
8-3/4
10-3/8
2-5/16 15-7/8
8-11/16
3-11/16
7/8
1×7/16 Oblong hole
7/16×13/16
Oblong hole
Installation plate
Indoor unit
Wall hole Ø3
Air in
Installation plate
8-1/16
15-3/16
1-5/8
8-11/16
3
1-11/16
2-9/16
2-9/16
4-1/2
5-3/4
1/4
Air out
Piping
Drain hose
3-15/16
NTXWST06A112AA NTXWST09A112AA NTXWST12A112AA NTXWST15A112AA
NTYWST09A112AA NTYWST12A112AA NTYWST15A112AA
Piping
Insulation ø1 - 3/8 O.D
Liquid line ø1/4 19 - 11/16 (Flared connection ø1/4)
Gas line ø3/8 16 - 15/16
(Flared connection: ø3/8 (NTX(Y)WST06/09/12A112AA),
ø1/2 (NTX(Y)WST15A112AA))
Drain hose Insulation ø1-1/8 O.D Connected part ø5/8 O.D
OBHT732

9
NTXWST24A112AA
NTYWST24A112AA Unit: inch
OBHT732

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NTXWST18A112AA
NTYWST18A112AA
5WIRING DIAGRAM
NTXWST06A112AA NTXWST09A112AA NTXWST12A112AA NTXWST15A112AA
NTYWST09A112AA NTYWST12A112AA NTYWST15A112AA
OBHT732

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NTXWST24A112AA
NTYWST24A112AA
OBHT732

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NTXWST18A112AA
NTYWST18A112AA
Unit: inch (mm)
Indoor
heat
exchanger
Flared connection
Room temperature
thermistor
RT11
Flared connection
Refrigerant pipe ø1/2 (ø12.7)
(with heat insulator)
Refrigerant pipe ø1/4 (ø6.35)
(with heat insulator)
Indoor coil
thermistor
RT12 (main)
Indoor coil
thermistor
RT13 (sub)
Refrigerant flow in cooling
Refrigerant flow in heating
6REFRIGERANT SYSTEM DIAGRAM
NTXWST24A112AA
NTYWST24A112AA
Indoor
heat
exchanger
Flared connection
Room temperature
thermistor
RT11
Flared connection
Refrigerant pipe ø5/8 (ø15.88)
(with heat insulator)
Refrigerant pipe ø3/8 (ø9.52)
(with heat insulator)
Indoor coil
thermistor
RT12 (main)
Indoor coil
thermistor
RT13 (sub)
Refrigerant flow in cooling
Refrigerant flow in heating
Indoor
heat
exchanger
Flared connection
Room temperature
thermistor
RT11
Flared connection
Refrigerant pipe ø3/8 (ø9.52) (NTXWST06/09/12A112AA, NTYWST09/12A112AA)
ø1/2 (ø12.7) (NTXWST15A112AA, NTYWST15A112AA)
(with heat insulator)
Refrigerant pipe ø1/4 (ø6.35)
(with heat insulator)
Indoor coil
thermistor
RT12 (main)
Indoor coil
thermistor
RT13 (sub)
Refrigerant flow in cooling
Refrigerant flow in heating
NTXWST06A112AA NTXWST09A112AA NTXWST12A112AA NTXWST15A112AA
NTYWST09A112AA NTYWST12A112AA NTYWST15A112AA
OBHT732

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7-1. 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.
7-2. 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, P.C. boards of remote controller must be
modified according to the number of the indoor unit.
How to modify the remote controller P.C. board
Remove batteries before modification.
The board has a print as shown below:
The 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.
NOTE: For modification, take out the batteries and
press the STOP/OPERATE (OFF/ON) button 2
or 3 times at first.
After finish modification, put back the batteries
then press the RESET button.
J2
J1
Table 1
1 unit operation 2 units operation 3 units operation 4 units operation
No. 1 unit No modication Same as at left Same as at left Same as at left
No. 2 unit — Solder J1 Same as at left Same as at left
No. 3 unit — — Solder J2 Same as at left
No. 4 unit — — — Solder both J1 and J2
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.
7SERVICE FUNCTIONS
NTXWST06A112AA NTXWST09A112AA NTXWST12A112AA NTXWST15A112AA
NTXWST18A112AA NTXWST24A112AA
NTYWST09A112AA NTYWST12A112AA NTYWST15A112AA
NTYWST18A112AA NTYWST24A112AA
OBHT732

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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.
7-3. 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
If the main power has been cut, the operation settings remain.
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”
Turn OFF the main power of the unit.
Solder the Jumper wire JR07 on the indoor electronic control P.C. board. (NTXWST06/09/12/15A112AA,
NTYWST09/12/15A112AA)
Cut the Jumper wire JR77 on the indoor electronic control P.C. board. (NTXWST18/24A112AA, NTYWST18/24A112AA)
(Refer to 9-7.)
CN111
CN112
CN152
CN10A
Indoor electronic
control P.C. board
JR77
CN151
JR77
Indoor electronic
control P.C. board
CN10ACN111
CN151
CN112
CN110
NTXWST24A112AA
NTYWST24A112AA
NTXWST18A112AA
NTYWST18A112AA
CN111CN112
CN151
CN10A
Indoor electronic
control P.C. board
JR07
NTXWST06/09/12/15A112AA
NTYWST09/12/15A112AA
OBHT732

15
WIRELESS REMOTE CONTROLLER
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.
ON TIMER button
CLOCK SET button
TIME SET buttons
FORWARD button
BACKWARD button
OFF TIMER button
RESET button
SMART SET button
VANE CONTROL button
WIDE VANE button
(Vertical vane button)
Signal transmitting section
Operation display section
TEMPERATURE buttons
STOP/OPERATE
(OFF/ON) button
FAN SPEED CONTROL button
OPERATION SELECT button
ECONO COOL button
Indication of
remote controller
model is on back
8MICROPROCESSOR CONTROL
NTXWST18A112AA
NTYWST18A112AA
NTXWST06A112AA NTXWST09A112AA NTXWST12A112AA NTXWST15A112AA
NTXWST18A112AA NTXWST24A112AA
NTYWST09A112AA NTYWST12A112AA NTYWST15A112AA
NTYWST18A112AA NTYWST24A112AA
NTXWST06A112AA NTXWST09A112AA NTXWST12A112AA NTXWST15A112AA
NTYWST09A112AA NTYWST12A112AA NTYWST15A112AA
ON TIMER button
CLOCK SET button
TIME SET buttons
FORWARD button
BACKWARD button
OFF TIMER button
RESET button
SMART SET button
VANE CONTROL button
Signal transmitting section
Operation display section
TEMPERATURE buttons
STOP/OPERATE
(OFF/ON) button
FAN SPEED CONTROL button
OPERATION SELECT button
ECONO COOL button
Indication of
remote controller
model is on back
E.g.: NTXWST type
OBHT732

16
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.
Indication Operation state Room temperature
The unit is operating to
reach the set temperature
About 4°F(2°C) or more
away from set tempera-
ture
The room temperature is
approaching the set tem-
perature
About 2 to 4°F(1 to 2°C)
from set temperature
Standby mode
(Only during multi system
operation)
-
INDOOR UNIT DISPLAY SECTION
Lit
Blinking
Not lit
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.
NTXWST24A112AA
NTYWST24A112AA
Signal transmitting section
Operation display section
Indication of
remote controller
model is on back
TEMPERATURE buttons
VANE CONTROL button
(Horizontal vane button)
WIDE VANE button
(Vertical vane button)
ON TIMER button
CLOCK SET button
TIME SET buttons
FORWARD button
BACKWARD button
OFF TIMER button
RESET button
POWERFUL button
STOP/OPERATE
(OFF/ON) button
FAN SPEED CONTROL button
OPERATION SELECT button
ECONO COOL button
OBHT732

17
8-1. 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).
1. 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.
2. Low outside temperature operation
When the outside temperature is lower, low outside temperature operation starts, and the outdoor fan slows or stops.
8-2. 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.
1. Coil frost prevention
Coil frost prevention works the same way as that in the COOL mode. (8-1.1.)
2. Low outside temperature operation
Low outside temperature operation works the same way as that in the COOL mode. (8-1.2.)
8-3. HEAT ( ) OPERATION (NTXWST)
(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 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 tem-
perature 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 con-
densing 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.
8-4. FAN( )OPERATION (NTYWST)
(1) Press STOP/OPERATE (OFF/ON) button.
OPERATION INDICATOR lamp of the indoor unit turns ON with a beep tone.
(2) Select FAN mode with OPERATION SELECT button.
(3) Select the desired fan speed. When AUTO, it becomes Low.
Only indoor fan operates. Outdoor unit does not operate.
8-5. “I FEEL CONTROL” ( ) OPERATION (NTYWST)
(1) Press STOP/OPERATE (OFF/ON) button on the remote controller. OPERATION INDICATOR lamp of the indoor unit
turns ON with a beep tone.
(2) Select “I FEEL CONTROL” mode with OPERATION SELECT button.
(3) The operation mode is determined by the room temperature at startup of the operation.
• Once the mode is fixed, the mode does not change by room temperature afterwards.
• Under the ON TIMER ( ) operation, mode is determined according to the room temperature at the startup of oper-
ation.
OBHT732

18
(4) The initial set temperature is decided by the initial room temperature.
Initial room temperature Model Initial set temperature
79°F (26°C) or more
COOL mode of
"I FEEL CONTROL"
75°F (24°C)
77 to 79°F (25 to 26°C) Initial room temperature minus 4°F (2°C)
Less than 79°F (25°C) DRY mode of
"I FEEL CONTROL" Initial room temperature minus 4°F (2°C)
(5) TEMPERATURE buttons
In “I FEEL CONTROL” ( ) mode, set temperature is decided by the microprocessor based on the room temperature.
In addition, set temperature can be controlled by TOO WARM or TOO COOL buttons when you feel too cool or too
warm.
Each time the TOO WARM or TOO COOL button is pressed, the indoor unit receives the signal and emits a beep tone.
• Fuzzy control
When the TOO COOL or TOO WARM button is pressed, the microprocessor changes the set temperature, consider-
ing the room temperature, the frequency of pressing TOO COOL or TOO WARM button and the user's preference to
heat or cool. So this is called “Fuzzy control”, and works only in “I FEEL CONTROL” mode.
In DRY mode of “I FEEL CONTROL”, the set temperature does not change.
TOO
COOL
…To raise the set temperature 2~4°F (1~2°C)
TOO
WARM
…To lower the set temperature 2~4°F (1~2°C)
8-6. AUTO CHANGE OVER ··· AUTO MODE OPERATION (NTXWST)
Once desired temperature is set, unit operation is switched automatically between COOL and HEAT operation.
Mode selection
(1) Initial mode
When unit starts the operation with AUTO operation from OFF:
• If the room temperature is higher than the set temperature, operation starts in COOL mode.
• If the room temperature is equal to or lower than the set temperature, operation starts in HEAT mode.
(2) Mode change
COOL mode changes to HEAT mode when about 15 minutes have passed with the room temperature 2°F (1°C) below
the set temperature.
HEAT mode changes to COOL mode when about 15 minutes have passed with the room temperature 2°F (1°C) above
the set temperature.
NOTE 1
If 2 or more indoor units are operating in multi system, there might be a case that the indoor unit, which is operating in
(AUTO), cannot change over to the other operating mode (COOL ↔ HEAT (NTXWST)) and becomes a state of standby.
Refer to NOTE 2 "FOR MULTI SYSTEM AIR CONDITIONER".
NOTE 2
FOR MULTI SYSTEM AIR CONDITIONER
OUTDOOR UNIT: NTXMMX, NTXMPH series
Multi system air conditioner can connect 2 or more indoor units with 1 outdoor unit.
• When you try to operate 2 or more indoor units with 1 outdoor unit simultaneously, 1 for the cooling and the oth-
ers for heating, the operation mode of the indoor unit that operates first is selected. Other indoor units cannot
operate, and operation indicator lamp blinks as shown in the figure below. In this case, please set all the indoor
units to the same operation mode.
• When indoor unit starts the operation while the defrosting of outdoor unit is being done, it takes a few minutes (max.
10 minutes) to blow out the warm air.
• In the heating operation, though indoor unit that does not operate may get warm or the sound of refrigerant flow-
ing may be heard, they are not malfunction. The reason is that the refrigerant continuously flows into it.
Lit
Blinking
Not lit
<Operation indicator lamp>
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8-7. AUTO VANE OPERATION
1. Horizontal vane
(1) 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.
(2) The horizontal vane angle and mode change as follows by pressing VANE CONTROL button.
(3) 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:
(a) When the operation starts or finishes (including timer operation).
(b) When the test run operation starts.
(c) When standby mode (only during multi system operation) starts or finishes.
(4) VANE AUTO ( ) mode
The microprocessor automatically determines the vane angle to make the optimum room temperature distribution.
Horizontal
position
5
In COOL and DRY operation
Vane angle is fixed to Horizontal position.
In HEAT operation
Vane angle is fixed to Angle 5.
(5) STOP (operation OFF) and ON TIMER standby
In the following cases, the horizontal vane returns to the closed position.
(a) When STOP/OPERATE (OFF/ON) button is pressed (POWER OFF).
(b) When the operation is stopped by the emergency operation.
(c) When ON TIMER is ON standby.
(6) Dew prevention
During COOL or DRY operation with the vane angle at Angle 4 or 5 when the compressor cumulative operation time
exceeds 1 hour, the vane angle automatically changes to Angle 1 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 (NTXWST)
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.
To cancel this operation, select a different mode or press one of the following buttons in ECONO COOL operation:
ECONO COOL, VANE CONTROL, or POWERFUL (NTXWST24A112AA NTYWST24A112AA) button.
(
10 ) POWERFUL ( ) operation. (NTXWST24A112AA NTYWST24A112AA)
The air conditioner automatically adjusts the fan speed and the set temperature, and operates the POWERFUL mode.
The POWERFUL mode is automatically released 15 minutes after operation starts, and the operation mode returns
to the mode prior to POWERFUL operation. To cancel this operation manually, select a different mode or press
POWERFUL or ECONO COOL button.
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2. Vertical vane (NTXWST18/24A112AA NTYWST18/24A112AA)
(1) Vane motor drive
These models are equipped with a stepping motor for the vertical vane. The rotating direction, speed, and angle of the
motor are controlled by pulse signals (approximately 12 V) transmitted from microprocessor.
(2) The vertical vane angle and mode change as follows by pressing WIDE VANE button.
(3) Positioning
(a) When STOP/OPERATE (OFF/ON) button is pressed (POWER ON).
(b) When SWING is started.
(c) When the power supply turns ON.
(4) SWING MODE ( )
By selecting SWING mode with WIDE VANE button, the vertical vane swings horizontally.
The remote controller displays “ ”. Swing mode is cancelled when WIDE MODE button is pressed once again.
61 2 3 4 5SWING
51 2 3 4SWING
(5) WIDE MODE ( ) (NTXWST24A112AA NTYWST24A112AA)
By selecting WIDE mode with WIDE VANE button, indoor fan speed becomes faster than setting fan speed on the
remote controller ( ). The remote controller displays “ ”.
NOTE: Indoor fan speed becomes faster than setting fan speed on the remote controller even when or is selected.
NTXWST24A112AA NTYWST24A112AA
NTXWST18A112AA NTYWST18A112AA
8-8. TIMER OPERATION
1. How to set the time
(1) Check that the current time is set correctly.
NOTE: Timer operation will not work without setting the current time. Initially “0:00 AM” blinks at the current time display
of TIME MONITOR, so set the current time correctly with CLOCK SET button.
How to set the current time
(a) Press the CLOCK set button.
(b) Press the TIME SET buttons ( and ) to set the current time.
• Each time FORWARD button ( ) is pressed, the set time increases by 1 minute, and each time BACK-
WARD button ( ) is pressed, the set time decreases by 1 minute.
• Pressing those buttons longer, the set time increases/decreases by 10 minutes.
(c) Press the CLOCK set button.
(2) Press STOP/OPERATE (OFF/ON) button to start the air conditioner.
(3) Set the time of timer.
ON timer setting
(a) Press ON TIMER button ( ) during operation.
(b) Set the time of the timer using TIME SET buttons ( and ).
OFF timer setting
(a) Press OFF TIMER button ( ) during operation.
(b) Set the time of the timer using TIME SET buttons ( and ).
Each time FORWARD button ( ) is pressed, the set time increases by 10 minutes: each time BACKWARD
button ( ) is pressed, the set time decreases by 10 minutes.
2. To release the timer
To release ON timer, press ON TIMER button ( ).
To release OFF timer, press OFF TIMER button ( ).
TIMER is cancelled and the display of set time disappears.
OBHT732