Hitachi RAK-18NH6AS User manual

NO. 0489E
SPECIFICATIONS AND PARTS ARE SUBJECT TO CHANGE FOR IMPROVEMENT
ROOM AIR CONDITIONER
INDOOR UNIT
APRIL 2011 Refrigeration & Air-Conditioning Division
SERVICE MANUAL
PM
REFER TO THE FOUNDATION MANUAL
TECHNICAL INFORMATION
FOR SERVICE PERSONNEL ONLY
(W)
(A)
(kW)
(B.T.U./h)
(W)
(A)
(kW)
(B.T.U./h)
W
H
D
(kg)
DC INVERTER (WALL TYPE)
TYPE
MODEL
POWER SOURCE
TOTAL INPUT
TOTAL AMPERES
CAPACITY
TOTAL INPUT
TOTAL AMPERES
CAPACITY
DIMENSIONS
(mm)
NET WEIGHT
SPECIFICATIONS
CONTENTS
SPECIFICATIONS------------------------------------------------------ 5
HOW TO USE ---------------------------------------------------------11
CONSTRUCTION AND DIMENSIONAL DIAGRAM---------33
MAIN PARTS COMPONENT --------------------------------------34
WIRING DIAGRAM ---------------------------------------------------35
CIRCUIT DIAGRAM --------------------------------------------------37
PRINTED WIRING BOARD LOCATION DIAGRAM --------39
BLOCK DIAGRAM ----------------------------------------------------43
BASIC MODE ----------------------------------------------------------45
REFRIGERATING CYCLE DIAGRAM---------------------------59
AUTO SWING FUNCTION -----------------------------------------61
DESCRIPTION OF MAIN CIRCUIT OPERATION-----------62
SERVICE CALL Q & A----------------------------------------------67
PARTS LIST AND DIAGRAM--------------------------------------77
RAK-18NH6AS
RAK-18NH6A
RAK-25NH6A
RAK-35NH6A
RAK-50NH6A
COOLING
HEATING
780
280
220
RAK-18NH6AS
RAK-18NH6A
RAK-25NH6A
RAK-35NH6A
RAK-50NH6A
RAK-35NH6A
1ø 50/60Hz, 220-240V
REFER TO THE SPECIFICATION (OUTDOOR)
INDOOR UNIT
RAK-18NH6AS RAK-18NH6A RAK-25NH6A
NOTE:
This manual describes only points that differ from
RAF-25, 35NH5, RAD-25, 35NH5, RAI-25, 35NH5 and
RAM-55QH5 (PM No. 0312E) for items not described
in this manual.
9.59.0 9.0
HITACHI
DC INVERTER
TEMPORARY
SWITCH
9.5 9.5
RAK-50NH6A

– 1 –
SAFETY DURING REPAIR WORK
1. In order to disassemble and repair
the unit in question, be sure to
disconnect the power cord plug
from the power outlet before starting
the work.
2. If it is necessary to replace any
parts, they should be replaced with respective genuine parts for the unit, and the replacement must be ef-
fected in correct manner according to the instructions in the Service Manual of the unit.
If the contacts of electrical
parts are defective, replace the
electrical parts without trying to
repair them.
3. After completion of repairs, the initial state
should be restored.
4. Lead wires should be connected and laid as
in the initial state.
5. Modification of the unit by user himself should
absolutely be prohibited.
6. Tools and measuring instruments for use in repairs or inspection should be accurately calibrated in advance.
7. In installing the unit having been repaired, be careful to prevent the occurence of any accident such as
electrical shock, leak of current, or bodily injury due to the drop of any part.
8. To check the insulation of the unit, measure the insulation resistance between the power cord plug and
grounding terminal of the unit. The insulation resistance should be 1M or more as measured by a 500V
DC megger.
9. The initial location of installation such as window, floor or the other should be checked for being and safe
enough to support the repaired unit again.
If it is found not so strong and safe, the unit should be installed at the initial location reinforced or at a new
location.
10. Any inflammable thing should never
be placed about the location of
installation.
11. Check the grounding to see whether
it is proper or not, and if it is found
improper, connect the grounding
terminal to the earth.

– 2 –
WORKING STANDARDS FOR PREVENTING BREAKAGE OF SEMICONDUCTORS
1. Scope
The standards provide for items to be generally observed in carrying and handling semiconductors in rela-
tive manufacturers during maintenance and handling thereof. (They apply the same to handling of abnormal
goods such as rejected goods being returned).
2. Object parts
(1) Micro computer
(2) Integrated circuits (IC)
(3) Field-effect transistors (FET)
(4) P.C. boards or the like on which the parts mentioned in (1) and (2) of this paragraph are equipped.
3. Items to be observed in handling
(1) Use a conductive container for carrying and storing of parts. (Even rejected goods should be handled
in the same way).
Fig. 1. Conductive Container
(2) When any part is handled uncovered (in counting, packing and the like), the handling person must always
use himself as a body earth. (Make yourself a body earth by passing 1M earth resistance through a
ring or bracelet).
(3) Be careful not to touch the parts with your clothing when you hold a part even if a body earth is being
taken.
(4) Be sure to place a part on a metal plate with grounding.
(5) Be careful not to fail to turn off power when you repair the printed circuit board. At the same time, try
to repair the printed circuit board on a grounded metal plate.
1M
Fig. 2. Body Earth
Body earth
(Elimik conductive band)
Clip for connection with a
grounding wire
IC
A conductive polyvinyl bag IC
Conductive sponge

– 3 –
(6) Use a three wire type soldering iron including a grounding wire.
Bare copper wire (for body earth)
Working
table
Resistor of 1 M (1/2W)
Earth wire
Fig. 3. Grounding of the working table
2
Screw stop at the screwed
part using a rag plate
Soldering iron
Grounding
wire
Fig. 4. Grounding a soldering iron
Use a high insulation mode (100V, 10M or higher) when ordinary iron is to be used.
(7) In checking circuits for maintenance, inspection or some others, be careful not to have the test probes of
the measuring instrument shortcircuit a load circuit or the like.
Metal plate (of aluminium, stainless steel, etc.)
Staple

– 4 –
1. In quiet operation or stopping the running, slight flowing noise of refrigerant in the refrigerating cycle is
heard occasionally, but this noise is not abnormal for the operation.
2. When it thunders near by, it is recommend to stop the operation and to disconnect the power cord plug
from the power outlet for safety.
3. The room air conditioner does not start automatically after recovery of the electric power failure for
preventing fuse blowing. Re-press START/STOP button after 3 minutes from when unit stopped.
4. If the room air conditioner is stopped by adjusting thermostat, or missoperation, and re-start in a moment,
there is occasion that the cooling and heating operation does not start for 3 minutes, it is not abnormal
and this is the result of the operation of IC delay circuit. This IC delay circuit ensures that there is no
danger of blowing fuse or damaging parts even if operation is restarted accidentally.
5. This room air conditioner should not be used at the cooling operation when the outside temperature is
below –10°C (14°F).
6. This room air conditioner (the reverse cycle) should not be used when the outside temperature is below
–15°C (5°F).
If the reverse cycle is used under this condition, the outside heat exchanger is frosted and efficiency
falls.
7. When the outside heat exchanger is frosted, the frost is melted by operating the hot gas system, it is not
trouble that at this time fan stops and the vapour may rise from the outside heat exchanger.
CAUTION

– 5 –
SPECIFICATIONS
MODEL
FAN MOTOR
FAN MOTOR CAPACITOR
FAN MOTOR PROTECTOR
COMPRESSOR
COMPRESSOR MOTOR CAPACITOR
OVERLOAD PROTECTOR
OVERHEAT PROTECTOR
FUSE (for MICROPROCESSOR)
POWER RELAY
POWER SWITCH
TEMPORARY SWITCH
SERVICE SWITCH
TRANSFORMER
VARISTOR
NOISE SUPPRESSOR
THERMOSTAT
REMOTE CONTROL SWITCH
(LIQUID CRYSTAL)
RAK-18NH6AS, RAK-18NH6A, RAK-25NH6A, RAK-35NH6A, RAK-50NH6A
35W
NO
NO
–
NO
NO
NO
NO
NO
NO
YES
NO
NO
NO
NO
YES(IC)
YES
----------
WITHOUT REFRIGERANT BECAUSE
COUPLING IS FLARE TYPE.
UNIT
PIPES
REFRIGERANT CHARGING
VOLUME
(Refrigerant 410A)

– 6 –

– 7 –

– 8 –

– 9 –

– 10 –
SWITCH SETTING TO SELECT 1.8 kW OR 1.2 kW CAPACITY
CAUTION
Before setting the switch, make sure to turn OFF power supply and then set the position of the switch otherwise
will cause damage to the Main PCB.
1.2kW
1.8kW
SWITCH POSITION CAPACITY SELECTION
NOTE:
FACTORY default setting is at 1.8kW capacity.

! 11 !
INDOOR UNIT
NAMES AND FUNCTIONS OF EACH PART
Air  lter
To prevent dust from coming into the indoor unit.
(Refer Instruction manual)
Front panel
Indoor unit indicators
Light indicator showing the operating condition.
(Refer page 12)
Horizontal de ector ● Vertical de ector
(Air Outlet)
Remote controller
Send out operation signal to the indoor unit. So as
to operate the whole unit.
(Refer Instruction manual)
● Air cleansing  lters are washable and can be use in 1 year time. Type number for this air cleansing
 lter is <SPX-CFH20>. Please use this number for ordering when you want to renew it.
● Air cleansing  lter should be cleaned every month or sooner if noticeable loading occurs. When
used overtime, it may loose its deodorizing function. For maximum performance, it is recommended
to replace it every 1 year depending on application requirements.
NOTE
MODEL NAME AND DIMENSIONS
MODEL WIDTH (mm) HEIGHT (mm) DEPTH (mm)
RAK-18NH6AS/RAK-18NH6A/RAK-25NH6A/
RAK-35NH6A/RAK-50NH6A 780 280 220
HITACHI
DC INVERTER
TEMPORAR
SWITCH
HITACHI

! 12 !
INDOOR UNIT INDICATORS
OPERATION INDICATOR
FILTER LAMP
When the device is operated for a total of about 200
hours, the FILTER lamp lights to indicate that it is time
to clean the  lter.
OPERATION LAMP
This lamp lights during operation.
The OPERATION LAMP  ashes in the following cases
during heating.
(1) During preheating
For about 2!3 minutes after starting up.
(2) During defrosting
Defrosting will be performed about once every one
hour when frost forms on the heat exchanger of the
outdoor unit, for 5!10 minutes each time.
TIMER LAMP
This lamp lights when the timer is working.
TEMPORARY SWITCH
Use this switch to start and stop when the remote controller does not work. [Use non-conductor stick
(example: toothpick)]
● By pressing the temporary switch, the operation is done in previously set operation mode.
● When the operation is done using the temporary switch after the power source is turned off and turn
on again, the operation is done in automatic mode.
TEMPORARY
SWITCH
TEMPORARY
SWITCH
Temporary Switch
Press
Non-conductor Stick

! 13 !
MEMO
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Note
● Avoid to use the room air conditioner for cooling operation when the outside temperature is below
21°C (70°F).
The recommended maximum and minimum operating temperatures of the hot and cold sides
should be as below:
Cooling Heating
Minimum Maximum Minimum Maximum
Indoor Dry bulb °C 21 32 20 27
Wet bulb °C 15 23 12 19
Outdoor Dry bulb °C 21 43 2 21
Wet bulb °C 15 26 1 15

– 14 –
l Please read the “Safety Precaution” carefully before operating the unit to ensure correct usage of the unit.
l Pay special attention to signs of “ Warning” and “ Caution”. The “Warning” section contains matters which,
if not observed strictly, may cause death or serious injury. The “Caution” section contains matters which may result
in serious consequences if not observed properly. Please observe all instructions strictly to ensure safety.
l The sign indicate the following meanings.
l Please keep this manual after reading.
!
SAFETY PRECAUTION
WARNING
PRECAUTIONS DURING INSTALLATION
lDo not reconstruct the unit.
 Waterleakage,fault, shortcircuitorremayoccurifyoureconstructtheunitby
yourself.
lPleaseaskyoursalesagentorqualiedtechnicianfortheinstallationofyourunit.
Water leakage, short circuit or re may occur if you install the unit by yourself.
lPlease use earth line.
Do not place the earth line near water or gas pipes, lightning-conductor, or the
earth line of telephone. Improper installation of earth line may cause electric
shock.
lBesureto use thespecied piping setforR410A. Otherwise,thismay resultin
broken copper pipes or faults.
lA circuit breakershouldbe installed dependingonthe mountingsiteof the unit.
Without a circuit breaker, the danger of electric shock exists.
lDonot installnearlocationwherethereisammablegas.The outdoorunitmay
catch re if ammable gas leaks around it.
lPlease ensure smooth ow of water when installing the drain hose.
CAUTION
!
!
PRECAUTIONS DURING OPERATION
lAvoid an extended period of direct air ow for your health.
W
A
R
N
I
N
G
!
lDonotinsertanger,arodorotherobjectsintotheairoutletorinlet.Asthefan
is rotating at a high speed, it will cause injury. Before cleaning, be sure to stop
the operation and turn the breaker OFF.
lDuring thunder storm, disconnect and turn off the circuit breaker.
lDo not use any conductor as fuse wire, this could cause fatal accident.
!
Make sure to connect earth line.
Indicates the instructions that must be followed.
The sign in the gure indicates prohibition.
PRECAUTIONS DURING SHIFTING OR MAINTENANCE
lShould abnormal situation arises (like burning smell), please stop operating the unit
andturnoffthecircuitbreaker.Contactyouragent.Fault,shortcircuitorremay
occur if you continue to operate the unit under abnormal situation.
lPlease contact your agent for maintenance. Improper self maintenance may cause
electric shock and re.
lPlease contact your agent if you need to remove and reinstall the unit. Electric
shock or re may occur if you remove and reinstall the unit yourself improperly.
lIf the supply cord is damaged, it must be replaced by the special cord
obtainable at authorized service/parts centers.
W
A
R
N
I
N
G
!

– 15 –
PRECAUTIONS DURING OPERATION
lDo not attempt to operate the unit with wet hands, this could cause fatal
accident.
lWhen operating the unit with burning equipments, regularly ventilate the
room to avoid oxygen insufciency.
lDo not direct the cool air coming out from the air-conditioner panel to face
household heating apparatus as this may affect the working of apparatus
such as the electric kettle, oven etc.
lDo not use any aerosol or hair sprays near the indoor unit. This chemical
 can adhere on heat exchanger n and blocked the evaporation water ow
to drain pan. The water will drop on tangential fan and cause water splashing
out from indoor unit.
lPlease ensure that outdoor mounting frame is always stable, rm and
without defect. If not, the outdoor unit may collapse and cause danger.
lDo not splash or direct water to the body of the unit when cleaning it as
this may cause short circuit.
lWhen operating the unit with the door and windows opened, (the room humidity is always above
80%) and with the air deector facing down or moving automatically for a long period of time,
waterwillcondenseontheairdeectoranddripsdownoccasionally.Thiswillwetyourfurniture.
Therefore, do not operate under such condition for a long time.
lIf the amount of heat in the room is above the cooling or heating capability of the unit (for
example: more people entering the room, using heating equipments and etc.), the preset room
temperature cannot be achieved.
l Thisappliance isnotintendedforuse byyoung childrenor inrmpersons unlessthey havebeen
adequately supervised by a responsible person to ensure that they can use the appliance safely.
lYoung children should be supervised to ensure that they do not play with the appliance.
lDo not climb on the outdoor unit or put objects on it.
lPlease switch off the unit and turn off the circuit breaker during cleaning,
the high-speed fan inside the unit may cause danger.
lTurn off the circuit breaker if the unit is not to be operated for a long period.
C
A
U
T
I
O
N
!
lThe product shall be operated under the manufacturer specication and
not for any other intended use.
lDo not put water container (like vase) on the indoor unit to avoid water
dripping into the unit. Dripping water will damage the insulator inside the
unit and causes short-circuit.
lDo notplaceplants directlyunderthe airow as itis badforthe plants.

– 16 –
SILENT
LOW
MED
HI
AUTO
HEAT
DEHUMIDIFY
COOL
FAN
FAN SPEED
SLEEPING
STOP (CANCEL)
START (RESERVE)
START/STOP
TIME
TIMER SET
TIMER SELECTOR
ON TIMER
OFF TIMER
AUTO SWING
NAMES AND FUNCTIONS OF REMOTE CONTROL UNIT
REMOTE CONTROLLER
lThis controls the operation of the indoor unit. The range of control is about 7 meters. If indoor lighting is controlled
electronically, the range of control may be shorter.
 Thisunitcanbexedonawallusingthextureprovided.Beforexingit,makesuretheindoorunitcanbecontrolled
from the remote controller.
lHandle the remote controller with care. Dropping it or getting it wet may compromise its signal transmission
capability.
l After new batteries are inserted into the remote controller, the unit will initially require approximately 10 seconds to
respond to commands and operate.
lSignal emitting window/transmission sign
Point this window toward the indoor unit when controlling it.
The transmission sign blinks when a signal is sent.
lDisplay
This indicates the room temperature selected, current time, timer status, function
and intensity of circulation selected.
lSTART/STOP button
Press this button to start operation. Press it again to stop operation.
lSLEEP button
Use this button to set the sleep timer.
lTEMPERATURE buttons
Use these buttons to raise or lower the temperature setting. (Keep pressed,
and the value will change more quickly.)
lTIME button
Use this button to set and check the time and date.
lRESET buttons
lFUNCTION selector
Use this button to select the operating mode. Every time you press it,
the mode will change from    (AUTO) to    (HEAT) to    (DEHUMIDIFY) to
   (COOL) and to    (FAN) cyclically.
lFAN SPEED selector
This determines the fan speed. Every time you press this button, the intensity
ofcirculationwillchangefrom(AUTO)to(HI)to(MED)to(LOW)
to(SILENT)(Thisbuttonallowsselectingtheoptimalorpreferredfanspeed
for each operation mode).
lAUTO SWING button
 Controls the angle of the horizontal air deector.
lTIMER control
Use this button to set the timer.
lOFF-TIMER button   Select the turn OFF time.
lON-TIMER button   Select the turn ON time.
lRESERVE button Time setting reservation.
lCANCEL button Cancel time reservation.
Precautions for Use
lDo not put the remote controller in the following places.
lUnder direct sunlight.
lIn the vicinity of a heater.
l Handle the remote controller carefully. Do not drop it on the oor,
and protect it from water.
l Once the outdoor unit stops, it will not restart for about 3 minutes
(unless you turn the power switch off and on or unplug the power
cord and plug it in again).
This is to protect the device and does not indicate a failure.
l If you press the FUNCTION selector button during operation, the
device may stop for about 3 minutes for protection.

– 17 –
AUTOMATIC OPERATION
The device will automatically determine the mode of operation, HEAT, COOL or DEHUMIDIFY depending on the current room
temperature. The selected mode of operation will change when the room temperature varies. However the mode of operation
will not change when indoor unit connected to multi type outdoor unit.
VARIOUS FUNCTIONS
nAuto Restart Control
lIf there is a power failure, operation will be automatically restarted when the power is resumed with previous operation mode
and airow direction.
 (As the operation is not stopped by remote controller.)
lIf you intend not to continue the operation when the power is resumed, switch off the power supply.
 Whenyouswitchonthecircuitbreaker,theoperationwillbeautomaticallyrestartedwithpreviousoperationmodeandairow
direction.
 Note: 1. If you do not require Auto Restart Control, please consult your sales agent or OFF by remote control.
  2. Auto Restart Control is not available when Timer or Sleep Timer mode is set.
nAs the settings are stored in memory in the remote controller, you only
have to press the     (START/STOP) button next time.
PresstheFUNCTIONselectorsothatthedisplayindicatesthe(AUTO)
mode of operation.
l WhenAUTOhasbeenselected,thedevicewillautomaticallydetermine
themodeofoperation,HEAT,COOLorDEHUMIDIFYdependingon
the current room temperature. However the mode of operation will
not change when indoor unit connected to multi type outdoor unit.
lIf the mode automatically selected by the unit is not satisfactory,
manually change the mode setting (heat, dehumidify, cool or fan).
Press the     (START/STOP) button.
Operation starts with a beep.
Press the button again to stop operation.
You can raise or lower the temperature setting as necessary by maximum
of 3°C.
Press the temperature button and the temperature
setting will change by 1°C each time.
lThe preset temperature and the actual room temperature may vary
somewhat depending on conditions.
l ThedisplaydoesnotindicatethepresettemperatureintheAUTOmode.
If you change the setting, the indoor unit will produce a beep.
1
START
STOP
°C
Press the     (FAN SPEED) button,AUTO, LOW and SILENT is available.

– 18 –
HEATING OPERATION
l Use the device for heating when the outdoor temperature is under 21°C.
 When it is too warm (over 21°C), the heating function may not work in order to protect the device.
l In order to keep reliability of the device, please use this device above -15°C of the outdoor
temperature.
Press the FUNCTION selector so that the display indicates
   (HEAT).
SetthedesiredFANSPEEDwiththe(FANSPEED)button
(the display indicates the setting).
 (AUTO) : The fan speed changes automatically
according to the temperature of the air which
blows out.
(HI) : Economical as the room will become warm
quickly.
But you may feel a chill at the beginning.
 (MED) : Fan speed slow.
 (LOW) : Fan speed slower.
 (SILENT) : Fan speed ultra slower.
Set the desired room temperature with the TEMPERATURE
buttons (the display indicates the setting).
The temperature setting and the actual room temperature may
vary somewhat depending on conditions.
Press the    (START/STOP) button. Heating operation starts
with a beep. Press the button again to stop operation.
n As the settings are stored in memory in the remote controller, you only
have to press the    (START/STOP) button next time.
1
2
3
START
STOP
nDefrosting
Defrosting will be performed about once an hour when frost forms on the heat exchange of the outdoor
unit, for 5~10 minutes each time.
During defrosting operation, the operation lamp blinks in cycle of 3 seconds on and 0.5 second off.
The maximum time for defrosting is 20 minutes.
However, if it is connected to multi type outdoor unit, the maximum time for defrosting is 15 minutes.
(If the piping length used is longer than usual, frost will likely to form.)

– 19 –
DEHUMIDIFYING OPERATION
Use the device for dehumidifying when the room temperature is over 16°C.
When it is under 15°C, the dehumidifying function will not work.
nDehumidifying Function
l When the room temperature is higher than the temperature setting: The device will dehumidify the
room, reducing the room temperature to the preset level.
When the room temperature is lower than the temperature setting: Dehumidifying will be performed at
the temperature setting slightly lower than the current room temperature, regardless of the temperature
setting. The function will stop (the indoor unit will stop emitting air) as soon as the room temperature
becomes lower than the setting temperature.
l The preset room temperature may not be reached depending on the number of people present in
the room or other room conditions.
Set the desired room temperature with the TEMPERATURE
button (the display indicates the setting).
 The range of 20-26˚C is recommended as
the room temperature for dehumidifying.
Press the (START/STOP)button.Dehumidifyingoperation
starts with a beep. Press the button again to stop operation.
2
nAsthesettingsarestored inmemoryin theremote controller,you
only have to press the  (START/STOP) button next time.
START
STOP
Press the FUNCTION selector so that the display indicates
    (DEHUMIDIFY).
The FAN SPEED is set at LOW or SILENT.
1