Hitachi RAD-25NH7 User manual

NO. 0366E
SPECIFICATIONS AND PARTS ARE SUBJECT TO CHANGE FOR IMPROVEMENT
ROOM AIR CONDITIONER
INDOOR UNIT + OUTDOOR UNIT
APRIL 2007 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 (DUCT TYPE)
TYPE
MODEL
POWER SOURCE
TO TAL INPUT
TOTAL AMPERES
CAPACITY
TOTAL INPUT
TOTAL AMPERES
CAPACITY
DIMENSIONS
(mm)
NET WEIGHT
SPECIFICATIONS
750
235
400
19
RAD-18NH7
RAD-25NH7
RAD-35NH7
RAD-50NH7
CONTENTS
SPECIFICATIONS ------------------------------------------------------------------- 4
HOW TO USE ------------------------------------------------------------------------ 6
CONSTRUCTION AND DIMENSIONAL DIAGRAM --------------------- 24
MAIN PARTS COMPONENT --------------------------------------------------- 27
WIRING DIAGRAM ---------------------------------------------------------------- 29
CIRCUIT DIAGRAM --------------------------------------------------------------- 31
BLOCK DIAGRAM ----------------------------------------------------------------- 37
BASIC MODE ----------------------------------------------------------------------- 39
REFRIGERATING CYCLE DIAGRAM --------------------------------------- 53
DESCRIPTION OF MAIN CIRCUIT OPERATION ----------------------- 55
SERVICE CALL Q & A ---------------------------------------------------------- 87
TROUBLE SHOOTING ----------------------------------------------------------- 90
PARTS LIST AND DIAGRAM ------------------------------------------------- 110
RAD-18NH7
RAD-25NH7/RAC-25NH5
RAD-35NH7/RAC-35NH5
RAD-50NH7/RAC-50NH5
RAC-25NH5
RAC-35NH5
RAC-50NH5
COOLING
HEATING
OUTDOOR UNIT INDOOR UNIT
750
235
400
19
850
650
298
60
1 PHASE, 50 Hz, 220-240V
2,000 (155-2,060)
9.20-8.40
5.0 (0.9 ~ 5.6)
17,070 (3,070-19,120)
2,300 (155-2,530)
10.60-9.70
6.0 (0.9 ~ 7.5)
20,490 (3,070-25,610)
RAD-50NH7 RAC-50NH5
OUTDOOR UNIT INDOOR UNIT
RAD-35NH7 RAC-35NH5
OUTDOOR UNIT INDOOR UNIT
RAD-25NH7 RAC-25NH5
INDOOR UNIT
RAD-18NH7
1 PHASE, 50 Hz, 220-240V
1,240 (155-1,280)
5.70-5.24
3.50 (0.9 ~ 4.0)
11,950 (3,070-13,660)
1,700 (155-1,920)
7.84-7.19
4.80 (0.9 ~ 6.6)
16,390 (3,070-22,530)
1 PHASE, 50 Hz, 220-240V
695 (155-1,050)
3.20-2.92
2.50 (0.9 ~ 3.0)
8,540 (3,070-10,240)
970 (155-1,400)
4.50-4.10
3.50 (0.9 ~ 5.0)
11,950 (3,070-17,070)
1 PHASE, 50 Hz, 220-240V
560 (155-850)
2.56-2.35
1.80 (0.9 ~ 2.5)
6,150 (3,070-8,540)
690 (155-1,050)
3.20-2.92
2.50 (0.9 ~ 3.2)
8,540 (3,070-10,930)
750
570
280
38
750
235
400
19
750
570
280
38
750
235
400
19

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 effected 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.
DANGER
First, I must disconnect
the power cord plug
from the power outlet.
– i –

WORKING STANDARDS FOR PREVENTING BREAKAGE OF SEMICONDUCTORS
1. Scope
The standards provide for items to be generally observed in carrying and handling semiconductors in relative
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 one M ohm 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
– 1 –

(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
– 2 –

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 (50°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
– 3 –

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)
20W
NO
NO
–
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
YES(IC)
YES
----------
40 W
NO
NO
NO
YES
YES
3.0A
G4A
NO
NO
YES
NO
450NR
YES
YES(IC)
NO
WITHOUT REFRIGERANT BECAUSE
COUPLING IS FLARE TYPE.
UNIT
PIPES (MAX. 20m)
REFRIGERANT CHARGING
VOLUME
(Refrigerant 410A)
RAC-25NH5
RAC-35NH5
RAC-50NH5
JU1012D JU1013D
1400g1150g
– 4 –
RAD-18NH7
RAD-25NH7
RAD-35NH7
RAD-50NH7

– 5 –
[Indoor unit installation]
275
CAUTION
Always install the indoor unit at level. If the
indoor unit is inclined, water may leak.
!
Be sure to completely
seal any gap with putty.
●The connecting pipe, no
matter big or small,
should all be insulated
with insulation pipe and
then wrapped with vinyl
tape. (The insulator will
deteriorate if it is not
wrapped with tape).
Drain pipe must be installed
separately. Insulate indoor part
of pipe to prevent condensation.
The indoor piping should be
insulated with the enclosed
insulation pipe. (If the
insulator is insufficient,
please use commercial
products.)
●“Height difference”and “Piping length”of Indoor and Outdoor unit are different by Outdoor unit.
Please refer to the installation manual in Outdoor unit.
Electrical
box
Air outlet
Filter Air inlet Remote
controller

– 6 –
!
SAFETY PRECAUTION
●
Please read the “Safety Precaution” carefully before operating the unit to ensure correct usage of the unit.
●
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.
●
The sign indicate the following meanings.
●
Please keep this manual after reading.
WARNING
PRECAUTIONS DURING INSTALLATION
●Do not reconstruct the unit.
Water leakage, fault, short circuit or fire may occur if you reconstruct the
unit by yourself.
●Please ask your sales agent or qualified technician for the installation of
your unit. Water leakage, short circuit or fire may occur if you install the unit
by yourself.
●Please 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.
●A circuit breaker should be installed depending on the mounting site of the
unit. Without a circuit breaker, the danger of electric shock exists.
●Do not install near location where there is flammable gas. The outdoor unit
may catch fire if flammable gas leaks around it.
●Please ensure smooth flow of water when installing the drain hose.
CAUTION
!
!
PRECAUTIONS DURING SHIFTING OR MAINTENANCE
PRECAUTIONS DURING OPERATION
●Avoid an extended period of direct air flow for your health.
W
A
R
N
I
N
G
!
●Should abnormal situation arises (like burning smell), please stop operating the unit
and turn off the circuit breaker. Contact your agent. Fault, short circuit or fire may
occur if you continue to operate the unit under abnormal situation.
●Please contact your agent for maintenance. Improper self maintenance may cause
electric shock and fire.
●Please contact your agent if you need to remove and reinstall the unit. Electric
shock or fire may occur if you remove and reinstall the unit yourself improperly.
●If the supply cord is damaged, it must be replaced by the special cord obtainable
at authorized service/parts centers.
●Do not insert a finger, 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.
●During thunder storm, disconnect and turn off the circuit breaker.
●Do 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 figure indicates prohibition.
W
A
R
N
I
N
G
!

– 7 –
PRECAUTIONS DURING OPERATION
●Do not attempt to operate the unit with wet hands, this could cause fatal
accident.
●When operating the unit with burning equipments, regularly ventilate the
room to avoid oxygen insufficiency.
●Do 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.
●Do not place plants directly under the air flow as it is bad for the plants.
●Please ensure that outdoor mounting frame is always stable, firm and
without defect. If not, the outdoor unit may collapse and cause danger.
●Do not splash or direct water to the body of the unit when cleaning it as this
may cause short circuit.
●When operating the unit with the door and windows opened, (the room humidity is always above
80%) and with the air deflector facing down or moving automatically for a long period of time,
water will condense on the air deflector and drips down occasionally. This will wet your furniture.
Therefore, do not operate under such condition for a long time.
●If 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.
●This appliance is not intended for use by young children or infirm persons unless they have been
adequately supervised by a responsible person to ensure that they can use the appliance safely.
●Young children should be supervised to ensure that they do not play with the appliance.
●Do not climb on the outdoor unit or put objects on it.
●Please switch off the unit and turn off the circuit breaker during cleaning, the
high-speed fan inside the unit may cause danger.
●Turn off the circuit breaker if the unit is not to be operated for a long period.
C
A
U
T
I
O
N
!
●The product shall be operated under the manufacturer specification and
not for any other intended use.
●Do 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.
●Do not use any aerosol or hair sprays near the indoor unit. This chemical
can adhere on heat exchanger fin and blocked the evaporation water flow
to drain pan. The water will drop on tangential fan and cause water splashing
out from indoor unit.

– 8 –
MULTI-AIR CONDITIONER
With this multi-air conditioner, several indoor units can be connected to one outdoor unit to be driven. You
can operate the required number of indoor units.
Combination of Operations:
●You cannot operate the indoor units in
the following combinations. ●The indoor unit which is switched on first continues
to operate, but other indoor units which is switched
on later does not operate while the lamp lights.
●To re-start an indoor unit which was operated later,
stop the indoor unit which was operated first or
later and reset the type of operation, then perform
operation again.
One unit
Heating
Other unit
Cooling
Dehumidifying
Circulating (fan)
Adjusting the Number of Indoor
Units:
Decrease the number of
indoor units to be operated
especially when it is very
hot or cold or when you
want to reach the present
temperature quickly.
Stopped Indoor Units:
When an indoor unit is operated in the
cooling, heating or dehumidifying mode in
the room, the sound of refrigerant flow may
be heard from a stopped indoor unit or a
stopped indoor unit may become warm.
This is because the indoor unit returns
refrigerant to the outdoor unit to be ready
for operation.
When operation mode is selected:
●When heating operation is automatically selected for the first indoor unit, the next indoor unit will then
start to heat. Also, if cooling or dehumidifying is automatically selected for the first indoor unit, the next
indoor unit will also start to cool or dehumidify.
During automatic operation: