Hitachi RAS-25CNH2 User manual

NO. 0081E
SERVICE MANUAL
PM
TECHNICAL INFORMATION
FOR SERVICE PERSONNEL ONLY
SPECIFICATIONS
CONTENTS
SPECIFICATIONS --------------------------------------------------------------5
HOW TO USE -------------------------------------------------------------------6
CONSTRUCTION AND DIMENSIONAL DIAGRAM ---------------- 22
MAIN PARTS COMPONENT --------------------------------------------- 23
PRINTED WIRING BOARD LOCATION DIAGRAM---------------- 25
BLOCK DIAGRAM ------------------------------------------------------------ 33
DESCRIPTION OF MAIN CIRCUIT OPERATION ------------------ 35
SERVICE CALL Q & A ----------------------------------------------------- 67
TROUBLE SHOOTING ------------------------------------------------------ 70
PARTS LIST AND DIAGRAM--------------------------------------------- 80
RAS-25CNH2
RAC-25CNH2
REFER TO THE FOUNDATION MANUAL
INDOOR UNIT
RAS-25CNH2
OUTDOOR UNIT
RAC-25CNH2
WALL TYPE
SPECIFICATIONS AND PARTS ARE SUBJECT TO CHANGE FOR IMPROVEMENT
ROOM AIR CONDITIONER
INDOOR UNIT + OUTDOOR UNIT
APRIL 1998
H.A.P.M.
TYPE
MODEL
1ø 220V – 240V 50HzPOWER SOURCE
910 (190 `1,150) [COOL] / 1,250 (160 `1,350) [HEAT]TOTAL INPUT
4.20 `3.85 [COOL] / 5.75 `5.25 [HEAT]TOTAL AMPERES (RATED / MAX.)
COOLING CAPACITY
HEATING CAPACITY
DIMENSIONS
NET WEIGHT
(W)
(A)
(kW)
(B.T.U./h)
(kW)
(B.T.U./h)
W
H
D
(kg)
(mm)
2.50 (0.90 `2.80)
8,870 (3,070 `9,550)
3.60 (0.90 `4.00)
12,280 (3,070 `13,650)
744
248
168
5.5
700
570
210
29
RAS-25CNH2
RAC-25CNH2

– 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 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.

– 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 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

– 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. If the room air conditioner is stopped by setting the temperature or mis-operation, and then re-started in a
moment, cooling 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.
4. This room air conditioner should not be used at the cooling operation when the outside temperature is below
20°C.
5. When the operation knob is set to “COOL” from another position, IC delay circuit functions and stops the
compressor for the first 3 minutes, which is not an abnormal phenomenon.
CAUTION

– 5 –
RAC-25CNH2
20 W
NO
NO
G920DP5H
NO
YES
YES
3.15A
G4A
NO
NO
YES
NO
450NR
NO
NO
NO
MODEL
FAN MOTOR
FAN MOTOR CAPACITOR
FAN MOTOR PROTECTOR
COMPRESSOR
COMPRESSOR MOTOR CAPACITOR
OVERLOAD PROTECTOR
OVERHEAT PROTECTOR
FUSE
POWER RELAY, STICK RELAY
POWER SWITCH
TEMPORARY SWITCH
SERVICE SWITCH
TRANSFORMER
VARISTOR
NOISE SUPPRESSOR
REMOTE CONTROL SWITCH (LIQUID CRYSTAL)
THERMOSTAT
FUSE CAPACITY
RAS-25CNH2
20 W
NO
NO
NO
NO
NO
NO
NO
NO
YES
YES
NO
NO
NO
NO
YES
YES (IC)
SPECIFICATIONS
NO
---------- ❈ 690g
UNIT
PIPES
❈690g for piping set of 5~8m.
REFRIGERANT
CHARGING VOLUME
(Refrigerant 22) WITHOUT REFRIGERANT BECAUSE
COUPLING IS FLARE TYPE.
P - 105 VK1 (5m), P - 108 VK1 (8m)

– 6 –
INDOOR UNIT
OUTDOOR UNIT
WIDTH (mm)
744
700
MODEL
RAS-25CNH2
RAC-25CNH2
HEIGHT (mm)
248
570
DEPTH (mm)
168
210
MODEL NAME AND DIMENSIONS
NAMES AND FUNCTIONS OF EACH PART
AIR FILTER
To prevent dust from coming into the indoor unit.
(Refer page 18)
POWER PLUG (NOT PROVIDED)
INDOOR UNIT INDICATORS
Light indicator showing the operating condition.
(Refer page 7)
SUCTION GRILL (AIR INLET)
HORIZONTAL DEFLECTOR ●VERTICAL
DEFLECTOR (AIR OUTLET)
(Refer page 14)
REMOTE CONTROL
Send out operation signal to the indoor unit. So as
to operate the whole unit.
(Refer page 8)
DRAIN PIPE
Condensed water drain to outside.
CONNECTING CORD
AIR INLET (BACK, LEFT SIDE)
AIR OUTLET

– 7 –
INDOOR UNIT INDICATORS
TEMPORARY SWITCH
Use this switch to start and stop when the remote
controller does not work.
●By setting 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.
OPERATION INDICATOR
OPERATION LAMP
This lamp lights during operation.
The OPERATION LAMP flashes 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 an 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.
SIGNAL RECEIVER
There will be a beep sound when this receiver receives
signal from remote controller.
POWER SWITCH

– 8 –
NAMES AND FUNCTIONS OF REMOTE CONTROL UNIT
■This controls the operation function and timer setting of the room air conditioner. The range of
control is about 4 meters. If indoor lighting is controlled electronically, the range of control may be
shorter.
Precautions for Use
●Do not put the remote controller in direct
sunlight and high temperature.
●Do not drop it on the floor, and protect
it from water.
●If you press the FUNCTION button
during operation, the air conditioner may
stop for about 3 minutes for protection
before you can start it again.
You can use the remote controller by fixing it on the
wall with the accessory parts.
●Before fixing it,
make sure the
unit can be
controlled by the
remote control
unit at the fixing
position.
REMOTE
CONTROLLER
HOLDER
START/STOP Button
Press this button to start operation.
Press it again to stop operation.
SLEEP Button
Use this button to set the sleep timer.
(Page 12)
Reserve Button
Timer setting reservation.
OFF TIMER Button
Select the turn OFF time.
ON TIMER Button
Select the turn ON time.
Transmission Sign
The transmission sign blinks
when a signal has been send.
TEMPERATURE Button
Room temperuture setting.
Value will change more quickly
when keep pressing.
(Page 9)
FAN SPEED Button
Select the fan speed for
cooling and heating mode.
(Page 10)
AUTO SWING Button
Control the angle of the
horizontal air deflector.
( Page 14)
CANCEL Button
Cancel timer reservation.
Signal Transmission
FUNCTION Button
Select the operation mode.
(Page 10)
C
˚
Hr.
HITACHI
°C

–9 –
AUTOMATIC OPERATION
■The device will automatically determine the mode of operation, HEAT, COOL or DEHUMIDIFY,
depending on the initial room temperature. The selected mode of operation will not change when
the room temperature varies.
1
Press the (START/STOP) button
●Operation start with a “beep”sound.
Press the (START/STOP) button
●Make sure the (Automatic) mode have been selected by using
the (FUNCTION) button.
●The fan speed selector does not work at this operation.
STOP
Press the (ROOM TEMPERATURE) button
●Temperature setting change by 1°C for each 1 time press.
Up
Down
●You can raise or lower the temperature setting by a maximum of
3°C.
●The display does not indicate the preset temperature in the Automatic
mode. Device will receive the setting by a “beep”.
■You can slightly adjust the room temperature.
1
°C
°C
▲ ▲
■CONDITION OF AUTOMATIC OPERATION
●The selected mode of operation will not change during the operation even though the room
temperature change.
Over 27°C COOL
23 ~ 27°C
FUNCTION
27°C
Slightly lower than the
room temperature LOW
FAN SPEED
HIGH at start, LOW after
the preset temperature is
reached
-
DRY
-
INITIAL ROOM
TEMPERATURE (APPROX.)
TEMPERATURE
SETTING
Under 23°C HEAT 23°C
HIGH at start, MED or
LOW after the preset
temperature is reached
-
HITACHI
°C
HITACHI
°C