Hitachi RAS-18YH4 User manual

AW NO. 0004E
SERVICE MANUAL
TECHNICAL INFORMATION
REFER TO THE FOUNDATION MANUAL
ROOM AIR CONDITIONER
INDOOR UNIT + OUTDOOR UNIT
SPECIFICATIONS AND PARTS ARE SUBJECT TO CHANGE FOR IMPROVEMENT
FOR SERVICE PERSONNEL ONLY
SPECIFICATIONS
SPECIFICATIONS ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 4
HOW TO USE ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5
CONSTRUCTION AND DIMENSIONAL DIAGRAM ‥‥ 15
MAIN PARTS COMPONENT ‥‥‥‥‥‥‥‥‥‥ 17
WIRING DIAGRAM ‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 19
WIRING DIAGRAM OF THE PRINTED WIRING BOARD ‥20
PRINTED WIRING BOARD LOCATION DIAGRAM ‥‥ 24
BLOCK DIAGRAM‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 27
BASIC MODE‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 29
REFRIGERATING CYCLE DIAGRAM ‥‥‥‥‥‥ 38
DESCRIPTION OF MAIN CIRCUIT OPERATION ‥‥‥ 39
SERVICE CALL Q & A ‥‥‥‥‥‥‥‥‥‥‥‥ 67
TROUBLE SHOOTING ‥‥‥‥‥‥‥‥‥‥‥‥ 70
PROCEDURE FOR DISASSEMBLY AND REASSEMBLY ‥‥96
PARTS LIST AND DIAGRAM ‥‥‥‥‥‥‥‥‥ 98
CONTENTS
RAS-18YH4 /
RAC-18YH4
RAC-18YH4
RAS-18YH4
(W)
(A)
(kW)
(B.T.U./h)
(W)
(A)
(kW)
(B.T.U./h)
W
H
D
(kg)
RAS-18YH4 RAC-18YH4
DC INVERTER (WALL TYPE)
TYPE
MODEL
POWER SOURCE
TOTAL INPUT
TOTAL AMPERES
CAPACITY
TOTAL INPUT
TOTAL AMPERES
CAPACITY
DIMENSIONS
(mm)
NET WEIGHT
780
280
205
9.5
COOLING
HEATING
INDOOR UNIT OUTDOOR UNIT
1 PHASE, 50Hz, 230V
550 (155 - 1,010)
2.81
2.00 (0.90 - 2.50)
6,820 (3,070 - 8,530)
580 (115 - 970)
2.81
2.50 (0.90 - 3.20)
8,530 (3,070 - 10,920)
750(+91)※
(+47)※ (+5)※
548
288
35
After installation
※
DECEMBER 2004 Hitachi Household Appliance (Wuhu) Co.,Ltd.

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.
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 the 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 occurrence 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 9 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 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 after reinforced or
at a new location.
10. Any inflammable object must not 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.
Spray
gasoline
gasbombe
thinner
SAFETY DURING REPAIR WORK
If the contacts of electrical
parts are defective, replace
the electrical parts without
trying to repair them
1
2
3
4
5
DANGER

– 1 –
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 manufactures 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 (I.C.)
(3) Field effective transistor (F.E.T.)
(4) P.C. boards or the like to 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.)
(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.
HITACHI IC401TH1, 188UV
Fig. 1 Conductive container
A conductive polyvinyl bag
IC
IC
Conductive sponge
Fig. 2 Body earth
Body earth (Elimik conductive band)
Clip for connection with
a grounding wire
1M 9

– 2 –
(6) Use a three wire type soldering iron including a grounding wire.
Fig.4 Grounding a solder iron
Use a high insulation mode (100V, 10M 9 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.
Bare copper wire (for body earth)
Metal plate (of Al. stainless steel, etc.)
Working table
Resistor 1M 9 (1/2W)
Earth wirte
Staple
Fig.3 Grounding of the working table
soldering iron
Grounding wire
Screw stop at the screwed
part using a rag plate

– 3 –
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 prevent-
ing 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