Hitachi RAC-18YH4 Service Manual Download Page 82

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Is 230V being generated at

terminals A

and

Are the connections for

terminals C and D correct?

Is 5V being generated between

Pin 4 (0V) and Pin 3 (5V) at CN

Is the 15A

fuse normal?

[No operation or abnormal operation]

Be sure to turn the power of

before correcting the connection.

mainly

, varistor (VS2), 3A

fuse,

smoothing capacitors, IPM, etc.

The SW power supply

s overcurrent protection is

activated, disabling the microcomputer

Correct properly

If the 15A

fuse has blown,

be aware that other parts

may also be defective

Replace defective parts.

Is the power circuit normal?

See the description on power

circuit for details.

Is the switching power

circuit OK?

Has the 3A

fuse blown?

Check to see if C and D cables are

connected correctly

If reversed or incompletely inserted,

correct the cable connection.

Replace any defective parts.

If the 3A

fuse has blown, the varistor 2, etc.

may also be defective.

With the piping and lines (A,

B, C, D) connected, operate

the unit in the forced cooling

mode using the outdoor unit

service switch.

How did the self-diagnosis

lamp (LD301) blink?

See the self-diagnosis

lamp mode.

Power is OK

(Fuse blown)

CHECKING OUTDOOR UNIT ELECTRICAL PARTS

18 (test pin)?

Summary of Contents for RAC-18YH4

Page 1: ...IAGRAM 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 N...

Page 2: ...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 1M9 or more as measured by a 500V DC megger 9 The initial location of installation such as window floor or the other should be che...

Page 3: ...ven 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 ...

Page 4: ...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 1M9 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 ...

Page 5: ...casion 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...

Page 6: ... TEMPORARY SWITCH SERVICE SWITCH TRANSFORMER VARISTOR NOISE SUPPRESSOR THERMOSTAT REMOTE CONTROL SWITCH LIQUID CRYSTAL 40 W NO NO NO ASC092SD A8JT1 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 18YH4 870g RAS 18YH4 PWM DC35V NO NO NO NO NO NO NO YES NO NO NO NO YES IC YES YES ...

Page 7: ... is plugged In addition wire the cable with some allowances to prevent the cable from stretching Not doing so will cause an electrical shock heat generation or fire PROHIBITION Do not put objects like thin rods into the panel of blower and suction side because the high speed fan inside may cause danger Do not bundle the power cable pull it put something on it heat it process it or put it between t...

Page 8: ... working FILTER LAMP Green When the device is operated for a total of about 200 hours the FILTER lamp lights indicates that it is time to clean the filter The lamp goes out when the AUTO SWING button is pressed while the operation is stopped OPERATION LAMP Yellow This lamp lights during operation The OPERATION LAMP flashes in the following cases during heating 1 During preheating For about 2 3 min...

Page 9: ...er cord and plug it in again This is to protect the device and does not indicate a failure If you press the FUNCTION selector button during operation the device may stop for about 3 minutes for protection AUTO HEAT DEHUMIDIFY COOL FAN FAN SPEED LOW MED HI SLEEPING STOP CANCEL START RESERVE START STOP TIME TIMER SET TIMER SELECTOR ON TIMER OFF TIMER AUTO SWING NAMES AND FUNCTIONS OF EACH PART 11 Au...

Page 10: ...n 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 If the piping length used is longer than usual frost will likely to form HEATING OPERATION 13 Use the device for dehumidifying when the room temperature is over 16 ...

Page 11: ...tons the display indicates the setting The temperature setting and the actual room temperature may vary somewhat depending on conditions 3 As the settings are stored in memory in the remote controller you only have to press the START STOP button next time COOLING OPERATION 15 Press the START STOP button Fan operation starts with a beep Press the button again to stop operation START STOP FAN OPERAT...

Page 12: ...lete AM PM PM PM Example The current time is 1 30p m 2 Set the turn off time with the TIMER control button PM 3 Point the signal window of the remote controller toward the indoor unit and press the RESERVE button The OFF mark starts lighting instead of flashing and the RESERVED sign lights A beep occurs and the TIMER lamp lights on the indoor unit PM Example The device will turn off at 11 00p m Th...

Page 13: ... The horizontal air deflector is automatically set to the proper angle suitable for each operation The deflector can be swung up and down continuously and also set to the desired angle using the AUTO SWING button In Cooling operation do not keep the horizontal air deflector swinging for a long time Some dew may form on the horizontal air deflector and dew may drop CAUTION 2 Adjustment of the condi...

Page 14: ...21 2 CLEANING OF FRONT PANEL Remove the front panel and wash with clean water Wash it with a soft sponge After using neutral detergent wash thoroughly with clean water When front panel is not removed wipe it with a soft dry cloth Wipe the remote controller thoroughly with a soft dry cloth Wipe the water thoroughly If water remains at indicators or signal receiver of indoor unit it causes trouble M...

Page 15: ... sleep timer operation the fan speed sets to LOW regardless of the preset speed The remote controller display indication will remain unchanged even with the LOW setting TIMER PROGRAMMING SLEEP TIMER OPERATION PROHIBITION INFORMATION 23 REGULAR INSPECTION PLEASE CHECK THE FOLLOWING POINTS EVERY EITHER HALF YEARLY OR YEARLY CONTACT YOUR SALES AGENT SHOULD YOU NEED ANY HELP 1 2 3 WARNING WARNING Chec...

Page 16: ...ording to room temperature changes Mist is generated as the air within the room is suddenly cooled by conditioned air Water generated during defrosting operation evaporates and steam is emitted Caused as the smells and particles of smoke food cosmetics etc present in room air become attached the unit and blown off into the room again Defrosting is underway as the heating operation is stopped the m...

Page 17: ...te Discharge grill Horizontal air diflector Front panel Cabinet Drain Drain cap connection port Narrow pipe 6 35 Wide pipe 9 52 Drain hose Power cord Connecting cable Vertical air deflector When piping is drawn from the left side exchange the drain hose for the drain cap CONSTRUCTION AND DIMENSIONAL DIAGRAM MODEL RAS 18YH4 INDOOR UNIT Unit mm 50 Service space 50 ...

Page 18: ...NIT 208 23 26 841 750 841 750 Handle Air suction 10 10 330 310 Drain hole Drain hole 500 125 12 35 Fixing hole Notch for anchor bolt for 2 φ8 0 bolt Holed for anchor bolt 2 φ12 16 slots for φ8 0 bolt Handle 202 335 288 27 5 19 5 10 91 548 528 5 19 5 162 5 50 Air outlet Rear side Air suction Unit mm ...

Page 19: ... 94 5 OFF 32 0 89 6 35 3 95 5 RED WHT YEL 35V 5V 0V 0 5V FG MODEL NAME RATING APPLICABLE MODELS REVERSING VALVE COIL 135Ω 20 C RAC 18YH4 REACTOR L1 13 mH 0 224Ω RAC 18YH4 REACTOR L2 25 5 mH 0 37Ω RAC 18YH4 FILM CAPACITOR 45 µF RAC 18YH4 RAS 18YH4 POWER SOURCE DC 5V 35V OUTPUT 25W 40W Control circuit built in BLU BLUE YEL YELLOW BRN BROWN WHT WHITE GRY ORN ORANGE GRN GREEN RED RED BLK BLACK PNK VIO...

Page 20: ... capillary tubes clogged or crushed or with too little refrigerant check the color of the refrigerating machine oil inside the compressor If the color has been changed conspicuously replace the compressor 2M 1 40 2M 1 15 U V W M M M WHITE WHITE COMPRESSOR YELLOW YELLOW RED RED FRONT SIDE OF OUTDOOR UNIT RAC 18YH4 ASC092SD A8JT1 750W DC 220 350 V Compressor Motor Specifications ...

Page 21: ... 19 GRAM 18YH4 RAC 18YH4 CAUTION The marked parts are very important ones for safety ...

Page 22: ...42 SEG41 SEG40 P40 P41 P42 P43 P00 P01 P02 P03 P10 P11 P12 P13 D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 BEEP P20 P30 P31 NCVL C1 VL C2 VL C3 XC IN XC OUT VDD X OUT X IN RESET CARR P23 P22 P21 VSS IC 1 M3455OM6A 504FP LCD 1 C8 50v 1u K 1 D3 RB425D 1 2 K2K3 K4 K5 P10 P11 P12 K6 K7 K8 K9 K10 K11K12 K18 K17 K15 K16 K13 K14 D0 D1 D2 D3 R1 100k SW1 R2 P 100k R3 100k R4 100k R5 Q1 2SC3443 or 2SC2982 R6 R7 R9 D2 D1 ...

Page 23: ... 21 RAS 18YH4 MODEL ...

Page 24: ... 23 RAC 18YH4 MODEL Ｈ８３０３９ＡＸ８Ｔ１０ ...

Page 25: ... 24 MODEL RAS 18YH4 MAIN P W B MARKING ON P W B COMPONENT SIDE SOLDERING SIDE PRINTED WIRING BOARD LOCATION DIAGRAM ...

Page 26: ... 25 COMPONENT SIDE SOLDERING SIDE MODEL RAS 18YH4 RECEIVING P W B MARKING ON P W B COMPONENT SIDE MODEL RAC 18YH4 POWER P W B MARKING ON P W B ...

Page 27: ... 26 MAIN P W B MARKING ON P W B COMPONENT SIDE SOLDERING SIDE MODEL RAC 18YH4 ...

Page 28: ...rotection circuit HARMONICS IMPROVEMENT CIRCUIT IPM Rotor magnetic pole position detection circuit lp ld ls Buzzer circuit Indicating lamp Indoor Outdoor interface circuit DC fan moter drive circuit Microcomputer clock circuit Indoor DC fan moter Overheat thermistor Defrost thermistor Outdoor temperature thermistor Indoor Outdoor interface circuit Reversing valve coil Power circuit Reset circuit O...

Page 29: ... 29 button MODEL RAS 18YH4 BASIC MODE 31 33 33 33 37 35 ...

Page 30: ...min 1 CMAX 3300 min 1 CMAX2 3300 min 1 CSTD 2500 min 1 CKYMAX 2500 min 1 CJKMAX 2500 min 1 CBEMAX 2500 min 1 WMIN 2500 min 1 CMIN 2500 min 1 STARTMC 90 Seconds DWNRATEW 80 DWNRATEC 60 SHIFTW 2 00 C SHIFTC 1 33 C CLMXTP 30 00 C YNEOF 25 00 C TEION 5 00 C TEIOF 9 00 C SFTDSW 1 00 C DFTIM1 43 Minutes DFTIM2 60 Minutes ...

Page 31: ... During normal cooling mode compressor maximum rpm CMAX will maintain for 60 minutes if indoor temperature is lower than CLMXTP No time constrain if indoor temperature is higher than CLMXTP 6 7 When fan is set to Med compressor rpm will be limited to CJKMAX 8 When fan is set to Lo compressor rpm will be limited to CBEMAX 9 During Cool Dashed when room temperature reaches set temperature 1 C compre...

Page 32: ... is cleared 1 33 C 0 66 C Notes 1 The operation is done assuming as the preset temperature room temperature at the time 2 C 2 The indoor fan is operated in the Lo mode During thermo OFF indoor fan will be OFF for 5 3 When the operation is started by the themostat turning ON the start of the indoor fan is delayed 32 seconds after the start of compressor operation 4 The compressor is operated forced...

Page 33: ...TDSW ii Thermo off 3 During Hot Dashed operation thermo off temperature is set temperature with shift value 3 C After thermo off operation continue in Fuzzy control mode 4 Compressor minimum ON time and OFF time is 3 minutes 5 During normal heating mode compressor maximum rpm WMAX will maintain for 120 minutes if indoor temperature is higher than 18 C No time limit constrain if outdoor temperature...

Page 34: ...o refresh defrosting 5 Auto refresh defrosting cannot be engaged within 15 minutes after operation is started or defrosting is finished Sleep Lo Notes 1 The sleep operation starts when the sleep button is pressed 2 When the sleep button is set the maximum compressor speed is limited to WBEMAX and the indoor fan is set to sleep Lo 3 The indoor fan speed does not change even when the fan speed mode ...

Page 35: ... 38 REFRIGERATING CYCLE DIAGRAM MODEL RAS 18YH4 RAC 18YH4 SUCTION TANK SUCTION TANK ...

Page 36: ...uter When power ON 5V voltage rises and reaches 4 4V pin 1 of IC521 is set to Hi At this time the microcomputer starts operation When power OFF voltage drops and reaches 4 2V pin 1 of IC521 is set to Low This will RESET the microcomputer Power OFF Power ON Reset enter at 4 2V Reset release at 4 4V Voltage Voltage Voltage supply to pin 2 of IC521 Voltage at pin 7 of microcomputer 5 0V Fig 1 2 Fig 1...

Page 37: ...Hz square signal is output from buzzer output pin 30 of the microcomputer After the amplitude of this signal has been set to 12Vp p by IC711 it is applied to the buzzer The piezoelectric element in the buzzer oscillates to generate the buzzer s sound GND VOUT C212 C211 R212 0V 0V 0V R211 0V ZD141 R141 R611 C611 0V RECEIVER I P Microcomputer 13 BZ1 R721 12V IC711 Microcomputer Buzzer output 16 1 30...

Page 38: ...excite to turn the rotor Table 4 1 shows the rotation angle of horizontal air deflectors Microcomputer 18 17 16 15 11 10 12 6 7 5 13 4 IC711 12V CN4 Rotor Auto sweep motor for horizontal air defectors Micro computer pins Step width 10ms Horizontal air deflectors 15 16 17 18 1 2 3 4 5 6 7 8 Table 4 1 Auto sweep Motor Rotation Rotation angle per step Time per step ms 0 0882 10 Horizontal air deflect...

Page 39: ...he DC DC converter and the 35 V power supply from the outdoor unit to generate 12 V control power which drives the stepping motor during the operation In addition use the regulator IC 121 to generate 5 V power required for driving the micro computer and controlling fan motor If the terminal block was overheated due to a connecting cable improper connection the thermal fuse built in the terminal bl...

Page 40: ...ch is input into the pin 14 on the micro computer This pulse is equivalent to a frequency of 12 60 speed Example 1000 min 1 x 12 60 200 Hz The micro computer monitors the frequency and adjusts command speed stopped temporarily as fan lock error After 10 seconds restart the output of the pulse If fan lock error is detected twice within 30 minutes all units are stopped and the unit will come in the ...

Page 41: ... for the outdoor unit is composed of two P W B a power P W B and main P W B and a harmonics improvement circuit as shown in Fig 1 1 This P W B is equipped with the rectification diode DC fan motor control circuit and the circuits around the micro computer which take various controls POWER P W B This P W B is equipped with the noise filter ICP power circuit interface circuit smoothing capacitor exp...

Page 42: ... DB3 L1 C023 and L2 The DB3 L1 C023 and L2 shape waveform of the input current When the current runs through the L1 is taken for I1 and the current runs through the L2 is taken for I2 as shown in Fig 2 2 I1 becomes an input current to the capacitor which peak value was crushed by the L1 and I2 becomes a resonance current which causes the LC resonance using the L2 and C023 By combining the I1 and I...

Page 43: ... electrical noise generated during operation of compressor and also absorb external noise entering from power line to protect electronic parts Be sure to connect the earth cable between the indoor unit and the outdoor unit Otherwise the noise filter circuit won t operate properly 6 SA1 and VS1 to VS3 These surge absorber and varistors absorb external power surge such as induced thunder Be sure to ...

Page 44: ...g a request signal The receiving circuit in the indoor unit consists of a comparator and transistor The interface signal from the outdoor unit on the DC 35V line is supplied to C821 where DC components are eliminated and is then shaped by the comparator The shaped signal is detected by diode amplified by amp and output to pin 9 of the indoor microcomputer Fig 3 2 shows the waveforms at each compon...

Page 45: ... 48 Fig 3 1 shows the interface circuit used for the indoor and outdoor microcomputers to communicate with each other Fig 3 1 ...

Page 46: ...line 0V 5V 0V 0V 35V Outdoor microcomputer Pin 1 Pin 8 Indoor microcomputer Pin 0 Pin 9 Outdoor microcomputer Pin 1 Pin 8 Indoor microcomputer Pin 0 Pin 9 Fig 3 2 Voltages Waveforms of Indoor Outdoor Microcomputers Outdoor to Indoor Communications Fig 3 3 Voltages Waveforms of Indoor Outdoor Microcomputers Indoor to Outdoor Communications ...

Page 47: ...nications waveforms Leader 100ms Leader 100ms When reset approx 100ms When reset approx 10ms 35 V 34 V 36 V 0 7 0 7 7 7 0 33 3ms 3 2 1 NO 0 Bit No 0 7 0 7 0 7 0 7 Bit No 0 3 2 1 33 3ms 33 3ms 33 3ms Transmit receive switching time 4 95ms 33 3ms 33 3ms Outdoor message Indoor message 33 3ms 33 3ms 0 Character No 1 frame 100ms 33 3ms 8 4 95ms 371 35ms 2 Indoor microcomputer to outdoor microcomputer H...

Page 48: ...is 1 Self diagnosis 0 LSB Outside temperature 0 LSB Compressor during operation Compressor command speed 0 LSB Compressor minimum rotation speed 0 LSB Compressor minimum rotation speed 1 Compressor minimum rotation speed 2 Compressor minimum rotation speed 3 Compressor minimum rotation speed 4 MSB Compressor command speed 1 Compressor command speed 2 Compressor command speed 3 Compressor command s...

Page 49: ... intelligent power module and its peripheral circuit The three transistors on the positive e side are called the upper arm and the three transistors on the negative d side the lower arm Fig 4 1 Intelligent power module circuit U is ON V is ON IP limitter ...

Page 50: ...Fig 4 3 shows voltage waveform at each point shown in Figs 4 1 and 4 4 First half of upper arm is chopper second half is ON and first half of lower arm is chopper second half is ON Return diode Point A Fig 4 4 When power is supplied U U because of that U is chopped current flows as shown below 1 When U transistor is ON U transistor U coil V coil V transistor DC current detection resistor Point B F...

Page 51: ... when U transistor and V transistor is ON the current waveform at point B becomes intermittent waveform as shown in Fig 4 3 Since current at point B is approximately proportional to the input current of the air conditioner input current is controlled by using DC current Id Table 4 1 Ip peak current cut LD301 Blinks 2 times Blinks 3 times Blinks 4 times LD301 LD301 Self diagnosis Self diagnosis lam...

Page 52: ...ile the inverter is driving the IPM outputs the Fail In this step the Q501 is turned on and the input signal of the upper arm is also shut off through the D501 and D502 so that all signals to the IGBT are shut off This signal is also distributed to two time signal into stand by state 3 minutes after this state the micro computer outputs the drive signal and restarts the operation signal immediatel...

Page 53: ...W B power supply for microcomputer peripheral circuits and IPM driver circuit and as well as DC 35V are produced by switching power circuit Switching power circuit performs voltage conversion effectively by switching transistor IC1 to convert DC 330V voltage to high frequency of about 20kHz to 200kHz ...

Page 54: ...emoved loads If any error is found in this step the power circuit has any failure Replace the power P W B A short circuited load may cause an output error not only in the load but also in the others Be sure to check all outputs of the loads Be sure to wait 15 minutes or more in order to discharge all the remaining voltage in the circuit to connect disconnect the wiring other wise the components ma...

Page 55: ...imiting the whole input of this room air conditioner system through the current sensor CT1 in order to keep the maximum rating of components by reading total operating current ID OVL is watching and limits the compressor current through the detection resistor which is built in IPM in order to control the compressor reliability Since the compressor reliability is related with its curve All of OVL o...

Page 56: ...owing to Detection resistor R245 and C217 average the voltage This compares this input with the set value and if the input exceeds the set value it enters overload control status the set value the microcomputer decreases the rotation speed of the compressor and reduces the load Fig 6 3 1 IS OVL voltage is then input to IC4 pin 5 and supplied to microcomputer pin 60 The microcomputer Fig 6 3 shows ...

Page 57: ...e DC voltage multiplied by DC current R247 R248 R249 are provided to perform the same overload judgement even when the voltage varies It is required to maintain the start current DC current constant to smooth the start of the DC motor of the compressor RAC 18YH4 uses software to control the start current The start current varies when the supply voltage varies This control method copes with variati...

Page 58: ... line voltages rise and 12V line voltage reaches 10 9V an reset voltage input to pin 48 of microcomputer is set to Hi Reset voltage will be hold Hi until the 12V line voltage drops to 9 90V even though the power shuts down Fig 6 7 Fig 6 8 MAIN P W B Microcomputer RESET OUT RESET 56 48 C204 0V R252 1 0V 8 2 3 IC5 1 2 5V D208 R287 C215 R284 R286 C215 R285 C226 R292 R289 R288 0V 0V 0V 0V 12V 12V line...

Page 59: ...red inside the microcomputer starts defrosting control During defrosting operation the microcomputer transfers the defrosting condition command to the indoor microcomputer via the circuit interface transfers it to the indoor unit thus controlling the compressor rotation speed according to the value set at the EEPROM in the indoor unit and switching the operation status outdoor fan on off etc in th...

Page 60: ...t 35V About 0 8V About 0 8V Collector voltage of Q701 MAX rotation speed instructed by indoor microcomputer after defrost is completed 8 Reversing valve control circuit Reversing valve control circuit will switch reversing valve ON OFF cooling ON according to instruction Voltage at Q701 between Collector and Emittor in each operation condition is approximately as shown in Table 8 1 when measured b...

Page 61: ... 12 V output Use a 4 phase coil and feed power to the phases 1 and 2 then switch over the filed poles to control the opening of the valve The reference between conducting phase switch over direction and the open close direction are shown in Table 9 1 When the power is turned on approx 0 9 V is applied to the CN15 and the pins 1 to 4 and when no power is supplied 12 V is applied When the power is r...

Page 62: ...rease pulse width FG feedback Slower Instruction Faster Increase pulse width FG pulse is also used for Fan Motor failure detection Microcomputer will monitor FG pulse 30 seconds after start the fan motor If there is no signal detected it will consider that the Fan Motor was malfunction and stop the operation In this case LD302 on control R107 and IC4 are used for Fan Motor over current Vsp high Fa...

Page 63: ... growing inside of outdoor unit by snowing unit will be restart again after a while In case of Fan Lock Stop even though the DC Fan Motor is rotating correctly the possible cause in Fan Motor problem or control board problem Stop after the Fan motor runs 2 minutes Fan Motor may be broken Caution Please take care for the electrical shock by high voltage of DC Fan Motor power source which is common ...

Page 64: ...ture is preset at 30 Check if the indoor heat exchanger is frosted Wait for 3 4 minutes until it is defrosted If the air conditioner operates in cooling mode when it is cold the evaporator may get frosted It occurs during defrost ing Wait for 5 10 minutes until the condenser is defrosted At the beginning of heating the fan speed remains LOW for 30 seconds If HIGH is selected it switches to LOW and...

Page 65: ... before stopping operation At this point fan speed is automatic This is because Nice temperature reservation function is operating This function starts operation earlier so the preset temperature is reached at the preset time Operation may start maximum 60 minutes before the preset time It does not work It works only during cooling and heating This is because Nice temperature reservation function ...

Page 66: ...djust the temperature within a range of 3 C by pressing the Room Temperature button If the temperature is 1 C higher than the auto preset temperature 1 C will appear If the temperature is 1 C lower than the auto preset temperature 1 C will appear heard when operation is started When operation is started the compressor rotation speed goes to maximum to increase the heating or cooling capability so ...

Page 67: ...ound it Don t forget that high voltage as noted in the figure above may apply to the oscilloscope Remember that voltage of 175 V is applied to the 0V line on the P W B or the like as shown in the right diagram Indoor Controller Outdoor Controller Power Switch Point 400 F I P M Compressor motor Point line Control P W B Control P W B Voltage at point A Ground voltage Grounding 350V Point B 0V line P...

Page 68: ...smoothing capacitors Discharge Procedure 1 Turn off the power of the indoor unit or pull out the power supply plug 2 After power is turned off wait for 10 minutes or more Then remove electrical parts cover and apply soldering iron of 30 to 75 W for 15 seconds or more to TAB3 GRAY and TAB4 RED terminals on the main P W B as shown in the figure below in order to discharge voltage in smoothing capaci...

Page 69: ... the connectors from the CN1 heat exchange thermistor CN4 stepping motor and CN10 fan motor 3 Remove two lock screws 4 Remove the electrical parts in the direction of arrow Removing control P W B 1 Remove the connectors from the CN2 and CN3 2 Remove the P W B from the P W B support RAS 18YH4 STRUCTURE OF AN INDOOR UNIT ELECTRIC PARTS ELEC COVER P W B SUPPORTER P W B SUPPORTER P W B SUPPORTER P W B...

Page 70: ... causing the ICP1 blowout and Q111 failure 4 During power feeding to the P W B do not remove and insert the CN10 fan motor connector 2 The CN3 power supply and CN10 fan motor are the connectors with lock mechanism Press the lock with your fingers to unlock and remove the connector 3 When checking the voltage and waveform do not connect the probes to the forbidden areas show below Touching them may...

Page 71: ...me failure modes only the retry operation is repeated without lamp indication Failure modes that will repeat a retry operation without the indoor unit lamp indication are as follows OH thermistor temperature rise Outdoor unit communication error Power voltage abnormal Less frequent defects The LD301 indicates a mode of failure detected on the outdoor unit side by blinking frequency Upon failure de...

Page 72: ... exchanger thermistor disconnected only in the heating mode Note The malfunction mode is entered the 3rd time this abnormal indication appears read every 3 minutes Electrical parts in the outdoor unit 1 Indoor interface circuit 2 Outdoor Outdoor unit electrical components For details operate again using remote comtroller and check from self diagnosis display of outdoor unit interface circuit 1 Roo...

Page 73: ... 76 SELF DIAGNOSIS LIGHTING MODE MODEL RAC 18YH4 IPM INTELLIGENT POWER MODULE SELF DIAGNOSIS LAMPS LD301 LD302 LD303 SERVICE SWITCH ...

Page 74: ...cycle Normal No Yes Check the drive circuit IMP using the PRD checker Check the position sensor circuit With the unit set in the operating state press the start stop button Does the unit operate for approximately 2 seconds the LD303 coming on and then stop due to a failure of switching the lamp blinking 4 times OUTDOOR UNIT IPM INTELLIGENT POWER MODULE SELF DIAGNOSIS LAMPS LD301 LD302 LD303 SERVIC...

Page 75: ... Is the voltage correct Is the compressor running Check if the connecting cable connected incorrectly inserted incompletely or disconnected Not running Running Open the outdoor unit and observe the self diagnosis lamp LD301 Count how many times the lamp blinks Blinks other than 1 time Blinks 1 time Can the unit be operated using the outdoor unit service switch See the nameplate on the outdoor unit...

Page 76: ...utdoor unit connection cable and correct any defective section wrong connection incomplete insertion Is AC230V being generated between terminals A and B on the outdoor unit terminal board Is DC35V or 20V being generated between terminals C and D on the indoor unit terminal board Is the microcomputer reset input pin 7 Hi Is the microcomputer clock signal generated normally Is DC35V is being generat...

Page 77: ...peration check Are pulse signals output at microcomputer pins 15 18 when auto swing is turned on in the fan mode Replace the microcomputer Is a voltage over 15 or below 10V being generated on the 12V line No No No No Perform final operation check output at pin 24 is 1 5V Check IC711 If it is normal replace the air deflector motor Replace IC111 3 Air deflector does not move others are normal Yes Ye...

Page 78: ...inal board Insert the connection cable securely Replace IC121 Check if a short occurs in the 5V line If the 5V line is shorted ICP1 will be open again Check to see if the connection cables are disconnected or reversed If normal check the outdoor unit P W B Has the terminal board thermal fuse blown open Replace Q111 and IC111 Is DC5V being generated Perform final operation check When the unit is no...

Page 79: ... The sensible area should flash in orange when you operate the remote control unit if it is good Ultra redray test card Sensible area Within 2 cm Check functions again If it does not work replace the remote controller Buzz Within 15 cm AM radio Check the LED D1 with a multimeter Replace the battery Install the battery in the correct polarity Yes Yes No No No Yes Does the radio buzz noisily Is batt...

Page 80: ...rvicing System Configuration of Outdoor Unit Electrical Parts Control P W B M board Contains a rectifier circuit and inverter module their controlling microcomputer and microcomputer peripheral control circuits The board incorporates high and low current sections Power P W B P board Contains a switching power circuit noise filter power factor improvement circuit etc The switching power circuit sup...

Page 81: ...ment capacitor Designed to improve power factor To replace the capacitor remove the power P W B and then 1 Remove two screws fastening the capacitor seat 2 Slide the capacitor seat in the direction of the arrow Sliding Direction ...

Page 82: ...o be defective Replace defective parts Is the power circuit normal See the description on power circuit for details Is the switching power circuit OK Has the 3A fuse blown Check to see if C and D cables are connected correctly If reversed or incompletely inserted correct the cable connection Replace any defective parts If the 3A fuse has blown the varistor 2 etc may also be defective With the pipi...

Page 83: ... W B Is the fan operating An error occurs after the fan operates for 2 minutes Is the voltage between 4 and 6 at CN24 normal Normally the voltage is above approx DC1 7V Connect the connector Remove any obstructions Replace the fan motor and control P W B Is the voltage between 4 and 7 at CN24 normal Check to see if the voltage is within 2 5V 0 5V using a tester In effect the output voltage is alte...

Page 84: ... the terminal board Apply AC230V Check the interior wiring Are TAB 1 TAB 2 TAB 3 TAB 4 TAB 5 TAB 6 TAB 11 TAB 12 reactor and C023 yellow green connected properly Connect properly Replace the power P W B Possible causes inclu de Power relay malfunction EDefective microcomputer terminal Yes Yes Yes No No No ...

Page 85: ... being output between terminals C and D Normal DC32V 39V Standby DC18V 23V Is DC35V being output at both ends of R35 Connect CN 3 and CN4 Connect properly Replace the power P W B Defective SW power supply Replace the power P W B NF coils IF coils etc may be broken Check the interface circuit and replace the control P W B if needed No No No No No Yes Yes Yes Yes Yes ...

Page 86: ...rgetting to connect after servicing Is the continuity of the thermistor normal Is the thermistor circuit normal Connect the thermistor Replace the thermistor Replace parts in the thermistor circuit Check continuity of pattern and lead wires according to he P W B and schematic diagrams Yes Yes Yes No No No No ...

Page 87: ...ilter Check the outdoor unit for defective shielding LD301 blinks 4 times Failure of switching Is the 15V power supply output normal Power P W B display Is the intelligent power module IPM normal Inverter section The intelligent power module may be defective Replace the control P W B See System Power Module Diagnosis With CN3 and CN4 disconnected is the 15V output between 15V and 15 0V on the powe...

Page 88: ...ol P W B LD301 blinks 1 time Reset stop However the unit always resets and stops just after power is supplied this does not indicate a fault Is the reset circuit normal Normally pin 7 of CN18 is approx 5V Replace the control P W B Make sure again that connectors are connected securely Perform final operation check Yes Yes Yes No No ...

Page 89: ...ant If the compressor checker for an inverter type air conditioner is available re check using it JUDGING BETWEEN GAS LEAKAGE AND COMPRESSOR DEFECTIVE Blinking off Time until the lamp lights Approx 10 seconds Approx 10 seconds Approx 10 seconds Within Approx 30 seconds Compressor Compressor Gas leakage Possible malfunctioning part LD301 Self diagnosis lamp Lighting mode Blinks 2 times Blinks 3 tim...

Page 90: ...econd again to stop the forced cool operation 1 Connect the large dia pipe side and small dia pipe side service valve using a pipe Parts to be prepared 1 Reducing union 2 8 6 35 mm 3 8 9 52 mm 2 Copper pipe 2 8 and 3 8 Connect the small diameter service value and the large diameter service valve using the reducing union and copper pipe as shown on the right Charge refrigerant of 300g The operation...

Page 91: ...uit diagram of the device Circuit diagram of the module Terminals symbol mark of the module See next page for measuring value using multimeter Collector Emitter IPM Intelligent Power Module DIAGNOSIS SSM1001MA ...

Page 92: ... battery connection inside note Sometimes it may misjudge as OK because of low conductivity when power module was damaged as disconnect mode In this case please check the resistance by reversing the probe polarity and consider OK when it was low resistance Also it is OK if the resistance was as same as the other phases U V W Driver circuit internal IC 15V will not be generated when the internal IC...

Page 93: ... pull the center of the front cover forward and release the claws 2 Hold the front cover at both lower sides and pull them forward to remove Fig 3 Reception indication P W B Main P W B Support hook 3 Main P W B and Reception Indication P W B 1 Remove each connector from the lead wire P W B 3 Pull the support hook at the upper side of the indication lamp of the reception indication Fig 4 Procedure ...

Page 94: ...lectrical parts 1 Remove the service value cover lock screws and lower the cover to remove it 2 Remove the top cover lock screw and raise the cover to remove it Fig 8 3 Remove the front cover lock screw 4 Lower the right side of the front cover and pull it forward Then remove the cover from the hook 5 Pull the right side of the front cover a little and pull up the left side to remove it from the h...

Page 95: ... 98 INDOOR UNIT MODEL RAS 18YH4 1 39 13 9 17 38 18 14 12 11 10 23 20 15 16 37 36 35 34 33 41 40 32 19 22 43 21 29 30 25 31 24 26 42 28 27 7 6 2 3 4 5 8 5 PARTS LIST AND DIAGRAM ...

Page 96: ...LY 19 HWRAS 25YH4 920 1 POWER SWICHI 20 1 P W B MAIN 21 HWRAS 25YH4 922 1 P W B INDICATION 22 HWRAS 25YH4 923 1 CONNECTING CORD 12PIN 23 HWRAS 25YH4 924 1 ELECTRIC PARTS COVER 24 HWRAS 25YH4 925 1 COVER TERMINAL 25 HWRAS 25YH4 926 1 DRAIN PAN 26 HWRAS 25YH4 927 1 HORIZONTAL AIR DEFLECTOR 27 HWRAS 25YH4 928 2 DEFLECTOR SUPPORT 28 HWRAS 25YH4 929 1 AUTO SWEEP MOTOR 29 HWRAS 25YH4 930 1 DRAIN CAP 30 ...

Page 97: ... 100 30 46 44 47 42 43 45 31 41 38 36 37 35 39 34 32 32 40 25 26 27 28 29 5 33 51 21 19 23 24 22 1 49 48 50 4 3 2 15 12 16 10 11 13 6 8 14 7 20 17 18 52 9 OUTDOOR UNIT MODEL RAC 18YH4 ...

Page 98: ...40W 1 5kg 23 HWRAC 25YH4 923 1 PROPELLER FAN 24 HWRAC 25YH4 924 1 NUT PROPELLER FAN 25 HWRAC 25YH4 925 1 SIDE COVER L 26 HWRAC 25YH4 926 HWRAC E08H 910 1 HANDLE 27 1 FRONT COVER 28 HWRAC 25YH4 928 1 DISCHARGE GRILL 29 HWRAC 25YH4 929 1 ELECTRIC PARTS PLATE 30 HWRAC E08H 915 1 ELECTRIC PARTS COVER 31 HWRAC 25YH4 931 1 TERMINAL PLATE 32 HWRAC 25YH4 932 2 TERMINAL BOARD 2P 33 HWRAC 25YH4 933 1 HEAT S...

Page 99: ...Printed in Japan TSK AW NO 0004E RAS 18YH4 RAC 18YH4 ...

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Hitachi RAC-18YH4, Service Manual

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