Hitachi RAC-25YH4 Service Manual Download Page 17

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Press the (START/STOP) button. Fan operation starts with a
beep.
Press the button again to stop operation.

START

STOP

FAN OPERATION

You can use the device simply as an air circulator. Use this function to dry the interior of the indoor unit
at the end of summer.

Press the FUNCTION selector so that the display indicates

(FAN).

Press the (FAN SPEED) button.

(HI)

: The strongest air blow.

(MED)

: Quiet.

(LOW)

: More quiet.

FAN SPEED (AUTO)

… When the AUTO fan speed mode is set in the cooling/heating operation:

For the heating operation

• The fan speed will automatically change according to the temperature of

discharged air.

• As room temperature reaches the preset temperature, a very light breeze

will blow.

• Operation starts in the “HI” mode to reach the preset temperature.
• As room temperature approaches the preset temperature, fan speed auto-

matically switches to “LOW”.

For the cooling operation

RAS_25_35_AW_001-024

2003.12.31, 10:44 AM

Summary of Contents for RAC-25YH4

Page 1: ...9 CIRCUIT DIAGRAM 31 PRINTED WIRING BOARD LOCATION DIAGRAM 37 BLOCK DIAGRAM 41 BASIC MODE 43 REFRIGERATING CYCLE DIAGRAM 55 DESCRIPTION OF MAIN CIRCUIT OPERATION 56 SERVICE CALL Q A 84 TROUBLE SHOOTING 87 PROCEDURE FOR DISASSEMBLY AND REASSEMBLY 113 PARTS LIST AND DIAGRAM 115 RAS25YH4 RAC25YH4 RAS35YH4 RAC35YH4 RAC25YH4 RAC35YH4 COOLING HEATING INDOOR UNIT OUTDOOR UNIT INDOOR UNIT OUTDOOR UNIT 1 P...

Page 2: ...ts 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 Th...

Page 3: ...d goods should be handled in the same way Fig 1 Conductive Container IC A conductive polyvinyl bag IC Conductive sponge 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 whe...

Page 4: ...teel etc Staple 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 ordinar y 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 RAS_25_35_AW_001 024...

Page 5: ...g 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 ...

Page 6: ...ITCH TRANSFORMER VARISTOR NOISE SUPPRESSOR THERMOSTAT REMOTE CONTROL SWITCH LIQUID CRYSTAL 40 W NO NO NO EU1011DF 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 25YH4 RAC 35YH4 870g RAS 25YH4 RAS 35YH4 PWM DC35V NO NO NO NO NO NO NO YES NO NO NO NO YES IC YES YES RAS_25_35_AW_0...

Page 7: ... 5 RAS_25_35_AW_001 024 2003 12 31 10 43 AM 5 ...

Page 8: ...e supports Please ensure smooth flow of water when installing the drain hose If any failure is found in the drain path water drops from the indoor and outdoor units causing wet household effects Make sure that a single phase 230V power source is used The use of other power sources may cause electrical components to overheat and lead to fire PROHIBITION CONNECT EARTH LINE PROHIBITION PROHIBITION Sh...

Page 9: ... 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 place plants or animals directly under the air flow as it is bad for the plants or animals Do not climb on the outdoor unit or put objects on it PROHIBITION PROHIBITION PROHIBITION DON T TOUCH DON T TOUCH When operating the unit with the door and windows ...

Page 10: ...ified water from the indoor unit to the outdoor during cooling or dehumidifying operation Piping and Wiring Air inlets Rear and left sides About the outdoor unit When Stop is selected during operation of the indoor unit the fan of the outdoor unit continues turning for 10 to 60 seconds to cool the electric parts down In heating operation condensate or water due to defrosting will flow Do not cover...

Page 11: ...e in automatic mode CAUTION Turn off the circuit breaker or pull out the power plug if the unit is not be operated for a long period If the power stays on and the unit is not operated power is slightly consumed in the control circuit The power is saved by turning off the power switch or the circuit breaker when the power is supplied from the outdoor unit Attaching the air cleansing and deodorizing...

Page 12: ...n Select the turn ON time RESERVE button Time setting reservation CANCEL button Cancel time reservation NAMES AND FUNCTIONS OF EACH PART REMOTE CONTROLLER This 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 in some cases the control signal may not be received This unit can be fixed...

Page 13: ... current room temperature When AUTO is first selected the device will determine the current room temperature and select the proper operation mode accordingly When the air conditioner has adjusted the room s temperature to the near preset temperature it will begin to monitor operation If the room temperature subsequently changes the air conditioner will once again select the appropriate operation h...

Page 14: ...blows out HI Economical as the room will become warm quickly But you may feel a chill at the beginning MED Quiet LOW More quiet 2 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 3 As the settings are stored in memory in the remote controller you only hav...

Page 15: ...ctor Set the desired temperature is available You also can use the FUNCTION selector to select this operation Dehumidifying Function Dehumidifying takes place with a target temperature which is slightly lower than the room temperature setting However target temperature is 16 C for a temperature setting of 16 C If the room temperature becomes lower than the target value operation stops If the room ...

Page 16: ...tlet grille of the indoor unit Press the FUNCTION selector so that the display indicates COOL 1 Set the desired FAN SPEED with the FAN SPEED button the display indicates the setting AUTO The FAN SPEED is HI at first and varies to MED automatically when the preset temperature has been reached HI Economical as the room will become cool quickly MED Quiet LOW More quiet 2 Set the desired room temperat...

Page 17: ...The strongest air blow MED Quiet LOW More quiet 2 FAN SPEED AUTO When the AUTO fan speed mode is set in the cooling heating operation For the heating operation The fan speed will automatically change according to the temperature of discharged air As room temperature reaches the preset temperature a very light breeze will blow Operation starts in the HI mode to reach the preset temperature As room ...

Page 18: ...t the designated times The switching occurs first at the preset time that comes earlier The arrow mark appearing on the display indicates the sequence of switching operations 1 Press the OFF TIMER button so that the OFF mark blinks 2 Set the turn off time with the TIMER control button Pressthe RESERVE button PM 3 Press the ON TIMER button so that the OFF mark lights and the ON mark blinks PM AM Ho...

Page 19: ...te controller toward the indoor unit and press the RESERVE button The ON mark starts lighting instead of flashing and the RESERVED sign lights A beep occurs and the TIMER lamp lights on the indoor unit AM Example The device will turn on at 7 00a m The setting of turn on time is now complete 4 Set the turn on time with the TIMER control button 5 Point the signal window of the remote controller towa...

Page 20: ... off time AM Example If you set 3 hours sleep time at 11 38 p m the turn off time is 2 38 a m Sleep timer Start The device will be turned off by the sleep timer and turned on by on timer 1 Set the ON timer 2 Press the SLEEP button and set the sleep timer AM AM For heating In this case the device will turn off in 2 hours at 1 38 a m and turn on early so that the preset temperature will be almost re...

Page 21: ...n the case 1 Do not use new and old batteries or different kinds of batteries together 2 Take out the batteries when you do not use the remote controller for 2 or 3 months CAUTION Push and pull to the direction of arrow Vertical Vertical about 15 about 60 about 45 about 30 When cooling dehumidifying When heating If the AUTO SWING button is pressed once the horizontal air deflector swings up and do...

Page 22: ... carefully and remove the filter 2 Vacuum dust from the air filter using vacuum cleaner If there is too much dust wash the filter with a detergent and rinse it thoroughly After that dry it in the shade 3 Set the filter with FRONT mark facing front and slot them into the original state After attaching the filters push the front panel at three arrow portions as shown in figure and close it Do not wa...

Page 23: ...ith both hands push the right arm to the inside to release it and while closing the front panel slightly put it out forward Move the shafts of the left and right arms into the steps in the unit and securely insert them into the holes Shaft Step Hole BENZINE THINNER A C I D Do not splash or direct water to the body of the unit when cleaning it as this may cause short circuit Never use hot water abo...

Page 24: ...are released the indication of settings will go off in 10 seconds and only the operation mode will be displayed Pressing the button while the unit is in operation will let the protective circuit work so that the unit will not operate for approximately 3 minutes During heating operation the indoor unit s color indicator lamp may flash with no air emitted for a while If you feel cold wind during hea...

Page 25: ...ir inlets or air outlets of indoor and outdoor units blocked Is the fan speed LOW When it does not operate When it does not cool well When it does not heat well If the remote controller is not transmitting a signal Remote controller display is dim or blank The following phenomena do not indicate unit failure Operation start The unit is preparing to blow warm air Please wait In operation The outdoo...

Page 26: ...perature 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 microcomputer check...

Page 27: ...AS 35YH4 Top air suction grill 147 56 17 5 When piping is drawn from the left side exchange the drain hose for the drain cap Mounting plate Discharge grill Horizontal air diflector Front panel Cabinet Drain Drain cap connection port Narrow pipe Wide pipe Drain hose Power cord Connecting cable Vertical air deflector INDOOR UNIT RAS_25_35_AW_025 028 2003 12 31 10 46 AM 25 ...

Page 28: ...uction grill Air outlet Handle Holes for anchor bolt 2 ø12 x 6 slots for ø8 0 bolt for 2 ø8 0 bolt Notch for anchor bolt Fixing hole Drain hole Drain hole Service space OUTDOOR UNIT More than 50 More than 100 More than 200 More than 300 RAS_25_35_AW_025 028 2003 12 31 10 46 AM 26 ...

Page 29: ...7 94 5 OFF 32 0 89 6 35 3 95 5 M RED BLK WHT YEL BLU 35V 5V 0V 0 5V FG MODEL NAME RATING APPLICABLE MODELS REVERSING VALVE COIL 135 Ω 20 C RAC 25YH4 35YH4 REACTOR L1 13 mH 0 224 Ω RAC 25YH4 35YH4 REACTOR L2 25 5 mH 0 37 Ω RAC 25YH4 35YH4 FILM CAPACITOR 45 µF RAC 25YH4 35YH4 RAS 25YH4 RAS 35YH4 POWER SOURCE DC 5V 35V DC 140 350V OUTPUT 25W 40W Control circuit built in BLU BLUE YEL YELLOW BRN BROWN ...

Page 30: ...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 U V 1 090 U W 1 090 W U 1 090 U V W M M M WHITE WHITE COMPRESSOR YELLOW YELLOW RED RED FRONT SIDE OF OUTDOOR UNIT RAC 25YH4 RAC 35YH4 EU1011DF 800W DC 270 320 V RAS_25_35_AW_025 028 2003 12 31 10 ...

Page 31: ... 29 RAS_25_35_AW_029 030_A3 2003 12 31 10 48 AM 29 ...

Page 32: ...RAS_25_35_AW_029 030_A3 2003 12 31 10 48 AM 30 ...

Page 33: ...EG42 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 D...

Page 34: ...RAS_25_35_AW_031 032 2003 12 31 10 49 AM 32 ...

Page 35: ... 33 RAS_25_35_AW_033 036_A2 2003 12 31 10 51 AM 33 ...

Page 36: ...RAS_25_35_AW_033 036_A2 2003 12 31 10 51 AM 34 ...

Page 37: ... 35 RAS_25_35_AW_033 036_A2 2003 12 31 10 51 AM 35 ...

Page 38: ...RAS_25_35_AW_033 036_A2 2003 12 31 10 51 AM 36 ...

Page 39: ... 37 MODEL RAS 25YH4 RAS 35YH4 MAIN P W B MARKING ON P W B PRINTED WIRING BOARD LOCATION DIAGRAM COMPONENT SIDE SOLDERING SIDE RAS_25_35_AW_037 040 2003 12 31 10 53 AM 37 ...

Page 40: ...8 COMPONENT SIDE SOLDERING SIDE MODEL RAS 25YH4 RAS 35YH4 RECEIVING P W B MARKING ON P W B COMPONENT SIDE MODEL RAC 25YH4 RAC 35YH4 POWER P W B MARKING ON P W B RAS_25_35_AW_037 040 2003 12 31 10 53 AM 38 ...

Page 41: ... 39 MODEL RAC 25YH4 RAC 35YH4 MAIN P W B MARKING ON P W B COMPONENT SIDE SOLDERING SIDE RAS_25_35_AW_037 040 2003 12 31 10 53 AM 39 ...

Page 42: ...RAS_25_35_AW_037 040 2003 12 31 10 53 AM 40 ...

Page 43: ...Protection 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 ...

Page 44: ...RAS_25_35_AW_041 042_A3 2003 12 31 10 54 AM 42 ...

Page 45: ... 43 button RAS_25_35_AW_043 044_A3 2003 12 31 10 55 AM 43 ...

Page 46: ...RAS_25_35_AW_043 044_A3 2003 12 31 10 55 AM 44 ...

Page 47: ...in 1 CKYMAX 2050 min 1 3000 min 1 CJKMAX 1800 min 1 2200 min 1 CBEMAX 1600 min 1 1700 min 1 WMIN 800 min 1 800 min 1 CMIN 1400 min 1 1400 min 1 STARTMC 90 Seconds 90 Seconds DWNRATEW 80 80 DWNRATEC 60 60 SHIFTW 2 00 C 2 00 C SHIFTC 1 33 C 1 33 C CLMXTP 30 00 C 30 00 C YNEOF 25 00 C 25 00 C TEION 5 00 C 5 00 C TEIOF 9 00 C 9 00 C SFTDSW 1 00 C 1 00 C DFTIM1 43 Minutes 43 Minutes DFTIM2 60 Minutes 6...

Page 48: ...RAS_25_35_AW_045 046 2003 12 31 10 55 AM 46 ...

Page 49: ...ode 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 compressor rpm is actual rpm x...

Page 50: ...RAS_25_35_AW_047 054_A3 2003 12 31 10 57 AM 48 ...

Page 51: ...ta 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 forc...

Page 52: ...RAS_25_35_AW_047 054_A3 2003 12 31 10 57 AM 50 ...

Page 53: ...ing 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 is lower than 4 C 6 Dur...

Page 54: ...RAS_25_35_AW_047 054_A3 2003 12 31 10 57 AM 52 ...

Page 55: ...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 is changed Sleep Lo 4 W...

Page 56: ...RAS_25_35_AW_047 054_A3 2003 12 31 10 57 AM 54 ...

Page 57: ...ve Reversing valve Single ended union Single ended union Single ended union Single ended union Charge port Charge port COMPRESSOR Service valve Service valve Service valve Service valve Silencer Electric Expansion valve Electric Expansion valve COMPRESSOR RAS_25_35_AW_055 086 2003 12 31 10 58 AM 55 ...

Page 58: ...OFF Low voltage at pin 7 resets the microcomputer and Hi activates the microcomputer 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 RAS_25_35_AW_055 086 2003 12 31 10 58 AM 56 ...

Page 59: ...and shapes the signal and outputs it 3 Buzzer Circuit When the buzzer sounds an approx 3 9kHz 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 RAS_25_35_AW_055 086 2003 12 31 10 58 AM 57 ...

Page 60: ...ls shown in Fig 4 2 are output from pin 15 18 of microcomputer As the microcomputer s outputs change as shown in Fig 4 2 the coils of the auto sweep motor is excite to turn the rotor Table 4 1 shows the rotation angle of horizontal air deflectors RAS_25_35_AW_055 086 2003 12 31 10 58 AM 58 ...

Page 61: ... the connecting cable Second use the 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 the...

Page 62: ...en the voltage at the point B and the speed Some differences will occur due to the condition of the unit The fan motor outputs the feedback pulse of the speed which 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 the output pulse range of the pin 24 so as to...

Page 63: ...or 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 Main P W B 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 expans...

Page 64: ...he 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 I2 the input current f...

Page 65: ...se 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 connect the ear...

Page 66: ...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 49 of the indoor microcomputer Fig 3 2 shows the waveforms at each component when data is trans...

Page 67: ... 65 Fig 3 1 shows the interface circuit used for the indoor and outdoor microcomputers to communicate with each other RAS_25_35_AW_055 086 2003 12 31 10 59 AM 65 ...

Page 68: ... 66 RAS_25_35_AW_055 086 2003 12 31 10 59 AM 66 ...

Page 69: ... 67 Fig 3 4 RAS_25_35_AW_055 086 2003 12 31 10 59 AM 67 ...

Page 70: ... 68 RAS_25_35_AW_055 086 2003 12 31 10 59 AM 68 ...

Page 71: ...ule 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 RAS_25_35_AW_055 086 2003 12 31 10 59 AM 69 ...

Page 72: ...Fig 4 2 shows the switching period and relation with rotation speed N of the compressor is shown by formula below N 60 2 X 1 T 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 Fig 4 3 Voltage waveform at each point When power is supplied U U because of that U is chopp...

Page 73: ...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 detection resistor Reference If power module is defected self diagnosis lamps on the MAIN P W B may indicate as shown below Fig 4 5 Table 4 1 RAS_25_35_AW_055 086 2003 12 31 10 59 AM 71 ...

Page 74: ... was detected while the inverter is driving the IPM outputs the Fail signal immediately from the pin 29 and forces the lower arm transistor to shut off at the same time 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 microcomputer 17 pin as a Lo signal...

Page 75: ...icrocomputer 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 RAS_25_35_AW_055 086 2003 12 31 10 59 AM 73 ...

Page 76: ...he 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 may be damaged The failures of the loads are as fol...

Page 77: ...oad judgement values There are two types of control which has named IS OVL and ID OVL IS OVL is limiting 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 t...

Page 78: ...icrocomputer enters the overload control state The set Value is determined by the amplification of the voltage amp circuit Amplification high DC current low Amplification low DC current high Fig 6 4 Fig 6 2 Power Main P W B Reset Reset output 2 ID OVL Fig 6 2 The filter consisting of R245 and C217 removes high harmonic frequencies from the voltage generated by the current flowing to Detection resi...

Page 79: ...quired to maintain the start current DC current constant to smooth the start of the DC motor of the compressor RAC 25YH4 RAC 35YH4 uses software to control the start current The start current varies when the supply voltage varies This control method copes with variations in the voltages as follows 1 Turns on the power module s U and V transistors so the current flows to the motor windings as shown...

Page 80: ... Fig 6 8 shows waveform at each point when power is turned on and off When power is turned on 12V line and 5V 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 RESET OUT 10 9V 9 9v RAS_25_35_AW_055 086...

Page 81: ... the set value stored inside the microcomputer starts defrosting control During defrosting operation the microcomputer transfers the defrosting condition command to the indoor microcomputer via the circuit interface The microcomputer always reads the outdoor temperature via a thermistor microcomputer pin 64 an transfers it to the indoor unit thus controlling the compressor rotation speed according...

Page 82: ...rol circuit will switch reversing valve ON OFF according to instruction from indoor microcomputer depending on the operation condition shows in Table 8 1 Voltage at Q701 between Collector and Emittor in each operation condition is approximately as shown in Table 8 1 when measured by multimeter Table 8 1 RAS_25_35_AW_055 086 2003 12 31 10 59 AM 80 ...

Page 83: ...n 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 reset the expansion valve starts initial operation for 5 to 10 seconds During the initial operation measure each pin of the CN15 1 to 4 with a multimeter If no change is found around 0 9 V or 12V in...

Page 84: ... to rotate when Vsp was proceeding over than 1 7V and generate FG pulse by rotation speed FG pulse will feed back to Outdoor microcomputer 15 DC Fan Motor circuit has to match the Fan Motor revolution with instructed revolution Such as FG feedback Faster Instruction Slower Decrease pulse width FG feedback Slower Instruction Faster Increase pulse width FG pulse is also used for Fan Motor failure de...

Page 85: ...door unit by snowing It may make Fan Lock Stop by strong wind ex 17m sec or above against the Fan rotation In this case 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 e...

Page 86: ...gh MED to LOW while the temperature 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 ...

Page 87: ...tion 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 is operating The start...

Page 88: ...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 noise becomes slightly...

Page 89: ...t 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 C 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 Power inlet RAS_25_3...

Page 90: ...h circuit part of the outdoor unit be sure to discharge the 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 fi...

Page 91: ...remove it When installing the parts use caution not to pinch any code between the part and cabinet Removing electrical parts 1 Remove the electrical parts cover 2 Remove 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 C 1 Remove the connectors from the CN...

Page 92: ...d remove the connector 3 When checking the voltage and waveform do not connect the probes to the forbidden areas show below Touching them may cause the ICP1 blowout and Q111 failure The Q111 is a MOS FET and its gate terminal is a high impedance When a probe such as a multimeter is contacted with the gate G the Q111 may have the continuous ON state to supply overcurrent in the circuit causing the ...

Page 93: ...ral times Note In some 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 frequ...

Page 94: ...nction 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 interface circuit 1 Room thermistor 2 Heat exchanger thermistor 1 Indoor fan locked 2 Indoor fan motor IC401 or IC402 abnormal Cautions 1 If the interface circuit is faulty when power is supplied the self diagnosis display will not be d...

Page 95: ... 93 SELF DIAGNOSIS LIGHTING MODE MODEL RAC 25YH4 RAC 35YH4 RAS_25_35_AW_087 108 2003 12 31 10 59 AM 93 ...

Page 96: ...Check outdoor electrical parts Check the refrigerating 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 RAS_25_35_AW_087 10...

Page 97: ...ct 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 for operating instru...

Page 98: ...n 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 pin7 Hi Is the microcomputer clock signal 10MHz at pins 10 and 11 being generated normally Is DC35V is being...

Page 99: ...l operation check 3 Air deflector does not move others are normal 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 Replace IC111 Yes Yes Yes Yes No No No No Check IC711 If it is normal replace the air deflector motor Perform final operation check RAS_25_35_AW...

Page 100: ...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 1 When the unit is not in operation the v...

Page 101: ...uld 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 battery polarity correct I...

Page 102: ...VICING Be sure that the power switch is turned off or the power cable is disconnected before servicing Removing the PWBs System Configuration of Outdoor Unit Electrical Parts The outdoor unit electrical parts consist of two PWBs as shown in the figure Control P W B M board Contains a rectifier circuit and inverter module their controlling microcomputer and microcomputer peripheral control circuits...

Page 103: ...d 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 RAS_25_35_AW_087 108 2003 12 31 10 59 AM 101 ...

Page 104: ...ive 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 line...

Page 105: ...ing An error occurs after the fan operates for 2 minutes Is the voltage between 4 and 5 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 5 at CN24 normal Check to see if the voltage is within 2 5V 0 5V using a tester In effect the output voltage is alternately switched betwe...

Page 106: ...ply 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 RAS_25_35_AW_087 108 2003 12 31 10 59 AM 104 ...

Page 107: ...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 Yes Yes Yes Yes Yes No No No No No RAS_25_35_AW_087 108 2003 12 31 10 59 AM 105 ...

Page 108: ...ter 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 RAS_25_35_AW_087 108 2003 12 31 10 59 AM 106 ...

Page 109: ...r 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 power P W B Replace the po...

Page 110: ...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 2 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 RAS_25_35_AW_087 108 2003 12 31 10 59 AM 108 ...

Page 111: ...al refrigerant 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 B...

Page 112: ... sure to push the service switch for a second again to stop the forced cool operation HOW TO OPERATE THE OUTDOOR UNIT INDEPENDENTLY 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 reducin...

Page 113: ...device Circuit diagram of the module Terminals symbol mark of the module See next page for measuring value using multimeter Collector Emitter RASF IPM Intelligent Power Module DIAGNOSIS RAS_25_35_AW_109 118 2003 12 31 11 00 AM 111 ...

Page 114: ...side 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 has malfunctioned To ...

Page 115: ...r removing two screws 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 2 Remove the four P W B supports from the main P W B 3 Pull the support hook at the upper side...

Page 116: ...35YH4 1 Electrical 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 f...

Page 117: ... AND DIAGRAM INDOOR UNIT MODEL RAS 25YH4 RAS 35YH4 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 RAS_25_35_AW_109 118 2003 12 31 11 00 AM 115 ...

Page 118: ...ER SWICHI 20 HWRAS 25YH4921 HWRAS 35YH4901 1 P W B MAIN 21 HWRAS 25YH4922 1 P W B INDICATION 22 HWRAS 25YH4923 1 CONNECTING CORD 12PIN 23 HWRAS 25YH4924 1 ELECTRIC PARTS COVER 24 HWRAS 25YH4925 1 COVER TERMINAL 25 HWRAS 25YH4926 1 DRAIN PAN 26 HWRAS 25YH4927 1 HORIZONTAL AIR DEFLECTOR 27 HWRAS 25YH4928 2 DEFLECTOR SUPPORT 28 HWRAS 25YH4929 1 AUTO SWEEP MOTOR 29 HWRAS 25YH4930 1 DRAIN CAP 30 HWRAS ...

Page 119: ...2 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 25YH4 RAC 35YH4 RAS_25_35_AW_109 118 2003 12 31 11 00 AM 117 ...

Page 120: ...N 24 HWRAC 25YH4924 1 NUT PROPELLER FAN 25 HWRAC 25YH4925 1 SIDE COVER L 26 HWRAC 25YH4926 1 HANDLE 27 HWRAC 25YH4927 1 FRONT COVER 28 HWRAC 25YH4928 1 DISCHARGE GRILL 29 HWRAC 25YH4929 1 ELECTRIC PARTS PLATE 30 HWRAC 25YH4930 1 ELECTRIC PARTS COVER 31 HWRAC 25YH4931 1 TERMINAL PLATE 32 HWRAC 25YH4932 2 TERMINAL BOARD 2P 33 HWRAC 25YH4933 1 HEAT SINK REGURATOR1 34 HWRAC 25YH4934 1 P W B POWER 35 H...

Page 121: ...29 CIRCUIT DIAGRAM 31 PRINTED WIRING BOARD LOCATION DIAGRAM 37 BLOCK DIAGRAM 41 BASIC MODE 43 REFRIGERATING CYCLE DIAGRAM 55 DESCRIPTION OF MAIN CIRCUIT OPERATION 56 SERVICE CALL Q A 84 TROUBLE SHOOTING 87 PROCEDURE FOR DISASSEMBLY AND REASSEMBLY 113 PARTS LIST AND DIAGRAM 115 RAS 25YH4 RAC 25YH4 RAS 35YH4 RAC 35YH4 RAC 25YH4 RAC 35YH4 COOLING HEATING INDOOR UNIT OUTDOOR UNIT INDOOR UNIT OUTDOOR U...

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Hitachi RAC-25YH4, Service Manual, Page: 17 / 121

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