Hitachi RAC-25CNH2 Service Manual Download Page 72

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LD301 blinks 8 time.

Acceleration defect.

LD301 blinks 7 time.

Thermistor abnormal.

Is the power module normal?

Is the drive circuit normal?

Is the thermistor connector

disconnected?

❈

The problem may be "forgetting

to connect after serving".

Is the continuty of thermistor normal?

Is the thermistor circuit normal?

Replace the power module.

Replace any defective parts.

Connect the ther

mistor

Replace the ther

mistor

Replace parts in the

thermistor circuit.

Check continuity of pattern and

lead wires according to the

. and schematic diag

rams

Check continuity of pattern and

lead wires according to the

. and schematic diag

rams

Summary of Contents for RAC-25CNH2

Page 1: ...2 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 50Hz POWER 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 ...

Page 2: ...r 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 ins...

Page 3: ...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 bo...

Page 4: ... 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 Stapl...

Page 5: ...peration 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 ...

Page 6: ...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 10...

Page 7: ...oor 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 ...

Page 8: ...e 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...

Page 9: ...ng 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 Transmissio...

Page 10: ...y 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 tempera...

Page 11: ...SETTING Every time you press the button fan speed will change as the below sequence HEATING AUTO HIGH MED LOW COOLING DEHUMIDIFYING LOW FIXED 4 Press the START STOP button Operation start with a signal received sound beep Press the START STOP button As the settings are stored in memory in the remote control unit you only have to press the Start Stop button in order to use the same setting next tim...

Page 12: ...the beginning of setting time 6 hours was set Setting time will change according to the below sequence The value change more quickly if you keep pressing the button ON Timer Reservation 0 5 1 0 1 5 9 5 10 11 12 0 5 hour interval 1 hour interval 1 Press the Cancel button As the time settings are stored in remote controller memory you only have to press the Reserve button in order to use the same se...

Page 13: ... controller toward the indoor unit and press the SLEEP button The timer information will be displayed on the remote controller The TIMER lamp lights with a beep from the indoor unit How to Cancel Reservation Point the signal window of the remote controller toward the indoor unit and press the CANCEL button The RESERVED sign goes out with a beep and the TIMER lamp turns off on the indoor unit NOTE ...

Page 14: ...e and circulation are not varied The FAN SPEED will be set to LOW immediately Fan Heating The room temperature will be controlled 5 C below the temperature setting 30 minutes after the setting of the sleep timer The FAN SPEED will be set to LOW immediately Operation with the sleep timer The room temperature is kept at about 12 C minimum The room temperature is kept at about 25 28 C Sleep timer set...

Page 15: ...r deflector as shown in the figure and adjust the conditioned air to the left and right If the AUTO SWING button is pressed once the horizontal air deflector swings up and down If the button is pressed again the deflector stops in its current position Several seconds about 6 seconds may be required before the deflector starts to move Use the horizontal air deflector within the adjusting range show...

Page 16: ...tall the new batteries The direction of the batteries should match the marks in 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 3 The batteries must be of the LR03 type CAUTION Push and pull to the direction of arrow ...

Page 17: ...with your wake up time in the morning This will enable you to enjoy a comfortable room temperature Please use the timer effectively Dusty air filter will reduce the air volume and the cooling efficiency To prevent from wasting electric energy please clean the filter every 2 weeks Please pay attention to the room temperature and air flow direction when operating the unit for baby children and old f...

Page 18: ...cannot be achieved When the power is resumed after a power failure the indoor unit will still remain OFF To operate the unit please press the ON OFF button again When the indoor unit is not to be used for a long period of time please switch off the power from the mains If the power from mains remains ON the indoor unit still consumes about 8W in the operation control circuit even if it is in OFF m...

Page 19: ...lift the filter and release the claws 4 locations at the lower part of the front cover and remove the filter from the lower side 2 Remove dust from the filter using a vacuumcleaner If there is too much dust use neutral detergent After using neutral detergent wash with clean water and dry in the shade 3 Install the filter Set them with FRONT mark facing front Be sure to hold the front grille with b...

Page 20: ...e suction grille with both hands to detach and attach it CAUTION 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 above 40 C benzine gasoline acid thinner or a brush because they will damage the plastic surface and the coating Removing the Suction Grille Arm When the suction grille is fully opened with both hands push the ri...

Page 21: ...sconnect the power plug 1 2 3 REGULAR INSPECTION PLEASE CHECK THE FOLLOWING POINTS EVERY EITHER HALF YEARLY OR YEARLY CONTACT YOUR SALES AGENT SHOULD YOU NEED ANY HELP Is the plug of power line firmly plugged into the socket Please ensure no loose contact between them Is the earth line disconnected or broken Is the mounting frame seriously affected by rust and is the outdoor unit tilted or unstabl...

Page 22: ...flowing noise of refrigerant in the refrigerating cycle 2 Slight rubbing noise from the fan casing which is cooled and then gradually warmed as operation stops The odor will possibly be emitted from the room air conditioner because the various odor emitted by smoke foodstuffs cosmetics and so on sticks to it So please clean the air filter and the evaporator regularly to reduce the odor Please cont...

Page 23: ...2 16 55 570 428 700 243 53 236 210 10 482 517 135 75 77 P Air suction grill Top air suction grill Mounting plate Wireless remote controller Cabinet Front cover VIEWED FROM BACK PIPE LEAD OUT Discharge grill Vertical air deflector Horizontal air deflector Hole on the wall for ø65 mm pipe Line cord Connecting cable Narrow pipe ø6 35 Wide pipe ø9 52 Drain cap connection part When piping is drawn hori...

Page 24: ...C 167 F TEMPERATURE C F INDICATION 16 INDICATION 24 INDICATION 32 MODEL RAS 25CNH2 THERMOSTAT MODEL IC ON 17 6 63 7 OFF 16 6 61 8 ON 25 6 78 1 OFF 24 6 76 3 ON 33 6 92 5 OFF 32 6 90 7 M RESISTANCE VALUE MODEL RAS 25CNH2 RAC 25CNH2 RATED VOLTAGE DC0 35V DC230V OUTPUT 20W 20W RED YELLOW BLUE 0 30V 5V U V W WHITE YELLOW RED ...

Page 25: ...ecifications CONNECTION 20 C 68 F 75 C 167 F RESISTANCE VALUE ORANGE RED WHITE CAUTION When the refrigerating cycle has been operated for a long time with the 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 3 21 2M 3 90 U V W WHITE YELLOW RE...

Page 26: ...D901 C B 35V E C803 R802 C802 IC401 64 R404 D403 R405 CN4 4 1 5 48 IC1 33 BLACK R403 R406 49 1 1 1 C940 I G 9 IF HIC OSC1 R205 C201 32 CN7 1 16 17 REG2 O C805 C801 L901 Q903 L102 ZD101 REG1 C109 ORZK23355A C105 CN10 5 1 C901 1 C103 D902 6 CN2 5V ZD201 1 ZD202 C933 R904 R905 CN6 C401 1 1 4 3 CN8 4 1 D401 CN1 X2 X1 ID R702 R703 Y BZ1 12V HA A B C D E F G ...

Page 27: ... D E F G R510 C510 C511 3 15A FUSE POWER RELAY VS2 C001 R503 R502 R502 JW1 CN3 3 D STACK C505 R505 RCP RELAY RED YEL CN10 CT1 WHT VS3 BLK VS1 GRN C503 NF1 R504 NF2 RED C508 GRN C507 C506 C502 C512 1 7 1 R511 BLU COIL ORZK23354A SA 15A FUSE ...

Page 28: ...9 Q908 Q910 R926 R909 R927 C920 ZD901 PQ7 PQ6 PQ5 WH4 BLACK WH13 BROWN C403 RED W YEL V C406 R406 R106 R104 R105 D405 D406 C402 R409 R102 5 8 4 1 PQ4 5 8 4 1 PQ3 5 8 4 1 PQ2 R405 D403 D404 C405 C404 WHT U R408 WHITE GLAY WH1 WH6 C504 R101 R404 BROWN WH13 R534 R533 R531 R532 R407 D401 D402 SW T C201 C231 D202 D203 R208 R224 C233 D215 R210 R209 PQ8 1 2 4 3 3 4 2 1 5 1 7 12 L701 C712 RED WH9 GREEN GR...

Page 29: ...V 5V 5V 5V 5V 5V 5V 5V 5V 5V 5V 5V 5V 5V 5V 5V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 0V 12V 12V 12V 12V 12V 5V FAN HIC VREF AVSS AVDD VDD VB F2 VA F1 VC F0 F3 A B C A B C RES 60 el Xin Xin1 Ncom HU HV HW S3 IP CNTR CNVSS VSS CHOP IP POR M34225M2 M50927 29 R101 180K 0 5 1 2 A ...

Page 30: ...SYMBOL MOUTING FORM INSERT BY HAND CHIP C H R101 1 0 5 1 4W C SYMBOL POWER TOLE RANCE Ω RETER VALUE RESISTOR R102 10K 2 1 16W C R103 1 2K 2 1 16W C R104 1 0 5 1 4W C R201 5 1K 5 1 10W C R204 5 1K 5 1 16W C R208 5 1K 5 1 10W C R210 12K 5 1 10W C R211 12K 5 1 10W C R303 10K 5 1 16W C R307 1K 5 1 16W C FORM R202 10K 5 1 10W C R203 2 7K 5 1 16W C R205 1M 5 1 16W C R206 10K 5 1 10W C R302 1K 5 1 16W C ...

Page 31: ...ehumidifying Indoor micro computer AX 7J01 Outdoor micro computer AX 8J01 LCD wireless Room temperature thermistor Wireless receive circuit DC current signal Rotor magnetic pole position detection circuit Peak current cut off circuit Overload control circuit Voltage amplification circuit Over heat thermistor Defrost thermistor Outdoor temperature thermistor Indoor Outdoor interface circuit Power c...

Page 32: ... computer Fig 1 2 shows the waveforms in each circuit when power is ON and OFF When the power is supplied the voltages on the 35V and 5V DC lines rise and when the 35V DC line becomes approx 24V ZD201 turns on and the voltage at the base of Q201 rises to turn Q201 on Since the collector of Q201 goes Lo at this time Q202 turns on and the reset input of the micro computer goes Hi The 5V DC line has ...

Page 33: ...Micro computer When the buzzer sounds an approx 3 9kHz square signal is output from buzzer output pin q of the micro computer After the amplitude of this signal has been set to 12Vp p by a transistor it is applied to the buzzer The piezoelectric element in the buzzer oscillates to generate the buzzer s sound Fig 3 1 Buzzer Circuit Sound wave Metal diaphragm V Pizoelectric element V Fig 3 2 Buzzer ...

Page 34: ...utput from pins k A of the micro computer Micro computer pins Step width Horizontal air deflectors 10ms 1 2 3 4 5 6 7 8 Horizontal air deflectors 51 50 49 48 Fig 4 2 Micro computer Output Signals As the micro computer s outputs change as shown in Fig 4 2 the core of the auto sweep motor is excited to turn the rotor Table 4 1 shows the rotation angle of horizontal air deflectors Rotation angle per ...

Page 35: ...erature input R308 A 5 4 3 2 1 0 0 10 10 Heat exchanger temperature C Fig 6 2 20 30 40 Voltage at V A 6 Heat exchanger temperature thermistor circuit The voltage at A depends on the room temperature as shown in Fig 5 2 The circuit detects the indoor heat exchanger temperature and controls the following 1 Preheating 2 Low temperature defrosting during cooling and dehumidifying operation 3 Detection...

Page 36: ... operation Fig 7 1 8 DC Fan Motor Drive Circuit Fig 8 1 shows the indoor DC fan motor drive circuit Fig 8 1 The circuit produces the fan motor drive voltages 8 33V from 35V DC supplied from the outdoor unit and controls the fan motor speed Q903 is switched on and off according to the signal at fan PWM output pin J to control the voltage which is smoothed by D901 L901 and C901 to drive the fan moto...

Page 37: ...between blue and red Characteristics Mode Fan Speed Connector blue red voltage V Rotation Speed min 1 SS 9 8 714 S 16 6 950 OVERLOAD 19 1 1 040 LO 19 1 1 040 HI 27 7 1 350 SUPER HI 27 7 1 350 S 16 0 930 LO 18 7 1 020 HI 20 9 1 100 SUPER HI 20 9 1 100 S 16 0 930 INDOOR FAN SPEED HEATING COOLING DEHUMIDIFYING ...

Page 38: ...9 1 DC 35V supplied from the outdoor unit is controlled by switching of regulator 1 and is smoothed by D102 L102 and C102 to produce 12V Output voltage is divided by R102 and R103 and input to output dividing pin 5 to control switching so that output voltage is 12V Fig 9 2 Waveform at A Waveform at Out put Voltage B ...

Page 39: ... DC power supply Reference In case of malfunction or defective connection Immediately after the compressor starts it may stop due to abnormally low speed active error etc The compressor may continue to operate normally but the power factor will decrease the operation current will increase and the overcurrent breaker of the household power board will probably activate In case of active module fault...

Page 40: ...oothes averages the voltage rectified by the diode stacks A DC voltage is generated in the same way as in Fig 1 3 5 C507 C508 C512 C513 C506 NF COIL1 NF COIL2 C502 C503 C514 These absorb electrical noise generated during operation of compressor and also absorb external noise entering from power line to protect electronic parts 6 Surge absorber varistor 1 2 3 These absorbs external power surge 7 In...

Page 41: ...utputs an approx 38 kHz high frequency signal via pin 11 and continues the output intermittently according to the request signal This high frequency signal is amplified by a transistor superimposed on the DC 36V line via C801 and L701 and supplied to the indoor unit To prevent erroneous reception the outdoor microcomputer is designed so that it cannot receive a signal while it is outputting a requ...

Page 42: ...0V I F 0V 0V IF transmit output SDO IF receive input SDI MICRO COMPUTER 5V 5V 5V 12V 5V 5V 5V 5V 5V 5V 5V C805 R812 R813 C808 64 19 IF transmit output SDO IF receive input SDI MICRO COMPUTER AX 8J00 70 11 32 69 33 0V L701 C801 R802 Q802 R801 R813 0V 0V 0V 0V 0V 0V 0V C710 NF COIL3 C708 C709 Interface relay 36V Communications from indoor micro computer to outdoor micro computer Communications from ...

Page 43: ...ndoor micro computer 4 95ms Transmit receive switching time 33ms 1 frame Outdoor micro computer AX 8J0I 11 Pin 0V 69 Pin 5V 0V 64 Pin 5V 0V 19 Pin 5V 0V 36V DC line 36V Fig 2 2 Voltages Waveforms of indoor Outdoor Micro computers Outdoor to Indoor Communications Fig 2 3 Voltages Waveforms of indoor Outdoor Micro computers Indoor to Outdoor Communications ...

Page 44: ... 100ms 33 3ms x 8 4 95ms 371 35ms Outdoor message Indoor message Example When the outdoor message is all 0s and indoor message is all 1s 37 V 36 V 35 V When reset approx 10ms Transmit receive switching time 4 95ms Character No 0 33 3ms 1 33 3ms 2 33 3ms 3 33 3ms Character No 0 33 3ms 1 33 3ms 2 33 3ms 3 33 3ms Bit No 0 Bit No 0 0 7 0 7 0 7 0 7 7 0 7 0 7 7 Leader 100ms When reset approx 10ms Leader...

Page 45: ...ation Multi bit Contents 0 1 2 3 1 Outdoor message 7 1 0 6 1 0 5 1 0 4 1 0 3 1 0 2 0 1 1 0 0 1 0 7 1 0 6 1 0 5 1 0 4 1 0 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 1 0 3 1 0 2 1 0 1 1 0 0 1 0 Character No Bit No Data 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 0 1 0 1 0 1 0 1 0 1 0 1 0 OVL up Compressor command speed 0 LSB Compressor ON Prohibit the compressor Reversing valve 2 way valve Fan 2 MSB Fan 1 Fan 0 LSB Capaci...

Page 46: ...called the upper arm and the three transistors on the negative d side the lower arm W U V W W V V U U A DC Compressor motor U coil V coil W coil Power module 6D115S C501 R24 0 35mH Power relay R503 R502 Inrush current protection relay C001 R504 Noise filter coil A B Terminal board FUSE 15A Fig 3 1 Power module circuit U is ON V is ON ...

Page 47: ...to ON OFF by 3 2kHz chopper signal Rotation speed of the compress is proportional to duty ratio ON time ON time OFF time of this chopper signal Time T in Fig 3 2 shows the switching period and relation with rotation speed N of the compressor is shown by formula below Fig 3 2 Switching order of power module N 60 2 X 1 T Fig 3 3 shows voltage waveform at each point shown in Figs 3 1 and 3 4 Fig 3 3 ...

Page 48: ... may indicate as shown below Simplified check of power module Lighting mode when operated with compressor leads disconnected 1 Disconnect connector of 3 pole WHT YEL RED lead wire connecting to compressor located at the lower part of electric parts box 2 Set to compressor operation state other than FAN mode and press Start stop switch of remote control 3 If normal operation continues for more than...

Page 49: ...uit for P W B In the power circuit for P W B power voltage for microcomputer peripheral circuits and power module drive and as well as DV39V are produced by switching power circuit Switching power circuit performs voltage conversion effectively by switching transistor IC1 to convert DC300V voltage to high frequency of about 70kHz to 200kHz Transistor IC1 operates as follows 1 Shifting from OFF to ...

Page 50: ...circuit for P W B seems to be faulty 1 Make sure that 5V and 12V on the control P W B upper arm U V and W and the lower arm power voltage are the specified values 2 When only the 5V output is low REG 1 regulator faulty 5V 0V shorted output is too high or REG 1 is abnormal 3 When 12V and 5V are abnormal The following defects can be considered 1 Fan operation power rush prevention relay shorting in ...

Page 51: ...e on the terminal board By reversing valve control circuit you can switch reversing valve ON OFF according to instruction from indoor microcomputer and depending on operation condition Voltage at each point in each operation condition is approximately as shown below when measured by tester When collector voltage of Q701 is measured 3 1 56 5 I F 0V Fig 5 1 D701 CN2 Q701 DC voltmeter or tester Rever...

Page 52: ...ng of R101 R104 and C101 to make triangular wave voltage at point B In HIC 3 phases of this triangular wave are synthesized to produce composite wave voltage at point C This composite wave becomes a triangular wave with period of 1 3 times compared with original triangular wave Voltages at points B and C are compared by comparator to make voltage at point D Voltage at point D is taken into microco...

Page 53: ...current OA When pin e of the micro computer goes HI LO a photocoupler between PQ2 pins 1 and 2 turns on and current flows to terminal A R401 PQ2 R404 power module s Bu terminals Eu terminals D402 D401 terminal B and drives the upper arm transistors Fig 7 2 As described in the rotor magnetic pole position detecting circuit the upper arm drive circuit supplies current to the bases of the transistors...

Page 54: ...s Eu terminals Bu terminals R404 PQ2 to cut off the upper arm transistors Fig 7 3 5 6 1 8 2 PQ2 7 b a 1 Bu Eu Power module U phase A 2 R401 R404 D401 D402 C401 R407 A Current at point Reverse bias current OA Fig 7 3 Waveform of Transistor Base Current Reverse Current at Point A R407 is used to charge C401 initally The operation is the same for V and W phases ...

Page 55: ...y of the micro computer goes HI LO a photocoupler between PQ5 pins 1 and 2 turns on and current flows to terminal C R411 PQ5 R414 power module s BU terminals Ew terminals D412 D411 terminal D and drives the lower arm transistors Fig 7 4 The signals which turn on or off according to the position detection signals are output from pins y ui of the micro computer in the same way as in the upper arm dr...

Page 56: ... with set voltage value in microcomputer and controls overload when set value exceeds input voltage Voltage amplifies DC current level detected by the detection resistor and inputs this to microcomputer Internal or external overload is judged in microcomputer Produces reset voltage Modulates chopper signal to drive signal and stops according to presence ab sence of lp signal or reset signal 48 29 ...

Page 57: ...8 B C 71 POR I p 8J HIC Fig 8 3 Peak Current Cut off Circuit and Waveforms at Each Section The Ip cut off circuit detects an instantaneous high level current and stops the inverter to protect components including the power module If a current exceeding 15A flows as shown in the diagram the voltage at point A detected by the detecation resistor is input to the positive e terminal of COM 2 and when ...

Page 58: ...tion speed internal judgement value Judgement OVL with respect to externally set value A D converter A D converter Judgement OVL according to the rotation speed Selects data according to the rotation speed and DC voltage OVL start current data Rotation speed data Motor control process AX 8J01 micro computer Detection resistor Fig 8 4 Overload Control System Configuration Fig 8 5 DC current Rotatio...

Page 59: ...his the micro computer converts it to a digital signal and compares it with the internal data to judge whether or not overload control is required During overload control The filter consisting of R2 and C515 removes high harmonic components from the voltage generated from the DC current flowing to the detection resistor and supplies it to OP1 pin 5 OP1 forms a non inverting voltage amp circuit tog...

Page 60: ...t 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 in Fig8 9 2 Varies the turn ON time of the W transistor according to the DC voltage level and the start is controlled so the start current is approx 10A as shown in Fig 8 10 Fig 8 8 DC curr...

Page 61: ... PQ2 PQ4 to which voltage is supplied with high frequencies to let current flow to them to transfer the upper arm drive signal When the reset voltage is Lo the current operating PQ5 P07 is stopped and the lower arm transistor drive signal is turned off The peak current cut off Ip cut off signal fixes the voltage at upper and lower arm drive circuits to Lo via D301 and D304 and turns off the drive ...

Page 62: ...ndition command to the indoor microcomputer via the SDO pin IF transfer output of the interface The microcomputer always reads the outdoor temperature via a thermistor microcomputer pin vvoltage and 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 t...

Page 63: ...in k of microcomputer is set to Hi By ZD501 reset voltage maintains input of pin k at Lo until Vdd of microcomputer rises to 5V to obtain operable status When power is shut off and potential of 12V is lowered ZD501 is shifted to OFF However since reset voltage is feed back to Q301 by R312 maintains ON state until 12V line voltage drops to about 7 6V This prevents reset voltage from chattering due ...

Page 64: ...3 4 minutes until it is defrosted If the air conditioner operates in cooling mode when it is cold the evaporator may get frosted Normal sound when refrigerant flows in pipe Compressor may not operate when room temperature is 10 C or less It also stops when the humidity is preset humidity or less It occurs during defrost ing Wait for 5 10 minutes until the condenser is defrosted At the beginning of...

Page 65: ...y 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: ...ling capability so noise becomes slightly louder This does not indicate a fault Noise from the outdoor unit occasionally changes The compressor rotation speed changes according to the difference between the thermostst set temperature and room temperature This does not indicate a fault There is a difference between the set temperature and room temperature There may be a difference between the set t...

Page 67: ...vel 2 Also note that it takes about 10 minutes until the voltage fall after the power switch is turned off DANGER Across a b 0V line Across a ground Across b 0V line ground approx 260 380V approx 155 170V approx 155 170V When using an oscilloscope never ground it Don t forget that high voltages as noted above may apply to the oscilloscope DANGER Always keep your hands and metallic things away from...

Page 68: ...r turning power switch off wait for at least 10 minutes and then remove the electrical unit cover Fit a 30 75 W soldering iron to the receptacles of white and black lead wires on the smoothing capacitor for at least 15 seconds to discharge the voltage at the smoothing capacitor F Cabel ø2 single lead Plug Soldering iron of 30 75W Do not use a soldering iron with built in transformer the fuse built...

Page 69: ... blinks Check the outdoor electrical parts Timer lamp Dehumidifying lamp No No Yes Yes No Is approx 3V DC being generated Is the polarity correct Remove the outdoor unit cover and electrical parts cover and check self diagnosis lamp LD301 Does LD301 blink one time Repeats 0 25 second on and 2 second off Check to see whether the F cable is connected incorrectly or disconnected Set the service switc...

Page 70: ...links 10 times Half voltage error If the 15A fuse has blown be aware that other parts may alsobe defective mainly varister 2 diode stack smoothing capacitors power module etc Is the switching power circuit OK Has the 3A fuse blown See the self diagnosis lamp lighting mode Are the cords etc of terminal board reactor diodes smoothing capacitors etc connected Replace any defective parts Check to see ...

Page 71: ...C being output across R213 Is 12V DC being supplied across the control side coil terminal of interface relay Is a voltage at least 10V being generated between the contact terminals of interface relay D207 and C210 may be defective There is a defective section between the 12V output of switching power supply on the main P W B and interface relay also check for contact with solder etc Replace the in...

Page 72: ...after serving Is the continuty of thermistor normal Is the thermistor circuit normal No No Yes No No Replace the power module Replace any defective parts Connect the thermistor Replace the thermistor Replace parts in the thermistor circuit Check continuity of pattern and lead wires according to the P W B and schematic diagrams Check continuity of pattern and lead wires according to the P W B and s...

Page 73: ...tor circuit normal Are R503 R541 R542 R549 and peripheral circuits normal Replace the main P W B Is the power module normal Is the drive circuit normal Replace parts in the thermistor circuit Replace any defective parts Replace the power module Replace any defective parts No No No Check continuity of new parts Check continuity of pattern and lead wires according to the P W B and schematic diagrams...

Page 74: ...normal Are R503 and peripheral circuits normal Is the microcomputer IP input signal normal Normally pin Z is approx 5V Is the reset circuit normal Normally pin k is approx 5V Yes Yes No No No No Replace the power module Replace any defective parts Replace any defective parts Replace any defective parts Operate the unit again Is it normal Perform final operation check Make sure again that connector...

Page 75: ...faulty 15 times blinking Removing the ACT module 1 Disconnect the connector and remove the 8 receptacles Caution The resin sleeve can be removed by pulling it up but the PVC sleeve or receptacle without sleeve cannot be removed this way remove it by the procedure on the right It cannot be removed unless the positive lock is released Do not pull or lift it forcibly this could break PWB or terminals...

Page 76: ... 79 Be sure to replace the rainproof cover after checking rainwater would enter if it is not installed Reinproof cover transparent ...

Page 77: ... 80 PARTS LIST AND DIAGRAM MODEL RAS 5CNH2 11 2 18 8 20 19 12 63 1 4 60 3 7 14 15 6 5 16 13 88 61 17 9 62 10 ...

Page 78: ...AS 25CNH2 011 1 FRONT COVER ASS Y 12 PMRAS 25CNH2 012 1 MOUNTING PLATE 13 PMRAS 25CNH2 013 1 REMOTE CONTROL 14 PMRAS 25CNH2 014 3 EVAPORATOR 15 PMRAS 25CNH2 015 3 UNION 2 16 PMRAS 5100C 017 1 UNION 3 17 PMRAS 25CNH2 016 1 STEP MOTOR 60 PMRAS 25CNH2 017 1 REMOTE CONTROL HOLDER 61 PMRAS 25CNH2 018 1 FILTER 62 PMRAS 25CNH2 019 2 CAP 63 PMRAS 25CNH2 020 1 PIPE SUPPORT 18 PMRAS 07C1 006 3 TERMINAL BOAR...

Page 79: ... 82 MODEL RAC 5CNH2 55 22 59 16 26 24 23 20 25 21 19 13 52 58 53 56 57 2 3 51 15 14 18 4 5 9 6 8 54 17 7 11 10 12 ...

Page 80: ...7 PMRAC 07CHV1 904 1 2S VALVE 18 PMRAC 05CV 914 1 3S VALVE 51 PMRAC 07CHV1 920 1 REVERSING VALVE 52 PMRAC 07CHV1 921 1 COIL REVERSING VALVE 53 PMRAC 07CHV1 922 1 CHECK VALVE 54 PMRAC 25CNH2 906 1 BASE 55 PMRAC 25CNH2 907 1 SILENT COVER 56 PMRAC 25CNH2 908 1 THERMISTOR OH 57 PMRAC 25CNH2 909 1 THERMISTOR OH SUPPORT 58 PMRAC 25CNH2 910 1 THERMISTOR 59 PMRAC 25CNH2 911 1 THERMISTOR SUPPORT 19 PMRAC 2...

Page 81: ...RAS 25CNH2 RAC 25CNH2 PM NO 0081E Printed in Malaysia HITACHI ...

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Hitachi RAC-25CNH2, Service Manual, Page: 72 / 81

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