Hitachi RAD-25NH7 Service Manual
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Hitachi RAD-25NH7 Service Manual

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SERVICE MANUAL
TECHNICAL INFORMATION
FOR SERVICE PERSONNEL ONLY
SPECIFICATIONS
TYPE
MODEL
POWER SOURCE
TOTAL INPUT
TOTAL AMPERES
COOLING
CAPACITY
TOTAL INPUT
TOTAL AMPERES
HEATING
CAPACITY
DIMENSIONS
(mm)
NET WEIGHT
SPECIFICATIONS AND PARTS ARE SUBJECT TO CHANGE FOR IMPROVEMENT
ROOM AIR CONDITIONER
APRIL 2007
RAD-18NH7
RAD-25NH7
RAD-35NH7
RAD-50NH7
RAC-25NH5
RAC-35NH5
RAC-50NH5
INDOOR UNIT
RAD-18NH7
1 PHASE, 50 Hz, 220-240V
(W)
560 (155-850)
(A)
2.56-2.35
(kW)
1.80 (0.9 ~ 2.5)
(B.T.U./h)
6,150 (3,070-8,540)
(W)
690 (155-1,050)
(A)
3.20-2.92
(kW)
2.50 (0.9 ~ 3.2)
(B.T.U./h)
8,540 (3,070-10,930)
W
750
H
235
D
400
(kg)
19
INDOOR UNIT + OUTDOOR UNIT
Refrigeration & Air-Conditioning Division
PM
RAD-18NH7
RAD-25NH7/RAC-25NH5
RAD-35NH7/RAC-35NH5
RAD-50NH7/RAC-50NH5
REFER TO THE FOUNDATION MANUAL
SPECIFICATIONS ------------------------------------------------------------------- 4
HOW TO USE ------------------------------------------------------------------------ 6
CONSTRUCTION AND DIMENSIONAL DIAGRAM --------------------- 24
MAIN PARTS COMPONENT --------------------------------------------------- 27
WIRING DIAGRAM ---------------------------------------------------------------- 29
CIRCUIT DIAGRAM --------------------------------------------------------------- 31
BLOCK DIAGRAM ----------------------------------------------------------------- 37
BASIC MODE ----------------------------------------------------------------------- 39
REFRIGERATING CYCLE DIAGRAM --------------------------------------- 53
DESCRIPTION OF MAIN CIRCUIT OPERATION ----------------------- 55
TROUBLE SHOOTING ----------------------------------------------------------- 90
PARTS LIST AND DIAGRAM ------------------------------------------------- 110
DC INVERTER (DUCT TYPE)
INDOOR UNIT
OUTDOOR UNIT
INDOOR UNIT
RAD-25NH7 RAC-25NH5
RAD-35NH7 RAC-35NH5
1 PHASE, 50 Hz, 220-240V
1 PHASE, 50 Hz, 220-240V
695 (155-1,050)
1,240 (155-1,280)
3.20-2.92
2.50 (0.9 ~ 3.0)
3.50 (0.9 ~ 4.0)
8,540 (3,070-10,240)
11,950 (3,070-13,660)
970 (155-1,400)
1,700 (155-1,920)
4.50-4.10
3.50 (0.9 ~ 5.0)
4.80 (0.9 ~ 6.6)
11,950 (3,070-17,070)
16,390 (3,070-22,530)
750
750
750
235
570
235
400
280
400
19
38
19
NO. 0366E
CONTENTS
OUTDOOR UNIT
INDOOR UNIT
OUTDOOR UNIT
RAD-50NH7 RAC-50NH5
1 PHASE, 50 Hz, 220-240V
2,000 (155-2,060)
5.70-5.24
9.20-8.40
5.0 (0.9 ~ 5.6)
17,070 (3,070-19,120)
2,300 (155-2,530)
7.84-7.19
10.60-9.70
6.0 (0.9 ~ 7.5)
20,490 (3,070-25,610)
750
750
570
235
280
400
38
19
850
650
298
60

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  • Page 1: Table Of Contents

    OUTDOOR UNIT INDOOR UNIT OUTDOOR UNIT INDOOR UNIT OUTDOOR UNIT MODEL RAD-18NH7 RAD-25NH7 RAC-25NH5 RAD-35NH7 RAC-35NH5 RAD-50NH7 RAC-50NH5 POWER SOURCE 1 PHASE, 50 Hz, 220-240V 1 PHASE, 50 Hz, 220-240V 1 PHASE, 50 Hz, 220-240V 1 PHASE, 50 Hz, 220-240V...
  • Page 2 SAFETY DURING REPAIR WORK 1. In order to disassemble and repair the unit in question, be sure to disconnect the power cord plug from the power outlet before starting the work. 2. If it is necessary to replace any parts, they should be replaced with respective genuine parts for the unit, and the replacement must be effected in correct manner according to the instructions in the Service Manual of the unit.
  • Page 3 WORKING STANDARDS FOR PREVENTING BREAKAGE OF SEMICONDUCTORS 1. Scope The standards provide for items to be generally observed in carrying and handling semiconductors in relative manufacturers during maintenance and handling thereof. (They apply the same to handling of abnormal goods such as rejected goods being returned).
  • Page 4 (6) Use a three wire type soldering iron including a grounding wire. Metal plate (of aluminium, stainless steel, etc.) Working table Resistor of 1 M (1/2W) Staple Earth wire Bare copper wire (for body earth) Fig. 3. Grounding of the working table Soldering iron Grounding wire...
  • Page 5 CAUTION In quiet operation or stopping the running, slight flowing noise of refrigerant in the refrigerating cycle is heard occasionally, but this noise is not abnormal for the operation. When it thunders near by, it is recommend to stop the operation and to disconnect the power cord plug from the power outlet for safety.

  • Page 6: Specifications

    SPECIFICATIONS RAD-18NH7 RAD-25NH7 RAC-25NH5 RAC-50NH5 MODEL RAD-35NH7 RAC-35NH5 RAD-50NH7 40 W FAN MOTOR FAN MOTOR CAPACITOR FAN MOTOR PROTECTOR – JU1012D JU1013D COMPRESSOR COMPRESSOR MOTOR CAPACITOR OVERLOAD PROTECTOR OVERHEAT PROTECTOR FUSE (for MICROPROCESSOR) 3.0A POWER RELAY POWER SWITCH TEMPORARY SWITCH...
  • Page 7 [Indoor unit installation] CAUTION Always install the indoor unit at level. If the indoor unit is inclined, water may leak. Be sure to completely seal any gap with putty. The connecting pipe, no matter big or small, should all be insulated with insulation pipe and then wrapped with vinyl tape.
  • Page 8 SAFETY PRECAUTION Please read the “Safety Precaution” carefully before operating the unit to ensure correct usage of the unit. Pay special attention to signs of “ Warning” and “ Caution”. The “Warning” section contains matters which, if not observed strictly, may cause death or serious injury. The “Caution” section contains matters which may result in serious consequences if not observed properly.
  • Page 9 PRECAUTIONS DURING OPERATION The product shall be operated under the manufacturer specification and not for any other intended use. Do not attempt to operate the unit with wet hands, this could cause fatal accident. When operating the unit with burning equipments, regularly ventilate the room to avoid oxygen insufficiency.
  • Page 10 MULTI-AIR CONDITIONER With this multi-air conditioner, several indoor units can be connected to one outdoor unit to be driven. You can operate the required number of indoor units. Combination of Operations: When operation mode is selected: G You cannot operate the indoor units in the following combinations.
  • Page 11 NAMES AND FUNCTIONS OF EACH PART INDOOR UNIT Electrical Air outlet Filter Air inlet MODEL NAME AND DIMENSIONS MODEL WIDTH (mm) HEIGHT (mm) DEPTH (mm) RAD-18NH7/RAD-25NH7/RAD-35NH7/RAD-50NH7 – 9 –...
  • Page 12 NAMES AND FUNCTIONS OF REMOTE CONTROL UNIT I This controls the operation function and timer setting of the room air conditioner. START/STOP Button Use this button to select the operating mode. Every time you press it, the mode will change from (AUTO) to (HEAT) to (DEHUMIDIFY) and to...
  • Page 13 VARIOUS FUNCTIONS I Auto Restart Control If there is a power failure, operation will be automatically restarted when the power is resumed with previous operation mode. (As the operation is not stopped by remote controller.) If you intend not to continue the operation when the power is resumed, switch off the power supply. When you switch on the circuit breaker, the operation will be automatically restarted with previous operation mode.
  • Page 14 HEATING OPERATION Use the device for heating when the outdoor temperature is under 21°C. When it is too warm (over 21°C), the heating function may not work in order to protect the device. In order to keep reliability of the device, please use this device above -15°C of the outdoor temperature. Press the FUNCTION selector so that the display indicates (HEAT).
  • Page 15 DEHUMIDIFYING OPERATION Use the device for dehumidifying when the room temperature is over 16°C. When it is under 15°C, the dehumidifying function will not work. Press the FUNCTION selector so that the display indicates (DEHUMIDIFY). The FAN SPEED is set at LOW automatically. The FAN SPEED button does not work.
  • Page 16 COOLING OPERATION Use the device for cooling when the outdoor temperature is –10 ~ 43°C. If indoor humidity is very high (80%), some dew may form on the air outlet grille of the indoor unit. Press the FUNCTION selector so that the display indicates (COOL).
  • Page 17 TIMER RESERVATION I ON Timer and OFF Timer are available. I Operation stop at setting time OFF Timer Reservation OFF TIME setting Select the OFF TIME by pressing the (OFF) Button. Setting time will change according to the below sequence when you press the button. 0.5 hour interval 1 hour interval 0 .
  • Page 18 HOW TO SET THE SLEEP TIMER Mode Indication 1 hour 2 hours 3 hours 7 hours Sleep timer Sleep timer off Sleep Timer: The device will continue working for the designated number of hours and then turn off. Press the SLEEP button, indoor unit will produce a beep. The timer information will be displayed on the remote controller.
  • Page 19 Explanation of the sleep timer The device will control the FAN SPEED and room temperature automatically so as to be quiet and good for people’s health. NOTE If you set the sleep timer after the off or on-timer has been set, the sleep timer becomes effective instead of the off or on-timer set earlier.

  • Page 20: How To Use

    CIRCUIT BREAKER When you do not use the room air conditioner, set the circuit breaker to “OFF”. HOW TO USE THE AIR CONDITIONER EFFECTIVELY 1. An average room temperature setting is probably the best for you as well as being economical. Excessive cooling or heating is not recommended for health reasons.
  • Page 21 THE IDEAL WAYS OF OPERATION Suitable Room Temperature Install curtain or blinds Warning It is possible to Freezing temperature reduce heat is bad for health and a entering the waste of electric power. room through windows. Ventilation Effective Usage Of Timer At night, please use the “OFF or ON timer Caution operation mode”, together with your wake up...
  • Page 22 FOR USER’S INFORMATION The Air Conditioner And The Heat Source In The Room Caution If the amount of heat in the room is above the cooling capability of the air conditioner (for example: more people entering the room, using heating equipments and etc.), the preset room temperature cannot be achieved.
  • Page 23 MAINTENANCE WARNING Before cleaning, stop unit operation with the remote controller and turn off the circuit breaker. CAUTION Do not expose the unit to water as it may cause an electric shock. For cleaning inside the air conditioner, consult your sales agent. Avoid using detergent when cleaning the heat exchanger of the indoor unit.
  • Page 24 REGULAR INSPECTION PLEASE CHECK THE FOLLOWING POINTS BY QUALIFIED SERVICE PERSONAL EITHER EVERY HALF YEARLY OR YEARLY. CONTACT YOUR SALES AGENT OR SERVICE SHOP. Is the earth line disconnected or broken? Is the mounting frame seriously affected by rust and is the outdoor unit tilted or unstable? Is the plug of power line firmly plugged into the socket? (Please ensure no loose contact between them).
  • Page 25 Please note: On switching on the equipment, particularly when the room light is dimmed, a slight brightness fluctuation may occur. This is of no consequence. The conditions of the local Power Supply Companies are to be observed. Note Avoid to use the room air conditioner for cooling operation when the outside temperature is below 21°C (70°F).

  • Page 26: Construction And Dimensional Diagram

    CONSTRUCTION AND DIMENSIONAL DIAGRAM FOR INDOOR MODEL RAD-18NH7, RAD-25NH7, RAD-35NH7, RAD-50NH7* Unit: mm – 24 –...
  • Page 27 BACK SUCTION DISCHARGE BOTTOM SUCTION Cautions: 1. Use insulated pipes for both large and small diameters. 2. An connection cable. – 25 –...
  • Page 28 CONSTRUCTION AND DIMENSIONAL DIAGRAM FOR OUTDOOR MODEL RAC-25NH5, RAC-35NH5 MODEL RAC-50NH5 Handle Handle Air suction Air outlet grille Holes for anchor bolt (2-ø12) More than More than Fixing hole Service space Notch for anchor bolt (2-ø12 Notchs) – 26 –...

  • Page 29: Main Parts Component

    MAIN PARTS COMPONENT THERMOSTAT Thermostat Specifications MODEL RAD-18NH7, RAD-25NH7, RAD-35NH7, RAD-50NH7 THERMOSTAT MODEL OPERATION MODE COOL HEAT 14.9 (59.3) 20.4 (68.8) INDICATION 14.3 (58.3) 21.0 (69.1) TEMPERATURE 22.9 (73.7) 28.4 (83.1) INDICATION °C (°F) 22.3 (72.7) 29.0 (84.1) 30.9 (88.1) 36.4 (97.7)
  • Page 30 COMPRESSOR MOTOR Compressor Motor Specifications MODEL RAC-25NH5. RAC-35NH5 RAC-50NH5 COMPRESSOR MODEL JU1012D JU1013D PHASE SINGLE RATED VOLTAGE AC 220 ~ 240 V RATED FREQUENCY 50 Hz POLE NUMBER WHITE CONNECTION YELLOW 20°C 2M = 1.05 (68°F) RESISTANCE VALUE 75°C 2M = 1.28 (167°F) WHITE YELLOW...

  • Page 31: Wiring Diagram

    WIRING DIAGRAM MODEL RAD-18NH7, RAD-25NH7, RAD-35NH7, RAD-50NH7 RAC-25NH5, RAC-35NH5, RAC-50NH5 OUTDOOR UNIT INDOOR UNIT OPTION PARTS – 29 –...

  • Page 32: Circuit Diagram

    CIRCUIT DIAGRAM Wired Remote Control – 31 –...
  • Page 33 CIRCUIT DIAGRAM MODEL RAD-18NH7, RAD-25NH7, RAD-35NH7, RAD-50NH7 (OPTION PART) – 33 –...
  • Page 34 MODEL RAC-25NH5, RAC-35NH5, RAC-50NH5 – 35 –...
  • Page 35 MODEL RAD-18NH7, RAD-25NH7, RAD-35NH7, RAD-50NH7 RAC-25NH5, RAC-35NH5, RAC-50NH5 SPM2 Outdoor unit Terminal board Trip signal synthesis circuit Wired remote control Wired remote control Buzzer circuit receiver circuit Operation Room temperature thermistor Indicating lamp Timer Heat exchanger thermistor Static pressure select switch...
  • Page 36 RAD-18NH7, RAD-25NH7, RAD-35NH7, RAD-50NH7 wireless remote controller. – 39 –...
  • Page 37 Table 1 Mode data file RAD-18NH7 RAD-25NH7 RAD-35NH7 RAD-50NH7 LABEL NAME VALUE –1 –1 –1 –1 WMAX 4400 min 4400 min 5500 min 5100 min –1 –1 –1 –1 WMAX2 4500 min 4500 min 5600 min 5100 min –1 –1 –1...
  • Page 38 ∆ Table 2 TCMAX Temperature Calculated difference compressor rpm 1.66 2265 min –1 2435 min –1 –1 2.33 2600 min 2.66 2765 min –1 2935 min –1 3.33 3100 min –1 –1 3.66 3265 min 3435 min –1 4.33 3600 min –1 –1 4.66...
  • Page 39 Cooling Sleep Operation Final set temperature (Cooling/dehumidifying set temperature (+) sleep shift) (Cooling/dehumidifying set 0.5hr 1.5hr 2.5hr 3.5hr temperature = Remote control set temperature (+) SHIFTC) Set to 7 hours Sleep key Operation lamp Timer lamp Indoor fan See basic operation Lo (sleep) Outdoor fan Horizontal air...
  • Page 40 Delay Notes: (1) If the room temperature is (cooling preset temperature) - (1.33°C) or less after 30 seconds from starting the operation, 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 minutes and ON for 1 minute. (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.
  • Page 41 ∆ Table 3 TWMAX Basic Heating Operation Temperature Calculated difference compressor rpm –1 1.66 1965 min –1 2135 min 2.33 2300 min –1 Heating set temperature 2.66 2465 min –1 (remote control set temperature (+)) –1 2635 min 3.33 2800 min –1 Dash period 18˚C...
  • Page 42 TDF TDF TDF 1 min WMIN Notes: The sleep operation starts when the sleep key is pressed. When the sleep key is set, the maximum compressor speed is limited to WSTD+2000/2, and the indoor fan is set to “sleep Lo”. 30 minutes after the sleep key is set, the sleep shift of set temperature starts.

  • Page 43: Refrigerating Cycle Diagram

    REFRIGERATING CYCLE DIAGRAM MODEL RAD-18NH7/RAD-25NH7/RAC-25NH5, RAD-35NH7/RAC-35NH5 COOLING, DEHUMIDIFYING, DEFROSTING OUTDOOR UNIT INDOOR UNIT SERVICE VALVE (3/8) SINGLE-ENDED UNION (3/8) SUCTION TANK REVERSING VALVE ELECTRIC EXPANSION VALVE SERVICE VALVE (1/4) SINGLE-ENDED UNION (1/4) STRAINER STRAINER CHARGING PIPE HEATING OUTDOOR UNIT INDOOR UNIT...
  • Page 44 REFRIGERATING CYCLE DIAGRAM MODEL RAD-50NH7 RAC-50NH5 COOLING, DEHUMIDIFYING, DEFROSTING OUTDOOR UNIT SERVICE VALVE INDOOR UNIT (1/2) SINGLE-ENDED UNION (1/2) 12.7 SUCTION TANK REVERSING VALVE ELECTRIC EXPANSION VALVE SERVICE VALVE (1/4) STRAINER SINGLE-ENDED UNION (1/4) STRAINER HEATING SERVICE VALVE OUTDOOR UNIT INDOOR UNIT (1/2) SINGLE-ENDED...

  • Page 45: Description Of Main Circuit Operation

    DESCRIPTION OF MAIN CIRCUIT OPERATION MODEL RAD-18NH7, RAD-25NH7, RAD-35NH7, RAD-50NH7 1. Reset Circuit R419 Wireless input R611 Light receiving unit C611 Microcomputer C405 Fig. 1-1 Voltage 5.0V Voltage supply to of IC521 Reset enter at 4.2V Reset release at 4.4V voltage 5.0V...
  • Page 46 2. Receiver Circuit R419 Wireless input R611 Light receiving unit C611 Microcomputer C405 Fig. 2-1 The light receiver unit receives the infrared signal from the wireless remote control (option part). The receiver amplifies and shapes the signal and outputs it. 3.
  • Page 47 4. Room Temperature Thermistor Circuit Fig. 4-1 shows the room temperature The voltage at depends on the room thermistor circuit. temperature as shown in Fig. 4-2. Room Microcomputer temperature thermistor R305 Room temp. input C302 R301 Fig. 4-1 Fig. 4-2 5.
  • Page 48 6. Initial Setting Circuit (IC401) When power is supplied, the microcomputer reads the data in IC401 (E PROM) and sets the preheating activation value and the rating and maximum speed of the compressor, etc. to their initial values. Data of self-diagnosis mode is stored in IC401; data will not be erased even when power is turned off. Microcomputer C401 External ROM...
  • Page 49 8. Drain pump drive circuit When cool or dehumidifying operation, pin of the micro computer goes “Hi”, Q333 and Q932 turn on and the drain pump drive. Drain pump motor D932 Micro computer L932 Q933 L933 R931 Drain pump Q932 R932 C932 Fig.
  • Page 50 11. High static-pressure switch (Full duct type and semi duct type) Main P.W.B. Temporary Operate switch Timer Buzzer Micro computer Fig. 13-1 Static pressure sw Normal High Drain pump test drive sw Fig. 11-1 For full duct type and semi duct type, set the high to HIGH STATIC-PRESSURE. If not set to HIGH, there will be reduction of cooling and heating capacities.
  • Page 51 Model RAC-25NH5, RAC-35NH5, RAC-50NH5 1. Power Circuit REACTOR SPM2 DIODE TERMINAL STACK 1 BOARD COIL POWER RELAY 25A FUSE NF COIL1 (D25VB60) SURGE- TB10 ABSORBER R007 R008 TB11 ICP RELAY TB12 C009 L001 L002 DIODE STACK 2 (RC2) R002 C014 C012 C007 C015...
  • Page 52 (3) Smoothing capacitor (C501, C502, C503) This smoothes (averages) the voltage rectified by the diode stacks. <Notes> Smoothing capacitor C501 is not available for model RAC-25NH5 and RAC-35NH5. Smoothing Capacitors SPM2 Fig. 1-2 Be careful to avoid an electric shock as a high voltage is generated.
  • Page 53 2. Indoor/Outdoor Interface Circuit The interface circuit superimposes an interface signal on the DC 35V line supplied from the outdoor unit to perform communications between indoor and outdoor units. This circuit consists of a transmiting circuit which superimposes an interface signal transmit from the microcomputer on the DC 35V line and a transmiting circuit which detects the interface signal on the DC 35V line and outputs it to the microcomputer.
  • Page 54 Fig. 2-1 shows the interface circuit used for the indoor and outdoor microcomputers to communicate with each other. R805 R813 R803 IC801 L801 R812 R810 IF transmit Q803 Q802 output (SDO) R804 R806 R811 C803 C802 C801 C804 MICROCOMPUTER Q801 R824 R826 R822...
  • Page 55 0.7V Outdoor HIC Indoor microcomputer DC 35V line 100ms. 33ms. Leader 1 frame Fig. 2-2 Voltages Waveforms of indoor / Outdoor Microcomputers (Outdoor to Indoor Communications) Outdoor HIC Indoor microcomputer DC 35V line 4.95ms. 33ms. Transmit / receive 1 frame switching time Fig.
  • Page 56 – 66 –...
  • Page 57 Compressor minimum rotation speed (4 MSB) Compressor minimum rotation speed (3) Compressor minimum rotation speed (2) Compressor minimum rotation speed (1) Compressor minimum rotation speed (0 LSB) Fan-7-step request OVL up 15/20(A) Actual compressor rotation speed (5 MSB) Compressor command speed (7 MSB) Actual compressor rotation speed (4) Compressor command speed (6) Actual compressor rotation speed (3)
  • Page 58 3. Power Module Circuit – 68 –...
  • Page 59 DC 260-360V is input to system power module and system power module switches power supply current according to rotation position of magnet rotor. The switching order is as shown in Fig. 3-2. At point E: U + is ON, V – is ON (circuit in Fig. 3-1) At point F: U + is chopped (OFF), V –...
  • Page 60 System Power Module 2 260V-360V DC compressor U coil motor V coil — — — W coil DC current (Id) detection resistor Fig. 3-4 Power module circuit (U + is ON, V – is ON) Since current flows at point only when U+ transistor is ON, the current waveform at point becomes intermittent waveform as shown in Fig.
  • Page 61 4. Power Circuit for P.W.B. Fig. 4-1 shows the power circuit for P.W.B. and waveform at each point. Switching transformer (T1) C909 D907 Diode stack 2 R914 C910 (RC2) R902 I/F0V D908 L902 R915 R901 C901 R916 C911 D911 FM–15V R917 D909 R002...
  • Page 62 (2) During ON The drain current at IC901 increases linearly. During this period, the gate voltage and current become constant because of the saturation characteristics of the transformer. (3) Shifting from ON to OFF This circuit applies a negative feedback signal from the 12V output. When the voltage across C919 reaches the specified value, REG2 turns on and current flows to PQ2 1-2.
  • Page 63 5. Reversing valve control circuit I/F 35V Reversing FUSE RESISTOR valve D702 PQ701 R703 Q701 Q705 R701 R219 R702 DC voltmeter or tester I/F 0V Fig. 5 – 1 Reversing valve control circuit can switch reversing valve ON/OFF according to instruction from indoor microcomputer depending on the operation condition shows in Table 5-1.
  • Page 64 6. Rotor magnetic pole position detection circuit System power module DC brushless motor for compressor 36 33 34 35 47 +12V C608 R604 C605 R605 C606 R606 R607 C607 No power Upper arm No power Lower arm No power supplied supplied supplied Induced voltage...
  • Page 65 7. Drive Circuit Fig. 7-1 shows the drive circuit. The circuits for U phase, V phase and W phase have the same Configuration. – 75 –...
  • Page 66 [Low speed rotation mode] Fig. 7-2 [High speed rotation mode] Fig. 7-3 – 76 –...
  • Page 67 8. HIC and Peripheral Circuits Fig. 8-1 shows the micro computer and its peripheral circuits, Table 8-1, the basic operations of each circuit block, and Fig. 8-2, the system configuration. Detection Resistor DC Current SPM2 – HIC Direct Current DC260-380V SPM2 CN14 CN13...
  • Page 68 Reset Voltage Reset circuit Chopper Chopper Drive signal signal signal Drive Compressor Circuit Over-load external motor setting circuit DC 260V -360V Power module IP signal Peak current Current cut off circuit level Current amplified circuit Detection resistor DC current Fig. 8-2 The following describes the operations of each circuit in detail.
  • Page 69 (2) Overload control circuit (OVL control circuit) Overload control is to decrease the speed of the compressor and reduce the load when the load on the air conditioner increases to an overload state, in order to protect the compressor, electronic components and power breaker.
  • Page 70 Detection Resistor Direct Current DC Current DC 260-380V SPM2 CN14 CN13 MAIN P.W.B. C205 – R245 R248 Microcomputer R222 D104 R005 R221 C218 Fig. 8-6 Voltage at microcomputer pin Rotation speed of compressor Commanded rotation speed Actual rotation speed Deceleration Acceleration Deceleration Acceleration...
  • Page 71 R500, R253, detect the DC voltage at the power circuit. The microcomputer receives a DC voltage (260- 380V) via HIC and applies correction to the overload set value so the DC current is low (high) when the DC voltage is high (low). (Since the load level is indicated by the DC voltage multiplied by DC current, R247, R248, R249 are provided to perform the same overload judgement even when the voltage varies.) Amplification : low...
  • Page 72 9. Temperature Detection Circuit O.H. thermistor Normal 2.7V or less Over heat 2.7V or more Reset 2.3V or less O.H. Microcomputer DEF. thermistor Normal 2.4V or more Over heat 2.4V or less Reset 2.9V or more DEF. Outdoor temperature thermistor Refer to the table 10-1 Outdoor CN10...
  • Page 73 10. Reset Circuit Main P.W.B Microcomputer R284 R289 – R252 JW10 RESET IC5 (1/2) R288 Fig. 10-1 The reset circuit initializes the microcomputer program when Power is “ON” or “OFF”. Low voltage at pin resets the microcomputer, and HI activates the microcomputer. Fig.
  • Page 74 11. Outdoor DC Fan Motor control circuit. System power module Power supply for DC fan motor from smoothing capacitor in system power module RC Filter CN12 Main P.W.B 2A-FUSE Motor coil C101 FM-15V FM-15V R107 Q101 PWM control voltage D101 FG Pulse R101 R102...
  • Page 75 < Reference > When operation stop with LD301 blinks 12 times, it may be caused by faulty DC fan motor. In this case, please check CN6 and CN12 connection first. It makes Fan Motor Lock also if those connectors are in misconnection. DC Fan Motor has broken when 2A Fuse was burned.
  • Page 76 12. Power Factor Control Circuit Power factor is controlled to almost 100%. (Effective use of power) With IC in ACT module, control is performed so that input current waveform will be similar to waveform of input voltage I (input current) input voltage V (input voltage) Effective...

  • Page 77: Service Call Q & A

    SERVICE CALL Q & A Model RAD-18NH7, RAD-25NH7, RAD-35NH7, RAD-50NH7 COOLING MODE The compressor has Check if the indoor heat If the air conditioner operates stopped suddenly during exchanger is frosted. in cooling mode when it is cooling operation. Wait for 3-4 minutes cold, the evaporator may get until it is defrosted.
  • Page 78 AUTO FRESH DEFROSTING Auto Fresh Defrosting is carried out : the After the ON/OFF button is pressed system checks the outdoor heat exchanger to stop heating, the outdoor unit is and defrosts it as necessary before stopping still working with the OPERATION operation.
  • Page 79 OTHERS The heat exchanger temperature The indoor fan varies among This is because the cool is sensed in the auto speed mode. high air flow, low air flow and wind prevention function When the temperature is low, the breeze in the auto fan speed is operating, and does fan speed varies among high air mode.

  • Page 80: Trouble Shooting

    TROUBLE SHOOTING Model RAC-25NH5, RAC-35NH5, RAC-50NH5 PRECAUTIONS FOR CHECKING System power module 2 Power source 220V-240V DANGER — — — 1. Remember that the Compressor motor 0V line is biased to 155-170V in (0V) reference to the ground level. Indoor unit 2.
  • Page 81 DISCHARGE PROCEDURE AND POWER SHUT OFF METHOD FOR POWER CIRCUIT Caution Voltage of about 300-330V is charged between both ends of smoothing capacitors During continuity check for each part of circuit in indoor unit electrical parts, disconnect red/gray WARNING lead wire connected from diode stack to system power module (SPM2) to prevent secondary trouble.
  • Page 82 TROUBLESHOOTING WHEN TIMER LAMP BLINKS Model RAD-18NH7, RAD-25NH7, RAD-35NH7, RAD-50NH7 Perform troubleshooting according to the number of times the indoor timer lamp and outdoor LD301 blink. SELF-DIAGNOSIS LIGHTING MODE Model: RAD-18NH7, RAD-25NH7, RAD-35NH7, RAD-50NH7 <Remark> If using wired remote controller, electrical cover have to be opened so that timer lamp at indoor p.w.b can be seen as Fig.
  • Page 83 SELF-DIAGNOSIS LIGHTING MODE MODEL: RAC-25NH5, RAC-35NH5, RAC-50NH5 – 93 –...
  • Page 84 CHECKING THE INDOOR/OUTDOOR UNIT ELECTRICAL PARTS AND REFRIGERATING CYCLE Model RAC-25NH5 RAC-35NH5 RAC-50NH5 Unit does not operate. Open electrical cover of indoor unit. Timer lamp See Troubleshooting when the timer lamp Does the timer lamp on the indoor unit blink? blinks .
  • Page 85 CHECKING INDOOR UNIT ELECTRICAL PARTS 1. Power does not come on (no operation) Is AC 220-240V AC being generated Is DC 35V being generated between Check AC outlet and breaker, and between terminals L and N on the terminals C and D on the terminal repair any defective part.
  • Page 86 2. Outdoor unit does not operate (but receives remote infrared signal) – 96 –...
  • Page 87 3. Only indoor fan does not operate (other is normal) Is approx 20 V DC generated Is 5 V DC generated between pins between pins (blue) and (red) Replace indoor fan motor. (blue) and (yellow) of CN10? of CN 10 when operated at high fan speed during cooling? Check disconnection, etc of lead wires.
  • Page 88 5. All systems stop from several seconds to several minutes after operation is started (all indicators are also off) Set to the "Hi" fan mode. The operation lamp lights once and goes out in 5-10 seconds. Disconnect, CN10 and set to the fan mode again. Check to see if shorting, etc.
  • Page 89 CHECKING THE OUTDOOR UNIT ELECTRICAL PARTS MODEL RAC-25NH5, RAC-35NH5, RAC-50NH5 – 99 –...
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  • Page 94 POWER CIRCUIT Phenomenon 1 <Rotation speed does not increase> Recheck cord, etc. of the Is the DC voltage at least 350V? system power module. If they are disconnected, connect them securely. Is the OVL lamp lit? If the lamp is lit, it does not If abnormality continues, replace the system indicate fault, but the unit...
  • Page 95 (JUDGING BETWEEN GAS LEAKAGE AND CHECKING THE REFRIGERATING CYCLE COMPRESSOR DEFECTIVE) 1. Troubleshooting procedure (No operation, No heating, No cooling) Lighting mode Blinks Blinks Blinks Blinks Blinks Blinks Connect U,V,W phase leads to the Self- 2 times 3 times 4 times 5 times 6 times 8times...
  • Page 96 HOW TO CHECK SYSTEM POWER MODULE Checking system power module using tester Set tester to resistance range (X 100) If indicator does not swing in the following conductivity check, the system power module is normal. (In case of digital tester, since built-in battery is set in reverse direction, + and – terminals are reversed.) CAUTION If inner circuit of system power module is disconnected (open), the indicator of tester will not swing and this may assumed as normal.
  • Page 97 HOW TO OPERATE USING THE SERVICE SWITCH THE OUTDOOR UNIT MODEL RAC-25NH5, RAC-35NH5, RAC-50NH5 1. Turn off the power supply to outdoor unit and then turn on again. 2. Remove the electrical box cover. LD303 (red) will light and the unit will operate in the forced cooling mode at this time. Never operate the unit for more than 5 minutes.
  • Page 98 SYSTEM POWER MODULE DIAGNOSIS Circuit diagram of Collector the device (excepting the reflux diode) BASE Emitter Circuit diagram of the module – Terminals symbol mark of the module See next page for measuring value using tester – L2 L1 – 108 –...

  • Page 99: Parts List And Diagram

    PARTS LIST AND DIAGRAM INDOOR UNIT MODEL : RAD-18NH7, RAD-25NH7, RAD-35NH7, RAD-50NH7 – 109 –...
  • Page 100 MODEL RAD-18NH7 PART N0. Q’TY / UNIT PARTS NAME RAD-18NH7 PMRAD-28MX DRAIN PAN PMRAMD-350BW R03 FAN MOTOR SUPPORT RUBBER PMRAMD-350BW R04 SPECIAL SCREW PMRAD-28MX DRAIN PUMP PMRAMD-350BW R05 DRAIN HOSE ASSY PMRAMD-350BW R11 FLOAT SWITCH PMRAD-18NH7 CYCLE ASSY PMRAS-10C8M BULB SUPPORT PMRAD-32CNH2 SIROCCO FAN PMRA-353B...
  • Page 101 MODEL RAD-25NH7 PART N0. Q’TY / UNIT PARTS NAME RAD-25NH7 PMRAD-28MX DRAIN PAN PMRAMD-350BW R03 FAN MOTOR SUPPORT RUBBER PMRAMD-350BW R04 SPECIAL SCREW PMRAD-28MX DRAIN PUMP PMRAMD-350BW R05 DRAIN HOSE ASSY PMRAMD-350BW R11 FLOAT SWITCH PMRAD-18NH7 CYCLE ASSY PMRAS-10C8M BULB SUPPORT...
  • Page 102 MODEL RAD-35NH7 PART N0. Q’TY / UNIT PARTS NAME RAD-35NH7 PMRAD-28MX DRAIN PAN PMRAMD-350BW R03 FAN MOTOR SUPPORT RUBBER PMRAMD-350BW R04 SPECIAL SCREW PMRAD-28MX DRAIN PUMP PMRAMD-350BW R05 DRAIN HOSE ASSY PMRAMD-350BW R11 FLOAT SWITCH PMRAD-18NH7 CYCLE ASSY PMRAS-10C8M BULB SUPPORT PMRAD-32CNH2 SIROCCO FAN PMRA-353B...
  • Page 103 MODEL RAD-50NH7 PART N0. Q’TY / UNIT PARTS NAME RAD-50NH7 PMRAD-28MX DRAIN PAN PMRAMD-350BW R03 FAN MOTOR SUPPORT RUBBER PMRAMD-350BW R04 SPECIAL SCREW PMRAD-28MX DRAIN PUMP PMRAMD-350BW R05 DRAIN HOSE ASSY PMRAMD-350BW R11 FLOAT SWITCH PMRAD-50NH7 CYCLE ASSY PMRAS-10C8M BULB SUPPORT PMRAD-32CNH2 SIROCCO FAN PMRA-353B...
  • Page 104 OUTDOOR UNIT MODEL : RAC-25NH5, RAC-35NH5, RAC-50NH5 – 114 –...
  • Page 105 MODEL RAC-25NH5 PART N0. Q’TY / UNIT PARTS NAME RAC-25NH5 PMRAC-25NH4 COMPRESSOR KPNT1 PUSH NUT RAC-2226H COMPRESSOR RUBBER PMRAC-25NH4 CONDENSER PMRAC-50YHA1 REVERSING VALVE PMRAC-25NH4 ELECTRICAL EXPANSION COIL PMRAC-25NH4 VALVE (2S) PMRAC-25NH4 VALVE (3S) PMRAC-40CNH2 THERMISTOR (OH) PMRAC-25NH4 OVERHEAT THERMISTOR SUPPORT PMRAC-25NH4 OVERLOAD RELAY COVER PMRAC-40CNH2...
  • Page 106 MODEL RAC-35NH5 PART N0. Q’TY / UNIT PARTS NAME RAC-35NH5 PMRAC-25NH4 COMPRESSOR KPNT1 PUSH NUT RAC-2226H COMPRESSOR RUBBER PMRAC-25NH4 CONDENSER PMRAC-50YHA1 REVERSING VALVE PMRAC-25NH4 ELECTRICAL EXPANSION COIL PMRAC-25NH4 VALVE (2S) PMRAC-25NH4 VALVE (3S) PMRAC-40CNH2 THERMISTOR (OH) PMRAC-25NH4 OVERHEAT THERMISTOR SUPPORT PMRAC-25NH4 OVERLOAD RELAY COVER PMRAC-40CNH2...
  • Page 107 MODEL RAC-50NH5 PART N0. Q’TY / UNIT PARTS NAME RAC-50NH5 PMRAC-50NH4 COMPRESSOR KPNT1 PUSH NUT RAC-2226HV COMPRESSOR RUBBER PMRAC-50NH4 CONDENSER PMRAC-50YHA1 REVERSING VALVE PMRAC-25NH4 ELECTRICAL EXPANSION COIL PMRAC-50NH4 VALVE (2S) PMRAC-50NH4 VALVE (4S) PMRAC-40CNH2 THERMISTOR (OH) PMRAC-25NH4 OVERHEAT THERMISTOR SUPPORT PMRAC-25NH4 OVERLOAD RELAY COVER PMRAC-40CNH2...
  • Page 108 HITACHI RAD-18NH7/RAD-25NH7/RAD-35NH7RAD-50NH7 PM NO. 0366E RAC-25NH5/RAC-35NH5/RAC-50NH5 Printed in Malaysia...

This manual is also suitable for:

Rad-18nh7Rac-25nh5Rad-35nh7Rac-35nh5Rad-50nh7Rac-50nh5

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