Mitsubishi Electric MS-18NN Series Service Manual Download Page 25

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10-2 Instruction of troubleshooting

Indoor unit oper-
ates. Outdoor unit
doesn’t operate.

Outdoor unit
operates in
only Test
Run mode.

Outdoor unit
doesn’t oper-
ate even in
Test Run
mode.

Check room
temperature
thermistor.

Refer to
“Check of
outdoor unit”
on page 28.

Indoor unit
dosen’t receive
the signal from
remote
controller.

Refer to
”Check of
receiver P.C.
board” on page
27.

Indoor unit operation
monitor lamp is flashing

Indoor unit doesn’t
receive the signal from
remote controller.
Also, operation monitor
lamp doesn’t flash, when
the emergency operation
switch is pressed.

Refer to “Check of
indoor electric control
P.C. board” on page 28.

Cause:Indoor unit

2-time-Room temperature/Indoor coil thermistor trouble.
3-times-Indoor fan motor trouble

Check room temperature.
Refer to“Test point dia-
gram and voltage” on
page 29.

Refer to
“Check of indoor
fan motor” on
page 27.

Check indoor coil
thermistor. Refer
to“Test point dia-
gram and voltage”
on page 29.

2-time flash

2.5-second OFF

3-time flash

2.5-second OFF

Start

10-2-1 troubleshooting check table

Operation Indicator

❈

Before taking measures make sure that the symptom reappears, for accurate troubleshooting.

Self check table

NO.

Abnormal

point

Indoor coil
thermistor

Room
tempera-
ture ther-
mistor

Indoor fan
motor

Indication

2-time flash

2.5-second OFF

3-time flash

2.5-second OFF

Symptom

Outdoor unit
does not run.

Indoor fan
repeats 12 sec-
onds ON and 3
minutes OFF.
When the indoor
fan breaks, the
fan keeps stop-
ping.

Detect method

Detects Indoor coil/room tem-
perature thermistor short or
open circuit every 2 seconds
during operation.

When rotational frequency
feedback pulse signal is not
emit during 12-second indoor
fan operation

Repair

●

Check thermistor calibration

●

Reconnect connector

●

Check indoor borad

●

Disconnect connector CN211 and then

check connector CN121 - to make
sure rotational frequency feedback signal
of on 1.5V or over exists.

●

Check indoor electronic control P.C.

board.

●

Check indoor fan motor

●

Reconnect conector

OB188--2.qxp 25/9/97 6:09 PM Page 5

Summary of Contents for MS-18NN Series

Page 1: ... OUTLINES AND DIMENSIONS 7 5 WIRING DIAGRAM 8 6 REFRIGERANT SYSTEM DIAGRAM 10 7 PERFORMANCE CURVES 13 8 MICROPROCESSOR CONTROL 15 9 SERVICE FUNCTIONS 23 10 TROUBLESHOOTING 24 11 DISASSEMBLY INSTRUCTIONS 30 12 PARTS LIST 34 13 OPTIONAL PARTS 38 Wireless type Models No OB188 MS 18NN WH MU 18NN MS 24NN WH MU 24NN S1 S1 S1 S1 ...

Page 2: ...as changed NHJ 36NBD NH 28NCDT 5 The remote controller has changed 6 Microprocessor control has changed 1 S1 S1 MS 24JN MS 24NN 1 Indoor unit model and outdoor unit model have changed 2 Indoor fan motor has changed S4N 26B BA RA4N30 AA 3 Outdoor fan motor has changed S6N 60F AB RA6V60 AB 4 Compressor has changed NHJ 38NBD NH 38NBDT 5 The remote controller has changed 6 Microprocessor control has c...

Page 3: ...3 PART NAMES AND FUNCTIONS 2 INDOOR UNIT OUTDOOR UNIT MU 18NN MU 24NN S1 S1 MS 18NN MS 24NN S1 S1 ...

Page 4: ...4 REMOTE CONTROLLER MS 18NN MS 24NN S1 S1 ...

Page 5: ... W 1 910 Power factor 98 Starting current A 55 Compressor motor current A 8 15 Fan motor current A 0 75 Coefficient of performance 2 67 Electrical data Model NH 28NCDT Output W 1 200 Width mm in 1 015 40 Indoor unit Height mm in 320 12 9 16 Depth mm in 190 7 1 2 Width mm in 850 33 1 2 Outdoor unit Height mm in 605 23 13 16 Depth mm in 290 11 3 8 Indoor unit kg lb 14 31 Outdoor unit kg lb 55 121 Ai...

Page 6: ... Power factor 99 Starting current A 56 Compressor motor current A 12 58 Fan motor current A 0 92 Coefficient of performance 2 25 Electrical data Model NH 38NBDT Output W 1 700 Width mm in 1 015 40 Indoor unit Height mm in 320 12 9 16 Depth mm in 190 7 1 2 Width mm in 850 33 1 2 Outdoor unit Height mm in 605 23 13 16 Depth mm in 290 11 3 8 Indoor unit kg lb 14 31 Outdoor unit kg lb 61 135 Air direc...

Page 7: ...Drain hose 16 Insulation 28 350 20 35 248 Air in Air out 290 310 345 30 Service panel 605 292 20 50 183 500 850 74 157 100 Drainage 3holes 16 2 161 Gas refrigerant pipe joint Refrigerant pipe flared 15 88 Liquid refrigerant pipe joint Refrigerant pipe flared 6 35 MS 18 9 52 MS 24 30o 35o INDOOR UNIT OUTDOOR UNIT If a front side or both side is vacant an upper side of a unit has only to be vacant 1...

Page 8: ...ONIC CONTROL P C BOARD TB N L BRN TO OUTDOOR UNIT CONNECTING MF POWER SUPPLY CORD 1 220V 60Hz TRANS NR11 HIC1 IC141 1 DSAR GRN YLW WHT WHT LD1 REMOTE CONTROLLER 3 3 BLU BLU BLU DISPLAY P C BOARD CN 102 3 WHT F12 2 1 CN201 1 3 3 4 F11 5 MV 151 CN 111 CN RT11 BRN YLW RED GRY WHT BLK RECEIVER P C BOARD BLU 112 CN 121 CN RT12 2 101 CN 52C CN211 C11 1 2 4 ELECTRONIC CONTROL P C BOARD TB GRN YLW N 3 RED...

Page 9: ...6 1 4 3 6 5 X1 7 8 b a 52C RED 3 N WHT YLW 52C 1 2 TB 2 C R S BLK RED C1 MC 3 RED ORN WHT BLK YLW RED ORN WHT BLK YLW C2 MF TO INDOOR UNIT CONNECTING 1 1 Side the sleeve 2 2 Pull the wire while pushing the locking lever SYMBOL NAME SYMBOL NAME SYMBOL NAME COMPRESSOR OUTDOOR FAN MOTOR THERMAL REED CAPACITOR INNER THERMOSTAT SWITCH OUTDOOR FAN CAPACITOR COMPRESSOR FAN MOTOR SURGE INNER THERMOSTAT RE...

Page 10: ... RT12 Outdoor heat exchanger REFRIGERANT SYSTEM DIAGRAM 6 INDOOR UNIT INDOOR UNIT OUTDOOR UNIT OUTDOOR UNIT Indoor heat exchanger RT11 Room temperature thermistor Flared connector Flared connector Refrigerant pipe Option 9 52 with heat insulator Refrigerant pipe Option 15 88 with heat insulator Stop Valve 2 0 600 1 6 350 DISCHARGE PRESSURE REGULATOR STRAINER 2 0 100 Flow of refrigerant Compressor ...

Page 11: ...50 0 45 120 S1 S1 MAX HEIGHT DIFFERENCE ADDITIONAL REFRIGERANT CHARGE R 22 g Additional piping Model Max length m A Gas Liquid Indoor unit Outdoor unit MS 18NN 15 6 35 MS 24NN 9 52 15 15 88 0 43 0 S1 S1 Piping size O D mm Length of connecting pipe m MAX REFRIGERANT PIPING LENGTH Note Calculation Xg 15g m A 7 m ...

Page 12: ...es Make sure the pointer gage manifold valve remains in the same position Check the vacuum with the gage manifold valve then close the gage manifold valve and stop the vacuum pump Run the vacuum pump Vacuumize for more than 15 minutes and at this time confirm that the pressure gage shows 0 1 Mpa 76cm Hg Connect the gage manifold valve and the vacuum pump to the service port of the stop valve on th...

Page 13: ...e difference between the indoor intake air wet bulb temperature and the indoor discharge air wet bulb temperature for your reference at service How to measure the indoor air wet bulb temperature difference 1 Attach at least 2 sets of wet and dry bulb thermometers to the indoor air intake as shown in the figure and at least 2 sets of wet and dry bulb thermometers to the indoor air outlet The thermo...

Page 14: ... at MAX Outdoor low pressure kg cm2 Outdoor unit current A MU 18NN S1 MU 24NN S1 MU 24NN S1 MU 18NN S1 Ambient temperature C Ambient humidity Ambient temperature C Ambient humidity Ambient temperature C Ambient humidity Ambient temperature C Ambient humidity Outdoor low pressure kg cm2 Outdoor unit current A Dry bulb temperature Relative humidity 20 50 25 60 30 70 ...

Page 15: ...EL CONTROL or COOL mode Once the mode is fixed the mode will not change by room temperature afterwards Under the ON TIMER operation the mode is determined according to the room temperature as the operation starts When the system is stopped with the OPERATE STOP button on the remote controller and restarted within 2 hours in I FEEL CONTROL mode the system operates in previous mode automatically reg...

Page 16: ... on the room temperature In addition set temperature is controlled by TOO WARM or TOO COOL buttons when you feel too cool or too warm Pressing the TOO WARM or TOO COOL button emits a beep tone Fuzzy control When the TOO COOL or TOO WARM button is pressed the microprocessor changes the set temperature considering the room temperature the frequency of pressing TOO COOL or TOO WARM button and the use...

Page 17: ...s are the fan speed in AUTO Room temperature minus set temperature more than 2 4 degrees C Hi Room temperature minus set temperature 1 4 degrees C Me Room temperature minus set temperature less than 1 1 5 degrees C Lo DRY mode of I FEEL CONTROL The system for dry operation uses the same refrigerant circuit as the cooling circuit The compressor and the indoor fan are controlled by the temperature a...

Page 18: ... fan continues to operate regardless of thermostat s OFF ON Coil frost prevention is same as COOL mode of I FEEL CONTROL 3 DRY OPERATION 1 Press OPERATE STOP button OPERATION INDICATOR of the indoor unit turns on with a beep tone 2 Select DRY mode 3 The microprocessor reads the room temper ature and determines the set temperature Set temperature is as shown in the right chart Thermostat SET TEMP i...

Page 19: ...ts fan motor electric current to make the current rotational frequency close to the target rotational frequency With this control when the fan speed is switched the rotational frequency changes more smoothly than before 2 Fan motor lock up protection When the rotational frequency feedback signal is not output for 12 seconds or when the microprocessor cannot detect the signal for 12 seconds the fan...

Page 20: ...on with the vane angle at Downward when the compressor cumulative operation the exceeds 1 hour the vane angle automatically changes to Horizontal for dew prevention 6 SWING MODE By pressing the SWING button vane swings vertically The remote controller displays SWING mode is cancelled when the SWING button is pressed again or the operation stops or changes to other mode or VANE button is pressed In...

Page 21: ...TIMER button AUTO START operation ON timer OFF TIMER button AUTO STOP operation OFF timer 4 Press HR and MIN button to set the timer Time setting is in 10 minute units HR and MIN button will work when ON or OFF TIMER button is flashing These marks disappear in 1minute When setting the ON timer check that OPERATION INDICATOR of the indoor unit lights NOTE1 Be sure to place the remote controller at ...

Page 22: ...peration The thermostat is ON and the timer is reset to normal After 30 minutes of test run operation the system shifts to emergency run operation with a set temperature of 24 C in cooling The fan shifts to MED speed This operation continues until the Emergency operation switch is pressed or a button on the remote controller is pressed then normal operation will start The coil frost prevention cir...

Page 23: ...sh the RESET button near the MIN button on the remote controller NOTE At power supply failure or installation indoor unit deletes the memory about remote controller When the power supply is turned on and indoor unit receives the first signals from the remote controller the remote controller number is designated as the indoor unit number Therefore at and after the second time indoor unit accepts th...

Page 24: ... LAMP on the indoor unit is flashing to indicate an abnormality To make sure check the abnormality indication for 2 or 3 times before starting service work 2 If the P C board is supposed to be defective check the copper foil pattern for disconnection and the components for bursting and discoloration 3 When troubleshooting refer to the flow chart and the check table on page 25 10 14 How to replace ...

Page 25: ...tor Refer to Test point dia gram and voltage on page 29 2 time flash 2 5 second OFF 3 time flash 2 5 second OFF Start C A 10 2 1 troubleshooting check table Operation Indicator Before taking measures make sure that the symptom reappears for accurate troubleshooting Self check table NO 1 2 Abnormal point Indoor coil thermistor Room tempera ture ther mistor Indoor fan motor Indication 2 time flash 2...

Page 26: ...ce between the terminals with a tester Coil wiring temperature 10 C 40 C Measure the resistance between the terminals with a tester Part temperature10 C 30 C Figure P Normal 8kΩ 20kΩ Abnormal Opened or short circuited Normal 18NN 0 88 1 08Ω 1 73 2 12Ω 0 73 0 90Ω 1 61 1 97Ω 24NN C R C S Normal Abnormal Opened or short circuited 116 126Ω WHT BLK BLK RED BRN YLW YLW GRY Normal 4 5 5 5V Abnormal Remai...

Page 27: ...Replace batteries see page 24 Turn a radio to AM and press switch on remote controller Is noise heard from radio Are there any fluorescent lights of inverter or rapid start type within the range of 1m Measure the voltage between receiver board connector No 2 and No 1 when remote controller button is pressed Is the voltage approx 4V DC Replace indoor electronic control P C board Replace the receive...

Page 28: ...Test mode operates for 30 minutes Replace indoor electronic control P C board Check outdoor unit fan motor and compressor Check continuity of indoor and outdoor unit connection No Yes Yes No Check voltage to terminal block of outdoor unit Is there AC220V to terminal block between 2 N Check voltage to terminal block of indoor unit Is there AC220V to terminal block between 2 N MS 18NN Start Press EM...

Page 29: ...nic control P C board S1 S1 Fan motor power supply Fuse AC250V 3 15A Power supply input AC220V DC5V Indoor coil thermistor RT12 Time short mode point Emergency switch Room temperaure thermistor RT11 DC12V Room temperature thermistor RT11 Indoor coil thermistor RT12 ...

Page 30: ... cover 4 Remove the screw of terminal block 5 Unhook the catch of the lamp holder 6 Remove the receiver holder 7 Disconnect the connector and remove the earth and the indoor coil thermistor 8 Remove the electronic P C board 11 1 MS 18NN MS 24NN INDOOR UNIT S1 S1 Photo 2 Photo 1 Front panel Screws Screw Terminal block screw Indoor coil thermistor Electrical P C board Earth DISASSEMBLY INSTRUCTIONS ...

Page 31: ...e screws of the bearing support 6 Remove the screw of the heat exchanger unhook the catch 7 Lifting the heat exchanger remove the bearing support 8 Remove the motor support 9 Loose the screw fixing the line flow fan remove the line flow fan 10 Remove the screws of the side cover remove the fan motor Photo 3 Photo 4 Heat exchanger screw Catch Bearing support screws Heat exchanger Indoor fan motor L...

Page 32: ... the electrical parts 1 Remove the cabinet Refer to 1 2 Remove the following parts Compressor capacitor C1 Outdoor fan capacitor C2 Terminal block Compressor contactor 52C MU 24 Surege absorber CR MU 24 Fan motor relay X1 MU 24 Thermal reed switch 26F1 MU 24 Photo 1 Photo 3 Photo 2 Screws Screws Service panel Compressor capacitor 11 2 MU 18NN MU 24NN OUTDOOR UNIT S1 S1 ...

Page 33: ...t Refer to 1 2 Remove the soundproof felt 3 Remove the terminal cover on the compressor 4 Remove the electrical assembly Refer to 2 5 Release gas from the refrigerant circuit 6 Disconnect the welded part of the discharge pipe 7 Disconnect the welded part of the suction pipe 8 Remove nuts fixing the compressor 9 Remove the compressor Photo 5 Compressor Discharge pipe Suction pipe Compressor set nut...

Page 34: ...138 010 GRILLE 1 1 3 E02 143 234 BOX 1 1 4 E02 141 100 AIR FILTER 2 2 1PC SET 5 E02 141 970 INSTALLATION PLATE 1 1 6 E02 143 067 SCREW CAP 3 3 3PCS SET E02 173 007 LANP PANEL 1 E02 177 007 LANP PANEL 1 8 AIR CLEANING FILTER OPTIONAL PARTS MAC 1100FT 9 DEODORIZING FILTER OPTIONAL PARTS MAC 1600DF S1 S1 7 OPTIONAL PARTS See page 37 8 9 Part number that are circled is not shown in the illustration ...

Page 35: ...LECTRONIC CONTROL P C BOARD 1 E02 176 450 ELECTRONIC CONTROL P C BOARD 1 8 E02 141 081 ELECTRICAL BOX 1 1 9 E02 141 302 LINE FLOW FAN 1 1 10 E02 141 303 VANE MOTOR 1 1 11 E02 138 329 DISPLAY P C BOARD 1 1 12 E02 141 509 BEARING MOUNT 1 1 E02 138 375 TERMINAL BLOCK TB 1 E02 209 375 TERMINAL BLOCK TB 1 14 E02 085 385 VARISTOR NR11 1 1 15 E02 139 350 INDOOR FAN CAPACITOR C11 1 1 1 8 440V 16 E02 138 3...

Page 36: ...NCDT E02 177 900 COMPRESSOR MC 1 NH38NBDT E02 138 290 BASE 1 E02 176 290 BASE 1 E02 144 301 OUTDOOR FAN MOTOR MF 1 RA6V50 E02 147 301 OUTDOOR FAN MOTOR MF 1 RA6V60 9 E02 141 501 PROPELLER FAN 1 1 10 E02 082 353 COMPRESSOR CAPACITOR C1 1 1 50 440V 11 E02 138 351 OUTDOOR FAN CAPACITOR C2 1 1 3 0 440V E02 141 374 TERMINAL BLOCK TB 1 E02 139 374 TERMINAL BLOCK TB 1 E02 176 936 CAPILLARY TUBE 1 3 0 x 1...

Page 37: ...ame in Wiring MS 18NN MS 24NN Remarks Diagram WH 1 E02 141 426 REMOTE CONTROLLER 1 2 E02 141 083 REMOTE CONTROLLER HOLDER 1 S1 S1 Symbol Q ty unit NO Part No Part Name in Wiring MS 18NN MS 24NN Remarks Diagram WH WH 1 E02 141 620 INDOOR HEAT EXCHANGER 1 1 E02 138 667 UNION LIQUID 1 6 35 E02 176 667 UNION LIQUID 1 9 52 3 E02 138 666 UNION GAS 1 1 15 88 S1 S1 2 1 2 ...

Page 38: ... static electricity Normal life of AIR CLEANING FILTER is 3 months However when it becomes dirty replace it as soon as possible Clogged AIR CLEANING FILTER may reduce the air conditioner capacity or cause frost on the air outlet DO NOT reuse AIR CLEANING FILTER even if it is washed DO NOT remove or attach AIR CLEANING FILTER during unit operation 3 DEODORIZING FILTER DEODORIZING FILTER removes amm...

Page 39: ......

Page 40: ...HEAD OFFICE MITSUBISHI DENKI BLDG MARUNOUCHI TOKYO100 TELEX J24532 CABLE MELCO TOKYO Issued in Mar 1997 MEE No OB188 342 Printed in Japan ...

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