1. TECHNICAL TRAINING INVERTER-Y
Introduction
TROUBLESHOOTING

2. CONTENTS Error Indication Error Diagnosis & Troubleshooting Guide
Tools , Equipment

3. ERROR INDICATION

4. ERROR INDICATION From indoor units
When any error occurs, indoor LED display will keep blinking – green light:
The blinking pattern not indicate error details
The error details have to retrieved from handset
in error code form.
LED blinks here

5. ERROR INDICATION Indoor : wireless handset -- G17 (McQuay)
-- G18 (Acson)
New -- GS01 (McQuay)
New -- GS02 (Acson)
: wired handset Netware 3 (standard for Ceiling Concealed)

6. ERROR INDICATION Using wireless handset G17/18 to retrieve error code:
For G17, hold down ON TIMER CANCEL or OFF TIMER CANCEL for 5 seconds. For G18, Hold down TIMER CANCEL for 5 seconds until “ ” indication flashes on the handset temperature display section.
G18
G17
ON TIMER CANCEL
OFF TIMER CANCEL

7. ERROR INDICATION
Then, press the same button repeatedly . A series of error code will appear until ID buzzer produces a long beep. The corresponding error code is indicated on the handset temperature display section.
ID unit buzzer will produce a long beep if the handset error code matched with unit error.
A short and two consecutive beeps is not the unit error.
The code display will cancel itself if the button is not pressed for 1 minute.

8. OFF TIMER CANCEL button
ERROR INDICATION
How to retrieved last state error
Remove battery from remote controller
Replace battery again into remote controller
Press Mode & ON/OFF buttons together
The “ 00 “ will show at temperature section
Press Mode button to 5:00
Press ON/OFF once
Repeat the normal step for faulty diagnosis by remote controller step
ON/OFF button
Mode button
OFF TIMER CANCEL button
ON TIMER CANCEL button

9. ERROR INDICATION Using wireless handset GS01/02:
Hold down ON TIMER CANCEL or OFF TIMER CANCEL for 5 seconds until “ ” indication flashes on the handset temperature display section.
ON TIMER CANCEL
OFF TIMER CANCEL

10. ERROR INDICATION
Then, press the same button repeatedly. A series of error code will appear until ID buzzer produces a long beep. The corresponding error code is indicated on the handset temperature display section.
ID unit buzzer will produce a long beep if the handset error code matched with unit error.
A short and two consecutive beeps is not the unit error.
The code display will cancel itself if the button is not pressed for 1 minute.

11. ERROR INDICATION Using wired handset Netware 3:
The error will show at last 2 digits of the clock display.
Netware 3 also can retrieved last state memory by :
Press SLEEP & TIMER ACTIVE simultaneously and the error will be flashed on the last 2 digits of the clock display.

12. ERROR INDICATION Error code description for Y-series inverter : No.
ERROR DESCRIPTION
5LCY
10/15 DR 20/25 CR
5LCY 10/15 ER
5LCY 30/40/50/60 CR
5MSY
20/25/30 BR 1 00
Normal √ 2 A1
INDOOR PCB ERROR 3 A3
DRAIN PUMP ABNORMAL x 4 A5
ANTIFREEZE PROTECTION 5 A6
INDOOR FAN MOTOR ABNORMAL 6 A7
AIR SWING MOTOR LOCK 7 A8
ABNORMAL POWER SUPPLY VOLTAGE 8 C4
INDOOR HEAT EXCHANGER THERMISTOR SHORT/OPEN 9 C9
INDOOR ROOM THERMISTOR SHORT/OPEN
= will be explain in error diagnosis

13. ERROR INDICATION Error code description for Y-series inverter : No.
ERROR DESCRIPTION
5LCY
10/15 DR 20/25 CR
10/15ER
5LCY 30/40/50/60 CR
5MSY
20/25/30 BR 10 E1
OUTDOOR PCB ERROR x √ 11 E3
HIGH PRESSURE PROTECTION 12 E4
LOW PRESSURE PROTECTION 13 E5
COMPRESSOR OVERLOAD 14 E6
COMPRESSOR LOCK /START-UP ERROR 15 E7
OUTDOOR FAN MOTOR LOCK 16 E8
AC INPUT OVER CURRENT 17 E9
EXV ERROR 18 EA
4 WAY VALVE ERROR 19 F3
DISCHARGE PIPE OVERHEAT

14. ERROR INDICATION Error code description for Y-series inverter : No.
ERROR DESCRIPTION
5LCY
10/15 DR 20/25 CR
5LCY 10/15 ER
5LCY 30/40/50/60 CR
5MSY20/25/30 BR 20 F6
HEAT EXCHANGER OVERHEAT √ x 21 H0
COMPRESSOR SENSOR SYSTEM ABNORMAL 22 H3
HIGH PRESSURE SWITCH ERROR 23 H6
POSITION SENSOR ABNORMAL ( compressor ) 24 H8
AC CURRENT SENSOR ERROR 25 H9
OUTDOOR AIR THERMISTOR SHORT/OPEN 26 J1
PRESSURE SENSOR ERROR 27 J3
COMPRESSOR DISCHARGE PIPE THERMISTOR SHORT/OPEN/MISPLACED 28 J5
SUCTION PIPE THERMISTOR SHORT/ OPEN X 29 J6
OUTDOOR HEAT EXCHANGER THERMISTOR SHORT/ OPEN

15. ERROR INDICATION Error code description for Y-series inverter : No.
ERROR DESCRIPTION
5LCY
10/15 DR
20/25 CR
5LCY 10/15 ER
5LCY 30/40/50/60 CR
5MSY20/25/30 BR 30 J7
SUBCOOLING HEAT EXCHANGER THERMISTOR SHORT/ OPEN x √ 31 J8
LIQUID PIPE THERMISTOR SHORT/ OPEN 32 J9
GAS PIPE THERMISTOR SHORT/ OPEN 33 L1
OUTDOOR PCB ERROR 34 L3
ELECTRICAL BOX TEMPERATURE RISE
( compressor off ) 35 L4
HEAT SINK OVERHEAT ( compressor on ) 36 L5
IPM ERROR / IGBT ERROR ( output over current ) 37 L8
ELECTRONIC THERMAL ( time lag-compressor signal disorder position)

16. ERROR INDICATION Error code description for Y-series inverter : No.
ERROR DESCRIPTION
5LCY
10/15 DR 20/25 CR
5LCY 10/15 ER
5LCY 30/40/50/60 CR
5MSY20/25/30 BR 38 P1
OPEN PHASE OR VOLTAGE UNBALANCE x √ 39 P4
HEAT SINK THERMISTOR SHORT / OPEN 40 U0
INSUFFICIENT GAS 41 U2
DC VOLTAGE OUT OF RANGE 42 U4
COMMUNICATION ERROR 43 UA
INSTALLATION ERROR 44 UH
ANTIFREEZE PROTECTION IN OTHER ROOM

17. ERROR INDICATION 1) 5LCY-10/15DR, 20/25CR : 7 segment display
From outdoor unit :
When unit error happen, the error will show at outdoor display .
1) 5LCY-10/15DR, 20/25CR : 7 segment display
2) 5MSY-20/25/30BR : 5 LED light indicator
3) 5LCY-30/40/50/60ER : 2 LED light indicator
4) 5LCY-10/15ER : Nil

18. ERROR INDICATION 1. 5LCY-10/15 DR, 20/25CR: 7 segment display
The 7 segment display is located inside outdoor unit control panel beside the terminal block. Control panel cover have to remove before access to the 7 segment display.
Overall photo for
slx10,25
Overall photo for
control box slx10,25

19. ERROR INDICATION
When there is no error, compressor running frequency is displayed.
When there is error, it flashes the error code as below:
Normal operation
Flashing error code

20. ERROR INDICATION
In addition, 7 segment also can be use to retrieve unit operating condition such as running current, DC voltage, ambient temperature, indoor air temperature , etc.
By pressing the tact switch, the 7 segment will start to flash from “00”. Press again, it will show “ 01”
and subsequent running number shows
the parameter number.
Then, the 7 segment will flashing again
showing the parameter measurement.
When the 7 segment display is left untouched
for 5 min, the display will light off (Dim).

21. ERROR INDICATION
For measurement of 125, the 7 segment will display as 25 first follow by 01

22. ERROR INDICATION
2. 5MSY-20/25/30BR: 5 LED display at display board
LED A – flashing GREEN LED indicates normal equipment condition.
LED – OFF condition of the red LED indicates normal equipment
condition.
LED blinking indicates error.

23. ERROR INDICATION
Error code for 5MSY :

24. ERROR INDICATION
3. 5LCY-30/40/50/60ER: 2 LED light indicator
LED HAP – flashing GREEN LED indicates normal condition.
LED HAP – OFF condition indicates power supply abnormal or faulty
outdoor PCB
LED H3P – OFF condition of the red LED indicates normal condition.
LED H3P – ON condition indicates protection devices activate

25. OTHERS 5LCY30/40/50/60 display PCB guide : 5LCY30 ER 5LCY 40/50/60 ER

26. ERROR INDICATION
4. 5LCY-10/15ER: Nil
For K-series inverter, the outdoor will not have error indicator, have to refer to indoor when error happen.

27. ERROR DIAGNOSIS

28. ERROR DIAGNOSIS ERROR A 1 : Indoor PCB error Troubleshooting flow :
Error message : A1
Method of malfunction detection : Evaluation of zero- cross detection of power supply by indoor unit
Malfunction decision condition : When there is no zero-cross detection in 10 seconds continuously.
causes : 1.) Faulty indoor PCB
2.) Faulty connector connection at indoor
Troubleshooting flow :
Turn off unit
Check indoor PCB connector conditions
( including PCB to terminal block and all PCB wire connector)
YES
Any sign of loose or abnormal
Connect correctly and operate again NO
Replace indoor PCB and operate again

29. ERROR DIAGNOSIS
ERROR A 3 : Drain pump abnormal (for ceiling cassette unit)
Error message : A3
Method of malfunction detection : Evaluation of water level upper limit and float switch condition
Malfunction decision condition : When water level reach upper limit and float switch turn off
causes : 1.) Faulty drain pump or float switch
2.) Improper drain piping work or drain pipe blockage
Troubleshooting flow :
Turn off unit
Check drain pump connector connect
to indoor PCB
YES
Any sign of loose or abnormal
Connect correctly and operate again NO
Restart back operation

30. ERROR DIAGNOSIS
ERROR A 3 : Drain pump abnormal (for ceiling cassette unit) NO
Drain pump works ?
Change drain pump
YES
Drain water level abnormal high
after sometimes ?
Float switch connect to
the PCB? NO NO
Connect float switch
YES
YES
Drainage system problem or blockage
Check float switch have
continuity? NO
Change float switch
YES
Change indoor PCB

31. ERROR DIAGNOSIS ERROR A 5 : Antifreeze Protection Error message : A5
Method of malfunction detection : Freeze-up protection control during cooling by detection of indoor heat exchanger thermistor.
Malfunction decision condition : When indoor heat exchanger thermistor less than 0 ◦ C .
causes : 1.) Indoor air filter , heat exchanger block .
2.) Indoor air short circuit .
3.) Indoor coil thermistor faulty, Indoor PCB faulty.
Troubleshooting flow :
Check indoor air flow
YES
Any air short circuit ?
Provide sufficient air passage NO
Check intake air filter

32. ERROR DIAGNOSIS ERROR A 5 : Antifreeze Protection YES
Is it very dirty ?
Clean the air filter NO
Check the dust accumulate at indoor coil
YES
Is it very dirty ?
Clean the indoor coil
Check indoor coil thermistor resistance
# Refer to thermistor resistance table
Does it conform to the thermistor
accuracy table?
YES
Change indoor PCB NO
Change indoor coil thermistor

33. ERROR DIAGNOSIS ERROR A 6 : Indoor fan motor abnormal
Error message : A6
Method of malfunction detection : Rotation speed detected by the indoor PCB during fan motor running is used to determine this error.
Malfunction decision condition : When the detected motor rotation speed does not reach the target rotation speed by the program
causes : 1.) Indoor fan motor winding short, or the motor lead wire broken
2.)Indoor PCB faulty.
Troubleshooting flow :

34. Turn off power supply and rotate fan by hand
ERROR DIAGNOSIS
ERROR A 6 : Indoor fan motor abnormal
Turn off power supply and rotate fan by hand NO
Does it rotate ?
Change fan motor
YES
Turn ON and run fan NO
Does it rotate ?
Change fan motor
YES
Change PCB

35. OTHERS : Inverter–Y series fan motor: 5LCY 10/15 DR 5LCY 20/25 CR
5LCY 10/15 ER
5MSY 20/25/30 BR
5LCY 30/40/50/
60 ER
Outdoor AC DC
Indoor WM
------
CC,CK, CM

36. ERROR DIAGNOSIS ERROR A 8 : Abnormal power supply voltage
Error message : A8
Method of malfunction detection : Checking of input voltage
Malfunction decision condition : When the voltage detected out of range of ± 10 % of 240 V.
causes : 1.) Power supply problem or blackout.
2.) Wiring problem or Indoor PCB faulty.
Troubleshooting flow :
Check the condition of power source :
1.) voltage is 220V-240V± 10%
2.) Check there is power open phase or wiring problem
3.) Check power supplier fluctuation within 6V
Any problem as describe above?
YES
Correct the supply problem NO
Possible of external factor such as blackout

37. ERROR DIAGNOSIS ERROR C4, C9 : INDOOR HEAT EXCHANGER , ROOM THERMISTOR
SHORT/OPEN
Error message : C4, C9
Method of malfunction detection : Temperature detected by the thermistor
Malfunction decision condition : When the thermistor input is > 4.96V or <0.04V during compressor operation.
causes : 1.) Thermistor , connector faulty.
2.) Indoor PCB faulty.
Troubleshooting flow :
Check the thermistor connector condition No
Normal ?
Correct the problem
Yes
Check thermistor resistance value
# Refer thermistor resistance table No
Normal ?
Replace thermistor
Replace PCB

38. ERROR DIAGNOSIS ERROR C4, C9 Indoor heat exchanger thermistor
( 5WMY10/15 JR ) Location of indoor coil thermistor:
CN COIL

39. Air intake gap for room temperature sensing
ERROR DIAGNOSIS
ERROR C4, C9
Indoor room thermistor
For room thermistor : WMY-J series, K-series = Chips type thermistor mount to the PCB.
other indoor - copper sensor attached to return air location
Air intake gap for room temperature sensing
RTH201
Unit design with air opening at the front panel to allow
sufficient space for air flow & measurement

40. ERROR DIAGNOSIS
ERROR E3 : High pressure protection (for 5LCY ER)
Error message : E3
Method of malfunction detection : Protection device check high pressure switch continuity
Malfunction decision condition : When the high pressure switch is turn off at 4MPa. ( 580 psi ) , turn on at 3 MPa ( 435 psi )
causes : 1.) faulty high pressure switch , connector or wire harness
2.) Indoor filter , outdoor coil dirty.
3.) Outdoor fan not running, unit overcharge, stop valve is closed.
Troubleshooting flow :
Check the installation condition No
Stop valve open?
Open the stop valve
Yes
High pressure switch connect
to outdoor PCB? No
Connect correctly
Turn off unit. Wait for compressor stop 10 minutes

41. ERROR DIAGNOSIS ERROR E3 : High pressure protection (for 5LCY30-60 ER)
Have continuity for high
pressure switch? No
Replace high pressure switch
Yes
Check the abnormal unit high
pressure condition
# Refer how to check high pressure condition
Have abnormal condition?
Yes
Correct the abnormal condition No
Replace outdoor PCB

42. Outdoor high pressure condition check :

43. ERROR DIAGNOSIS Installation condition : 5LCY10/15 DR
Where a wall or other obstacle is in the path of outdoor unit’s intake or exhaust airflow
Follow this installation guidelines to avoid air short circuit

44. ERROR DIAGNOSIS ERROR E4 : Low pressure protection (for 5LCY30-60 ER)
Error message : E4
Method of malfunction detection : Protection device check low pressure switch continuity
Malfunction decision condition : When the pressure detected is < 0.12 MPa ( 17 psi )for continues 5 minutes.
causes : 1.) faulty low pressure switch , faulty outdoor PCB
2.) Stop valve closed, unit leakage or refrigerant not enough.
3.) Abnormal refrigerant piping system ,faulty EXV
Troubleshooting flow :
Stop valve open? No
Open the stop valve
Yes
Low pressure switch connect
to outdoor PCB? No
Connect correctly
Yes
Measure the voltage between low pressure switch
# Refer how to check low pressure voltage

45. ERROR DIAGNOSIS ERROR E4 : Low pressure protection (for 5LCY30-60 ER)
Relation between Voltage and
pressure follow the graph? No
Change the low pressure switch
Yes No
Is the refrigerant pressure
abnormally low?
Change the Outdoor PCB
Yes
Correct refrigerant system
( gas shortage, leakage or piping block )
# Refer how to check low pressure condition

46. Outdoor low pressure condition check :

47. Outdoor pressure sensor condition check :
For 5LCY30-60 ER pressure switch:
PH = detected pressure ( MPa )
V = Output Dc voltage
PH = 1.38 V -0.69

48. ERROR DIAGNOSIS ERROR E5 : Compressor overload Error message : E5
Method of malfunction detection : Detected by compressor overload
Malfunction decision condition : When compressor overload activate twice. If active once, will be reset if not happen in following 60 mins.
causes : 1.) Stop valve , EXV defective
2.) 4wv , outdoor PCB defective
3.) Refrigerant shortage, water mixed in the piping
Troubleshooting flow :
Turn off unit. Disconnect
Compressor wire hardness
( U,V,W )
Check compressor winding resistance
# Refer compressor resistance table
Resistance normal? No
Change compressor
Yes

49. ERROR DIAGNOSIS ERROR E5 : Compressor overload
Connect back wire and turn on unit
Compressor stop without running?
Yes
Change outdoor PCB No
Compressor run for sometimes.
Check EXV, stop valve, refrigerant level, 4WV and
water in the piping, installation condition

50. ERROR DIAGNOSIS Inverter –Y series Compressor spec:
5LCY 10/15 DR
5LCY 20/25 CR
5LCY 10/15 ER
5MSY 20 BR
5MSY25/30 BR
5LCY 30 ER
5LCY 40/50/60 ER
Compressor type
Rotary
(swing)
rotary
scroll
Compressor manufacturer
Panasonic
Daikin
Compressor model
5RS102XBJ01
2YC32GXD
1YC23AEXDA
2YC36BXD
2YC45BXD
2YC63DXD
JT-100G-VD
Compressor winding resistance
( U,V,W ) -Ω
0.858
1.18
1.764
0.828
0.787
0.31
motor
6 pole brushless motor
4 pole brushless motor
General guide :1) Resistance of compressor winding < 10 Ω consider Ok
2) All 3 terminal resistance value must be same.

51. Other : Inverter –Y series Compressor spec : 6 poles motor

52. ERROR DIAGNOSIS ERROR F3 : Discharge pipe overheat Error message : F3
Method of malfunction detection : Compressor discharge thermistor is checked with discharge temperature control.
Malfunction decision condition : When compressor discharge temperature is at abnormal high level or rise suddenly.
E.g. : degree C varies by model degree C when compressor frequency low.
causes : Faulty discharge thermistor, compressor, Outdoor PCB
2. Refrigerant shortage
Troubleshooting flow :
Check discharge thermistor condition
Any wire damage,
not insert to connector?
Yes
Correct wiring No
Check discharge thermistor resistance value
# Refer resistance table : for discharge thermistor, different spec.

53. ERROR DIAGNOSIS ERROR F3 : Discharge pipe overheat Resistance value
Normal? No
Change discharge thermistor
Yes
Check refrigerant level, compressor,
EXV & stop valve.

54. ERROR DIAGNOSIS ERROR F6 : Heat exchanger overheat Error message : F6
Method of malfunction detection : Detect heat exchanger ( outdoor coil ) temperature during cooling mode .
Malfunction decision condition : Activate when outdoor coil temperature exceed 65 º C. Error reset when temperature drop to 50º C.
causes : 1.) Faulty outdoor coil thermistor, faulty outdoor PCB
2.) Installation space not enough, hot air short circuit, fan motor not running , coil dirty
Troubleshooting flow :
Check outdoor installation condition
Any abnormal?
Yes
Change outdoor location,
clean outdoor coil. No
Check outdoor fan motor

55. ERROR DIAGNOSIS ERROR F6 : Heat exchanger overheat No
Fan motor running smoothly? No
Change fan motor
Yes
Check outdoor coil thermistor resistance
# Refer resistance table
Resistance normal? No
Change thermistor
Yes
Change outdoor PCB

56. ERROR DIAGNOSIS ERROR H0 : Compressor sensor system abnormal
Error message : F6
Method of malfunction detection : Detect the compressor current and voltage before compressor start.
Malfunction decision condition : Detected DC voltage is too low or too high. No current detected when compressor start
causes : 1.) Outdoor PCB, compressor problem
2.) Compressor wrong wiring, reactor not connected.
Troubleshooting flow :
Check reactor connection
Any abnormal?
Yes
Connect back reactor No
Check reactor resistance

57. ERROR DIAGNOSIS ERROR H0 : Compressor sensor system abnormal
Check reactor resistance
# disconnect the reactor wire and measure resistance between terminal No
<10 Ω ?
Change reactor
Yes
Check compressor resistance
<10 Ω ? No
Change compressor
Yes
Change outdoor PCB

58. ERROR DIAGNOSIS
ERROR H9, J3,J5,J6,J7,J8,J9,P4 : Outdoor Thermistor related abnormal
Error message : H9,J3,J5,J6,J7,J8,J9,P4
Method of malfunction detection : Detect the temperature detected by the thermistor.
Malfunction decision condition : When thermistor is disconnected or short circuit during operation.
J3 is judged when compressor discharge thermistor temperature is smaller compare to the condenser
thermistor temperature.
causes : 1.) Thermistor, connector problem
2.) Outdoor PCB problem
Troubleshooting flow :
Check connector for the thermistor with error
Yes
Thermistor disconnected or loose?
Connect thermistor back No
Check thermistor resistance
# Refer thermistor spec and the table.

59. Resistance value normal?
ERROR DIAGNOSIS
ERROR H9, J3,J5,J6,J7,J8,J9,P4 : Outdoor Thermistor related abnormal
Resistance value normal? No
Change thermistor
Yes
Change outdoor PCB
H9 :Outdoor air thermistor
J3 : Compressor discharge thermistor
J5 : Suction pipe thermistor (for 5LCY30-60 model)
J6 : Outdoor heat exchanger thermistor
J7 : Sub-cool heat exchanger thermistor (for 5LCY model)
J8 : Liquid pipe thermistor (for 5LCY30-60, 5MSY20-30)
J9 : Gas pipe thermistor (for 5MSY20-30)
P4 : Heat sink thermistor (for 5MSY20-30, 5LCY10-15ER, 5LCY10-15DR)

60. ERROR DIAGNOSIS Inverter –Y series Thermistor spec : 5LCY 10/15 DR
5LCY 20/25 CR
5LCY 10/15 ER
5LCY 30/40/50/60 ER
5MSY 20/25/30 BR
Indoor WM
10K
20K
------
CC,CK, CM
Outdoor
Except for
discharge pipe thermistor =230K
(Refer 20k table)

61. How to check thermistor resistance
Use multi meter to check the thermistor resistance value.

62. Inverter–Y series Thermistor spec : (10 KΩ)
At 25C
Resistance value: 10 k

63. Inverter–Y series Thermistor spec : (20 KΩ)
At 25C
Resistance value: 20 k

64. Inverter–Y series Thermistor spec : (discharge thermistor)
Discharge thermistor spec for 5LCY 30/40/50/60

65. ERROR DIAGNOSIS For Outdoor 5LCY10/15 DR :
Outdoor air thermistor with PVC protection sleeve
All thermistor ( discharge, air, coil ) share a same connector and connect to PCB
Outdoor discharge , heat exchanger
Thermistor : copper type

66. ERROR DIAGNOSIS
ERROR L3 : Electrical Box temperature rise (compressor off)
Error message : L3
Method of malfunction detection : Detect the temperature of heat sink when compressor off.
Malfunction decision condition : Heat sink temperature >80 º C( MSY ), > 93 º C ( K-series ) when compressor off. Error reset when
temperature drop < 70 º C.
causes : 1.) Outdoor fan , PCB problem
2.) Heat sink thermistor, connector problem

67. ERROR DIAGNOSIS
ERROR L3 : Electrical Box temperature rise (compressor off)
Troubleshooting flow :
Turn off the unit and turn on back after 20 mins No
Error again ?
Check outdoor fan
# Refer thermistor spec and the table.
Yes No
Check heat sink thermistor resistance
Outdoor fan functioning?
Change outdoor
fan motor
Yes No No
Heat sink dirty?
Check installation
condition
Change thermistor
Resistance normal?
Yes
Yes No
Heat sink temperature
> 80 ºC ?
Clean the heat sink
Change outdoor PCB
Change heat sink or check outdoor fan condition

68. ERROR DIAGNOSIS ERROR L4 : Heat sink overheat (compressor on)
Error message : L4
Method of malfunction detection : Detect the temperature of heat sink when compressor on.
Malfunction decision condition : Heat sink temperature >103º C( MSY ), > 93 º C ( K-series ) when compressor on. Error clear when
not happen in the following 60 mins.
causes : 1.) Outdoor fan , PCB problem
2.) Heat sink thermistor, connector problem

69. ERROR DIAGNOSIS ERROR L4 : Heat sink overheat (compressor on)
Troubleshooting flow :
Turn off the unit and turn on back after 20 mins No
Error again ?
Check outdoor fan
# Refer thermistor spec and the table.
Yes No
Outdoor fan functioning?
Change outdoor
fan motor
Check heat sink thermistor resistance
Yes No
Heat sink dirty?
Check installation
condition
Change thermistor No
Resistance normal?
Yes
Yes No
Heat sink temperature
> 93 ºC ?
Clean the heat sink
Change outdoor
PCB
Yes
Change heat sink or check outdoor fan condition
# Make sure condition of silicon grease apply to IPM , and diode bridge is good.

70. Application of silicon grease to IPM board and diode bridge :

71. ERROR DIAGNOSIS Bad condition of silicon grease can cause
L4 ( heat sink overheat )
L5 ( IPM error )
Heat sink
Silicon grease
IPM board

72. ERROR DIAGNOSIS
For Outdoor 5LCY10/15 DR : The heat sink thermistor is screw and connect
the PCB ( port : CN HTSK )

73. Turn off the unit and turn on back after 20 mins
ERROR DIAGNOSIS
ERROR L5 : IPM (inverter power module) / IGBT error
(output over current)
Error message : L5
Method of malfunction detection : Detect the output current that flows into IPM board inverter DC section.
Malfunction decision condition : When over current has been detected by IPM and feedback MCU.
A position signal , speed signal error happen during compressor running.
causes : 1.) Over current due to IPM board, internal wiring, wire connector loose, PCB problem
2.) Over current due to stop valve close, compressor failure, abnormal supply voltage.
3.) Over current due to silicon grease not apply to the IPM board contact point properly. No
Stop valve fully open?
Open stop valve
Yes
Turn off the unit and turn on back after 20 mins
Continue monitor for supply voltage, discharge,
suction pressure, compressor overload,
Check for silicon grease at IPM condition
Error again ? No
Yes

74. ERROR DIAGNOSIS ERROR L5 : IPM / IGBT error (output over current)
Turn off the unit and disconnect
compressor U,V,W wire
Check compressor winding resistance
Resistance normal No
Change compressor
Yes
Change the Outdoor PCB

75. ERROR DIAGNOSIS ERROR U0 : Insufficient gas Error message : L5
Method of malfunction detection : Checking compressor running frequency and input current.
Checking compressor discharge temperature versus target discharge temperature and EXV opening.
Malfunction decision condition : When input current is smaller compare to target current.
When compressor discharge temperature is higher compare to target discharge temperature and the EXV
opening is high( >450 pulse )
causes : 1.) Refrigerant shortage, unit leakage
2.)Refrigerant piping system block,
3.) EXV defective, thermistor disconnected, stop valve closed

76. ERROR DIAGNOSIS ERROR U0 : Insufficient gas Yes
Any thermistor disconnected?
Yes
Connect back No
Stop valve closed?
Yes
Open stop valve No
Check for EXV function
EXV functioning? No
Change EXV
Yes
Check for refrigerant level
# How to check refrigerant level

77. ERROR DIAGNOSIS ERROR U0 : Insufficient gas Refrigerant level normal?
Check for leakage
Yes
Change thermistor, outdoor PCB or compressor
Any leakage?
Yes
Repair the leak point No
Add refrigerant

78. How to check refrigerant level
- To set unit run in force cooling (unit will run at rated compressor fixed frequency).
- Connect pressure gauge outdoor suction service valve and measure the suction
pressure.
- Ideal suction pressure level : psi
(depends on the outdoor ambient temperature).

79. ERROR DIAGNOSIS Press & hold
Press and hold on the ID ON/OFF button for 5-9 s when unit is in standby mode.
Set to high fan mode and temperature at 16 °C using remote controller

80. ERROR DIAGNOSIS
ERROR U4 : Communication error (between indoor and outdoor)
Error message : U4
Method of malfunction detection : Data received from the outdoor unit in indoor unit -outdoor unit signal transmission is checked whether it is
normal.
Malfunction decision condition : When the data send from the outdoor cannot be received in ( XX second ) or the data content is abnormal.
causes : 1.) Faulty indoor, outdoor PCB
2.)Indoor-outdoor signal wire line wiring error ( loose or broken ).
3.) External noise, power supply waveform disturbance
Check indoor-outdoor wiring connection
#Refer wiring check
Any wiring problem?
Yes
Correct the wiring No
Check outdoor unit PCB “ status LED “

81. ERROR DIAGNOSIS
ERROR U4 : Communication error (between indoor and outdoor) No
LED light on?
Change outdoor PCB
Yes
Check voltage of indoor-outdoor connection between No.1-No.3 and No.2-No.3
Voltage =0?
Yes
Replace connection between indoor and outdoor No
Check power supply waveform
#Refer supply waveform check
Any disturbance?
Yes
Find the source of power disturbance and correct it No
Replace indoor unit PCB ,
external noise ( interference )

82. Wiring – How to check communication wire :
Maximum communication wire length: 50 meters
Make sure the recommended type of wire is used
Check for loose connection

83. Power supply disturbance check
Using power analyzer to check the supply voltage

84. ERROR DIAGNOSIS ERROR UA : Installation error
Error message : UA
Method of malfunction detection : Detected different type of transmission signal ( for different model )
Malfunction decision condition : When detected different coupling of indoor-outdoor unit.
causes : 1.) Outdoor and indoor unit not match ( wrong model , horsepower, )
2.)Wrong indoor-outdoor PCB.
3.) External noise, power supply waveform disturbance
X-series inverter unit can not couple with Y-series inverter
K-series inverter unit can not couple with X, Y series inverter and only available in 1.0 ,1.5 Hose power.

85. ERROR DIAGNOSIS ERROR UA : Installation error 5WMY10/15 JR
5LCY10/15 DR

86. TOOLS & EQUIPMENT

87. TOOLS & EQUIPMENT : to check resistance , voltage, current,
Digital clamp meter
Digital multi-meter
: to check resistance , voltage, current,
wire continuity
AC CURRENT
RESISTANT
AC VOLTAGE

88. TOOLS & EQUIPMENT Manifold (pressure) gauge and hose Gauge :
High side :800 psig
Low side :250 psig for low-side
(500 low-side retard)
Hose : rated 800 psig

89. TOOLS & EQUIPMENT Refrigerant tank Weighing machine Thermocouple
Test pen

90. TOOLS & EQUIPMENT Replacement parts : Indoor/outdoor PCB
5LCY10/15DR –Outdoor PCB
5WMY10/15JR –indoor PCB

91. TOOLS & EQUIPMENT
Brazing equipment
Vacuum pump & vacuum meter.

92. THANK YOU
&
Q & A