Indoor
Unit
FTXS30LVJU, FTXS36LVJU
Outdoor
Unit
RKS30LVJU, RKS36LVJU
U0
Refrigerant Shortage
Refrigerant shortage detection I: Refrigerant shortage is detected by checking
the input current value and the compressor running frequency. If the
refrigerant is short, the input current is lower than the normal value.
Refrigerant shortage detection II: Refrigerant shortage is detected by checking
the discharge pipe temperature and the opening of the electronic expansion
valve. If the refrigerant is short, the discharge pipe temperature tends
to rise.
Refrigerant shortage detection III: Refrigerant shortage is detected by checking
the difference between suction and discharge temperature.
Supposed Causes
Disconnection of the discharge
pipe thermostat, indoor or outdoor heat exchanger thermostat, room or
outdoor temperature thermistor
Closed stop valve
Refrigerant shortage
(refrigerant leakage)
Poor compression performance of
compressor
Defective electronic expansion
valve.
U2
Low-voltage Detection or Over-voltage
Detection
Indoor
Unit
The zero-cross detection of the power
supply is evaluated by the indoor unit PCB.
Outdoor
Unit
Low-voltage
detection:
An abnormal voltage drop is detected
by the DC voltage detection circuit.
Over-voltage
detection:
An abnormal voltage rise is detected
by the over-voltage detection circuit.
Supposed Causes
Supply voltage is not as
specified.
Defective DC voltage detection
circuit
Defective over-voltage detection
circuit
Defective PAM control part
Disconnection of compressor
harness
Noise
Momentary fall of voltage
Momentary power failure
Defective indoor unit PCB
U4
Signal Transmission Error (between
Indoor Unit and Outdoor Unit)
The data received from the outdoor
unit in indoor unit-outdoor unit signal transmission is checked whether it
is normal.
The data sent from the outdoor unit
cannot be received normally, or the content of the data is abnormal.
Supposed Causes
Wiring error
Breaking of the connection wires
between the indoor and outdoor units (wire No. 3)
Defective outdoor unit PCB
Defective indoor unit PCB
Disturbed power supply waveform.
U7
Signal Transmission Error on Outdoor
Unit PCB
Communication error between
microcomputer mounted on the main microcomputer and PM1.
The abnormality is determined when the
data sent from the PM1 can not be received for 9
seconds.
The error counter is reset when
the data from the PM1 can be successfully received.
Supposed Causes
Defective outdoor unit PCB.
UA
Unspecified Voltage
The supply power is detected for its
requirements (different from pair type and multi type) by the
indoor / outdoor transmission signal.
The pair type and multi type are
interconnected.
Supposed Causes
Wrong models interconnected
Wrong wiring of connecting wires
Wrong indoor unit PCB or outdoor
unit PCB mounted
Defective indoor unit PCB
Defective outdoor unit PCB
E1
Outdoor Unit PCB Abnormality
The system checks if the
microprocessor is working in order.
The system checks if the
zero-cross signal comes in properly.
The microprocessor program runs
out of control.
The zero-cross signal is not
detected.
Supposed Causes
Defective outdoor unit PCB
Broken harness between PCBs
Noise
Momentary fall of voltage
Momentary power failure, etc.
E5
OL Activation
A compressor overload is detected
through compressor OL.
If the error repeats, the system
is shut down.
Reset condition: Continuous run
for about 60 minutes without any other error.
* The operating temperature
condition is not specified.
Supposed Causes
Defective discharge pipe
thermistor
Defective electronic expansion
valve or coil
Defective FourWay valve or coil
Defective outdoor unit PCB
Refrigerant shortage
Water mixed in refrigerant
Defective stop valve.
E6
Compressor Lock
A compressor lock is detected by
checking the compressor running condition through the position detection
circuit.
09/12 class
Operation stops due to over
current.
If the error repeats, the system
is shut down.
Reset condition: Continuous run
for about 11 minutes without any other error
15/18/24/30/36 class
A compressor lock is detected by
the current waveform generated when applying high frequency voltage to the
motor.
If the error repeats, the system
is shut down
Reset condition: Continuous run
for about 5 minutes without any other error.
Supposed Causes
Compressor locked
Compressor harness disconnected
E7
DC Fan Lock
An error is determined with the
high-voltage fan motor rotation speed detected by the Hall IC.
The fan does not start in 15 ~
30 seconds (depending on the model) even when the fan motor is running.
If the error repeats, the system
is shut down.
Reset condition: Continuous run
for about 11 minutes (09/12 class) or 5 minutes (15/18/24/30/ 36 class) without
any other error.
Supposed Causes
Foreign matter stuck in the fan
Defective fan motor
Defective outdoor unit PCB
E8
Input Over current Detection
An input overcurrent is detected by
checking the input current value with the compressor running.
The current exceeds about 9.25 ~
20 A for 2.5 seconds with the compressor running.
(The upper limit of the current
decreases when the outdoor temperature exceeds a certain level.)
Supposed Causes
Outdoor temperature is out of
operation range.
Defective compressor
Defective power module
Defective outdoor unit PCB
Short circuit
EA
FourWay Valve Abnormality
The room temperature thermistor and
the indoor heat exchanger thermistor are checked if they
function within their normal ranges in
each operation mode.
A following condition continues over 1
~ 10 minutes after operating for 5 ~ 10 minutes.
Cooling / Dry
(room thermistor temp. – indoor heat
exchanger temp.) < –5°C (–9°F)
Heating
(indoor heat exchanger temp. – room
thermistor temp.) < –5°C (–9°F)
If the error repeats, the system
is shut down.
Reset condition: Continuous run
for about 60 minutes without any other error.
Supposed Causes
Disconnection of fourway valve
coil
Defective fourway valve, coil,
or harness
Defective outdoor unit PCB
Defective thermistor
Refrigerant shortage
Water mixed in refrigerant
Defective stop valve
F3
Discharge Pipe Temperature Control
An error is determined with the
temperature detected by the discharge pipe thermistor.
Supposed Causes
Defective discharge pipe thermistor
(Defective outdoor heat exchanger
thermistor or outdoor temperature thermistor)
Defective electronic expansion
valve or coil
Refrigerant shortage
Defective fourway valve
Water mixed in refrigerant
Defective stop valve
Defective outdoor unit PCB
F6
High Pressure Control in Cooling
High-pressure control (operation halt,
frequency drop, etc.) is activated in cooling operation if the
temperature sensed by the outdoor heat
exchanger thermistor exceeds the limit.
Supposed Causes
The installation space is not
large enough.
Dirty outdoor heat exchanger
Defective outdoor fan motor
Defective stop valve
Defective electronic expansion
valve or coil
Defective outdoor heat exchanger
thermistor
Defective outdoor unit PCB
H0
Compressor System Sensor Abnormality
The system checks the DC current
before the compressor starts.
The DC current before compressor
start-up is out of the range 0.5 ~ 4.5 V (sensor output
converted to voltage value)
The DC voltage before compressor
start-up is below 50 V.
Supposed Causes
Broken or disconnected harness
Defective outdoor unit PCB
H0
The system checks the supply
voltage and the DC voltage before the compressor starts.
The system checks the compressor
current right after the compressor starts.
The supply voltage and the DC
voltage is obviously low or high.
The compressor current does not
run when the compressor starts.
Supposed Causes
Disconnection of reactor
Disconnection of compressor
harness
Defective outdoor unit PCB
Defective compressor
H6
Position Sensor Abnormality
A compressor start-up failure is
detected by checking the compressor running condition through the position
detection circuit.
If the error repeats, the system is
shut down.
Reset condition: Continuous run for
about 11 minutes (09/12 class) or 5 minutes (15/18/24/30/ 36 class) without any
other error
Supposed Causes
Disconnection of the compressor
relay cable
Defective compressor
Defective outdoor unit PCB
Start-up failure caused by the
closed stop valve
Input voltage is outside the specified
range.
H8
DC Voltage / Current Sensor
Abnormality
DC voltage or DC current sensor
abnormality is identified based on the compressor running frequency and the
input current.
If the error repeats, the system
is shut down.
Reset condition: Continuous run
for about 60 minutes without any other error
Supposed Causes
Defective outdoor unit PCB
H8
CT or Related
Abnormality
A CT or related error is detected by
checking the compressor running frequency and CT-detected input current.
Supposed Causes
Defective power module
Broken or disconnected wiring
Defective reactor
Defective outdoor unit PCB
H9,J3,J6,P4
Thermistor or Related
Abnormality (Outdoor Unit)
This fault is identified based on the
thermistor input voltage to the microcomputer. A thermistor fault is identified
based on the temperature sensed by each thermistor.
Supposed Causes
Disconnection of the connector
for the thermistor
Defective thermistor
corresponding to the error code
Defective heat exchanger
thermistor in the case of J3 error (outdoor heat exchanger thermistor in
cooling operation, or indoor heat exchanger thermistor in heating operation)
Defective outdoor unit PCB
L3
Electrical Box
Temperature Rise
An electrical box temperature
rise is detected by checking the radiation fin thermistor with
the compressor off.
Supposed Causes
Defective outdoor fan motor
Short circuit
Defective radiation fin
thermistor
Disconnection of connector
Defective outdoor unit PCB
L4
Radiation Fin
Temperature Rise
A radiation fin temperature rise is
detected by checking the radiation fin thermistor with the compressor on.
Supposed Causes
Defective outdoor fan motor
Short circuit
Defective radiation fin
thermistor
Disconnection of connector
Defective outdoor unit PCB
Silicon grease is not applied
properly on the radiation fin after replacing the outdoor unit PCB.
L5
Output Overcurrent
Detection
An output overcurrent is detected by
checking the current that flows in the inverter DC section.
Supposed Causes
Poor installation condition
Closed stop valve
Defective power module
Wrong internal wiring
Abnormal power supply voltage
Defective outdoor unit PCB
Defective compressor
