18
Error Code
Abnormal point and detection method
Judgment and action
U1
High pressure (High-pressure switch
63H operated)
Abnormal if high-pressure switch 63H oper-
ated (
w
) during compressor operation.
w
4.15 MPa
63H: High-pressure switch
1
Short cycle of indoor unit
2
Clogged filter of indoor unit
3
Decreased airflow caused by
dirt of indoor fan
4
Dirt of indoor heat exchanger
5
Locked indoor fan motor
6
Malfunction of indoor fan motor
7
Defective operation of stop
valve (Not full open)
8
Clogged or broken pipe
9
Locked outdoor fan motor
0
Malfunction of outdoor fan
motor
1
Short cycle of outdoor unit
2
Dirt of outdoor heat exchanger
3
Decreased airflow caused by
defective inspection of outside
temperature thermistor
(It detects lower temperature
than actual temperature.)
4
Disconnection or contact failure
of connector (63H) on outdoor
controller board
5
Disconnection or contact failure
of 63H connection
6
Defective outdoor controller
board
7
Defective action of linear
expansion valve
8
Malfunction of fan driving
circuit
1
~
6
Check indoor unit and repair defectives.
7
Check if stop valve is fully open.
8
Check piping and repair defect.
9
~
2
Check outdoor unit and repair defect.
3
Check the detected temperature of outside
temperature thermistor on LED display.
(SW2 on A-Control Service Tool : Refer to
8-8.)
4
~
6
Turn the power off and check F5 is
displayed when the power is turned again.
When F5 is displayed, refer to “Judgment
and action” for F5.
7
Check linear expansion valve.
Refer to 8-6.
8
Replace outdoor controller board.
Case
U2
<Abnormalities detected while unit is operating>
U3
Open/short circuit of discharge
temperature thermistor (TH4)
Abnormal if open (3
:
or less) or short
(217
:
or more) is detected during
compressor operation.
(Detection is inoperative for 10 minutes
of compressor starting process and for 10
minutes after and during defrosting.)
1
Disconnection or contact
failure of connector (TH4) on
the outdoor controller circuit
board
2
Defective thermistor
3
Defective outdoor controller
circuit board
1
Check connection of connector (TH4) on the
outdoor controller circuit board.
Check breaking of the lead wire for
thermistor (TH4). Refer to 8-7.
2
Check resistance value of thermistor (TH4)
or temperature by microcomputer.
(Thermistor/TH4: Refer to 8-4.)
(SW2 on A-Control Service Tool: Refer to 8-8.)
3
Replace outdoor controller board.
<Abnormalities detected while unit is operating>
High discharging temperature
(1) Abnormal if discharge temperature ther-
mistor (TH4) exceeds 125
:
or 110
:
continuously for 5 minutes.
Abnormal if discharge temperature ther-
mistor (TH4) exceeds 110
:
or more
continuously for 30 seconds after 90
seconds have passed since the defrost-
ing operation started.
(2) Abnormal if discharge superheat
(Cooling: TH4 – T
63HS
/ Heating: TH4 –
T
63HS
)
exceeds
70
:
continuously for 10 min-
utes.
1
Overheated compressor opera-
tion caused by shortage of
refrigerant
2
Defective operation of stop
valve
3
Defective thermistor
4
Defective outdoor controller
board
5
Defective action of linear
expansion valve
6
Clogging with foreign objects in
refrigerant circuit
w
Clogging occur in the parts
which become below freez-
ing point when water enters in
refrigerant circuit.
1
Check intake superheat.
Check leakage of refrigerant.
Charge additional refrigerant.
2
Check if stop valve is fully open.
34
Turn the power off and check if U3 is dis-
played when the power is turned on again.
When U3 is displayed, refer to “Judgement
and action” for U3.
5
Check linear expansion valve.
Refer to 8-6.
6
After recovering refrigerant, remove water
from entire refrigerant circuit under vacuum
more than 1 hour.
