Service manual

17
Error Code
Abnormal points and detection method Judgment and action
U1
High pressure (High-pressure switch
63H operated)
Abnormal if high-pressure switch 63H
operated ( w ) during compressor opera-
tion.
w SW40,50 (63H) : 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 defect.
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
10-10.)
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 10-6.
8 Replace outdoor controller board.
Case
U2
<Abnormalities detected while unit is operating>
High discharging temperature
(1) Abnormal if discharge temperature
thermistor (TH4) exceeds 125: or
110: continuously for 5 minutes.
Abnormal if discharge temperature
thermistor (TH4) exceeds 110: or
more continuously for 30 seconds
after 90 seconds have passed since the
defrosting operation started.
(2) Abnormal if discharge superheat
(Cooling: TH4 – T63HS /
Heating: TH4 – T63HS) exceeds 70:
continuously for 10 minutes.
High comp. surface temperature
Abnormal if comp. surface temperature
(TH34) exceeds 125:.In the case of
high comp. surface temperature error,
compressor does not restart unless the
thermistor (TH34) becomes less than
95:.
1 Overheated compressor
operation 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 freezing
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
displayed 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 10-6.
6 After recovering refrigerant, remove water
from entire refrigerant circuit under vacuum
more than 1 hour.
U3
Open/short circuit of discharge
temperature thermistor (TH4) / comp.
surface thermistor (TH34)
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/TH34) on
the outdoor controller circuit
board
2 Defective thermistor
3 Defective outdoor controller
circuit board
1 Check connection of connector (TH4/TH34)
on the outdoor controller circuit board.
Check breaking of the lead wire for
thermistor (TH4/TH34). Refer to 10-9.
2 Check resistance value of thermistor (TH4/
TH34) or temperature by microcomputer.
(Thermistor/TH4/TH34: Refer to 10-6.)
(SW2 on A-Control Service Tool: Refer to 10-10.)
3 Replace outdoor controller board.
OCH525