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<Abnormalities detected while unit is operating>
Error Code
Abnormal point and detection method
Judgment and action
U1
(1302)
High pressure (High-pressure switch
63H worked)
Abnormal if high-pressure switch 63H
worked ( w ) during compressor operation.
w 4.15 MPa [602PSIG]
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
1~6Check indoor unit and repair the defect.
7 Check if stop valve is fully open.
8 Check piping and repair the defect.
9~2 Check outdoor unit and repair the defect.
3 Check the inspected temperature of outside
temperature thermistor on LED display.
(SW2 on A-Control Service Tool : Refer to 10-
10.)
4~6Turn the power off and check F5 is
displayed when the power is on again.
When F5 is displayed, refer to “Judgment
and action” for F5.
7 Check linear expansion valve.
Refer to 10-6, 7.
8 Replace outdoor controller board.
Case
U2
(1102)
High discharging temperature
(1) Abnormal if discharge temperature ther-
mistor (TH4) exceeds 125:[257˚F] or
110: [230˚F] continuously for 5 min-
utes.
Abnormal if condenser/evaporator tem-
perature thermistor (TH5) exceeds 40:
[104˚F] during defrosting and discharge
temperature thermistor (TH4) exceeds
110: [230˚F].
(2) Abnormal if discharge superheat
(Cooling: TH4 – TH5 / Heating: TH4 –
TH6) increases.
All the conditions in A or B are detected
simultaneously for 10 minutes continu-
ously after 6 minutes past from com-
pressor start-up (including the thermo-
stat indication or recovery from defrost-
ing).
<Condition A>
• Heating mode
• When discharge superheat is less
than 70 deg [126˚F].
• When the TH6 temp is more than the
value obtained by TH7 – 5 deg [9˚F].
• When the condensing temp of TH5 is
less than 35: [95˚F].
<Condition B>
• During comp operation (Cooling and
Heating)
• When discharge superheat is less
than 80 deg [144˚F] in cooling
• When discharge super heat is less
than 90 deg [162˚F] in heating
• When condensing temp of TH6 is
more than –40: [–40˚F] (In cooling
only)
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
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 on again.
When U3 is displayed, refer to “Judgement
and action” for U3.
5 Check linear expansion valve.
Refer to 10-6, 7.
<Abnormalities detected while unit is operating>
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