37
<Abnormalities detected while unit is operating>
Error Code
Abnormal point and detection method
Judgment and action
U1
(1302)
High pressure (High-pressure switch
63H operated)
Abnormal if high-pressure switch 63H oper-
ated (
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
~
6
Check 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
11-10.)
4
~
6
Turn 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 11-6, 7.
8
Replace outdoor controller board.
Case
U2
(TH4: 1102)
(TH32: 1132)
High discharging temperature
High comp.shell temperature
(1) Abnormal if discharge temperature
thermistor (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).
(3) Abnormal if comp.shell temperature
thermistor (TH32) exceeds 125
:
[257˚F].
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 11-6, 7.
OCH481C
