37
OCH737
<Abnormalities detected while unit is operating>
Check Code Abnormal points and detection method
Cause
Judgment and action
U1
(1302)
High pressure(High pressure switch 63H
operated)/High compressor temperature
(Thermal protector TRS operated)
Abnormal if high pressure switch
63H(4.15MPa) or thermal protector
TRS(130°C) operated during compressor
operation
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 or TRS) on out-
door controller board
5
Disconnection or contact failure of
63H or TRS connection
6
Defective outdoor controller board
7
Defective action of linear expan-
sion valve
8
Malfunction of fan driving circuit
9
Overheated compressor operation
caused by shortage of refrigerant
)
Defective operation of stop valve
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. FUNCTION OF SWITCHES,
CONNECTORS AND JUMPERS".)
4
–
6
Turn the power off and check if F5 is
displayed when the power is turned on
again.
When F5 is displayed, refer to
“Judgment and action” for F5.
7
Check linear expansion valve.
Refer to "10-6. HOW TO CHECK THE
PARTS".
8
Replace outdoor controller board.
9
Check intake superheat.
Check leakage of refrigerant.
Charge additional refrigerant.
)
Check if stop valve is fully open.
U2
(TH4:1102)
(TH33:1132)
High comp. surface temperature
1. Abnormal if comp. surface temperature
thermistor (TH4/TH33) exceeds 117°C
or
110°C continuously for 5 minutes.
Abnormal if condenser/evaporator temperature
thermistor (TH5) exceeds 40°C during
defrosting and comp. surface temperature
thermistor (TH4/TH33) exceeds 110°C.
2. Abnormal if discharge superheat
(Cooling: TH4/TH33−TH6 / Heating: TH4/
TH33−TH5) increases.
All the conditions in A or B are detected
simultaneously for 10 minutes continuous-
ly after 6 minutes past from compressor
Startup (including the thermostat indication
or recovery from defrosting).
<Condition A>
• Heating mode
• When discharge superheat is less than 70°C.
• When the TH6 temp is more than the
value obtained by TH7−5
:
.
• When the condensing temp of TH5 is
less than 35
:
.
<Condition B>
• During compressor operation (Cooling
and Heating)
• When discharge superheat is less than
80°C in Cooling.
• When discharge superheat is less than
90°C in Heating.
• When condensing temp of TH6 is more
than −40
:
. (In Cooling only.)
3. Abnormal if comp. surface temperature
thermistor (TH4/TH33) exceeds 117°C or
110°C continuously for 5 minutes.
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 expan-
sion 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
displayed when the power is on again.
When U3 is displayed, refer to “Judgment
and action” for U3.
5
Check linear expansion valve.
Refer to "10-6. HOW TO CHECK THE
PARTS".
U3
(TH4:5104)
(TH33:5132)
Open/short circuit of discharge
temperature thermistor (TH4)/comp.
surface thermistor (TH33)
Abnormal if open (−20
°C or less) or
short (217°C 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/TH33) on the
outdoor controller circuit board
2
Defective thermistor
3
Defective outdoor controller circuit
board
1
Check connection of connector (TH4/TH33)
on the outdoor controller circuit board. Check
breaking of the lead wire for thermistor
(TH4/TH33). Refer to "10-9. TEST POINT
DIAGRAM".
2
Check resistance value of thermistor (TH4/
TH33) or temperature by microprocessor.
(Thermistor/TH32: Refer to "10-6. HOW TO
CHECK THE PARTS".)(SW2 on A-Control
Service Tool: Refer to "10-10. FUNCTION
OF SWITCHES, CONNECTORS AND
JUMPERS".)
3
Replace outdoor controller board.
