SiAF332111E Troubleshooting by Error Code
Part 6 Service Diagnosis 295
5.55.2 Refrigerant Shortage (6/8 HP Models)
Applicable
Models
RXMQ6/8AR
Error Code U0
Sub code: 05
Method of Error
Detection
Detects refrigerant shortage according to the ending conditions of cooling oil return control.
Error Decision
Conditions
Cooling oil return control does not finish according to the ending conditions, and the time is
up for 3 consecutive times.
No abnormality is determined, and the operation continues.
Supposed
Causes
Refrigerant shortage and refrigerant clogging (wrong piping)
Defective thermistor
Defective low pressure sensor
Defective outdoor unit main PCB
Troubleshooting
CHECK 2 Refer to page 338.
CHECK 3 Refer to page 339.
CHECK 7 Refer to page 346.
Replace the thermistor
(R3T).
NO
Replace the outdoor unit
main PCB (A1P).
YES
YES
Are the
characteristics of the
suction pipe thermistor
normal?
NO
Are the
characteristics of the
low pressure sensor
normal?
Replace the low pressure
sensor (S1NPL).
Correct the abnormally low
pressure.
Correct the insufficient low
refrigerant condition.
Correct the superheat
operation.
NO
YES
Is refrigerant shortage detected
as a cause of abnormally
low pressure?
NO YES
YES
YES
Is refrigerant
insufficient?
NO
NO
YES
Caution
Be sure to turn off the power switch before connecting or disconnecting
connectors, or parts may be damaged.
NO
CHECK 2
Is another cause detected as a
cause of abnormally low
pressure?
CHECK 2
Is refrigerant shortage detected
as a cause of superheat
operation?
CHECK 3
CHECK 7
Is another cause detected
as a cause of superheat
operation?
CHECK 3
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