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SiUS30-1301
Troubleshooting by Indication on the Remote Controller
Service Diagnosis
213
3.37 Refrigerant Shortage Alert
Error Code
U0
Applicable
Models
RWEYQ72P, 84P
Method of Error
Detection
Detect refrigerant shortage based on the temperature difference between low pressure equivalent
saturation temperature or suction pipe and heat exchanger temperature.
Error Decision
Conditions
[In cooling]
Low pressure becomes 14.5 psi or less.
[In heating]
The degree of superheat of suction gas becomes 68°F and over.
SH = Ts1 –Te
Ts1: Suction pipe temperature detected by thermistor
Te : Saturated temperature corresponding to low pressure
Error is not determined. The unit continues the operation.
Supposed
Causes
Refrigerant shortage or refrigerant clogging (piping error)
Defective thermistor
Defective low pressure sensor
Defective condensing unit PCB (A1P)