ESIE13-02
Error Codes: System Malfunctions
139
Part 4 – Troubleshooting
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5
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5
Error Codes: System Malfunctions
5.1
“U0”
Gas Shortage (Malfunction)
Remote controller
display
U0
Method of
malfunction
detection
(In cooling operation)
Detection based on difference in temperature between temperature preset by remote controller and
indoor suction air temperature, motorized valve opening degree, compressor frequency and low
pressure.
(In heating operation)
Detection based on difference in temperature between temperature preset by remote controller and
indoor suction air temperature, motorized valve opening degree during the control of suction air
superheating, high pressure, indoor heat exchanger temperature and indoor suction air temperature.
Malfunction
decision conditions
(In cooling operation)
When compressor frequency does not increase even though the load is heavy because the motorized
valve is opened to the fullest extent
[If low pressure drops when the compressor is at 41Hz, malfunction is confirmed.]
(In heating operation)
When suction gas superheat degree is large, compressor frequency is low and the motorized valve is
opened to the fullest extent even though heating load is heavy
[If high pressure is lower than saturated pressure for indoor heat exchanger temperature (or indoor
suction air temperature), malfunction is confirmed.]
Supposed causes
Refrigerant shortage (out of gas)
Clogged refrigerant piping system
Mismatching of wiring and piping
