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113
18.4.19 F11 (4-way Valve Switching Failure)
Malfunction Decision Conditions
When indoor heat exchanger is cold during heating (except deice) or when indoor heat exchanger is hot during
cooling and compressor operating, the 4-way valve is detected as malfunction.
Malfunction Caused
Indoor heat exchanger (pipe) thermistor
4-way valve malfunction
Troubleshooting
Troubleshooting
* Check gas side pipe – for hot gas flow in cooling mode
114
18.4.20 F17 (Indoor Standby Units Freezing Abnormality)
Malfunction Decision Conditions
When the different between indoor intake air temperature and indoor pipe temperature is above 10°C or indoor
pipe temperature is below -1.0°C.
Remark:
When the indoor standby unit is freezing, the outdoor unit transfers F17 error code to the corresponding indoor
unit and H39 to other indoor unit(s).
Remark:
When the indoor standby unit is freezing, the outdoor unit transfers F17 error code to the corresponding indoor
unit and H39 to other indoor unit(s).
Malfunction Caused
Wrong wiring connection
Faulty
sensor
Faulty expansion valve
Troubleshooting
Troubleshooting
115
18.4.21 F90 (Power Factor Correction Protection)
Malfunction Decision Conditions
To maintain DC voltage level supply to power transistor.
To detect high DC voltage level after rectification.
Malfunction Caused
Malfunction Caused
During startup and operation of cooling and heating, when Power Factor Correction (PFC) protection circuitry at
the outdoor unit main PCB senses abnormal DC voltage level for power transistors.
When DC voltage detected is LOW, transistor switching will turn ON by controller to push-up the DC level.
When DC voltage detected is HIGH (391Vdc – 425Vdc), active LOW signal will send by the controller to turn OFF
relay RY-C.
Troubleshooting
116
18.4.22 F91 (Refrigeration Cycle Abnormality)
Malfunction Decision Conditions
The input current is low while the compressor is running at higher than the setting frequency.
Malfunction Caused
Lack of gas.
3-way valve close.
Troubleshooting
Troubleshooting
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