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85 

  Indoor high pressure is detected when indoor heat exchanger is detecting very high temperature when the unit is 

operating in heating operation. 

  Phenomena: unit is stopping and re-starting very often in heating mode 

  Indoor heat exchanger thermistor 

  Clogged air filter or heat exchanger 

  Over-bent pipe (liquid side) 

 
Troubleshooting 
 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

86 

Error Code will not display (no Timer LED blinking) but store in EEPROM 
 
Malfunction Decision Conditions 

  Freeze prevention control takes place (when indoor pipe temperature is lower than 2°C) 

 
Malfunction Caused 

  Air short circuit at indoor unit 

  Clogged indoor unit air filter 

  Dust accumulation on the indoor unit heat exchanger 

  2/3 way valve closed 

  Faulty indoor unit fan motor 

 Refrigerant 

shortage 

(refrigerant leakage) 

  Clogged expansion valve or strainer 

  Faulty indoor pipe temperature sensor 

  Faulty indoor unit PCB 

 
Troubleshooting 
 

 

 
 
 
 
 

87 

  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. 

  Indoor heat exchanger (pipe) thermistor 

  4-way valve malfunction 

 
Troubleshooting 
 

 

 

* Check gas side pipe – for hot gas flow in cooling mode 
 
 
 
 
 
 
 

88 

  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). 

  Wrong wiring connection 

 Faulty 

sensor 

  Faulty expansion valve 

 
Troubleshooting