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12.5     Low Pressure Protection Control (Gas Leakage Detection) 
•  Control start conditions 
o  For 5 minutes, the compressor continously operates and outdoor total current is between 0.64A and 0.85A 
o  During Cooling and Soft Dry operation: 
Indoor suction temperature – indoor piping temperature is below 39.2°F 
• Control contents 
o  Compressor stops (and restart after 3 minutes). 
o  If the conditions above happened 2 times within 20 minutes, the unit will: 
 Stop operation 
  Timer LED blinks and “F91” indicated. 
 
12.6    Low Frequency Protection Control 1 
•  When the compressor operates at frequency lower than 24Hz continued for 240 minutes, the operation frequency 
will be changed to 23Hz for 2 minutes. 
 
12.7    Low Frequency Protection Control 2 
•  When all below conditions comply, minimum limit of compressor frequency will be set. 
 
Cooling / Soft Dry 
Temperature, T, for: 
S9NK and S12NK 
Indoor intake air (°F)  T < 57.2 or T ≥ 86 
Outdoor air (°F)  T < 55.4 or T ≥ 100.4 
Indoor heat exchanger (°F)  T < 86 
 
12.8    Outdoor Air Temperature Control 
•  The compressor operating frequency is regulated in accordance to the outdoor air temperature as shown in the 
diagram below. 
•  This control will begin 1 minute after the compressor starts. 
• Compressor frequency will adjust based on outdoor air temperature. 
 
Free
Limited Frequency
Compressor OFF
Outdoor air temperature
100.4°F or 77°F
1.4°F
98.6°F or 71.6°F
1.4°F
 
12.9    Cooling Overload Control 
•  Pipe temperature limitation / restriction. 
o  Detects the outdoor pipe temperature and carry out restriction / limitation below (Limit the compressor 
operation frequency) 
o  The compressor stops if outdoor pipe temperature exceeds 141.8°F. 
o  If the compressor stops 4 times in 20 minutes, Timer LED blinks (“F95” indicated: Outdoor high pressure rise 
protection)