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Send oil return signal   oil return begins     oil return over 
  60s    ref. eliminated     30s   
   Oil return frequency           auto frequency 
    Low frequency  
Inverter compressor   auto frequency 
350pulse(E)
running indoor PMV      auto angle      auto angle 
120pulse(E) 
    80(E) 
stopped indoor PMV      OFF angle 5(E)    OFF angle 5(E) 
Outdoor motor  AUTO  AUTO (TC or ambient temp. control)    AUTO 
running indoor motor AUTO  AUTO (set fan speed)   AUTO 
stopped indoor motor STOP  STOP  STOP 
4-way valve    OFF      OFF       OFF 
Multi:
D: Entering condition 
When the compressor running frequency is lower than 58Hz (E) continuously for 4 hrs, the system will enter oil 
return operation. In the course of mode changeover, manual unit stop or protective unit stop, the time will be 
accumulative. After the compressor restarts up, the time will be counted continuously. In a continuous 4 hrs, if the 
compressor running frequency is not less than 72Hz for over 10 minutes continuously, the accumulative time will be 
cleared. Also after the heating defrosting, the time will be cleared. 
E: Procedure 
Cooling mode: refer to “the oil return procedure in cooling mode” 
Heating mode: refer to “the oil return procedure in heating mode” 
F: The protection treatment in oil return operation  
In the course of oil return, because of protection or abnormal unit stop, after the unit restarts up, the time will not be 
cleared, the system will need another oil return operation. In the refrigerant ow course in the oil return of cooling 
mode or after the oil return, and within 5 minutes after the refrigerant being eliminated is over, the anti-freezed 
protection is invalid, and also the low voltage protection is invalid. But the other protection is valid. 
In the course of oil return from heating mode to cooling mode, if abnormal condition occurs or the unit stops for 
protection, then the system needs not another oil return within 3 minutes after the unit stops and it will start up 
directly, then to heating mode. 
In the course of oil return from heating mode to cooling mode, the anti-freezed protection is null and void, and the 
low voltage protection is null either. The other protection is valid. 
Oil return procedure in cooling mode: