1.If the compressor frequency keeps lower than 
RET_OIL_FREQ1_ADD for 
RET_OIL_TIME1_ADD,the AC will rise the 
frequency  to RET_OIL_FREQ2_ADD for 
RET_OIL_TIME2_ADD and then resume to 
former frequency.  
2.During the oil return process, the EXV will keep 
300p while the indoor units will keep the current 
running mode. 
 
7.3.11 Compressor preheating functions 
----Preheating permitting condition: 
If T4(outdoor ambient temperature)<3℃ and 
newly powered on or if T4<3℃ and compressor 
has stopped for over 3 hours, the compressor 
heating cable will work. 
----Preheating mode: 
A weak current flow through the coil of 
compressor from the wiring terminal of 
compressor, then the compressor is heated 
without operation. 
----Preheating release condition: 
If T4>5℃ or the capacity demand isn’t zero, 
preheating function will stop. 
7.3.12 Compressor crankcase heater 
----Preheating permitting condition: 
①  When  T4<3 ℃   within  5  seconds  of  being 
plugged  in,  the  crankcase  heater  will  be 
active. 
②  When  T4<3 ℃   and  the  compressor  is  not 
running for 3 hours, the crankcase heater will 
be active. 
----Preheating release condition: 
When T4≧5℃ or the indoor has capacity 
demand, the crankcase heater will stop work.  
 
7.4 Control and Functions 
7.4.1 Capacity Request  Calculation 
Total capacity Request=Σ(Norm code × HP) /10× 
modify rate+ correction  
Cooling mode: 
 
 
 
Note: The final result is integer. 
Plus all the indoor capacity request together, then 
modify it by T4 
When there’s only one indoor unit 
When there’re  more than one indoor unit  
Note: The final result is integer. 
In low ambient cooling mode, modify rate is fixed 
as 40%.  
According to the final capacity request to 
confirm the operating frequency,  as following 
table. 
Amendatory 
capacity 
demand.