Haier Smart Power Series Service Manual page 213

Smart Power
6.2.4 Oil return control
Control purpose: Make the system oil regularly return to the compressor when the compressor work in a low
frequency.
Condition:
When the indoor units are working, if the compressor continuous frequency is lower than the parameters C HZ (E)
and the temperature TC is lower than 50°C (E) ,and it lasts 5 hours. Unit will enter oil return mode. When changing
the mode or manual stop or protective stop, time will pause. After the compressor restart, it will continue to time.
When timing, if the compressor working frequency is higher than B HZ (E) and lasts more than 10 minutes, the time
reset.
When heating, the time will reset if the defrost mode work.
After oil return, oil return timer reset
Process control chart of oil return:
Send oil return signal
Inverter compressor
PMV
OD fan
ID fan
Auto working
4-way valve
SV valve (auto running according to some condition)
After oil return, the condition of end of refrigerant ruled running
Oil return after 1 minutes
Td-TC>30°C
OR Ts-TM>30°C
OR
TM<-35°C
The longest 3 minutes
Start
60S
Oil return frequency B Hz（E）
Auto frequency
Auto opening
Auto working
Auto working
OFF
300 pulses（E）
120pulses（E）
Auto working
Auto working
OFF
211
End
Refrigerant ruled working
30s
Auto
40HZ （ E ）
Auto
Auto working
OFF