Haier 1U71S2SG1FA Service Manual page 222

2.3.12 .
Oil return operation control
Unitary:
A
Entering condition
2.3.12 Oil return operation control
When the compressor running frequency is lower than 58Hz continuously in all and outdoor
Unitary:
unit Tcm is lower than 50 degree for 5 hours, the system will enter oil return operation. In the
A: Entering condition course of mode changeover, manual unit stop or protective unit stop, the time will be
accumulative. After compressor restarts up, the time will counted continuously. In counting
When the compressor running frequency is lower than 58Hz continuously in all and outdoor unit Tcm is lower
than 50 degree for 5 hours, the system will enter oil return operation. In the course of mode changeover, manual
time for 5 hour, if the compressor running frequency is over 80Hz for 10 minutes continuously,
unit stop or protective unit stop, the time will be accumulative. After compressor restarts up, the time will counted
the time will be cleared. Also after the heating defrosting , the time will be cleared.
continuously. In counting time for 5 hour, if the compressor running frequency is over 80Hz for 10 minutes
B
Procedure
continuously, the time will be cleared. Also after the heating defrosting , the time will be cleared.
Cooling mode: refer to "the oil return procedure in cooling mode"
B: Procedure
Heating mode: refer to "the oil return procedure in heating
Cooling mode: refer to "the oil return procedure in cooling mode"
C
The protection treatment in oil return operation:
Heating mode: refer to "the oil return procedure in heatingmode" mode"
C: The protection treatment in oil return operation: In the course of cooling oil return, because of all kinds of protection or abnormal unit stop,
after the unit restart, the time will not be cleared, the system need another oil return operation.
In the course of cooling oil return, because of all kinds of protection or abnormal unit stop, after the unit restart, the
In the refrigerant flow course in oil return of cooling mode or after oil return, and within 5
time will not be cleared, the system need another oil return operation. In the refrigerant flow course in oil return of
minutes after the refrigerant being eliminated is over, the anti-freeze protection and low
cooling mode or after oil return, and within 5 minutes after the refrigerant being eliminated is over, the anti-freeze
pressure protection are invalid, other protection is valid.
protection and low pressure protection are invalid, other protection is valid.
In the course of heating oil return ,because of all kinds of protection or abnormal unit stop, the
In the course of heating oil return, because of all kinds of protection or abnormal unit stop, the system need not
system need not another oil return operation after the unit stop for 3 minutes and enter in
another oil return operation after the unit stop for 3 minutes and enter in heating mode directly. In the course of
changing to cooling oil return, the anti-freeze protection and low pressure protection are invalid, other protection is heating mode directly. In the course of changing to cooling oil return, the anti-freeze
valid.
protection and low pressure protection are invalid, other protection is valid.
Oil return procedure in cooling mode:
Oil return procedure in cooling mode:
Send oil return signal
Inverter compressor
outdoor unit PMV auto open angle
Outdoor fan motor auto operation
running indoor motor auto operation
stop indoor motor
4-way valve
oil return beginning
60S
80 Hz（E）
auto FQY
auto（TC or ambient control）
auto（set fan speed）
stop
OFF
mode"
ref.eliminated
40HZ（E）
300pulse （E）
120pulse（E）
stop
OFF
219
oil return over
30s
auto open angle
auto operation
auto operation
stop
OFF