York YHKMXH009BARX-FX, Service Manual, Page: 239 / 269

3.2.11 .
Oil return operation control
Unitary:
A
Entering condition
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 unit stop or protective unit stop, the time will be
accumulative. After compressor restarts up, the time will counted continuously. In counting
time for 5 hour, if the compressor running frequency is over 80Hz for 10 minutes continuously,
the time will be cleared. Also after the heating defrosting , the time will be cleared.
B
Procedure
Cooling mode: refer to “the oil return procedure in cooling mode”
Heating mode: refer to “the oil return procedure in heating 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 refrigerant flow course in oil return of cooling mode or after oil return, and within 5
minutes after the refrigerant being eliminated is over, the anti-freeze 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
system need not 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 valid.
Oil return procedure in cooling mode:
Send oil return signal oil return beginning oil return over
ref.eliminated 30s
80 Hz
（
E
）
40HZ
（
E
）
Inverter compressor auto FQY
300pulse
（
E
）
outdoor unit PMV auto open angle auto open angle
120pulse
（
E
）
Outdoor fan motor auto operation auto
（
TC or ambient control
）
auto operation
running indoor motor auto operation auto
（
set fan speed
）
auto operation
stop indoor motor stop stop stop
4-way valve OFF OFF OFF
60S
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