Special Control
SiUS28-902_B
18
Function
3.2
Oil Return Operation
Oil flown from the compressor to the side of system is collected by oil-returning operation, in
case of that oil in the compressor runs down.
3.2.1 Oil Return Operation in Cooling
Tc: High pressure equivalent saturation temperature
Te: Low pressure equivalent saturation temperature
Ts: Suction pipe temperature detected by thermistor
[Conditions to start]
The cooling oil-returning operation is started referring following conditions.
Integrated amount of displaced oil
Timer
(After the power is turned ON, integrated operating-time is 2 hours and subsequently every 8
hours.)
In addition, integrated amount of displaced oil is derived from Tc, Te, and the compressor
load.
Outdoor unit actuator
Oil return preparation
operation
Oil return operation
Post-oil-return operation
Compressor
Upper limit control
124 Hz
124 Hz
Outdoor unit fan
Fan control
Fan control
Fan control
Four-way valve
OFF
OFF
OFF
Main electronic expansion valve
(EV1)
1400 pls
1400 pls
1400 pls
Hot gas bypass valve (SVP)
OFF
ON
ON
Receiver gas discharging valve
(SVG)
OFF
OFF
OFF
Ending conditions
20 seconds
6 minutes
Ts – Te < 9°F
3 minutes
OR
Indoor unit actuator
Cooling oil return operation
Fan
Thermostat ON unit
Set air volume
Stopping unit
OFF
Thermostat OFF unit
OFF
Electronic expansion valve
Thermostat ON unit
Normal opening
Stopping unit
200 pls
Thermostat OFF unit
200 pls