SiUS281117
Special Control
38
Function and Control
3.2
Oil Return Operation
Oil flown from the compressor to the side of system is collected by oil return 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 return 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.
Parts Name
Symbol
Electric Symbol
Oil return
preparation
operation
Oil return operation
Post-oil-return
operation
RZR18/24/32P
RZQ18/24/30P
RZR36/42P
RZQ36/42P
Compressor
(INV.)
M1C
M1C
Upper limit
control
124 Hz
124 Hz
Outdoor unit fan
M1F
M1F
M2F
Fan control
Fan control
Fan control
Four-way valve
20S1
Y1S
Y1S
OFF
OFF
OFF
Electronic
expansion valve
(Main)
EV1
Y1E
Y1E
1400 pls
1400 pls
1400 pls
Solenoid valve
(Hot gas)
SVP
Y2S
Y2S
OFF
ON
ON
Solenoid valve
(Receiver gas
discharging)
SVG
Y3S
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
