Oil Return Operation - Daikin Aurora Series Service Manual

Special Control
7.2

Oil Return Operation

In order to prevent the compressor from running out of oil, the oil return operation is conducted to recover oil that has
flowed out from the compressor to the system side.
Tc : High pressure equivalent saturation temperature
Te : Low pressure equivalent saturation temperature
TsA: Suction pipe temperature detected by thermistor R3T
7.2.1 Oil Return Operation in Cooling Operation
Starting conditions
Referring to the set conditions for the following items, start the oil return operation in cooling
• Cumulative oil feed rate
• Timer setting (Make this setting so as to start the oil return operation when the initial cumulative operating time reaches 2
hours after power supply is turned ON and then every 8 hours.)
Furthermore, the cumulative oil feed rate is computed from Tc, Te, and compressor loads.
Part Name
Inverter compressor
Inverter fan
Electronic expansion valve (Heat exchanger
upper)
Electronic expansion valve (Heat exchanger
lower)
Electronic expansion valve (Subcooling
heat exchanger)
Electric expansion valve (Subcooling
injection)
Electronic expansion valve (Refrigerant
cooling)
Electronic expansion valve (Receiver gas
purge)
Solenoid valve (Oil separator oil return)
Solenoid valve (Hot gas bypass)
Solenoid valve (Liquid shutoff)
Four way valve (HP/LP gas pipe)
Four way valve (Heat exchanger lower)
Four way valve (Heat exchanger upper)
Solenoid valve (Accumulator oil return)
Ending condition
Fan
Electronic expansion valve
61
Electric Symbol
M1C
M1F, M2F
Y1E
Y3E
Y2E
Y4E
Y5E
Y7E
Y1S
Y2S
Y3S
Y4S
Y5S
Y6S
Y7S
Indoor unit actuator
Thermostat ON unit
Stopping unit
Thermostat OFF unit
Thermostat ON unit
Stopping unit
Thermostat OFF unit

Oil return operation

Constant low pressure control
For heat exchanger mode
Same as normal operation
0 pulse
760 pulse
Same as normal operation
0 pulse
ON
Same as normal operation
ON
Hold
Hold
Hold
Same as normal operation
• A lapse of 3 minutes
• TsA – Te < 3°C (5.4°F)
&
• A lapse of 12 minutes while the frequency is
OR
more than that of oil return operation.
Remote controller setting
Remote controller setting
Forced thermostat ON (PI control)
SiUS341802E
Oil return operation
OFF
Normal control
224 pulse
Functions and Control