Oil Return Operation - Daikin RXSQ24TAVJU Service Manual

Special Control
3.2

Oil Return Operation

In order to prevent the compressor from running out of oil, oil return operation is conducted to recover oil that has
flowed out from the compressor to the system side.
3.2.1 Oil Return Operation in Cooling
HTdi : Compressor discharge pipe temperature (Tdi) compensated with outdoor air temperature
Pc : High pressure sensor detection value
Pe : Low pressure sensor detection value
Tc : High pressure equivalent saturation temperature
Te : Low pressure equivalent saturation temperature
Ts1 : Suction pipe temperature detected by thermistor R3T (suction pipe 1)
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 two hours after power supply is turned ON and then every eight hours.)
Furthermore, the cumulative oil feed rate is computed from Tc, Te, and compressor loads.
Electric symbol
Outdoor unit
actuator
24/36 class 48 class 60 class
Compressor M1C
Outdoor fan M1F
Four way valve Y1S
Main electronic
Y1E
expansion valve
Subcooling

electronic
expansion valve
Hot gas bypass
Y2S
valve
Injection valve Y3S
Ending conditions
Indoor fan
Electronic expansion valve
47
Oil return preparation
operation
M1C M1C Normal control
M1F, Fan control (Normal
M1F
M2F cooling)
Y1S Y1S OFF
Y1E Y1E 480 pulse (Fully open)

Y3E SH control
 
OFF

Y3S OFF
15 seconds
Indoor unit actuator
Thermostat ON unit
Non-operating unit
Thermostat OFF unit
Thermostat ON unit
Non-operating unit
Thermostat OFF unit
Oil return operation
Control dependent on the
values of Pc and Pe
(→ Low pressure
protection control)
Fan control (Normal
cooling)
OFF
480 pulse (Fully open)
0 pulse
OFF
OFF
• 3 minutes
• Ts1–Te < 3°C
(5.4°F)
• A lapse of 20
minutes
&
• System rps is
OR
large than oil
return rps for
more than 6
minutes.
Cooling oil return operation
Remote controller setting
Remote controller setting
Normal opening
Normal opening with forced thermostat ON
SiUS331708EA
After oil return operation
Normal control from current
rps
Fan control (Normal
cooling)
OFF
480 pulse (Fully open)
0 pulse
OFF
OFF
• 3 minutes
• Pe < 0.6 MPa (87 psi)
OR
• HTdi > 110°C (230°F)
• Pc > 3.6 MPa (522 psi)
OFF
224 pulse
Functions and Control