SiME332106E
Special Control
Part 4 Functions and Control
65
7. Special Control
7.1 Pump Down Residual Control
Pc : High pressure sensor detection value
Pe : Low pressure sensor detection value
To avoid refrigerant emigration when outdoor unit stops operation (thermostat or safety), all
electronic expansion valves are closed.
7.2 Oil Return Control
In order to prevent the compressor from running out of oil, the oil return control 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
Ts1: Suction pipe temperature detected by thermistor R3T
Starting conditions
Oil return control is not conducted before 2 hours have elapsed from the activation of power
supply.
After 2 hours have elapsed, oil return control starts when the following item meets the
reference value.
• Total amount of oil discharged from the compressor
(The total amount of oil discharged from the compressor is computed from Tc, Te, and
compressor loads.)
Oil return control starts every 8 hours of cumulative operation of the compressor, even if the
reference value is not met.
7.2.1 Oil Return Control in Cooling Operation
Part Name
Electric
Symbol
RXYMQ-A
Function
Compressor motor
M1C
Capacity step PI control
Fan motor
M1F
TC control
Electronic expansion valve (Main)
Y1E
480 pulse
Electronic expansion valve (Injection)
Y2E
0 pulse
Electronic expansion valve
(Refrigerant jacket)
Y3E
480 pulse
Electronic expansion valve
(Refrigerant auto charge)
Y4E
480 pulse
Four way valve
Y1S
ON
Ending conditions
&
OR
· A lapse of 3 minutes.
· Ts1–Te < 3°C
· A lapse of 6 minutes
while the frequency
is more than that of
oil return control.
Indoor unit actuator
Cooling oil return control
Fan
Thermostat ON unit
Remote controller setting
Non-operating unit
OFF
Thermostat OFF unit
Remote controller setting
Electronic expansion valve
Thermostat ON unit
Normal control
Non-operating unit
224 pulse
Thermostat OFF unit
Normal control with forced thermostat
ON
