Special Control; Pump Down Residual Control; Oil Return Control - Daikin VRV RXYMQ-A Series Service Manual

SiME332106E

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
 After 2 hours have elapsed, oil return control starts when the following item meets the
 Oil return control starts every 8 hours of cumulative operation of the compressor, even if the
7.2.1 Oil Return Control in Cooling Operation
Part Name
Compressor motor
Fan motor
Electronic expansion valve (Main)
Electronic expansion valve (Injection)
Electronic expansion valve
(Refrigerant jacket)
Electronic expansion valve
(Refrigerant auto charge)
Four way valve
Ending conditions
Fan
Electronic expansion valve
Part 4 Functions and Control
supply.
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.)
reference value is not met.
Electric
Symbol
M1C
M1F
Y1E
Y2E
Y3E
Y4E
Y1S
Indoor unit actuator
Thermostat ON unit
Non-operating unit
Thermostat OFF unit
Thermostat ON unit
Non-operating unit
Thermostat OFF unit
RXYMQ-A







Remote controller setting
OFF
Remote controller setting
Normal control
224 pulse
Normal control with forced thermostat
ON
Special Control
Function
Capacity step PI control
TC control
480 pulse
0 pulse
480 pulse
480 pulse
ON
· A lapse of 3 minutes.
&
· Ts1–Te < 3°C
OR
· A lapse of 6 minutes
while the frequency
is more than that of
oil return control.
Cooling oil return control
65