Special Control; Pump Down Residual Operation - Daikin Aurora Series Service Manual

SiUS341802E

7. Special Control

7.1

Pump Down Residual Operation

Pc : High pressure sensor detection value
Pe : Low pressure sensor detection value
Ta : Outdoor air temperature
Te : Low pressure equivalent saturation temperature
DSH : Discharge pipe superheated degree
If the liquid refrigerant stays in the evaporator at the startup of a compressor, this liquid refrigerant enters the compressor,
thus resulting in diluted oil in the compressor and then degraded lubrication performance.
Consequently, in order to recover the refrigerant in the evaporator while the compressor stops, the pump down residual
operation is conducted.
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
Functions and Control
Electric Symbol
M1C 24 rps/37 rps∗
M1F, M2F For heat exchanger mode
Y1E
Same as normal operation
Y3E
Y2E 0 pulse
Y4E 760 pulse
Y5E Same as normal operation
Y7E Open slightly
Y1S ON
Y2S OFF
Y3S ON
Y4S Hold
Y5S Hold
Y6S Hold
Y7S ON
A lapse of 5 minutes
OR Master unit HTdi > 118°C (244.4°F)
Pc_max > 2.94 MPa (426 psi)
Function of Functional Part
Normal Cooling
24 rps/37 rps∗
For heat exchanger mode
Same as normal operation
0 pulse
760 pulse
Same as normal operation
Open slightly
ON
OFF
ON
Hold
Hold
Hold
ON
OR

Special Control

Normal Heating
A lapse of 3 minutes
Pe_min < 0.19 MPa (27.6 psi)
&
Ta_min – Te_max > 8°C (14°F)
HTdi_max > 118°C (244.4°F)
∗RXYQ72TA
60