Special Control; Pump Down Residual Control - Daikin REYQ-XA Service Manual

Special Control

7. Special Control
7.1

Pump Down Residual Control

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 superheating 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
control is conducted.
Part name
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
123
Electric symbol
M1C 24 rps
M1F, M2F For heat exchanger mode
Y1E
Same as normal control
Y3E
Y2E 0 pulse
Y4E 760 pulse
Y5E Same as normal control
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
For heat exchanger mode
Same as normal control
0 pulse
760 pulse
Same as normal control
Open slightly
ON
OFF
ON
Hold
Hold
Hold
ON
OR
SiUS371901E
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)
Functions and Control