Daikin REYQ-XA, Service Manual

Page: 136 / 441

Special Control SiUS371901E
123 Functions and 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 Electric symbol
Function of functional part
Normal cooling Normal heating
Compressor M1C 24 rps 24 rps
Inverter fan M1F, M2F For heat exchanger mode For heat exchanger mode
Electronic expansion valve (Heat
exchanger upper)
Y1E
Same as normal control Same as normal control
Electronic expansion valve (Heat
exchanger lower)
Y3E
Electronic expansion valve
(Subcooling heat exchanger)
Y2E 0 pulse 0 pulse
Electric expansion valve (Subcooling
injection)
Y4E 760 pulse 760 pulse
Electronic expansion valve
(Refrigerant cooling)
Y5E Same as normal control Same as normal control
Electronic expansion valve (Receiver
gas purge)
Y7E Open slightly Open slightly
Solenoid valve (Oil separator oil
return)
Y1S ON ON
Solenoid valve (Hot gas bypass) Y2S OFF OFF
Solenoid valve (Liquid shutoff) Y3S ON ON
Four way valve (HP/LP gas pipe) Y4S Hold Hold
Four way valve (Heat exchanger
lower)
Y5S Hold Hold
Four way valve (Heat exchanger
upper)
Y6S Hold Hold
Solenoid valve (Accumulator oil
return)
Y7S ON ON
Ending condition
A lapse of 5 minutes
Master unit HTdi > 118
°
C (244.4°F)
Pc_max > 2.94 MPa (426 psi)
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)
OR
OR
&