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

SiUS371614E

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
HTdi : Value of inverter compressor discharge pipe temperature (Tdi) compensated with outdoor air temperature
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 1
Inverter compressor 2
Inverter fan
Electronic expansion valve (Heat
exchanger upper)
Electronic expansion valve (Heat
exchanger lower)
Electronic expansion valve
(Subcooling heat exchanger)
Electronic expansion valve
(Receiver gas purge)
Electronic expansion valve
(Inverter cooling)
Solenoid valve (Oil separator oil
return)
Solenoid valve (Liquid pipe)
Four way valve (HP/LP gas pipe) Y4S
Four way valve (Heat exchanger
lower)
Four way valve (Heat exchanger
upper)
Ending condition
Functions and Control
Electric Symbol
REYQ72TA REYQ96-168TA
M1C M1C
— M2C
M1F M1F, M2F
Y1E Y1E
Y3E Y3E
Y2E Y2E
Y4E Y4E
Y5E Y5E
Y1S Y1S, Y2S
Y3S Y3S
Y4S
Y5S Y5S
Y6S Y6S
Function of Functional Part
Normal Cooling
124 Hz/120 Hz∗
0 Hz
For heat exchanger mode
Same as normal operation
0 pulse
Open slightly
Same as normal operation
ON
ON
Hold
Hold
Hold
A lapse of 5 minutes
OR Master unit HTdi > 118°C (244.4°F)
Pc_max > 2.94 MPa (426 psi)

Special Control

Normal Heating
124 Hz/120 Hz∗
0 Hz
For heat exchanger mode
Same as normal operation
0 pulse
Open slightly
Same as normal operation
ON
ON
Hold
Hold
Hold
A lapse of 3 minutes
Pe_min < 0.19 MPa (27.6 psi)
&
Ta_min – Te_max > 8°C (14°F)
OR
HTdi_max > 118°C (244.4°F)
∗REYQ72TA
80