Special Control; Pump Down Residual Operation - Daikin RTSQ20PY1 Service Manual

Special Control

8. Special Control

8.1

Pump down Residual Operation

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.
8.1.1 Pump down Residual Operation in Cooling Operation (Outdoor Unit)
Actuator
Compressor 1
Compressor 2
Compressor 3
Outdoor unit fan 1
Outdoor unit fan 2
Electronic expansion valve (Main) Y1E
Electronic expansion valve
(Subcooling)
Electronic expansion valve
(Refrigerant charge)
Solenoid valve (Refrigerant
regulator gas purging pipe)
Four way valve (Heat exchanger
switch)
Solenoid valve (Refrigerant
regulator liquid pipe )
Solenoid valve (Hot gas)
Solenoid valve (Main bypass)
Solenoid valve (Refrigerant
regulator discharge pipe)
Solenoid valve (Refrigerant
regulator discharge pipe)
Four way valve (High/low pressure
gas pipe switch)
Ending conditions
105
STEP 1
Elect.
Master unit
symbol
operation
M1C 124 Hz
M2C OFF
M3C OFF
M1F
Fan control
M2F
480 pls
Y3E 0 pls
Y2E 80 pls
Y1S OFF
Y3S OFF
Y4S OFF
Y5S OFF
Y6S ON
Y7S OFF
Y8S OFF
Y2S ON
• 5 min.
• Master unit Pe<0.49 MPa
• Master unit Pc>2.94 MPa
or
• Master unit Tdi>110°C
• Master unit Tp>125°C
Slave unit
operation Master unit
(RTSYQ20PY1 operation
only)
52 Hz
OFF OFF
OFF
OFF Fan control
0 pls 240 pls
0 pls 0 pls
80 pls 80 pls
OFF OFF
OFF OFF
OFF OFF
OFF OFF
ON ON
OFF OFF
OFF OFF
ON ON
or
SiBE31-801_C
STEP 2
Slave unit
operation
(RTSYQ20PY1
only)
OFF
OFF
0 pls
0 pls
80 pls
OFF
OFF
OFF
OFF
ON
OFF
OFF
ON
• 45 sec.
• Master unit Pe<0.24 MPa
• Master unit Tp>160°C
• Master unit Pc>3.14 MPa
Function