Daikin FXYBP20K7V1, Service Manual

Page: 77 / 193

Outline of Control (Outdoor Unit) SiE 00-07
66 Function R-407C PLUS Series
3.17 Heating Pump-Down Residual Operation
Conduct an operation during stop mode to discharge refrigerant from the low pressure side, since liquid
refrigerant remaining in the accumulator can be sucked into the compressor during startup and dilutes the
refrigerating machine oil in the compressor and lowers the lubricating performance.
[Residual operation starting condition]
DSHi : INV discharge pipe superheat degree
Th6-Te : Suction pipe temp. -Low pressure equivalent saturation temp.
[Description of movement]
∗
Receiver gas relief solenoid valve is open and liquid refrigerant is moved to liquid line for 60 seconds
after entering pump-down residual operation.
However, this relief solenoid valve closes at Th6-Te < 0.
[Ending condition]
&
Thermostat ON
→
OFF
OR
DSHi < 20˚C
Th6 – Te < 10˚C
Outdoor unit Indoor unit
Compressor Motorized valve Solenoid valve for hot gas Motorized valve
Movement 67Hz+OFF
Initial 2000 pls
→
PI control when SHS = 10˚C
ON (equalization) 500 pls (all indoor unit)
&
DSHi > 90˚C
Th6 – Te < 10˚C
LP < 0.07MPa
Tc > 48.6˚C
10 min elapse