Daikin RXYQ96PYDN Service Manual page 72

SiUS34-801A_b
Solenoid valve (discharge pipe
of refrigerant regulator)
Ending conditions
7.4.2 Multi Outdoor Unit System
[Start conditions]
Referring to the following conditions, start defrost operation.
• When there is a decrease in the coefficient of heat transfer of outdoor unit heat exchanger
• When there is a drop in the temperature of outdoor unit heat exchanger outlet (Tb)
&
• When the low pressure stays low for a certain amount of time (2 hours minimum)
Furthermore, the thermal conductivity of outdoor unit heat exchanger is calculated by Tc, Te, and compressor loads.
Defrosting outdoor unit actuator
Compressor 1
Compressor 2
Outdoor unit fan 1
Four way valve (for heat
exchanger selection)
Four way valve (for high- and low-
pressure gas pipe selection)
Electronic expansion valve (main) EVM
Electronic expansion valve
(subcooling)
Electronic expansion valve
(refilling refrigerant)
Solenoid valve (main bypass)
Solenoid valve (hot gas)
Solenoid valve (liquid pipe of
refrigerant regulator)
Solenoid valve (gas discharge
pipe of refrigerant regulator)
Solenoid valve (drain pipe of
refrigerant regulator)
Solenoid valve (discharge pipe of
refrigerant regulator)
End conditions
VRVIII R-410A Heat Pump 60Hz
SVT Y6S
Elect. symbol
For any model
Symbol
other than
144PTJU
M1C
— 210Hz+ON
M2C
Pcmax>355.25psi
— M1F
Pcmax>440.8psi
20SA Y3S OFF
20SB Y2S Holds
Y1E 1375pls
EVT Y3E SH control
EVJ Y2E 80pls
SVE Y6S ON
SVP Y5S OFF
SVL Y4S 0pls
SVG Y1S 0pls
SVO Y7S 0pls
SVT Y8S 0pls
RXYQ72~120P (by unit)
or
Y8S 0pls
• 10 min.
• Tb>51.8°F
or
continues for a
period of consecutive
90 sec.
Defrost operation
OFF
Pcmax<342.2psi
FANSTEP4
Pcmax<427.75psi
FANSTEP6
• 5 min. and 30 sec.
• Tb > 51.8°F for a period
of 10 consecutive sec.
• Pc_max > 440.8psi
Special Control
0pls
• 160 sec.
• Pc-Pe>58psi
or
continues for a period
of consecutive
120 sec.
Operation after defrost
210Hz+ON
OFF
Pcmax>355.25psi Pcmax<342.2psi
FANSTEP4
Pcmax>440.8psi
Pcmax<427.75psi
FANSTEP6
OFF
Holds
0pls
0pls
80pls
OFF
OFF
0pls
0pls
0pls
0pls
• 30 sec.
or
• Pc_max>440.8psi
57