Defrost Operation - Daikin VRV RXYQ72-384XAYCA Service Manual

SiUS342004EB
7.3

Defrost Operation

To defrost the outdoor heat exchanger while in Evaporator, the defrost operation is conducted to
recover the heating capacity.
Tb: Heat exchanger deicer temperature
Part name
Compressor
Fan motor
Electronic expansion valve
(Heat exchanger upper)
Electronic expansion valve
(Heat exchanger lower)
Electronic expansion valve
(Subcooling heat exchanger)
Electric expansion valve
(Subcooling injection)
Electronic expansion valve
(Refrigerant cooling)
Electronic expansion valve
(Receiver gas purge)
Solenoid valve (Oil separator oil return)
Solenoid valve (Hot gas bypass)
Solenoid valve (Liquid pipe)
Four way valve (HP/LP gas pipe)
Four way valve (Heat exchanger lower)
Four way valve (Heat exchanger upper)
Solenoid valve (Accumulator oil return)
Ending condition
Fan
Electronic expansion valve
Low-temperature hydrobox unit actuator
Pump
Electronic expansion valve
Part 4 Functions and Control
Electric symbol
M1C
M1F, M2F
Y1E
Y3E
Y2E
Y4E
Y5E
Y7E
Y1S
Y2S
Y3S
Y4S
Y5S
Y6S
Y7S
Indoor unit actuator
Thermostat ON unit
Non-operating unit
Thermostat OFF unit
Thermostat ON unit
Non-operating unit
Thermostat OFF unit
Thermostat ON unit
Non-operating unit
Thermostat OFF unit
Thermostat ON unit
Non-operating unit
Thermostat OFF unit
Defrost operation
RXYQ72-120XA, RXYQ72-120XB: 134 rps
RXYQ144/168XA, RXYQ144/168XB: 119 rps
With high pressure
OFF Step X/2  Step X
100%
0 pulse
760 pulse
Same as normal control
0 pulse
ON
OFF
ON
Hold
Hold
Hold
ON
• A lapse of 15 minutes
OR
• Tb>11°C (51.8°F) continues for 30 seconds or more
Special Control
Defrost operation
OFF
OFF
OFF
Defrost EV opening degree
Defrost EV opening degree
Defrost EV opening degree
Defrost operation
Normal control
Normal control
Normal control
0 pulse
0 pulse
0 pulse
102