Defrost Control - Daikin REYQ-XA Service Manual

Special Control
7.3

Defrost Control

To defrost the outdoor heat exchanger while in Evaporator, the defrost control is conducted to recover the heating capacity.
Tb: Heat exchanger deicer temperature
Part name
Compressor
Inverter fan
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
Indoor unit actuator
Fan
Electronic expansion valve
Branch Selector unit actuator
Electronic
expansion Y1E
valve (EVSC)
Electronic
expansion Y2E
valve (EVH)
Electronic
expansion Y3E
valve (EVL)
127
Electric symbol
M1C
M1F, M2F
Y1E
Y3E
Y2E
Y4E
Y5E
Y7E
Y1S
Y2S
Y3S
Y4S
Y5S
Y6S
Y7S
Thermostat ON unit
Non-operating unit
Thermostat OFF unit
Thermostat ON unit
Non-operating unit
Thermostat OFF unit
Normal cooling
Thermostat ON 0 pulse
Non-operating 0 pulse
Thermostat OFF 0 pulse
Thermostat ON 6,000 pulse
Non-operating 6,000 pulse
Thermostat OFF 6,000 pulse
Thermostat ON 6,000 pulse
Non-operating 6,000 pulse
Thermostat OFF 6,000 pulse
Defrost control
REYQ72-120XA: 134 rps
REYQ144/168XA: 119 rps
With high pressure
←→ ←→
OFF Step X/2
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
Defrost control
OFF
OFF
OFF
Defrost EV opening degree
Defrost EV opening degree
Defrost EV opening degree
Normal simultaneous cooling/heating
Cooling
Subcooling degree
0 pulse
0 pulse
0 pulse
0 pulse
0 pulse
0 pulse
6,000 pulse
6,000 pulse
6,000 pulse
SiUS371901E
Step X
Normal heating
Heating
0 pulse
control
0 pulse 0 pulse
0 pulse 0 pulse
6,000 pulse 6,000 pulse
6,000 pulse 6,000 pulse
6,000 pulse 6,000 pulse
0 pulse 0 pulse
0 pulse 0 pulse
0 pulse 0 pulse
Functions and Control