Daikin REYQ-AATJA, Service Manual, Page: 156 / 495

Special Control SiUS372201EA
149 Part 4 Functions and Control
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
REYQ72-168AA single system and REYQ192-240AA single system when outside temperature is lower than 0°C
(32°F)
Part name Electric symbol Function of functional part
Compressor motor
M1C, M2C
REYQ72AA: 127.3 rps
REYQ96/120AA: 125.4 rps + 140.0 rps
REYQ144/168AA: 85.2 rps + 114.9 rps
REYQ192/216/240AA: 135.0 rps + 140.0 rps
Fan motor
M1F, M2F
With high pressure
OFF ↔ Step X/2 ↔ Step X
Electronic expansion valve (Heat exchanger right upper) Y1E 100%
Electronic expansion valve (Heat exchanger right lower) Y2E
Electronic expansion valve (Heat exchanger left) Y5E
Electronic expansion valve (Subcooling heat exchanger) Y3E Discharge temperature control
Electronic expansion valve (Receiver gas purge) Y4E Liquid recovery control
Electronic expansion valve (Refrigerant cooling IPM) Y6E Same as normal control
Electronic expansion valve (Refrigerant cooling air) Y7E
Solenoid valve (Oil separator oil return) Y1S, Y2S ON
Solenoid valve (Liquid shutoff) Y3S ON
Solenoid valve (Accumulator oil return) Y4S ON
Solenoid valve (Refrigerant adjustment) Y5S OFF
Solenoid valve (Injection) Y6S ON
Four way valve (Heat exchanger right upper) Y10S OFF
Four way valve (Heat exchanger right lower) Y7S OFF
Four way valve (Heat exchanger left) Y9S OFF
Four way valve (HP/LP gas pipe) Y8S ON
Solenoid valve (Refrigerant cooling bypass) Y11S Same as normal control
Ending condition
A lapse of 15 minutes
Tb > 11°C (51.8°F) continues for 60 seconds or more
OR
Indoor unit actuator Defrost operation
Fan
Thermostat ON unit OFF
Non-operating unit OFF
Thermostat OFF unit OFF
Electronic expansion valve
Thermostat ON unit Defrost EV opening degree
Non-operating unit Defrost EV opening degree
Thermostat OFF unit Defrost EV opening degree
Branch Selector unit actuator Normal cooling
Normal simultaneous cooling/heating
Normal heating
Cooling Heating
Electronic
expansion
valve (EVSC)
Y1E
Thermostat ON 0 pulse 0 pulse
Subcooling degree control
0 pulse
Non-operating 0 pulse 0 pulse 0 pulse 0 pulse
Thermostat OFF 0 pulse 0 pulse 0 pulse 0 pulse
Electronic
expansion
valve (EVH)
Y2E
Thermostat ON 6,000 pulse 0 pulse 6,000 pulse 6,000 pulse
Non-operating 6,000 pulse 0 pulse 6,000 pulse 6,000 pulse
Thermostat OFF 6,000 pulse 0 pulse 6,000 pulse 6,000 pulse
Electronic
expansion
valve (EVL)
Y3E
Thermostat ON 6,000 pulse 6,000 pulse 0 pulse 0 pulse
Non-operating 6,000 pulse 6,000 pulse 0 pulse 0 pulse
Thermostat OFF 6,000 pulse 6,000 pulse 0 pulse 0 pulse