Defrost Operation - Daikin REYQ-TA Series Service Manual

Special 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
Part Name
Inverter compressor 1
Inverter compressor 2
Inverter fan
Electronic expansion valve (Heat
exchanger upper)
Electronic expansion valve (Heat
exchanger lower)
Electronic expansion valve
(Subcooling heat exchanger)
Electronic expansion valve
(Receiver gas purge)
Electronic expansion valve
(Inverter cooling)
Solenoid valve (Oil separator oil
return)
Solenoid valve (Liquid pipe)
Four way valve (HP/LP gas pipe) Y4S
Four way valve (Heat exchanger
lower)
Four way valve (Heat exchanger
upper)
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)
83
Electric Symbol
REYQ72TA
M1C
—
M1F
Y1E
Y3E
Y2E
Y4E
Y5E
Y1S
Y3S
Y5S
Y6S
Thermostat ON unit
Stopping unit
Thermostat OFF unit
Thermostat ON unit
Stopping unit
Thermostat OFF unit
Normal cooling
Cooling
Thermostat ON 0 pulse
Stopping 0 pulse
Thermostat OFF 0 pulse
Thermostat ON 6,000 pulse
Stopping 6,000 pulse
Thermostat OFF 6,000 pulse
Thermostat ON 6,000 pulse
Stopping 6,000 pulse
Thermostat OFF 6,000 pulse
REYQ96-168TA
REYQ72TA: 282 Hz
M1C
REYQ96-168TA: 252 Hz + 252 Hz
M2C
With high pressure
←→
OFF
M1F, M2F
Y1E
100%
Y3E
Y2E 0 pulse
Y4E 0 pulse
Y5E Same as normal operation
Y1S, Y2S ON
Y3S ON
Y4S Hold
Y5S Hold
Y6S Hold
• A lapse of 15 minutes
OR
• Tb>11°C (51.8°F) continues for 30 seconds or more
OFF
OFF
OFF
Defrost EV opening degree
Defrost EV opening degree
Defrost EV opening degree
Normal Simultaneous Cooling / Heating
Cooling
0 pulse
0 pulse
0 pulse
0 pulse
0 pulse
0 pulse
6,000 pulse
6,000 pulse
6,000 pulse

Defrost operation

←→
Step X/2 Step X
Defrost operation
Normal heating
Heating
Subcooled degree
control
0 pulse
0 pulse
6,000 pulse
6,000 pulse
6,000 pulse
0 pulse
0 pulse
0 pulse
Functions and Control
SiUS371614E
Heating
0 pulse
0 pulse
0 pulse
6,000 pulse
6,000 pulse
6,000 pulse
0 pulse
0 pulse
0 pulse