Special Control
SiUS331604E
41
Functions and Control
3.3
Defrost Operation
Pc : High pressure sensor detection value
Pe : Low pressure sensor detection value
Tc : High pressure equivalent saturation temperature
Te : Low pressure equivalent saturation temperature
Ts1 : Suction pipe temperature detected by suction 1 thermistor
Tb : Heat exchanger temperature
Defrost operation is performed to melt frost on the outdoor unit heat exchanger when heating, and thus recover
heating capacity.
Starting conditions
Defrost operation is started referring to the following conditions.
•
Outdoor heat exchanger heat transfer co-efficiency
•
Timer setting (Two hours at the minimum)
In addition, outdoor heat-exchange co-efficiency is derived from Tc, Te, and compressor load.
∗
From the preparation operation to the defrost operation, and from the defrost operation to the operation after
defrost, the compressor stops for 1 minute to reduce noise on changing of the four way valve.
Outdoor unit
actuator
Electric symbol
Defrost preparation
operation
Defrost operation
After defrost operation
RXTQ36
TAVJU
RXTQ48
TAVJU
RXTQ60
TAVJU
Compressor
M1C
M1C
M1C Upper limit control
140 Hz Full load
Increases 2 steps every 20
seconds from minimum
frequency until Pc – Pe >
0.4 MPa (58 psi) is achieved.
Outdoor fan
M1F
M1F
M1F,
M2F
STEP 8
OFF
STEP 8
Four way valve
Y1S
Y1S
Y1S
ON
OFF
ON
Main electronic
expansion valve
Y1E
Y1E
Y1E
SH control
480 pulse (Fully open)
55 pulse
Subcooling
electronic
expansion valve
Y3E
0 pulse
0 pulse
0 pulse
Hot gas bypass
valve
Y2S
OFF
ON
ON
Ending conditions
2 minutes
•
12 minutes
•
Tb > 11°C (51.8°F)
•
Ts1 – Te < 5°C (9°F)
•
160 seconds
•
Pc – Pe > 0.4 MPa
(58 psi)
OR
&
OR
Indoor unit actuator
Defrost operation
Indoor fan
Thermostat ON unit
OFF
Stopping unit
OFF
Thermostat OFF unit
OFF
Electronic expansion valve
Thermostat ON unit
416 pulse
Stopping unit
256 pulse
Thermostat OFF unit
416 pulse
Summary of Contents for VRV IV-S RXTQ-TAVJU Series
Page 1: ...Service Manual SiUS331604E RXTQ36 48 60TAVJU Heat Pump 60 Hz...
Page 254: ...Wiring Diagrams SiUS331604E 241 Appendix RXTQ48TAVJU 3D100496A...
Page 255: ...SiUS331604E Wiring Diagrams Appendix 242 RXTQ60TAVJU 3D100497A...
Page 260: ...Wiring Diagrams SiUS331604E 247 Appendix FXEQ07 09 12 15 18 24PVJU C 3D098557...
Page 267: ...SiUS331604E Wiring Diagrams Appendix 254 FXTQ12 18 24 30 36 42 48 54PAVJU 3D065036G...
Page 270: ...Wiring Diagrams SiUS331604E 257 Appendix VAM1200GVJU 3D073270C...
Page 271: ...Revision History Month Year Version Revised contents 06 2016 SiUS331604E First edition...