![background image](http://html1.mh-extra.com/html/daikin/reyq72/reyq72_serveice-manual_4175337185.webp)
Troubleshooting by Indication on the Remote Controller
SiUS39-602
174
Troubleshooting
2.42
“
UO
”
Outdoor Unit:
Low Pressure Drop due to Refrigerant
Shortage or Electronic Expansion Valve Failure
Remote Controller
Display
U0
Applicable Models
REYQ72M, 96M
Method of
Malfunction
Detection
Short of gas malfunction is detected by discharge pipe temperature thermistor.
Malfunction
Decision
Conditions
Microcomputer judge and detect if the system is short of refrigerant.
★
Malfunction is not decided while the unit operation is continued.
Supposed
Causes
Out of gas or refrigerant system clogging (incorrect piping)
Defect of pressure sensor
Defect of outdoor unit PC board (A1P)
Defect of thermistor R2T or R4T
Troubleshooting
∗
1: Refer to thermistor resistance / temperature characteristics table on P.239.
∗
2: Refer to pressure sensor, pressure / voltage characteristics table on P.241.
(V2819)
The suction
pipe temperature minus
coil temperature is 57 ˚F
or higher.
Resistance
is normal when
measured with the
suction pipe thermistor
(R2T) and coil thermistor
(R4T) disconnected
from the outdoor
unit PC
board.
∗
1
Out of gas or refrigerant
system is clogged. Requires
check of refrigerant system.
Replace the thermistor.
Replace the outdoor unit PC
board (A1P).
YES
NO
NO
Out of gas, closing of stop
valve or refrigerant system is
clogged. Requires check of
refrigerant system.
Replace main outdoor unit
PC board (A1P).
YES
YES
NO
Cooling
Low pressure
is 14.5 psi
or less.
The
voltage
of X45A pins (2)
and (3) on main
outdoor unit PC board
(A1P) is 0.8 VDC or less.
(Low pressure
sensor output
voltage)
∗
2
NO
NO
YES
YES
Replace low pressure sensor.
Caution
Be sure to turn off power switch before connect or disconnect connector,
or parts damage may be occurred.
Summary of Contents for REYQ72
Page 35: ...Specifications SiUS39 602 24 Specifications...
Page 121: ...Field Setting SiUS39 602 110 Test Operation...
Page 129: ...Troubleshooting by Remote Controller SiUS39 602 118 Troubleshooting...
Page 225: ...Troubleshooting OP Unified ON OFF Controller SiUS39 602 214 Troubleshooting...
Page 232: ...SiUS39 602 Piping Diagrams Appendix 221 1 3 BS Unit BSVQ36MVJU BSVQ60MVJU 4D045338...
Page 235: ...Wiring Diagrams for Reference SiUS39 602 224 Appendix REYQ144 168 192MTJU C 3D050354A...
Page 240: ...SiUS39 602 Wiring Diagrams for Reference Appendix 229 2 4 BS Unit BSVQ36M 60MVJU 3D045069A...
Page 249: ...Example of Connection R 410A Type SiUS39 602 238 Appendix...
Page 255: ...Method of Replacing The Inverter s Power Transistors and Diode Modules SiUS39 602 244 Appendix...
Page 265: ...Precautions for New Refrigerant R 410A SiUS39 602 254 Precautions for New Refrigerant R 410A...
Page 269: ...SiUS39 602 iv Index...