SiUS371901E
Check
Service Diagnosis
376
4.3
Superheat Operation Check
Referring to the Fault Tree Analysis (FTA) shown below, probe the defective points.
Notes:
∗
1: Refer to Low pressure protection control for hot gas bypass control.
∗
2: Superheating temperature control in cooling is conducted by indoor unit electronic expansion valve.
∗
3: Superheating temperature control in heating is conducted by outdoor unit electronic expansion
valve (main).
∗
4: Judgment criteria of superheat operation:
(1) Suction gas superheating degree: 10°C (18°F) and over. (2) Discharge gas superheating
degree: 45°C (81°F) and over, except immediately after compressor starts up or is running under
dropping control.
(Use the above values as a guide. Depending on the other conditions, the unit may be normal
despite the values within the above range.)
CHECK 3
Abnormal piping length
Bent or crashed pipe
(Including moisture choke)
Stop valve closed.
Defective valve coil
Defective valve body
Defective valve coil
Defective valve body
←
Are the coil resistance and insulation normal?
←
Refer to
CHECK 7
.
←
Does the piping length fall in the permissible range?
←
Conduct visual checks.
←
Eliminate moisture by vacuum operation. (Refer to
CHECK 8
.
)
←
Check if the stop valve is open.
Defective
discharge
pipe
temperature
control
Defective hot
gas bypass
control
Hot gas circuit clogging
Defective solenoid
valve coil
Defective solenoid
valve body
Defective outdoor unit
main PCB
Defective outdoor
unit main PCB
Defective valve coil
Defective low
pressure sensor
Defective subcooling
heat exchanger outlet
thermistor
Defective valve
body
Defective
injection
electronic
expansion
valve control
Superheat due to
shaft damage
Superheat due to
defective compressor
Defective indoor
unit electronic
expansion valve
Defective
control
Defective
control
Defective
outdoor unit
electronic
expansion valve
Defective four
way valve
operation
[In cooling only]
(
∗
1)
Compressor
overheat
Refrigerant
shortage
High pipe
resistance
Defective
superheating
degree
control.
[In cooling]
If the indoor unit
electronic
expansion valve is
throttled too much:
(
∗
2)
[In heating]
If the outdoor unit
electronic
expansion valve
excessively
throttled: (
∗
3)
Temperature
increase of
discharge
pipe
Defective
injection
electronic
expansion
valve
←
Are the coil resistance and
insulation normal?
←
Is the connector properly connected?
Are the thermistor resistance characteristics
normal?
←
Are the voltage characteristics normal?
←
Is the pressure value checked with the
Service Checker corresponding to the
measurement value of the pressure sensor?
←
Check if the piping temperature connected
to the four way valve is normal.
Four way valve is in the
middle position.
Leak from hot gas bypass
valve
Defective
control
Defective thermistor for
indoor unit gas pipe
Defective thermistor for
indoor unit liquid pipe
Defective indoor
unit control PCB
Defective low pressure
sensor
Defective suction pipe
thermistor
Defective outdoor
unit main PCB
←
Are the voltage characteristics normal?
←
Is the pressure value checked with the Service
Checker corresponding to the measurement
value of the pressure sensor?
←
Is the connector properly connected?
Are the thermistor resistance characteristics normal?
←
Is the connector properly connected?
Are the thermistor resistance characteristics normal?
←
Are the coil resistance and insulation normal?
←
Are the coil resistance and insulation normal?
←
Is the connector properly connected?
Are the thermistor resistance characteristics normal?
Summary of Contents for REYQ72-456XATJU
Page 415: ...SiUS371901E Wiring Diagrams Appendix 402 REYQ144 168XATJU 2D119206A ...
Page 416: ...Wiring Diagrams SiUS371901E 403 Appendix REYQ72 96 120XAYDU 2D119207B ...
Page 417: ...SiUS371901E Wiring Diagrams Appendix 404 REYQ144 168XAYDU 2D119208B ...
Page 418: ...Wiring Diagrams SiUS371901E 405 Appendix REYQ72 96 120 144 168XAYCU 2D119209A ...
Page 421: ...SiUS371901E Wiring Diagrams Appendix 408 FXZQ05 07 09 12 15 18TAVJU 3D110443A ...
Page 423: ...SiUS371901E Wiring Diagrams Appendix 410 FXEQ07 09 12 15 18 24PVJU 3D098557A ...
Page 426: ...Wiring Diagrams SiUS371901E 413 Appendix FXMQ07 09 12 15 18 24 30 36 48 54PBVJU 3D093209B ...
Page 428: ...Wiring Diagrams SiUS371901E 415 Appendix FXHQ12 24 36MVJU 3D048116C ...
Page 429: ...SiUS371901E Wiring Diagrams Appendix 416 FXAQ07 09 12 18 24PVJU C 3D075354D ...
Page 435: ...SiUS371901E Wiring Diagrams Appendix 422 VAM1200GVJU 3D073270D ...
Page 437: ...SiUS371901E Wiring Diagrams Appendix 424 1 4 2 Multi Branch Selector Unit BS4Q54TVJ 3D089123B ...
Page 438: ...Wiring Diagrams SiUS371901E 425 Appendix BS6 8Q54TVJ 2D089122B ...
Page 439: ...SiUS371901E Wiring Diagrams Appendix 426 BS10 12Q54TVJ 2D089121B ...
Page 440: ...Revision History Month Year Version Revised contents 04 2019 SiUS371901E First edition ...