Check
SiUS371901EB
417
Part 6 Service Diagnosis
Note(s)
4.2 Low
Pressure
Check
Referring to the Fault Tree Analysis (FTA) shown below, probe the defective points
CHECK 2
Abnormal drop in
low pressure
(Low evaporating
temperature)
[In cooling]
(
1.)
Defective
low pressure
control
Defective
compressor
capacity
control
Defective low pressure
sensor
Defective outdoor unit
main PCB
Defective outdoor unit
main PCB
Defective outdoor unit
main PCB
Defective outdoor unit
main PCB
Defective
low pressure
protection
control
Defective low pressure
sensor
Defective hot gas
solenoid valve
[In both cooling
and heating]
(
2.)
[In cooling]
If the indoor unit
electronic
expansion valve is
excessively
throttled: (
3.)
Defective indoor
unit electronic
expansion valve
Defective valve coil
Defective valve body
Defective
control
Defective gas pipe
thermistor of indoor unit
Defective liquid pipe
thermistor of indoor unit
Defective outdoor
unit electronic
expansion valve
Defective valve coil
Defective valve body
[In heating]
If the outdoor unit
electronic
expansion valve
is excessively
throttled:
(
4.)
Defective
control
Defective low pressure
sensor
Defective suction pipe
thermistor
[In cooling]
Low suction air
temperature of
the evaporator
[In heating]
Low suction air
temperature of
indoor unit
Short circuit
Low room temperature
Defective suction air thermistor of indoor unit
Low suction air temperature of outdoor unit
Defective outdoor air temperature thermistor of outdoor unit
High pipe
resistance
Abnormal piping length
Bent or crashed pipe
Clogging of foreign materials
Stop valve closed
Less
circulation
quantity of
refrigerant
Degradation
in evaporating
capacity
Refrigerant shortage
Moisture choke
Dirty
evaporator
Decreased
airflow rate
Decreased
fan output
Defective fan motor
Can the fan motor be rotated with hands?
Are the motor coil resistance and insulation normal?
If a spare PCB is mounted, is the
capacity setting properly made?
Is the air filter clogged?
Is there any obstacle in the airflow passage?
Defective outdoor unit main
PCB (Including capacity setting)
High
airflow
passage
resistance
Dirty filter
Obstacle
Defective electronic
expansion valve
control
Is the pressure value checked with the Service Checker
corresponding to the measurement value of the pressure sensor?
Are the voltage characteristics normal?
Is the pressure value checked with the Service Checker
corresponding to the measurement value of the pressure sensor?
Are the coil resistance and insulation normal?
Are the voltage characteristics normal?
Are the coil resistance and insulation normal?
Check for the thermistor resistance and connection.
Check for the thermistor resistance and connection.
Are the voltage characteristics normal?
Are the coil resistance and insulation normal?
Is the pressure value checked with the Service Checker
corresponding to the measurement value of the pressure sensor?
Check for the thermistor resistance and connection.
Is the suction air temperature more than 14°C (57.2°F)?
Is the room temperature less than 14°C (57.2°F)?
Is the connector properly connected?
Are the thermistor resistance characteristics normal?
Is the outdoor air temperature more than –20°C (–4°F)?
Is the connector properly connected?
Are the thermistor resistance characteristics normal?
Does the piping length fall in the permissible range?
Conduct visual checks for pipe conditions.
Is there any temperature difference caused before
and after the filter or branch pipe?
Check if the stop valve is open.
Refer to
CHECK 7
.
Eliminate moisture by vacuum operation. (Refer to
CHECK 8
)
Is the heat exchanger clogged?
∗
1. For details of compressor capacity control while in cooling, refer to Compressor PI
control.
∗
2. The low pressure protection control includes low pressure protection control and
hot gas bypass control.
∗
3. In cooling, the indoor unit electronic expansion valve is used for superheating
degree control.
Содержание REYQ72-432XAYCU
Страница 1: ...Service Manual Heat Recovery 60 Hz REYQ72 456XATJU A REYQ72 456XAYDU A REYQ72 432XAYCU A SiUS371901EB ...
Страница 92: ...Refrigerant Circuit Piping Diagrams SiUS371901EB 85 Part 2 Refrigerant Circuit BSF6Q54TVJ 3D125655 ...
Страница 93: ...SiUS371901EB Refrigerant Circuit Piping Diagrams Part 2 Refrigerant Circuit 86 BSF8Q54TVJ 3D125656 ...
Страница 455: ...SiUS371901EB Wiring Diagrams Part 7 Appendix 448 REYQ144 168XATJU REYQ144 168XATJA 2D119206B ...
Страница 456: ...Wiring Diagrams SiUS371901EB 449 Part 7 Appendix REYQ72 96 120XAYDU REYQ72 96 120XAYDA 2D119207C ...
Страница 457: ...SiUS371901EB Wiring Diagrams Part 7 Appendix 450 REYQ144 168XAYDU REYQ144 168XAYDA 2D119208C ...
Страница 458: ...Wiring Diagrams SiUS371901EB 451 Part 7 Appendix REYQ72 96 120 144 168XAYCU REYQ72 96 120 144 168XAYCA 2D119209B ...
Страница 459: ...SiUS371901EB Wiring Diagrams Part 7 Appendix 452 1 2 Indoor Unit FXFQ07 09 12 15 18 24 30 36 48TVJU 3D086460B ...
Страница 460: ...Wiring Diagrams SiUS371901EB 453 Part 7 Appendix BYCQ125BGW1 Self Cleaning Decoration Panel for FXFQ TVJU 3D076375A ...
Страница 461: ...SiUS371901EB Wiring Diagrams Part 7 Appendix 454 FXZQ05 07 09 12 15 18TAVJU 3D110443A ...
Страница 463: ...SiUS371901EB Wiring Diagrams Part 7 Appendix 456 FXEQ07 09 12 15 18 24PVJU 3D098557A ...
Страница 464: ...Wiring Diagrams SiUS371901EB 457 Part 7 Appendix FXDQ07 09 12 18 24MVJU C 3D050501C ...
Страница 465: ...SiUS371901EB Wiring Diagrams Part 7 Appendix 458 FXSQ05 07 09 12 15 18 24 30 36 48 54TAVJU C 3D110467C ...
Страница 466: ...Wiring Diagrams SiUS371901EB 459 Part 7 Appendix FXMQ07 09 12 15 18 24 30 36 48 54PBVJU 3D093209B ...
Страница 468: ...Wiring Diagrams SiUS371901EB 461 Part 7 Appendix FXHQ12 24 36MVJU 3D048116C ...
Страница 469: ...SiUS371901EB Wiring Diagrams Part 7 Appendix 462 FXAQ07 09 12 18 24PVJU 3D075354F ...
Страница 475: ...SiUS371901EB Wiring Diagrams Part 7 Appendix 468 VAM1200GVJU 3D073270D ...
Страница 477: ...SiUS371901EB Wiring Diagrams Part 7 Appendix 470 1 4 2 Multi Branch Selector Unit Standard Series BS4Q54TVJ 3D089123B ...
Страница 478: ...Wiring Diagrams SiUS371901EB 471 Part 7 Appendix BS6 8Q54TVJ 2D089122B ...
Страница 479: ...SiUS371901EB Wiring Diagrams Part 7 Appendix 472 BS10 12Q54TVJ 2D089121B ...
Страница 480: ...Wiring Diagrams SiUS371901EB 473 Part 7 Appendix 1 4 3 Multi Branch Selector Unit Flex Series BSF4Q54TVJ 3D123904A ...
Страница 481: ...SiUS371901EB Wiring Diagrams Part 7 Appendix 474 BSF6 8Q54TVJ 2D123905A ...