
SiUS331708EA
Check
Service Diagnosis
258
5.2
Low Pressure Check
Referring to the Fault Tree Analysis (FTA) shown below, probe the defective points.
Notes:
∗
1: For details of compressor capacity control while in cooling, refer to Compressor PI control on
∗
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 superheated degree control.
∗
4: In heating, the outdoor unit electronic expansion valve is used for superheated degree control of
outdoor heat exchanger.
CHECK 2
Abnormally dropin
low pressure
(Low evaporating
temperature)
[In cooling]
(
∗
1.)
Defective
low pressure
control
Defective
compressor
capacity
control
Defective low pressure
sensor
Defective main PCB
Defective
low pressure
protection
control
Defective low pressure
sensor
Defective hot gas
solenoid valve
Defective main PCB
[In both cooling
and heating]
(
∗
2.)
[In cooling]
If the indoor unit
electronic
expansion valve is
throttled too much:
(
∗
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 main PCB
Defective outdoor
unit electronic
expansion valve
Defective valve coil
Defective valve body
[In heating]
If the outdoor unit
electronic
expansion valve
excessively
throttled:
(
∗
4.)
Defective
control
Defective low pressure
sensor
Defective suction pipe
thermistor
Defective main PCB
[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 installed, is the
capacity setting properly made?
←
Is the air filter clogged?
←
Is there any obstacle in the airflow passage?
Defective 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 less 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 less 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?
←
Refer to the
CHECK 7
.
←
Eliminate moisture by vacuum operation. (Refer to
CHECK 8
)
←
Is the heat exchanger clogged?
Содержание RXSQ24TAVJU
Страница 1: ...Service Manual SiUS331708EA RXSQ24 36 48 60TAVJU Heat Pump 60 Hz...
Страница 289: ...SiUS331708EA Wiring Diagrams Appendix 276 1 Wiring Diagrams 1 1 Outdoor Unit RXSQ24 36TAVJU 3D109545A...
Страница 290: ...Wiring Diagrams SiUS331708EA 277 Appendix RXSQ48TAVJU 3D109546A...
Страница 291: ...SiUS331708EA Wiring Diagrams Appendix 278 RXSQ60TAVJU 3D109547A...
Страница 292: ...Wiring Diagrams SiUS331708EA 279 Appendix 1 2 Indoor Unit FXFQ07 09 12 15 18 24 30 36 48TVJU 3D086460B...
Страница 293: ...SiUS331708EA Wiring Diagrams Appendix 280 BYCQ125BGW1 Self Cleaning Decoration Panel for FXFQ TVJU 3D076375A...
Страница 295: ...SiUS331708EA Wiring Diagrams Appendix 282 FXZQ05 07 09 12 15 18TAVJU 3D110443A...
Страница 298: ...Wiring Diagrams SiUS331708EA 285 Appendix FXEQ07 09 12 15 18 24PVJU 3D098557A...
Страница 300: ...Wiring Diagrams SiUS331708EA 287 Appendix FXSQ05 07 09 12 15 18 24 30 36 48 54TAVJU 3D110467B...
Страница 301: ...SiUS331708EA Wiring Diagrams Appendix 288 FXMQ07 09 12 15 18 24 30 36 48 54PBVJU 3D093209B...
Страница 302: ...Wiring Diagrams SiUS331708EA 289 Appendix FXHQ12 24 36MVJU 3D048116C...
Страница 303: ...SiUS331708EA Wiring Diagrams Appendix 290 FXAQ07 09 12 18 24PVJU 3D075354C...
Страница 308: ...Wiring Diagrams SiUS331708EA 295 Appendix 1 3 2 Energy Recovery Ventilator VAM Series VAM300 470 600GVJU 3D073269D...
Страница 309: ...SiUS331708EA Wiring Diagrams Appendix 296 VAM1200GVJU 3D073270D...