Check
SiUS371901E
383
Service Diagnosis
4.6
Refrigerant Shortage Check
In case of
VRV
Systems, the only way to judge as the shortage of refrigerant is with operating
conditions due to the relationship to pressure control and electronic expansion valve control.
As information for making a judgment, refer to the information below.
Diagnosis of shortage of refrigerant
1. The superheating degree of suction gas rises. Consequently, the compressor discharge gas
temperature becomes higher.
2. The superheating degree of suction gas rises. Consequently, the electronic expansion valve
turns open.
3. Low pressure drops to cause the unit not to demonstrate cooling capacity (heating capacity).
CHECK 7
Cooling
High pressure
Low pressure
Frequency
The opening degree of the indoor unit
electronic expansion valve becomes
larger.
Either of the electronic expansion
valves becomes fully open.
Frequency comes to the minimum level.
Fan control is activated for high
pressure protection under
cooling control at low outdoor
air temperature, i.e., the fan is
hunting at high pressure.
High pressure drops
with decrease in
compressor capacity.
If frequency comes to the
minimum level, low
pressure cannot be
maintained.
Low pressure rises as the
opening degree of the indoor
unit electronic expansion
valve becomes larger.
Frequency slightly increases
under the capacity control.
To maintain low
pressure,
frequency drops
due to the
capacity control.
Heating
High pressure
Low pressure
Frequency
The opening degree of the outdoor unit electronic expansion valve becomes larger.
The outdoor unit electronic expansion valve fully opens and frequency increases.
Discharge pipe or low pressure dropping control
(High pressure
is maintained at
a constant
level.)
To maintain low pressure,
frequency drops due to the
capacity control.
Frequency drops
due to the dropping
control.
(Degree of refrigerant shortage)
Higher degree of shortage
Proper amount
(Low pressure
is maintained at
a constant
level.)
Frequency comes to
the minimum level.
Summary of Contents for REYQ-XA
Page 1: ...Service Manual SiUS371901E REYQ72 456XATJU REYQ72 456XAYDU REYQ72 432XAYCU Heat Recovery 60 Hz...
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 425: ...SiUS371901E Wiring Diagrams Appendix 412 FXSQ05 07 09 12 15 18 24 30 36 48 54TAVJU C 3D110467C...
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...
