Check
SiUS371901EB
427
Part 6 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 judgement, 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/heating capacity.
CHECK 7
Cooling
High press
u
re
Lo
w
press
u
re
Fre
qu
ency
The opening degree of the indoor
u
nit
electronic expansion
v
al
v
e
b
ecomes
larger.
Either of the electronic expansion
v
al
v
es
b
ecomes f
u
lly open.
Fre
qu
ency comes to the minim
u
m le
v
el.
Fan control is acti
v
ated for high
press
u
re protection
u
nder
cooling control at lo
w
o
u
tdoor
air temperat
u
re, i.e., the fan is
h
u
nting at high press
u
re.
High press
u
re drops
w
ith decrease in
compressor capacity.
If fre
qu
ency comes to the
minim
u
m le
v
el, lo
w
press
u
re cannot
b
e
maintained.
Lo
w
press
u
re rises as the
opening degree of the indoor
u
nit electronic expansion
v
al
v
e
b
ecomes larger.
Fre
qu
ency slightly increases
u
nder the capacity control.
To maintain lo
w
press
u
re,
fre
qu
ency drops
d
u
e to the
capacity control.
Heating
High press
u
re
Lo
w
press
u
re
Fre
qu
ency
The opening degree of the o
u
tdoor
u
nit electronic expansion
v
al
v
e
b
ecomes larger.
The o
u
tdoor
u
nit electronic expansion
v
al
v
e f
u
lly opens and fre
qu
ency increases.
Discharge pipe or lo
w
press
u
re dropping control
(High press
u
re
is maintained at
a constant
le
v
el.)
To maintain lo
w
press
u
re,
fre
qu
ency drops d
u
e to the
capacity control.
Fre
qu
ency drops
d
u
e to the dropping
control.
(Degree of refrigerant shortage)
Higher degree of shortage
Proper amo
u
nt
(Lo
w
press
u
re
is maintained at
a constant
le
v
el.)
Fre
qu
ency comes to
the minim
u
m le
v
el.
Summary of Contents for REYQ72-432XAYCU
Page 455: ...SiUS371901EB Wiring Diagrams Part 7 Appendix 448 REYQ144 168XATJU REYQ144 168XATJA 2D119206B ...
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Page 463: ...SiUS371901EB Wiring Diagrams Part 7 Appendix 456 FXEQ07 09 12 15 18 24PVJU 3D098557A ...
Page 464: ...Wiring Diagrams SiUS371901EB 457 Part 7 Appendix FXDQ07 09 12 18 24MVJU C 3D050501C ...
Page 468: ...Wiring Diagrams SiUS371901EB 461 Part 7 Appendix FXHQ12 24 36MVJU 3D048116C ...
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Page 475: ...SiUS371901EB Wiring Diagrams Part 7 Appendix 468 VAM1200GVJU 3D073270D ...
Page 478: ...Wiring Diagrams SiUS371901EB 471 Part 7 Appendix BS6 8Q54TVJ 2D089122B ...
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