SiUS30-1301
Troubleshooting by Indication on the Remote Controller
Service Diagnosis
247
Check for Refrigerant Shortage.
In case of VRV Systems, the only way to judge as the refrigerant shortage is with operating
conditions due to the relationship to pressure control and electronic expansion valve control.
As information for making a judgement, refer to information provided below.
Diagnosis of refrigerant shortage
1. The superheated degree of suction gas rises. Consequently, the compressor discharge gas
temperature becomes higher.
2. The superheated 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 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 condensing
u
nit electronic expansion
v
al
v
e
b
ecomes larger.
The condensing
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 drooping 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 drooping
control.
(Degree of refrigerant shortage)
Higher degree of shortage
Proper
qu
antity
(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.