SiBE341027
Troubleshooting by Remote Controller
Service Diagnosis
185
Check for shortage of refrigerant.
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 information provided below.
Diagnosis of shortage of refrigerant
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
The opening degree of the indoor unit
electronic expansion valve becomes larger.
Either of the electronic expansion
valves becomes fully open.
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.
The opening degree of the outside unit electronic expansion valve becomes larger.
The outside unit electronic expansion valve fully opens and frequency increases.
Discharge pipe or low pressure drooping 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 drooping
control.
(Low pressure is
maintained at a
constant level.)
Cooling
High pressure
Low pressure
Frequency
Heating
High pressure
Low pressure
Frequency comes to the minimum level.
Frequency comes to
the minimum level.
(Degree of refrigerant shortage)
Higher degree of shortage
Proper quantity
Frequency
