Troubleshooting by Remote Controller
SiBE341027
184
Service Diagnosis
Check for overcharge of refrigerant.
In case of VRV Systems, the only way to judge as the overcharge 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 overcharge of refrigerant
1. High pressure rises. Consequently, overload control is exercised to cause scant cooling
capacity.
2. The superheated degree of suction gas lowers (or the wet operation is performed).
Consequently, the compressor becomes lower in discharge pipe temperature despite of
pressure loads.
3. The subcooled degree of condensing rises. Consequently, in heating operation, the
temperature of outlet air passing through the subcooled section becomes lower.
CHECK 6
High pressure
gradually rises with
increase in frequency.
Subcooled degree
becomes higher.
(Liquid connection
pipe temperature
lowers.)
Low pressure rises
due to reduced
compressor output.
The outside unit electronic
expansion valve is closed due to
the overload control.
Frequency comes to
the minimum level.
(High pressure is maintained
at a constant level.)
Low pressure rises
due to reduced
frequency.
To maintain high pressure,
frequency reduces under the
capacity control.
High pressure drops or rises
immediately after the overload
control is complete.
Low pressure drops due to
closed outside unit electronic
expansion valve.
Hot gas bypass is activated
for low pressure protection,
i.e., hunting at low pressure.
Cooling
High pressure
Low pressure
Frequency
Heating
High pressure
Low pressure
Frequency
Proper quantity
High pressure
drooping control
(Low pressure is
maintained at a
constant level.)
To maintain low pressure,
frequency increases under
the capacity control.
(Degree of overcharge)
Higher degree of overcharge
Frequency comes to
the minimum level.
