Refrigerant Overcharge Check - Daikin RXYQ-TA Series Service Manual

SiUS341615E
4.5

Refrigerant Overcharge Check

CHECK 6
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 the information below.
Diagnosis of overcharge of refrigerant
1. High pressure rises. Consequently, overload control is conducted to cause insufficient cooling
2. The superheated degree of suction gas lowers (or the wet operation is performed).
3. The subcooled degree of condensate rises. Consequently, in heating, the temperature of
Service Diagnosis
capacity.
Consequently, the compressor becomes lower in discharge pipe temperature despite of
pressure loads.
discharge air through the subcooled section becomes lower.
Cooling
High pressure
Low pressure
Frequency
Heating
High pressure
Low pressure
Frequency
To maintain
frequency
capacity control.
Proper amount
High pressure
drooping control
High pressure
gradually rises with
increase in
frequency.
(Low pressure is
maintained at a
constant level.)
To maintain low pressure, frequency
increases under the capacity
control.
The outdoor 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 decreased
frequency.
high pressure,
decreases under the
(Degree of overcharge)
Frequency comes to
the minimum level.
Subcooling degree
becomes higher.
(Liquid connection
pipe temperature
lowers.)
Low pressure rises due
to decreased
compressor output.
High pressure drops or rises
immediately after the overload
control is complete.
Low pressure drops due to
closed outdoor unit
electronic expansion valve.
Hot gas bypass is activated
for low pressure protection,
i.e., hunting at low pressure.
Higher degree of overcharge
Check
296