Refrigerant Overcharge Check - Daikin VRV RXYMQ-A Series Service Manual

Check
6.5

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 judgment, refer to the information below.
Diagnosis of refrigerant overcharge
1. High pressure rises. Consequently, overload control is conducted to cause insufficient
2. The superheating degree of suction gas lowers (or wet operation is performed).
3. The subcooling degree of condensate rises. Consequently, in heating, the temperature of
278
cooling capacity.
Consequently, the compressor becomes lower in discharge pipe temperature despite of
pressure loads.
discharge air through the subcooled section decreases.
Cooling
High pressure
Low pressure
Frequency
Proper amount
Heating
High pressure
Low pressure
Frequency
To maintain high pressure,
frequency decreases under the
capacity control.
Proper amount
High pressure
dropping 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.
(Degree of overcharge)
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.
(Degree of overcharge)
SiME332106E
Frequency comes to
the minimum level.
Subcooling degree
becomes higher.
(Liquid connection
pipe temperature
lowers.)
Low pressure rises due
to decreased
compressor output.
Higher degree of overcharge
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
Part 6 Service Diagnosis