Daikin REYQ14PY1B [402/477] Cooling

Daikin REYQ16PY1B [402/477] Cooling
Troubleshooting (OP: Unified ON/OFF Controller) SiBE37-701_B
391 Troubleshooting
[Check 11] 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 supercooled degree of condensate rises. Consequently, in heating operation, the
temperature of outlet air passing through the supercooled section becomes lower.
Cooling
High pressure
drooping control
Frequency comes to
the minimum level.
High pressure
gradually rises with
increase in frequency.
High pressure
Low pressure
Frequency
Supercooled degree
becomes higher.
(Liquid connection
pipe temperature
lowers.)
Low pressure rises
due to reduced
compressor output.
(Low pressure is
maintained at a
constant level.)
To maintain low pressure,
frequency increases under
the capacity control.
Heating
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.)
High pressure drops or rises
immediately after the overload
control is complete.
Low pressure rises
due to reduced
frequency.
Low pressure drops due to
closed outdoor unit
electroni c expansion valve.
Hot gas bypass is activated
for low pressure protection,
i.e., hunting at low pressure.
To maintain high pressure,
frequency reduces under the
capacity control.
High pressure
Low pressure
Frequency
Proper quantity
(Degree of overcharge)
Higher degree of overcharge

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