Check For Shortage Of Refrigerant; Diagnosis Of Shortage Of Refrigerant - Daikin VRVII Manual

Troubleshooting by Indication on the Remote Controller
CHECK 7
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 the
information 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).
Cooling
The opening degree of the indoor unit
electronic expansion valve becomes
larger.
High pressure
Low pressure
Low pressure rises as the
opening degree of the indoor
unit electronic expansion
valve becomes larger.
Frequency slightly increases
under the capacity control.
Frequency

Check for shortage of refrigerant.

Either of the electronic expansion
valves becomes fully open.
(Low pressure
is maintained at
a constant
level.)
To maintain low
pressure,
frequency drops
due to the
capacity control.
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.
Frequency comes to the minimum level.
High pressure drops
with decrease in
compressor capacity.
If frequency comes to the
minimum level, low
pressure cannot be
maintained.
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