Daikin VRV - WII Service Manual page 266

SiUS30-604
[CHECK 5] Check for excessive refrigerant charging
In case of the VRV, judgment must be made based on operation conditions in relation to pressure control and
electronic expansion valve control. Refer to the following criteria to make such decisions.
Diagnosis of excessive refrigerant charging
(1) Since high pressure rises, overload control is carried out and therefore capacity tends to be
insufficient.
(2) Since superheated degree of suction gas decreases (or it starts wet operation), the temperature of
the compressor discharge pipe drops too much for pressure applied.
(3) Since the subcooling degree of condensate liquid increases, the temperature of air blown through
subcooled part decreases in heating.
Cooling
"ªáº
High pressure
Low pressure
Frequency
Heating
å~áº
High pressure
Low pressure
Frequency
Adequate level
Troubleshooting
No changes within the range where the receiver is capable of absorbing.
High pressure
step-down control
Gradually rises as the
frequency increases.
Maintains a certain
level of low pressure
In order to maintain low
pressure, frequency rises
due to capacity control.
No changes within the
range where the receiver is
capable of absorbing.
Reaches the lowest frequency
Maintains a certain level
of high pressure
Low pressure rises due
to decreased frequency
In order to maintain high
pressure, frequency decreases
due to capacity control.
(Degree of excessive charging)
Troubleshooting (OP: Unified ON/OFF Controller)
Reaches the
lowest frequency
Low pressure rises
due to decreased
compressor output
Outside unit electronic expansion valve opens due
to overload control
High pressure drops
immediately after overload
control, however high
pressure rises again.
Low pressure drops because the outside
unit electronic expansion valve is closed.
Low pressure protection activates hot gas
bypass = In fact, low pressure hunting.
Increase in the degree of
excessive charging
Subcooling increases
(Liquid connecting pipe
temperature drops)
253