Daikin RZQ Series FCQ20EVA Service Manual page 169

SiME281501E
CHECK 9
Check for Excessive Refrigerant Charging
As criteria for judging whether refrigerant is excessively charged or not, refer to the following operating
conditions.
<Diagnosis of excessive refrigerant charging>
(1)Because high pressure rises due to excessive charging, overload control is carried out and capacity tends
to run short.
(2)Considering pressure load, compressor discharge pipe temperature is low.
(3)Subcooled degree of condensate liquid becomes large. Therefore, temperature of blown air passing
through subcooled part decreases in heating operation.
Cooling
High pressure
(∗1)
Low pressure
(∗2)
Compressor
frequency
Compressor frequency
increases in order to
maintain low pressure.
Electronic
expansion valve
Suction Suction superheated degree is approx. 0 deg.
superheated degree
Discharge
superheated degree
Adequate level
Heating
High pressure
(∗1)
Low pressure
(∗2)
Compressor
frequency
Compressor frequency
decreases in order to
maintain high pressure.
Electronic
expansion valve
Suction superheated degree is approx. 0 deg.
Suction
superheated degree
Discharge
superheated degree
Adequate level
3 This measured temperature is used to calculate the equivalent saturation pressure of the refrigerant.
(Refer to P.165.)
Service Diagnosis
As compressor
frequency decreases,
low pressure rises.
Maximum frequency
(Degree of excessive refrigerant charging)
As compressor
frequency decreases,
low pressure rises.
(Degree of excessive refrigerant charging)
Compressor frequency
decreases due to high
pressure protection control
Minimum frequency
Electronic expansion valve
opening degree decreases
due to wet protection control
Minimum opening degree
Excessive charge
Minimum frequency
Electronic expansion valve
opening degree decreases
due to wet protection control
Minimum opening degree
Excessive charge
Troubleshooting by Remote Controller
Cooling
Model RZQ
1
Intermediate heat
High exchanger thermistor
Pressure (3)
2
Pressure sensor
Low
Pressure
Heating
Model RZQ
1
Pressure sensor
High
Pressure
2
Intermediate heat
Low exchanger thermistor
Pressure (3)
160