Daikin FTXP20-71L Service Manual page 146

4 | Third party components
To check if the refrigerant circuit is correctly charged
Service manual
146
Due to the relationship to pressure control and electronic expansion valve control,
the amount of refrigerant needs to be examined according to operating conditions.
Refer to the procedures shown below for correct examination.
Refrigerant overcharge diagnosis
1 High pressure rises. Consequently, overload control is conducted to cause
insufficient cooling capacity.
2 The superheated degree of suction gas lowers (or the wet operation is
performed). Consequently, the compressor consumes more power and is
noisy (before over‑current relay trips).
3 The subcooling degree of refrigerant in liquid form rises (values >4~5K are
NOT normal).
Cooling
High pressure gradually rises with
increasing operating frequency.
High
pressure
(Low pressure is maintained
Low
at a certain level.)
pressure
Operating
frequency
To maintain low pressure, operating
frequency increases on the capacity control.
(Degree of overcharge)
Proper amount
Heating
(High pressure is
High
maintained at a
pressure
constant level.)
Low
pressure
Low pressure rises
due to decreased
frequency.
Frequency
To maintain high pressure, frequency
decreases under the capacity control.
Proper amount
Refrigerant shortage diagnosis
1 The superheated degree of suction gas rises. Consequently, the compressor
discharge gas temperature becomes higher than normal.
High pressure drooping control
Operating frequency comes to
the lowest level.
Subcooling degree becomes
higher. (The temperature of
liquid connection piping
becomes lower.)
Low pressure rises with lowering
compressor output.
Further overcharge
The electronic expansion valve
is closed due to the overload control.
Frequency comes to
the minimum level.
High pressure drops or rises
immediately after the
overload control is complete.
Low pressure drops due to
closed outdoor unit
electronic expansion valve.
(Degree of overcharge)
Higher degree of
overcharge
ATXP20~35 + FTXP20~71 + ARXP20~35 + RXP20~71
Split Comfora R32
ESIE18-01E – 2023.01