Daikin Perfera RXM R Series Service Manual page 207

RXM20~71R + ARXM25~71R + FTXM20~71R + ATXM25~50R +
FVXM25~50A
Split New Perfera R32
ESIE20-11 – 2021.01
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.
(Degree of overcharge)
Proper amount
Refrigerant shortage diagnosis
1 The superheated degree of suction gas rises. Consequently, the compressor
discharge gas temperature becomes higher than normal.
2 The superheated degree of suction gas rises. Consequently, the electronic
expansion valve turns open more than normal or completely open for average
output.
3 Low pressure drops to cause the unit not to reach cooling capacity (or heating
capacity).
Cooling
The opening degree of the electronic
expansion valve comes larger.
Electronic expansion valve
fully opens.
High
pressure
(Low pressure is
Low
maintained at a
pressure
certain level.)
Low pressure rises with increasing
opening degree of the electronic
expansion valve, and the operating
frequency slightly increases due to the
capacity control.
Operating
frequency
To maintain low pressure, operating
frequency decreases on the capacity control.
Proper amount
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.
Higher degree of
overcharge
Fan control, i.e.,
actually hunting to
maintain high pressure
on the cooling control
with low outdoor air.
Operating frequency comes
to the lowest level.
High pressure decreases
due to compressor
capacity decreasing.
Even with compressor
operating at lowest level,
low pressure drops
(refrigerant shortage).
(Degree of shortage)
Higher degree of
shortage
4 Third party components
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Service manual
207