Refrigerant Recovery Control - Mitsubishi Electric PFD-P250 Service Handbook

-6- Refrigerant Recovery Control

Recovery of refrigerant is performed during heating operation to prevent the refrigerant from accumulating inside the unit
while it is stopped (unit in fan mode), or inside the indoor unit that is in cooling mode or in heating mode with thermo off. It
is also performed during cooling operation to prevent an excessive amount of refrigerant from accumulating in the outdoor
heat exchanger.
(1) During heating operation
[Starting refrigerant recovery mode]
The refrigerant recovery mode in heating starts when all of the following three conditions are met:
15 minutes have passed since the completion of previous refrigerant recovery.
Td > 105°C
Frequencies below 50 Hz
[Refrigerant recovery]
1) Refrigerant is recovered with the LEV on the applicable indoor unit (unit under stopping mode, fan mode, cooling,
heating with thermo off) being opened for 15 seconds.
2) Periodic capacity control of the outdoor units and periodic LEV control of the indoor units will be suspended during
refrigerant recovery operation; they will be performed after the recovery has been completed.
3) Defrost operation will be suspended until refrigerant recovery has been completed.
(2) During cooling operation
[Starting refrigerant recovery mode]
The refrigerant recovery mode starts when all the following conditions are met
30 minutes have passed since the completion of previous refrigerant recovery.
When the unit keeps running for 3 minutes in a row or more with high discharge temperature
Td > 105°C or
Pd > 3.43 MPa (35 kg/cm
[Refrigerant recovery]
Increase the opening of LEV1 (Periodic control begins when 30 seconds have elapsed).
Opening of LEV during refrigerant recovery
(Opening of indoor unit LEV: 500 pulses)
Initial opening of LEV
2
G) and SC0 > 10 deg°C
15 seconds
Start Finish
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[ III Control ]