Mitsubishi Electric City Multi PQHY-P72 Service Handbook page 140

-5- Refrigerant Recovery Control <PQHY>
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 heat
source 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 > 115°C [239°F]
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 30 seconds.
Opening of LEV during refrigerant recovery
(Opening of indoor unit LEV: 400 pulses)
2) Periodic capacity control of the heat source 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.
(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 [221°F] or
Pd > 3.43 MPa [497 psi] (35 kg/cm
[Refrigerant recovery]
Increase the opening of LEV1 (Periodic control begins when 30 seconds have elapsed).
Initial opening of LEV
2
G) and SC0 > 10 deg°C [18 deg°F]
- 131 -
30 seconds
Start Finish
[ VII Control ]