Mitsubishi Electric PURY-P72 Service Handbook page 158

[ VII Control ]
Refrigerant Recovery Control
-8- Refrigerant Recovery Control
Refrigerant recovery is performed for each BC port during heating operation to prevent the refrigerant from accumulating in-
side the units that are stopped (in the fan mode), in the cooling mode, or in the heating Thermo-OFF mode.
It is also performed during cooling operation to prevent an excessive amount of refrigerant from accumulating in the outdoor
heat exchanger.
Starting criteria for the refrigerant recovery cycle (during Cooling-only, Cooling-main, Heating-only, or Heating-main
mode)
The refrigerant recovery mode starts when all of the following conditions are met:
1) When 5 minutes have passed in the Heating-only or Heating-main mode or 30 seconds have passed in the Cooling-only or
Cooling-main mode since the completion of the previous refrigerant recovery cycle AND the when following conditions are
met.
TH4 > 105°C [221°F]
2) When the port is not in the 4-minute restart delay mode
Starting criteria for the refrigerant recovery cycle (during Cooling-only, Cooling-main, Heating-only, or Heating-main
mode)
1) When the port is in the cooling Thermo-OFF, fan, or stop mode
SV C at the port turns on for 30 seconds. (
2) The opening of LEV1 and LEV3 is increased.
Capacity Control of Outdoor Fan
-9- Capacity Control of Outdoor Fan and Heat Exchanger
(1) Control method
ŒDepending on the capacity required, the rotation speed of the outdoor unit fan is controlled by the inverter to keep a constant
condensing temperature of (outside temperature +10°C [50°F]) during cooling operation and a constant evaporation temper-
ature of (0°C [32°F] =0.71 <Pa [103psi]) during heating operation.
ŒThe OS in the multiple-outdoor-unit system operates at the actual outdoor unit fan control value that is calculated by the OS
based on the preliminary outdoor unit fan control value that the OC determines.
(2) Control
ŒOutdoor unit fan stops while the compressor is stopped (except in the presence of input from snow sensor).
ŒThe fan operates at full speed for 5 seconds after start-up.(Only when TH7<0°C [32°F])
ŒThe outdoor unit fan stops during defrost operation.
ŒOn the P120 and P144 models of outdoor units, before the second fan goes into operation, the capacity of the first fan is
reduced to 50%.
(3) Outdoor unit heat exchanger capacity control patterns
Model
P72, P96 models
P120, P144 models
HWE1116D
indicates port No.)
Operation
Operation mode
patterns
Cooling-only 1
Cooling-main
2
3
Heating-only 1
Heating-main 1
2
Defrost 1
Cooling-only 1
Cooling-main
2
3
4
5
Heating-only 1
Heating-main 1
2
Defrost 1
- 149 -
Solenoid valve
SV4a SV4b SV4c
OFF ON -
OFF ON -
ON ON -
ON ON -
ON ON -
ON ON -
ON ON -
OFF ON OFF
OFF ON OFF
ON ON OFF
ON ON OFF
ON ON ON
ON ON ON
ON ON ON
ON ON ON
ON ON ON
SV4d
ON
OFF
OFF
OFF
ON
OFF
OFF
ON
OFF
OFF
OFF
OFF
OFF
ON
OFF
OFF
GB