Mitsubishi Electric CITY MULTI PUHY-P108 Service Handbook page 164

-11- Capacity Control of Outdoor Fan and Heat Exchanger <PUHY>
(1) Control method
Depending on the capacity required, the rotation speed of the outdoor unit fan is controlled by the inverter, targeting a
constant evaporation temperature of (0°C [32°F]= 0.71 MPa [103 psi]) during cooling operation and constant condensing
temperature of (49°C [120°F]= 2.88 MPa [418 psi]) during heating operation.
The capacity of the heat exchanger on the P126-234 models of outdoors is controlled by the 4-way valve (21S4b) or the
solenoid valve (SV5b).
(2) Control
Outdoor unit fan stops while the compressor is stopped (except in the presence of input from snow sensor).
The fan operates at full speed for 5 seconds after start-up.
The outdoor unit fan stops during defrost operation.
(3) Capacity control of outdoor heat exchanger
[P126, P144 models]
Operation Heat exchanger
mode
Cooling
Heating
Defrost
[P168-P234 models]
Operation Heat exchanger
mode
Cooling
Heating
Defrost
Notes:
The unit runs a cooling cycle when 21S4b is not powered and runs a heating cycle when it is powered.
SV5b is open when it is not powered and is closed when it is powered.
While the unit is stopped, 21S4b is not powered cooling cycle, and SV5b is open.
-12- Capacity Control of Outdoor Fan and Heat Exchanger <PURY>
(1) Control method
Depending on the capacity required, the rotation speed of the outdoor unit fan is controlled by the inverter, targeting a
constant evaporation temperature of (0°C [32°F]= 0.71 MPa [103 psi]) during cooling operation and constant condensing
temperature of (49°C [120°F]= 2.88 MPa [418 psi]) during heating operation.
(2) Control
Outdoor unit fan stops while the compressor is stopped (except in the presence of input from snow sensor).
The fan operates at full speed for 5 seconds after start-up.
The outdoor unit fan stops during defrost operation.
Inverter control
capacity
50% 5-100%
100% 10-100%
100% 10-100%
100% 0%
Number of fans
capacity
50% 1
100% 2
100% 2
100% 0
Notes
21S4b ON, SV5b ON
21S4b OFF, SV5b OFF
21S4b ON, SV5b OFF
21S4b OFF, SV5b OFF
Inverter control
5 -100% 21S4b ON
SV5b ON
10 -100% 21S4b ON
SV5b ON
10 -100% 21S4b OFF
SV5b OFF
0% 21S4b ON
SV5b OFF
- 155 -
[ VII Control ]
Notes