Panasonic U-72MF2U9 Service Manual page 25

4. Output of PCB
4-9-3. Expansion valves for heat exchanger control
The configuration of the heat exchangers is different depending on the capacity of the outdoor unit.
Operation of electronic control valves during normal unit operation
Normal
All
Low ambient
cooling
temperature
mode
All
heating System stopped
mode
Other outdoor
units operating
Heat exchanger
[condenser] of
Mixed
outdoor unit
cooling/
heating
Heat exchanger
mode
[evaporator] of
outdoor unit
When operating in all cooling or all heating mode, the heat exchangers of which the compressors are driving in the
outdoor units are used.
However, when operating in cooling mode with low ambient temperature, the number of pieces for using the heat
exchanger is changed according to the operating condition of indoor units and the status of outdoor units.
When operating in mixed cooling/heating mode, the condition and the number of pieces for using the heat
exchanger are changed according to the operating condition of indoor units and the status of outdoor units.
The heat exchanger is selected in turn from the outdoor unit 2nd heat exchanger as the shortest operating time of
the inverter compressor.
SH control is controlled so that the difference of temperature between the liquid tube temperature and gas tube
temperature should be set within the range as shown below.
Mixed cooling/heating mode (Heat exchanger [evaporator] of outdoor unit) 3.6deg F ~ 9deg F (2deg C ~ 5deg C)
Status of
heat exchanger
Condenser
Condenser
Stop
Evaporator
Stop
Stop
Condenser
Stop
Evaporator
Stop
Outdoor unit Capacity
All heating mode
MOV1 MOV2
480 480 Maximum flow control
0 ~ 480 0 ~ 480 Heat exchanger capacity control
0 0 Refrigerant shut-off
12 ~ 480 12 ~ 480 SH control
0 0 Refrigerant shut-off
0 0 Refrigerant shut-off
0 ~ 480 0 ~ 480 Heat exchanger capacity control
0 0 Refrigerant shut-off
12 ~ 480 12 ~ 480 SH control
0 0 Refrigerant shut-off
-1.8deg F ~ 9deg F (-1deg C ~ 5deg C)
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3WAY VRF SYSTEM
Control Functions
Remarks
Target value of SH control
1
2
3
4
5
6
7
8
9