Protection Control; Freeze Prevention Control (Cool); Dew Prevention Control (Cool); Electronic Parts Temperature Rise Protection 1 (Cool) - Panasonic CU-4E24RBU Service Manual

13. Protection Control

13.1 Freeze Prevention control (Cool)


When received freeze prevention signal from indoor unit, the compressor frequency changes according to indoor
heat exchanger temperature.

When indoor unit request capability OFF due to freeze condition, immediately the capability supply to targeted
indoor unit stops.

13.2 Dew Prevention control (Cool)


When received dew prevention signal from indoor unit, which according to indoor intake temperature and indoor
heat exchanger temperature the compressor frequency changes.

13.3 Electronic Parts Temperature Rise Protection 1 (Cool)


This control prevents electronic parts temperature rise during cooling overload condition.

Start conditions:
Outdoor ambient temperature is at protection region as shown in figure below:
o
Outdoor unit total current is above 5.0A.
o

Control content
Outdoor fan speed is adjusted accordingly.
o

Control stop condition
When outdoor ambient temperature is back to normal region.
o

During this control, outdoor fan speed does not reduce for Quiet operation.

13.4 Electronic Parts Temperature Rise Protection 2 (Cool)


This control prevents electronic parts temperature rise during cooling/dry operation.

Start conditions:
Total current is at protection region as shown in figure below:
o

Control content
Outdoor fan speed is adjusted accordingly.
o

Control stop conditions
When total current is back to normal region.
o

During this control, outdoor fan speed does not reduce for Quiet operation.
89.6°F (32°C)
OD temp
Protection
Region
4.74A
Normal
Region
Total current
3E19RBU
Protection
Region
Normal
86.0°F (30°C)
Region
Protection
Region
11.91A
Normal
3.29A
Region
Total current
4E24RBU
44
11.82A