Cooling Overload Control (Cool); Heating Overload Control (Heat); Extreme Low Temperature Compressor Low Pressure Protection Control (Heat) - Panasonic CU-3TZ52TBE Service Manual

14.5 Cooling overload control (Cool)


This control detect outdoor pipe temperature and perform the compressor frequency restriction during cooling
operation.

14.6 Heating overload control (Heat)


This control detect indoor pipe temperature and perform the compressor frequency restriction during heating
operation.

This control detect outdoor ambient temperature and perform the fan speed adjustment during heating operation.
14.7 Extreme Low Temperature Compressor low pressure protection control
(Heat)

This control is to prevent low pressure drops too low during extremely low outdoor ambient temperature to
improve the compressor reliability.

During heating operation, when outdoor ambient temperature is in Zone 1, this control will be activated.
Compressor frequency restriction will be based on outdoor piping temperature.
64°C
60°C
OD Pipe
temp
60°C
53°C
48°C
ID Pipe
temp
12°C
OD temp
Zone 0
-5°C
Zone 1
OD temp
Comp stop
Comp freq
restricted
57°C
Comp freq
free
Comp stop
Comp freq
restricted
Comp freq
maintain
Comp freq
free
RPM controlled
10°C
RPM free
Comp freq
-25°C
Comp freq
-3°C
restricted
-28°C
Comp freq
OD pipe
37
free
-23°C
-26°C
stop