Extreme Low Temperature Compressor Low Pressure Protection Control (Heat); Deice Control; Time Delay Safety Control (Restart Control); Seconds Force Operation - Panasonic CU-4E24RBU Service Manual

13.7 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.
23.0°F (-5°C)

13.8 Deice Control


When outdoor pipe temperature and outdoor air temperature is low, deice operation starts where indoor fan
motor and outdoor fan motor stop, indoor unit horizontal vane close and operation LED blink with compressor ON.

13.9 Time Delay Safety Control (Restart Control)


The compressor will not restart within three minutes after compressor is stopped.

This control is not applicable if the power supply reset or after deice condition.

13.10 30 seconds Force Operation


Once the compressor starts operation, it will not stop its operation for 30 seconds in order to cycle back
compressor oil.

However, it can be stopped using remote control or Auto OFF/ON button at indoor unit.

13.11 Total Current Control


By referring to table below, during normal (default) operation, the running current refer to Hi values and during
Power Save Mode, the running current refer to Lo values.

When the outdoor unit total running current (AC) exceeds X value, compressor frequency will decrease.

If the running current does not exceed X value for 5 seconds, compressor frequency will increase.

However, if total outdoor unit running current exceeds Y value, compressor will be stopped immediately for
3 minutes.
Operation Mode
Cooling/Soft Dry (A)
Cooling/Soft Dry (B)
Heating
Zone 0
26.6°F (-3°C)
Zone 1
OD temp
Hi
Lo
Hi
Lo
Hi
Lo
-13.0°F (-25°C)
-18.4°F (-28°C)
OD pipe
CU-3E19RBU
X (A) Y (A)
14.0
9.8
14.0
17.5
9.8
14.0
9.8
46
Comp freq
free
-9.4°F (-23°C)
Comp freq
restricted
-14.8°F (-26°C)
Comp freq
stop
CU-4E24RBU
X (A) Y (A)
18.06
12.63
17.32
23.07
12.63
20.33
14.03