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2-11. EXPANSION VALVE CONTROL/LEV CONTROL (MUZ-GC/FD/GE HC35)
(1) Outline of LEV control
The LEV basic control is setting of LEV opening degree to the standard opening degrees set for each operational fre-
quency of the compressor. However, when any change in indoor/outdoor temperatures or other factors cause air condi-
tioning load fluctuation, the LEV control also works to correct LEV opening degree based on discharge temperature (Shell
temperature) of the compressor, developing the unit’s performance.
Standard
specification
Control range
Minimum : 54 pulse
Maximum : 500 pulse
Actuating speed
Open: 40 pulse/second
Close: 90 pulse/second.
Opening degree adjustment
LEV opening degree is always adjusted in opening direction.
(When reducing the opening degree, LEV is once over-closed,
and then adjusted to the proper degree by opening.
General operation
Unit OFF
LEV remains at maximum opening degree. (LEV is reached
maximum opening degree approximate in 15 minutes after
compressor stops)
Remote controller ON
LEV is positioned. (First LEV is full closed at zero pulse and
then positioned.)
During 1 to 15 minutes after compressor starts
LEV is fixed to standard opening degree according to opera-
tional frequency of compressor.
More than about 15 minutes have passed since com-
pressor start-up
LEV opening degree is corrected to get target discharge tem-
perature of compressor.
(For lower discharge temperature than target temperature,
LEV is corrected in closing direction.)
(For higher discharge temperature than target temperature,
LEV is corrected in opening direction.)
It may take more than 30 minutes to reach target tempera-
ture, depending on operating conditions.
Thermostat OFF
LEV is adjusted to exclusive opening degree for thermostat
OFF.
Thermostat ON
LEV is controlled in the same way as that after the compressor
has started up.
Defrosting in HEAT mode
LEV is adjusted to open 500 pulse.
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(2) Time chart
OFF Time
Time
ON
Operational frequency
of the compressor
Commanded
to open
Standard
opening
degree
Opening degree is
corrected according
to discharge
temperature.
(Refer to (3))
Positioning
Air conditioner ON
Air conditioner OFF
(thermostat off)
LEV opening degree
About 15 minutes
