18
(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
2-9. EXPANSION VALVE CONTROL (LEV CONTROL)
(1) Outline of LEV control
The LEV basic control is comprised of setting LEV opening degree to the standard opening degrees set for each opera-
tional frequency of the compressor. However, when any change in indoor/outdoor temperatures or other factors cause
air conditioning load fluctuation, the LEV control also works to correct LEV opening degree based on discharge tempera-
ture (Shell temperature) of the compressor, developing the unit's performance.
Standard specification
Control range
Minimum: 33 pulses (
MUZ-A09/12/15/17
MUY-A15/17
)
59 pulses (
MUZ-A24
MUY-A24 MUZ-GA MUY-GA
)
54 pulses (
MUZ-FD MUZ-FE MUZ-GE MUY-GE
)
58 pulses (
MUZ-D
MUY-D
)
Maximum: 500 pulses
Actuating speed
Open: 40 pulses/second
Close: 90 pulses/second
Opening degree adjustment
LEV opening degree is always adjusted in opening direction. (When reduc-
ing 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 (reaches maximum opening
degree approximate in 15 minutes after compressor stops)
Remote controller ON
LEV is positioned. (First full-closed at zero pulses and then positioned.)
During 1 to 15 minutes after compressor
starts
LEV is fixed to standard opening degree according to operational frequen-
cy of compressor.
More than about 15 minutes have passed
since compressor start-up
LEV opening degree is corrected to get target discharge temperature of
compressor.
(For lower discharge temperature than target temperature, LEV is correct-
ed in closing direction.)
(For higher discharge temperature than target temperature, LEV is cor-
rected in opening direction.)
It may take more than 30 minutes to reach target temperature, depend-
ing 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 pulses
Summary of Contents for MS-A WA
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