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3-2. EXPANSION VALVE CONTROL (LEV CONTROL)
Linear expansion valve (LEV) is controlled by "Thermostat ON" commands given from each unit.
When outdoor unit is operating,
some indoor units stop and
some operate.
• LEV opening for each indoor unit is determined by adding adjustment in accordance
with the number of operating unit and the capacity class to standard opening, based
on the operation frequency:
Ex.) Opening 130 pulse in standard opening 1 ➝ Minimum 80 pulse, Maximum 205
pulse. (Capacity code 4 at 1 unit operation) (Capacity code 1 at 3 units operation)
• After starting operation, adjustment in accordance with intake super heat, discharge
temperature is included in standard opening. w1
Note: LEV opening in each frequency at DRY operation and COOL operation is the
same. However, velocity and compressor operation frequency controls are
different. See 2-3. OPERATIONAL FREQUENCY RANGE
(As far as the indoor unit velocity control goes, refer to DRY operation in
MICROPROCESSOR CONTROL in indoor unit.)
• LEV opening for each indoor unit is determined by adding adjustment in accordance
with the number of operating unit and the capacity class to standard opening, based
on the operation frequency:
Ex.) Opening 120 pulse in standard opening 1 ➝ Minimum 70 pulse, Maximum 165
pulse. (Capacity code 4 at 1 unit operation) (Capacity code 1 at 3 units operation)
• After starting operation, opening becomes the one that adjustment in accordance
with discharge temperature was added to basic opening. w1
Thermostat ON in HEAT mode
LEV opening
Thermostat OFF in
COOL or DRY mode
Thermostat OFF in HEAT mode
Stop of all indoor unit
Indoor unit status
COOL : 5 pulse (full closed)
HEAT :140 pulse (slightly opened)
Thermostat ON in
COOL or DRY mode
Opening before stop ➝ 500 pulse in 15 minutes
When the outdoor unit operates (When the other indoor unit operates): 5 pulse.
When outdoor unit stops. (When the other indoor unit stops or thermo off):
Maintain LEV opening before stop ➝ 500 pulse in 15 minutes
• When the outdoor unit operates. (When the other indoor unit operates): 140pulse .
• When the outdoor unit stops. (When the other indoor unit stops or thermo off):
Maintain LEV opening before stop ➝ 500 pulse in 15 minutes.
w1 LEV opening when the outdoor unit is operating: Upper limit 500 pulse, Lower limit 53pulse.
• The standard opening is on the straight line, which connects an each standard point in the section where divided
into seven according to the operation frequency of compressor as shown in the figure below.
(LEV opening is controlled in proportion to the operation frequency.)
Note: Opening is adjusted at the standard opening according to the indoor unit conditions.
However, inclination of standard opening in each point of opening does not change with the original curve.
• Add opening provided in Difference in Capacity in the table below to the standard opening from 1 to 8,
when capacity of the indoor unit is excluding code 1.
• Add opening provided in Difference in Operation number in the table below to determined LEV opening for
each indoor unit, when 2 or 3 indoor units are operated at the same time.
Note: Even when the adjusted standard opening exceeds the driving range from 59 to 500 pulse, actual
driving output opening is in a range from 59 to 500 pulse.
Determination of LEV standard opening in each indoor unit
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