Lev Control; Determination Of Lev Standard Opening In Each Indoor Unit - Mitsubishi Electric MSH09TW Service Manual

10-12. LEV control

Linear expansion valve (LEV) is controlled by "Thermostat ON" commands given from each unit.
Indoor unit status
Stop of all indoor unit
When outdoor unit is operating,
some indoor units stop and
some operate.
Thermostat OFF in
COOL or DRY mode
Thermostat ON in
COOL or DRY mode
Thermostat OFF in HEAT mode
Thermostat ON in HEAT mode
w1 LEV opening when the outdoor unit is operating: Upper limit 500, Lower limit 59

Determination of LEV standard opening in each indoor unit

• 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.
< Calculation example of LEV opening >
Cool operation: Compressor frequency 70Hz: 2 units ON: 18 class
(170-150)p(80-60)o(70-60)+150+75-30=205 pulse
Opening before stop
When the outdoor unit operates (When the other indoor unit operate): 5 pulse.
When outdoor unit stops. (When the other indoor unit stops or thermo off):
Maintain LEV opening before stop
• 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
pulse. (Capacity code 4 at 1 unit operation) (Capacity code 1 at 4 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 10-10 Operational frequency range.
(As far as the indoor unit velocity control goes, refer to DRY operation in
MICROPROCESSOR CONTROL in the indoor unit service manual.)
• When the outdoor unit operates. (When the other indoor unit operates): 59 pulse
• When the outdoor unit stops. (When the other indoor unit stops or thermo off):
Maintain LEV opening before stop
• 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
pulse. (Capacity code 4 at 1 unit operation) (Capacity code 1 at 4 units operation)
• After starting operation, opening becomes the one that adjustment in accordance
with discharge temperature was added to basic opening. w1
67
LEV opening
500 pulse in 15 minutes
COOL : 5 pulse (full closed)
HEAT : 59 pulse (slightly opened)
500 pulse in 15 minutes
Minimum 80 pulse, Maximum 205
500 pulse in 15 minutes.
Minimum 70 pulse, Maximum 165