Expansion Valve Control (Lev Control) - Mitsubishi Electric MS-A WA Service Technical Manual

3-2. EXPANSION VALVE CONTROL (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
1 LEV opening when the outdoor unit is operating: Upper limit 500 pulses, Lower limit 53 pulses (MXZ-2A/3A30NA/2B)/59
pulses (MXZ-3A30NA-
LEV opening
Opening before stop → 500 pulses in 15 minutes
COOL: 5 pulses (full closed)
HEAT: (MXZ-2A/3A30NA/2B): 140 pulses (slightly opened)
: (MXZ-3A30NA-
When the outdoor unit operates (When the other indoor unit operates): 5 pulses
When outdoor unit stops. (When the other indoor unit stops or thermo OFF):
Maintain LEV opening before stop → 500 pulses in 15 minutes
• LEV opening for each indoor unit is determined by adding adjustment according to the
number of operating unit and the capacity class to standard opening, based on the
operation frequency:
e.g.) Opening 130 pulses in standard opening 1 → Minimum 80 pulses/Maximum 205
pulses (Capacity code 4 at 1 unit operation) (Capacity code 1 at 3 units operation)
• After starting operation, adjustment according to intake super heat, discharge tempera-
ture is included in standard opening. 1
NOTE: LEV opening in each frequency at DRY operation and COOL operation is the
same. However, velocity and compressor operation frequency controls are differ-
ent. See 3-3. OPERATIONAL FREQUENCY RANGE
(As far as the indoor unit velocity control goes, refer to DRY operation in MICRO-
PROCESSOR CONTROL in indoor unit.)
• When the outdoor unit operates. (When the other indoor unit operates): 140 pulses
• When the outdoor unit stops. (When the other indoor unit stops or thermo OFF): Main-
tain LEV opening before stop → 500 pulses in 15 minutes "
• LEV opening for each indoor unit is determined by adding adjustment according to the
number of operating unit and the capacity class to standard opening, based on the
operation frequency:
e.g.) Opening 120 pulses in standard opening 1 → Minimum 70 pulses/Maximum 165
pulses (Capacity code 4 at 1 unit operation) (Capacity code 1 at 3 units operation)
• After starting operation, opening becomes the one that adjustment according to dis-
charge temperature was added to basic opening. 1 "
/4A/3B/4B).
1
/4A/3B/4B): 100 → 59 pulses
1
23