Mitsubishi Electric MSC-GE-VB Service Manual page 10

1-6. EXPANSION VALVE CONTROL (LEV CONTROL) (MU-GD80VB, MUH-GD80VB)
LEV (Expansion valve) is controlled by "Thermostat ON" commands given from the unit.
Control range
Drive speed
Opening set
Stop of indoor unit
Remote controller ON
Power ON (Breaker ON)
Approximately for 2 minutes after
compressor has started.
Approximately 2 to 13 minutes (for
11 minutes) after compressor has
started.
13 minutes after compressor has
started.
Thermostat OFF
Thermostat ON
Remote controller OFF
(1) Control data
Reference value of target discharge temperature
HEAT (MUH-GD80VB)
COOL (Normal)
COOL (∆RT is less than 2°C, or ∆RT is 2°C or more and less than 3°C.)
COOL (∆RT is 3°C or more.)
NOTE: When the discharge temperature is 50°C or less on the cool operation, or is 49°C or less on heat operation
(MUH-GD80VB), LEV opening is set in 54 pulse.
When this state continues for 20 minutes, the compressor is stopped and restarts in 3 minutes.
When the compressor is stopped, the indoor unit indicates the abnormality of refrigerant system and stops.
(OPERATION INDICATOR lamp is 10-time flashing ON and OFF.)
(2) LEV time chart
Opening
Power ON
completely
Open
Remote
controller
ON
Initial opening
Positioning
Close
NOTE : Opening increases and decreases to be in the target discharge temperature during operation.
Minimum: 54 pulse, Maximum: 500 pulse
30 ~ 90 pulse/second
The setting is always in opening direction.
(To close LEV, it is closed to the pulse smaller than the one set finally.
Then LEV is opened to the final setting pulse.)
Opening in stop: 150 pulse → LEV opening is set to become 500 pulse after 3 min-
utes.
LEV positioning (LEV is closed completely at once)
LEV is positioned. However, afterwards, LEV is not positioned when the remote
controller is turned ON for the first time after the power ON.
Opening is set by the initial opening.
(Initial opening is set according to each operation mode and outer temperature con-
ditions.)
Opening is set by standard opening.
(Standard opening is set according to each operation mode and outer temperature
conditions.)
LEV opening is corrected every 2 minutes so that discharge temperature becomes
the target discharge temperature.
(When the discharge temperature is lower than the target temperature: LEV is cor-
rected in closed direction, when the discharge temperature is higher than the target
temperature: LEV is corrected in opening direction.)
Opening in stop: 150 pulse → LEV is set to the initial opening after about 3 minutes.
Same as the starting of compressor operation
Opening in stop: 150 pulse → LEV is set so that the opening is opened completely
at the speed of 4 pulse every 5 seconds in opening after about 3 minutes.
Operation mode
Thermostat
Operation OFF
Standard opening
Standard opening Thermostat
ON
Opening in stop
Opening
Remote
completely
controller
Operation
OFF
Initial opening
Opening in stop
10
Target discharge temperature (°C)
85
80
70
65
Remote
controller
ON
Operation
Standard opening
Initial opening
Positioning
Time