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1
MS MICROPROCESSOR CONTROL
MS-A09WA MU-A09WA
MS-A12WA MU-A12WA
1-1. COOL (
) OPERATION
1. Thermostat control
Thermostat is ON or OFF by difference between room temperature and set temperature
Room temperature minus set temperature : -1.8 degrees or more·····································ON
Room temperature minus set temperature : less than -1.8 degrees···································OFF
2. Indoor fan speed control
Indoor fan operates continuously at the set speed by FAN SPEED CONTROL button
regardless of the thermostat's OFF-ON.
In AUTO the fan speed is as follows.
Room temperature minus set temperature : 3.1 degrees or more ·······························High
Room temperature minus set temperature : Between 1.8 and 3.1 degrees ···················Med.
Room temperature minus set temperature : less than 1.8 degrees ····························Low
3. Coil frost prevention
Temperature control
When the indoor coil thermistor RT12 reads 37 ºF or below the coil frost prevention mode starts immediately.
However, the coil frost prevention doesn't work for 5 minutes since the compressor has started.
The indoor fan operates at the set speed and the compressor stops for 5 minutes.
After that, if RT12 still reads below 37 ºF this mode prolonged until the RT12 reads over 37 ºF.
Time control
When the three conditions as follows have been satisfied for 1 hour and 45 minutes, compressor stops for 3 minutes.
a. Compressor has been continuously operating.
b. Indoor fan speed is Low or Med.
c. Room temperature is below 79 ºF.
When compressor stops, the accumulated time is cancelled and when compressor restarts, time counting starts from the
beginning.
Time counting also stops temporarily when the indoor fan speed becomes High or the room temperature exceeds
79 ºF. However, when two of the above conditions (b.and c.) are satisfied again. Time accumulation is resumed.
Operation chart
Example
OFF
Compressor
Outdoor fan
ON
Indoor fan
1-2. DRY (
) OPERATION
Set temperature is as shown on the right chart.
The system for dry operation uses the same refrigerant circuit as the
cooling circuit.
The compressor and the indoor fan are controlled by the room tem-
perature.
By such controls, indoor flow amounts will be reduced in order to
lower humidity without much room temperature decrease.
Initial temperature difference
Initial temperature difference
ON
(continuously at set speed)
Fan speed
ON
OFF
Set temperature and
ºF
initial room temperature in dry mode
95
86
77
68
59
50
50
59
Initial room temperature
3
Difference between room
temperature and set temper-
ature during operation.
Set temperature
Thermostat
-1.8deg.
Difference between room
temperature and set temper-
ature during operation (
1.8 deg.
3.1 deg.
ºF
68
77
86
95
-1.3deg.
T)
5.4 deg.
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