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MS MICROPROCESSOR CONTROL
1
1-1. COOL ( ) OPERATION
MS-A•WA MU-A•WA
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.
1. Thermostat control
Thermostat is ON or OFF by difference between room temperature and set temperature
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.
1-2. DRY (
) OPERATION
95
86
77
68
59
50
°F
50 59 68 77 86 95
Set temperature
Initial room tem
p
erature
Set temperature and
initial room temperature in dry mode
°F
3. Coil frost prevention
Temperature control
When the indoor coil thermistor RT12 reads 37 °F 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 the indoor coil thermistor still reads below 37 °F, this mode is prolonged until the indoor coil thermistor reads
over 37 °F.
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 °F.
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 °F.
However, when two of the above conditions (b. and c.) are satisfied again. Time accumulation is resumed.
ON -1.8 °F or more
OFF less
than
-1.8 °F
-1.3 °F
Room temperature minus
set temperature (During operation)
Room temperature minus
set temperature (Initial)
Thermostat
-1.8 °F
High 3.1 °F or more
Med. between 1.8 and 3.1 °F
Low less than 1.8 °F
3.1 °F
5.4 °F
1.8 °F
Fan speed
Room temperature minus
set temperature (Initial)
Room temperature minus
set temperature (During operation)
Compressor
Outdoor fan
Indoor fan
Operation chart
Example
OFF
( Continuously at set speed)
ON
ON