Cool Mode Of “I Feel Control”; Temperature Buttons; Coil Frost Prevention; Indoor Fan Speed Control - Mitsubishi Electric MSH09TW Service Manual

(5) TEMPERATURE buttons

In "I FEEL CONTROL" mode, set temperature is decided by the microprocessor based on the room temperature.
In addition, set temperature can be controlled by TOO WARM or TOO COOL buttons when you feel too cool or too
warm.
Each time the TOO WARM or TOO COOL button is pressed, the indoor unit receives the signal and emits a beep tone.
Fuzzy control
When the TOO COOL or TOO WARM button is pressed, the microprocessor changes the set temperature, consider-
ing the room temperature, the frequency of pressing TOO COOL or TOO WARM button and the user's preference to
heat or cool. So this is called "Fuzzy control", and works only in "I FEEL CONTROL" mode.
In DRY mode of "I FEEL CONTROL", the set temperature doesn't change.
TOO
COOL
... To raise the set temperature 2~4 degrees(°F)
TOO
WARM
... To lower the set temperature 2~4 degrees(°F)
— COOL mode of "I FEEL CONTROL" —

1. Indoor fan speed control

Indoor fan operates at the set speed by FAN SPEED CONTROL button.
In AUTO the fan speed is as follows.
Room temperature minus set temperature : 2 degrees or more········································High
Room temperature minus set temperature : Between 1 and 2 degrees····························Med.
Room temperature minus set temperature : less than 1 degrees······································Low

2. Coil frost prevention

Temperature control
<MSH09> When the indoor coil thermistor RT12 reads 39˚F or below for 5 minutes, the coil frost prevention mode starts.
<MSH12/15/17> 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 the compressor stops for 5 minutes.
After that, if RT12 still reads below 39˚F (MSH09) or below 37˚F (MSH12/15/17) this mode is prolonged until the RT12
reads over 39˚F (MSH09) or 37˚F (MSH12/15/17).
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.
OFF
Compressor and
Outdoor fan motor
ON
Indoor fan motor
Initial temperature difference
ON
(continuously at set speed)
ON
OFF
56
Difference between room
temperature and set temperature
Fan speed
during operation
4 deg. 7 deg.
2 deg. 3 deg.