Cool Mode Of "I Feel Control"; Dry Mode Of “I Feel Control”; Coil Frost Prevention; Outdoor Fan Speed Control - Mitsubishi Electric MSH-18RV Service Manual

9-1-1. 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 : 3 degrees or more····························High
Room temperature minus set temperature : Between 1 and 1.7 degrees·················Med.
Room temperature minus set temperature : less than 1 degree····························Low

2. Coil frost prevention

Temperature control
When the indoor coil thermistor RT12 reads 3°C or below(MSH-18/24RV)/ RT12 or RT13 reads -1°C or below(MSH-30RV),
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 3°C(MSH-18/24RV)/ RT12 or RT13 still reads below-1°C(MSH-30RV) this mode
prolonged until the RT12 reads over 3°C(MSH-18/24RV)/ RT12 or RT13 still reads over-1°C(MSH-30RV) .
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 26°C.
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
26°C. 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
3. Outdoor fan speed control <MSH-24/30RV only>
Outdoor fan speed is controlled according to the temperature of ambient temperature thermistor RT63.
Outdoor fan Low operation : When the outside temperature decreases to 28°C(MSH-24RV)/ 23°C(MSH-30RV) or less.
Outdoor fan High operation : Until the outside temperature decreases to 28°C(MSH-24RV)/ 23°C(MSH-30RV) or less.
NOTE1. : If the temperature of RT63 reads from 28: to 31:(MSH-24RV)/ from 23:to 27:(MSH-30RV) at the air
conditioner starting outdoor fan speed is High.
NOTE2. : <MSH-30RV only>
When indoor fan speed is Low except HEAT operation mode and the outside temperature is 29: or less, the
outdoor fan operates at Low.
Outdoor fan Low operation is cancelled according to the following conditions(1 or 2):
1 When the operation is not changed and the outside temperature goes to 31: or more.
2 When the operation is changed. (Change to HEAT operation mode / Change of the indoor fan speed)
4. Discharge temperature protection <MSH-30RV only>
The compressor is controlled by the temperature of discharge temperature thermistor RT62 for excess rise protection of compressor
discharge pressure.
• Compressor
When the temperature of discharge temperature thermistor RT62 goes to 120: or more, the compressor is turned OFF.
After 3 minutes since the compressor has been turned OFF, if the temperature of discharge temperature thermistor RT62
becomes 100: or less, the compressor is turned ON.
9-1-2. DRY mode of "I FEEL CONTROL"
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 temperature.
By such controls, indoor flow amounts will be reduced in order to lower humidity without much room temperature decrease.
Initial temperature difference
ON
(continuously at set speed)
Until the outside temperature goes to 31°C(MSH-24RV)/ 27°C(MSH-30RV) or more.
When the outside temperature goes to 31°C(MSH-24RV)/ 27°C(MSH-30RV) or more.
Fan Speed
ON
OFF
Ambient temperature
thermistor RT63 temperature
38
Difference between room
temperature and set temperature
during operation
2deg. 4deg.
1deg. 1.7deg.
Outdoor fan speed
28: 31: (MSH-24RV)
23: 27: (MSH-30RV)
High
Low