Msc/Ms/Msh Microprocessor Control - Mitsubishi Electric MSC-GE-VB Service Manual

1

MSC/MS/MSH MICROPROCESSOR CONTROL

1-1. COOL ( ) OPERATION
1. Thermostat control (MSC-GE20/25/35VB)
Thermostat turns ON or OFF by the difference between room temperature and set temperature
Room temperature minus set temperature : 0.3°C or more ················································ ON
Room temperature minus set temperature : less than -0.3°C ············································· OFF
2. 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: 1.7°C or more ························································ High
Room temperature minus set temperature: between 1 and 1.7°C ·············································Med.
Room temperature minus set temperature: less than 1°C ························································· Low
3. Coil frost prevention
Temperature control
The coil frost prevention mode in the temperature control is that the indoor fan operates at the set speed and the com-
pressor stops for 5 minutes or more.
Model
MSC-GE20VB
MSC-GE25VB
MSC-GE35VB
MS-GD80VB
MS-GE50VB
MSH-GD80VB
MSH-GE50VB
The coil frost prevention does not work for 5 minutes after the compressor started.
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 26°C or less.
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
4. Outdoor fan speed control (MU-GD80VB, MUH-GD80VB)
Outdoor fan speed control is as follows.
Indoor
fan speed
High
or
Med.
Low
5. Discharge temperature protection (MU-GD80VB, MUH-GD80VB)
The compressor is controlled by the temperature of discharge temperature thermistor for excess rise protection of compres-
sor discharge pressure.
• Compressor
When the temperature of discharge temperature thermistor goes to 120°C or more, the compressor is turned OFF. After 3
minutes since the compressor has been turned OFF, if the temperature of discharge temperature thermistor becomes 100
°C or less, the compressor is turned ON.
Initial temperature difference
Initial temperature difference
ON
Indoor coil thermistor (°C)
4 °C or less
0 °C or less
-1 °C or less
3 °C or less
1 °C or less
ON
(Continuously at set speed)
Outdoor
Temperature of
fan speed
ambient temperature
thermistor
High
Low
20°C 22°C
High
Low
30°C 33°C
Coil frost prevention
Indoor coil thermistor (°C)
More than 4 °C
More than 0 °C
More than -1 °C
More than 3 °C
More than 1 °C
ON
OFF
4
Difference between room
temperature and set tem-
perature during operation
Thermostat
Set temperature
-0.3
Difference between room
temperature and set tem-
Fan Speed
perature during operation
1°C
OFF
°C
°C
0.3
3°C
1.7°C