SiMT041311E
Control Specification
Function and Control
52
2.8
Dew Prevention Control
Outline
Cooling the air around us means that the air is dehumidified (condensation of water on the
indoor heat exchanger). But because the air is cooled down, less moisture can present in the air
and as a consequence the relative humidity of the air rises. When the relative humidity of the
outlet air nears 100%, water may be blown out. To prevent this from happening, the unit
changes, its target evaporating temperature and the frequency of the compressor under certain
circumstances. Normally speaking, even under these conditions (dew prevention safety active),
the room should still be cooled down, only slower. Of course, if the capacity of the indoor unit is
small in comparison to the heat load, this is not the case and capacity shortage complaints may
follow.
Detail
When the indoor heat exchanger temperature is lower than the target temperature of the
indoor heat exchanger, the compressor frequency decreases by 2 Hz in every minute.
The target temperature of the indoor heat exchanger is calculated with the room temperature
and the indoor humidity.
2.9
Outdoor Fan Control
1. Fan OFF delay when stopped
The outdoor fan is turned OFF 70 seconds after the compressor stops.
2. Fan ON control to cool down the electrical box
The outdoor fan is turned ON when the electrical box temperature is high while the compressor
is OFF.
3. Fan OFF control during defrosting
The outdoor fan is turned OFF during defrosting.
4. Fan ON/OFF control when operation starts / stops
The outdoor fan is turned ON when the operation starts. The outdoor fan is turned OFF when
the operation stops.
5. Fan speed control during cooling operation
The rotation speed of the outdoor fan is fixed. However, when the outdoor temperature is low,
the unit may lower the fan rotation frequency to set a pressure difference. Also, when the
outdoor temperature is high, the unit may raise the fan rotation frequency to cool the electrical
box.
6. Fan speed control during heating operation
The rotation speed of the outdoor fan is fixed. However, when the outdoor temperature is high,
the unit may lower the fan rotation frequency to set a pressure difference.
Class
Cooling
25 class
710 rpm
35 class
780 rpm
50 class
860 rpm
Class
Heating
25 class
700 rpm
35 class
780 rpm
50 class
820 rpm