Service Manual

SiUS071735E Main Functions
Functions and Control 16
The following drawing shows a schematic view of the inverter principle:
Inverter Features The inverter provides the following features:
 The regulating capacity can be changed according to the changes in the outdoor temperature
and cooling/heating load.
 Quick heating and quick cooling
The rotation speed of the compressor is increased when starting the heating (or cooling). This
enables to reach the set temperature quickly.
 Even during extreme cold weather, high capacity is achieved. It is maintained even when the
outdoor temperature is 2°C (35.6 °F).
 Comfortable air conditioning
A fine adjustment is integrated to keep the room temperature constant.
 Energy saving heating and cooling
Once the set temperature is reached, the energy saving operation enables to maintain the room
temperature at low power.
Frequency Limits The following functions regulate the minimum and maximum frequency:
Forced Cooling
Operation
Refer to page 113 for details.
Refrigerant circulation rate (high)
high f
low f
freq=variable
Refrigerant circulation rate (low)
high speed
low speed
(R2812)
Amount of heat
exchanged air (large)
freq=
constant
50 Hz
60 Hz
capacity=
variable
Amount of heat
exchanged air (small)
AC
power
DC
power
Amount of heat
exchanged air (large)
Amount of heat
exchanged air (small)
Frequency Functions
Low  Four way valve operation compensation. Refer to page 32.
High  Compressor protection function. Refer to page 32.
 Discharge pipe temperature control. Refer to page 33.
 Input current control. Refer to page 34.
 Freeze-up protection control. Refer to page 35.
 Heating peak-cut control. Refer to page 36.
 Defrost control. Refer to page 38.