Fujitsu AB*A12, Service Manual

Page: 64 / 322

4-2-1 Operation / Stop Condition
(1) Compressor operation condition
When cooling requirement capacity or heating requirement capacity from either of the indoor units in the same
refrigerant system is input, the compressor operates.
But in the following case, the compressor operates in accordance with operation of each mode.
During 3 minute restart prevention operation
During deicing operation
Failure (except for a part) (Refer to 6-2-4)
Oil recovery
Under expansion valve initialization
At protective operation
(2) Compressor stop condition
When all the indoor units in no "cooling requirement capacity" or "heating requirement capacity ", the compressor
is stopped.
But, in the following case, the compressor operates in accordance with operation of each mode.
Oil recovery operation
Defrost operation
04-02
4-2 COMPRESSOR OPERATION
4-2-2 Capacity control
(1) Capacity of compressor operation
(2) Target low-pressure and high-pressure control
By combining the operation of DC inverter scroll compressor
and the constant speed scroll compressor,
the amount of required refrigerant circulation acceding to
cooling and heating load can be supplied from compressor
efficiently.
In order to make the evaporation pressure of the indoor unit at the proper pressure on a variety of operations,
capacity of the compressor will be controlled by low-pressure sensor of the outdoor unit (Master unit).
In order to make the condensation pressure of the indoor unit at the proper pressure on a variety of operations,
capacity of the compressor will be controlled by high-pressure sensor of the outdoor unit (Master unit).
Target low-pressure and high pressure temperature depends on system capacity, capacity of compressor operation,
pipe length, and capacity shift switch settings.
DC inverter scroll compressor is able to control the amount of
required refrigerant circulation in details.
<Cooling>
<Heating>
Cooling/Heating load
Capacity of constant speed
scroll compressor operation
C
ap
ac
ity
o
f
co
m
pr
es
so
r o
pe
ra
tio
n
Capacity of DC inverter scroll
compressor operation
(Revolution adjustment)
Total capacity