FILE NO. SVM-03008
– 29 –
Fig. 8-2-8
(4) Defrost control
1) Detection of frost
In heating operation, time duration while the
compressor operates is counted, and defrost
operation starts by any condition described
below.
a. The counted time is 28 minutes or more,
and status that temperature of the outdoor
heat exchanger detected by the outdoor
heat exchanger is –20°C or lower continued
for 2 minutes or more.
b. The counted time is 28 minutes or more,
and status that temperature of the outdoor
heat exchanger detected by the outdoor
heat exchanger is –7°C or lower and
temperature lowered by 2.5°C than the
minimum value of the outdoor heat
exchanger during 10 to 15 minutes count
time continued for 2 minutes or more.
c. The counted time is 34 minutes or more,
and status that temperature of the outdoor
heat exchanger detected by the outdoor
heat exchanger is -5°C or lower and
temperature lowered by 3.0°C than the
minimum value of the outdoor heat
exchanger during 10 to 15 minutes count
time continued for 2 minutes or more.
d. If the following three conditions are satis-
fied, defrost operation (Timer defrost) starts
after heating operation for 37 minutes.
1Setting on remote control, HEAT
(mode), HIGH (Fan), 30°C
(temp.).
2Room temp. is 19°C to 24°C, and
outside air temp. is 5°C or lower.
3Defrost operation has been already
performed once.
[In starting and in stability]
The outdoor unit controls the outdoor fan based upon
the operation signal sent from the indoor unit, and also
controls revolution speed of the compressor motor.
The power coupler (IC20) for 4-way valve is turned on,
and turned off in defrost operation.
(1) Heating capacity control
Calculate the difference between temperature
detected by room temp. sensor every minute and
the set temp. set on “Temp. indicator” and variation
amount of room temp.
Then, obtain the correction amount of the com-
mand signal, and correct the current frequency
command signal.
(2) High-temp. release control
If temperature of the indoor heat exchanger
detected by the indoor heat exchanger sensor is
55°C or higher, compressor motor speed is
gradually lowered to prevent over-temp. rising of
compressed pressure.
If temperature becomes below 48°C, return to
above item (1).
(3) Current release control
The input current of compressor and outdoor fan
motor (Precisely inverter main circuit control
section) which occupies most of air conditioner
input is detected by the outdoor current sensor.
The compressor motor speed is lowered gradually
according to the range of TO (outside air temp.) if
the input current exceeds the current value
determined in each zone as shown in Fig. 8-2-8 so
that the input current does not exceed the set
value.
In case that the current lowered by approx. 0.5A
than each set value, return to above item (1).
Outside air temp. (°C)
16.0
10.3A
10.8A
9.8A
TO
15.5
11.0
10.5
In starting
•Until 12 minutes
passed after
operation start
•When 12 to 25
minutes passed
after operation
start and room
temp. is 3°C or
lower than set
temp.
•Room temp. < Set
temp. –4°C
FAN
AUTO
FAN
Manual
In stability
•When 12 to 25
minutes passed
after operation
start and room
temp. is higher
than (set temp.
–3°C)
•When 25 minutes
or more passed
after operation
start
•Room temp.
Set temp. –3.5°C