– 30 –
8-15-2. Current Limit Control and High-tempera-
ture Limit Control (during Heating)
When the load increases (overload) or the line volt-
age drops during operation of the air conditioner, the
operating current increases, and when the power ca-
pacity is exceeded, the circuit breaker is activated.
This control is performed automatically when the cur-
rent (heat exchanger temperature) exceeds a certain
value so that it is decreased automatically to prevent
overload to the supply. Control is performed as de-
scribed in (1) and (2).
(1) Current limit control'
Control is performed as shown below by detect-
ing the compressor operation current with a cur-
rent sensor.
Fig. 8-28
(2) High-temperature limit control
Control is performed as shown in Fig. 8-29 by
detecting the heat exchanger temperature with a
heat exchanger sensor (TC).
Fig. 8-29
8-16. Cool Airflow Prevention Control
(1) When control is performed with a thermostat, and
the thermostat is set to off, the indoor fan stops
operating, and restarts at the ultra low speed af-
ter 2 minutes and 20 seconds.
Fig. 8-30
(2) When the heat operation starts, the indoor fan is
kept off until the indoor heat exchanger tempera-
ture reaches a set temperature.
Fig. 8-31
(3) As soon as the defrost operation starts, the in-
door fan stops.
When the value than I
2
point continues for 5 minutes
the compressor is tuned off.
When the value than I
3
point
continues for 3 seconds
the compressor is tuned off.
Outdoor fan operation
I
3
8.2
(A)
I
2
6.9
I
1
5.8
I
0
5.5
Compressor
Outdoor fan
ON OFF ON
ON OFF ON
Set temperature
-1
Indoor fan
ON
OFF ON
Thermostat
ON
ON
ON(OFF)
Heat
exchanger
temperature
33
( C)
25
20
Fan ON
UL
UL
Fan OFF
(Control is performed
according to the air volume
changeover position.)
Fan stop
Heat
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