Hitachi RAS-50WX8 Service Manual page 59

3. Room Temperature Thermistor Circuit
A room temperature thermistor circuit is shown in Fig. 3-1.
According to room temperature, the voltage of point
5V
Room Temperature
Thermistor
R305
R301
⃝ A
Fig. 3-1
4. Heat Exchanger Thermistor Circuit
Heat exchanger temperature is noticed inside the room
(1) Preheating
(2) Low-temperature defrosts at cooling･dehumidification operation time.
(3) Not working of reversing valve or detection of opening of heat exchange thermistor is controlled.
According to heat exchange temperature, the voltage of point
5V
Heat exchanger
thermistor
R306
R302
⃝ A
0V
Fig. 4-1
Microcomputer
Room
64
temperature input
C302
Microcomputer
Heat exchanger
63
input
C303
0V
becomes as it is shown in Fig.3-2.
5
4
3
2
1
0
becomes as it is shown in Fig. 4-2.
5
4
3
2
1
0
-10
– 98 –
0 10 20 30
Room temperature (℃)
Fig. 3-2
0
10 20 30
Room temperature ( )
℃
Fig. 4-2
40
40