Hitachi RAF-25NH5 Instructions De Service page 234

. Room Temperature Thermistor Circuit
ODEL RAD-25NH5, RAD-35NH5, RAK-18NH5, RAK-25NH5, RAK-35NH5, RAK-50NH5, RAI-25NH5, RAI-35NH5, RAI-50NH5
Fig. 5-1 shows the room temperature
thermistor circuit.
5V
Room temperature
thermistor
R305
C302
R301
A
0V
0V
Fig. 5-1
6. Heat exchanger temperature thermistor circuit
ODEL RAD-25NH5, RAD-35NH5, RAK-18NH5, RAK-25NH5, RAK-35NH5, RAK-50NH5, RAI-25NH5, RAI-35NH5, RAI-50NH5
5V
Heat exchanger
temperature thermistor
The circuit detects the indoor heat exchanger
temperature and controls the following.
(1) Preheation.
(2) Low-temperature defrosting during cooling
and dehumidifying operation.
(3) Detection of the reversing valve non-operation
or heat exchanger temperature thermistor open.
The voltage at depends on the heat exchanger
A
temperature as shown in Fig. 6-2
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icro
computer
Room
62
temp. input
R306
C303
R302
A
0V
0V
Fig. 6-1
5
4
3
2
1
0
- 264 -
The Voltage at depends on the room
A
temperature as shown in Fig. 5-2
5
4
3
2
1
0
0 10
Room temperature(
Fig. 5-2
icro computer
61
Heat exchanger
temperature input
-10 0 10
Heat exchanger temperature (
Fig. 6-2
20 30 40
)
℃
20 30 40
)
℃