Hitachi RAS-E10H2 - Reversing Valve Control Circuit Details

Main P.W.B.
HIC
O.H. thermistor
DEF. thermistor
Outdoor temperature
thermistor
Microcomputer
AX-8V10
OH
DEF
Outdoor
temperature
59
63
64
0V
0V
0V
C302
0V
R303
R306
0V
R302
R305
C303
C304
R304
R301
0V
CN8
CN9
+5V
+5V
+5V
CN10
1
2
1
2
1
2
20
21
22
Fig. 6-12
R303 Voltage (V)
Table 6-2
1
CN2
3
2
D701
32
29
C
−
35V
D
−
0V
12V
16
1
ⅠC2
6-5. Reversing valve control circuit
●
In this unit, reversing valve control circuit turns ON/OFF the power to the reversing valve coil by
opening/closing the reversing valve relay
.
●
Opening/closing of relay will differ depending on the operation condition. (In the cooling cycle,
reversing valve relay is normally ON (close).)
●
Table 6-3 shows the circuit operation of each operation mode. If the following result is not obtained,
reversing valve control circuit may be defective.
Table 6-3
Point
Operation mode
Cooling
In normal cooling operation
In normal heating operation
In defrosting operation
approx. 35 V
approx. 35 V
0VHi
0VHi
12VLo 0V (not fixed)
Heating
Between Pin 29
of microcomputer and 0V
Between Pin 32 of HIC
and 0V
Between 1 and 3 CN2
Main P.W.B.
Reversing
valve
Reversing valve
relay coil
(RL5)
HIC
Fig. 6-13
Microcomputer
Reversing valve relay
RL5
- 63
-