Reversing Valve Control Circuit - Hitachi RAS-18FH6 Service Manual

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.
Operation mode
Cooling In normal cooling operation
In normal heating operation
Heating
In defrosting operation
Reversing
CN2
valve
3
2
1
Point
Between Pin 29
of microcomputer and 0V
Hi
Lo
Hi
Reversing valve relay
D701
12V
Reversing valve
relay coil
(RL5)
Table 6-3
Between Pin 32 of HIC
and 0V
0V
12V
0V
−
C 35V
RL5
−
D 0V
32
Fig. 6-13
– 56 –
Between 1 and 3 CN2
approx. 35 V
0V (not fixed)
approx. 35 V
Main P.W.B.
HIC
IC2
16 1 29