Reversing Valve Control Circuit - Hitachi RAK-25NH4 Service Manual

5. Reversing valve control circuit

Reversing
valve
V
DC voltmeter
or tester
Reversing valve control circuit can switch reversing valve ON/OFF according to instruction from indoor
microcomputer depending on the operation condition shows in Table 5-1.
Voltage at each point in each operation condition is approximately as shown below when measured by
tester. (When collector voltage of Q701 is measured)
Table 5-1
Cooling
Heating
Dehumidifying
CN2 FUSE RESISTOR
3
D702
1
Q701
I/F 0V
Operation condition
General operation of Cooling
In normal heating operation
MAX. rotation speed instructed
by indoor microcomputer after
defrost is completed
Defrosting
Sensor dry
I/F 35V
5V
1
4
PQ701
3 2
R703
R701
R702
0V
Fig. 5 – 1
Collector voltage of Q701
– 79 –
HIC
Q705
R219
16
24
About 35V
About 0.8V
About 0.8V
About 35V
About 35V