Hitachi RAF-25FX8 Service Manual page 122

8. Reversing valve control circuit
Reversing
valve
DC voltmeter
V
or tester
Reversing valve control circuit will switch reversing valve ON/OFF according to instruction from indoor
microcomputer depending on the operation condition shows in Table 8-1.
Voltage at Q701 (between Collector and Emitter) in each operation condition is approximately as shown
in Table 8-1 when measured by multimeter.
Cooling
Heating
Dehumidifying
POWER P.W.B.
CN2
2
D701
4
Q701
R705
D-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
C-35V
12V
R701
PQ701
CN4B
R706
Fig. 8-1
Table 8-1
Collector voltage of Q701
– 140 –
MAIN P.W.B.
Microcomputer
CN4A
6 6
24
About 0.8V
About 35V
About 35V
About 0.8V
About 0.8V