Hitachi RAI-50NH5 - Reversing Valve Control; Reversing Valve Operation Circuit

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5. Reversing valve control circuit
● 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)
3
1
16
24
I/F 0V
0V
Fig. 5 – 1
D702
CN2
Q701
DC voltmeter
or tester
Reversing
valve
R701
R703
R219
Q705
FUSE RESISTOR
MICROCOMPUTER
PQ701
1
23
4
5V
HIC
I/F 35V
R702
V
Operation condition Collector voltage of Q701
Cooling
Heating
Dehumidifying
General operation of Cooling
In normal heating operation
MAX. rotation speed instructed
by indoor microcomputer after
defrost is completed
Defrosting
Sensor dry
About 35V
About 0.8V
About 0.8V
About 35V
About 35V
Table 5-1
0274E Pg 57-88(RAI-50NH5) 19/10/05, 3:35 PM76