– 73 –
5. Reversing valve control circuit
❈
Since the reversing valve is differential pressure system, even when reversing valve is ON (collector
voltage of Q701 is about 0.8V normally), compressor rotation speed instructed by indoor microcomputer
exceeds 3300min-
1
, signal at pin
24
of microcomputer changes, and collector voltage of Q701 will be about
36V.
This does not indicate trouble. When rotation speed is reduced under 2700min-
1
, collector voltage of Q701
will fall to about 0.8V again. To measure voltage, connect
Œ
terminal of tester to D701 anode and
œ
terminal to D line on the terminal board.
●
By reversing valve control circuit you can switch reversing valve ON/OFF according to instruction from
indoor microcomputer and depending on operation condition.
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
£
£
Reversing
valve
CN2
D 701
Q 701
R 705
R 706
I/F 0V
0
0
0
0
0
0
0
I/F 35V
12V
R 233
PQ 701
DC voltmeter
or tester
HIC
8E21
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 36V
About 0.8V
About 0.8V
About 35V
About 35V
Table 5-1
Fig. 5 - 1
Содержание RAC-25CNH11
Страница 35: ... 35 CIRCUIT DIAGRAM MODEL RAS 25CNH11 ...
Страница 36: ... 37 CIRCUIT DIAGRAM MODEL RAC 25CNH11 ...
Страница 104: ... 113 PARTS LIST AND DIAGRAM MODEL RAS 25CNH11 11 2 18 8 20 19 12 63 1 4 60 3 7 14 15 6 5 16 13 88 61 17 9 62 10 ...
Страница 106: ... 115 MODEL RAC 25CNH11 55 22 59 16 26 24 23 20 21 19 13 52 58 53 56 57 2 3 51 15 14 18 4 5 9 6 8 54 17 7 11 10 12 25 ...
Страница 108: ...RAS 25CNH11 RAC 25CNH11 PM NO 0164E Printed in Malaysia HITACHI ...