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・
The electrical expansion valve is driven with a 12 V DC power source, which is designed specifically for
the expansion valve. Four phases of windings are energized for 1 or 2 phases, while the magnetic
poles of the windings are switched over to control the valve aperture. (It is insulated from
microcomputer potential.)
・
The switchover direction of energization phases and the opening/closing direction are as shown in Table
5-1. When energized, pins
①
to
④
of CN15 are at about 1.2 V, and when not energized, they are at about
12 V. When the power supply is reset, the expansion valve is initially operated for 30 to 40 seconds.
During initial operation, the pins
①
to
④
of CN15 are measured with a tester. If there is any pin which
shows no change at 1.2 V or 12 V, then either the expansion valve or microcomputer should be
abnormal.
・
Fig. 5-2 shows the logical waveform generated when the expansion valve is operating.
5. Electrical expansion valve circuit
1
20
GND
05
01
VDD
CLK
1
2
3
4
5
6
7
8
11
13
14
15
16
17
18
19
20
ENABLE
LATCH
S-OUT
P-GND
COM2
06
08
9
12
07
10
RES
S-IN
P-GND
COM1
02
03
04
6
5
4
3
2
1
6
5
4
3
2
1
2
3
4
CN15
XA-6P
CN21
(unmounted)
6
5
4
3
2
1
7
8
9
10
5
6
11
13
14
15
16
17
18
19
12
ZD401
R415
B-0V
B-12V
R416
R417
B-0V
1
3
2
4
5V
PQ401
B-0V
1
2
4
5V
PQ403
R411
3
B-0V
R413
1
3
2
4
5V
R412
PQ402
B-0V
ZD402
C401
R418
R419
B-0V
C413
C412
C414
C411
R420
IC11
IC12(unmounted)
B-0V
R421
C421
B-0V
C423
C422
C424
D401
+
B-0V
ZD403
C415
B-0V
C425
B-0V
34
35
36
16
15
14
1
2
3
32
33
34
HIC
IC2
R356
R357
R358
Electrical
expansion
valve 1
CN19
(unmounted)
Red
Microcomputer
Clock signal
Latch signal
Serial signal
Fig. 5-1
– 190 –