Hitachi RAC-25FPA, Service Manual

Page: 69 / 117

Fig. 7-1
Table 7-1
Fig.7-2
CN15
pin#
Lead
wire
Driving state
White
Yellow
Orange
Blue
Operation mode
• To drive the expansion valve, use the B-12 V output. Use a 4-phase coil and feed power to the phases
1 and 2, then switch over the filed poles to control the opening of the valve.
• The reference between conducting phase switch over direction and the open/close direction are
shown in Table 7-1. When the power is turned on, approx. 0.9 V is applied to the CN15 and the pins
(
①
to
④
) and when no power is supplied, 12 V is applied. When the power is reset, the expansion
valve starts initial operation for 5 to 10 seconds.
• During the initial operation, measure each pin of the CN15 (
①
to
④
) with a multimeter. If no change
is found around 0.9 V or 12V in this step, the expansion valve or the microcomputer has failure.
• The logic waveform during the operating of the expansion valve is shown in Fig. 7-2.
7. Electric expansion valve control circuit
④
③
②
①
1→2→3→4→5→6→7→8 VALVE CLOSE
8→7→6→5→4→3→2→1 VALVE OPEN
④
③
②
①
12V
0.9V
50ms. 75ms.
200ms.
1
ON
OFF
OFF
OFF
2
ON
ON
OFF
OFF
3
OFF
ON
OFF
OFF
4
OFF
ON
ON
OFF
5
OFF
OFF
ON
OFF
6
OFF
OFF
ON
ON
7
OFF
OFF
OFF
ON
8
ON
OFF
OFF
ON
ＩＣ２
３
２
４
１
Ｒ221
Ｒ220
Ｒ219
２９
３０
３４
Ｒ222
３２
５Ｖ
Ｒ
４
１
２
Ｒ
４
１
１
ＰＱ４０１
ＰＱ４０２
ＰＱ４０３
ＰＱ４０４
６
５
４
３
２
１
Ｒ219
Ｒ220
1 2 2 Ｒ
Ｒ４２４
４５
４６
４７
４８
８
３ １
２ １
１
０ １
６ １
５ １
４ １
９
４
７
６
５
３
２
１
１
Ｒ４１８
Ｂ−０Ｖ
Ｂ−１２Ｖ
ＩＣ１１
Ｃ
４
０
１
ＣＮ１５
ＥＬＥＣＴＲ ＩＣ
ＥＸＰＡＮＳ ＩＯＮ
VALVE
１３
１４
１５
１６
VALVE２
VALVE３
VALVE4
VALVE１
ＭＩＣＲＯ
ＣＯＭＰＵＴＥＲ
69