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7. Electric expansion valve control circuit
Ｂ − １ ２ Ｖ
Ｒ ４ １ ８
１
６
Ｃ Ｎ １ ５
１
５
６
１
４
５
１
３
４
１
２
３
１
２
１
０
１
Ｅ Ｌ Ｅ Ｃ Ｔ Ｒ Ｉ Ｃ
Ｅ Ｘ Ｐ Ａ Ｎ Ｓ Ｉ Ｏ Ｎ
VALVE
• 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.
Table 7-1
CN15
pin#
④
③
②
①
Operation mode
④
③
②
①
９
１
２
３
４
５
１
６
７
８
Ｉ Ｃ １ １
Ｂ − ０ Ｖ
Lead
wire
1
2
ON
ON
OFF
White
OFF
ON
Yellow
Orange
OFF
OFF
OFF
OFF
OFF
OFF
Blue
1→2→3→4→5→6→7→8 VALVE CLOSE
8→7→6→5→4→3→2→1 VALVE OPEN
50ms.
５ Ｖ
Ｐ Ｑ ４ ０ １
Ｒ219
Ｒ219
４ ８
Ｒ220
Ｒ220
Ｐ Ｑ ４ ０ ２
４ ７
Ｒ221
Ｒ
2
2
1
Ｐ Ｑ ４ ０ ３
４ ６
Ｒ ４ ２ ４
Ｒ222
Ｐ Ｑ ４ ０ ４
４ ５
Fig. 7-1
Driving state
3
4
5
6
OFF
OFF
OFF
ON
ON
OFF
OFF
ON
ON
ON
OFF
OFF
ON
75ms.
200ms.
Fig.7-2
69
Ｍ Ｉ Ｃ Ｒ Ｏ
Ｉ Ｃ ２
Ｃ ＯＭ Ｐ Ｕ Ｔ Ｅ Ｒ
１ ３
４
３ ４
VALVE4
VALVE３
１ ４
３
３ ２
１ ５
２
３ ０
VALVE２
２ ９
VALVE１
１ ６
１
7
8
OFF
ON
OFF
OFF
OFF
OFF
ON
ON
12V
0.9V
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