Hitachi RAC-08PH1, Service Manual, Page: 76 / 114

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
(
㽲
to
㽵
) 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 (
㽲
to
㽵
) 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
㽵
㽴
㽳
㽲
1
→
2
→
3
→
4
→
5
→
6
→
7
→
8 VALVE CLOSE
8
→
7
→
6
→
5
→
4
→
3
→
2
→
1 VALVE OPEN
㽵
㽴
㽳
㽲
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
䌉 䌃䋲
䋳
䋲
䋴
䋱
䌒 221
䌒 220
䌒 219
䋲䋹
䋳䋰
䋳䋴
䌒 222
䋳䋲
䋵䌖
䌒
䋴䋱䋲
䌒
䋴䋱䋱
䌐䌑䋴䋰䋱
䌐䌑䋴䋰䋲
䌐䌑䋴䋰䋳
䌐䌑䋴䋰䋴
䋶
䋵
䋴
䋳
䋲
䋱
䌒 219
䌒 220
1 2 2 䌒
䌒䋴䋲䋴
䋴䋵
䋴䋶
䋴䋷
䋴䋸
䋸
䋳 䋱
䋲 䋱
䋱
䋰 䋱
䋶 䋱
䋵 䋱
䋴 䋱
䋹
䋴
䋷
䋶
䋵
䋳
䋲
䋱
䋱
䌒䋴䋱䋸
䌂䋭䋰䌖
䌂䋭䋱䋲䌖
䌉 䌃䋱䋱
䌃
䋴䋰䋱
䌃䌎䋱䋵
䌅䌌䌅䌃䌔䌒䌉 䌃 䇭
䌅䌘䌐䌁䌎䌓䌉 䌏䌎䇭
VALVE 䇭
䋱䋳
䋱䋴
䋱䋵
䋱䋶
VALVE 䋲
VALVE 䋳
VALVE4
VALVE 䋱
䌍䌉䌃䌒䌏䇭
䌃䌏䌍䌐䌕䌔䌅䌒
76