Hitachi RAC-25YH4, Руководство по обслуживанию, Страница: 83 / 121

– 81 –
Fig. 9-1
Table 9-1
Fig.9-2
POWER P.W.B
MAIN P.W.B
Electric
CN15
expansion
valve
Microcpmputer
Valve4
Valve3
Valve2
Valve1
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 9-1. 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 micro computer has failure.
• The logic waveform during the operating of the expansion valve is shown in Fig. 9-2.
9. Electric expansion valve control circuit
RAS_25_35_AW_055-086 2003.12.31, 10:59 AM 81