Hitachi RAC-25YH4, Service Manual, Page: 73 / 121

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Fig. 4-4 Power module circuit (U + is ON, V – is ON)
Since current flows at point (B) only when U+ transistor is ON, the current waveform at point (B becomes
intermittent waveform as shown in Fig. 4-3. Since current at point (B) is approximately proportional to
the input current of the air conditioner, input current is controlled by using DC current (Id) detection
resistor.
<Reference>
If power module is defected, self diagnosis lamps on the MAIN P.W.B. may indicate as shown below:
Fig. 4-5
Table 4-1
RAS_25_35_AW_055-086 2003.12.31, 10:59 AM 71