Hitachi Summit RAC-18YH6, Service Manual, Page: 46 / 96

– 44 –
Fig. 3-4 Power module circuit (U + is OFF, V – is ON)
Since current flows at point B only when U
+
transistor and V
–
transistor are ON, the current waveform
at point B becomes intermittent waveform as shown in Fig. 3-3. 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:
LD303
LD302
LD301
MAIN P.W.B.
SERVICE SWITCH
HIC
IPM
Fig. 3-5
Table 3-1