Hitachi RAC-25FX8, Service Manual

Page: 104 / 191

– 122 –
Fig. 4-4 Power module circuit (U
+
is OFF, V
–
is ON)
Since current flows at point only when U
+
transistor is ON, the current waveform at point becomes
intermittent waveform as shown in Fig. 4-3. Since current at point 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
B B
B
Ip (peak current cut)
LD301
Blinks 2
times
Blinks 3
times
Blinks 4
times
LD301
LD301
Self-diagnosis
Self-diagnosis lamp
and mode
Abnormal low speed
rotation
Switching incomplete