Hitachi RAS-E10H2 - Electric Expansion Valve Control Circuit Details

detection resistor.
<Ref
erence>
If
po
wer
module
is
def
ected,
self
diagnosis
lamps
on
the
MAIN
P.
W.
B.
m
ay
indicate
as
sho
wn
belo
w:
Fig.
3-5
Fig. 3-4 Power module circuit (U
+
is OFF, V
–
is ON)
–
is ON)
–
Since current flows at point B only when U
+
transistor and V
–
transistor is ON, the current
–
transistor is ON, the current
–
wavefo
rm
at
point B
point B
becomes intermittent wa
vefo
rm
as shown in Fig.3
-3.
S
ince current at point B is approximately
proportional to the input current of the air conditioner, input current is controlled b
y
using DC current (Id)
y using DC current (Id)y
Table 3-1
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
LD303
LD302
LD301
MAIN P
.W
.B.
SER
VICE SWITC
H
HIC
IPM
- 51
-