Hitachi RAM-36NP2A, Service Manual, Page: 73 / 87

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2. Only indoor fan does not operate (other is normal)
Is approx 20 V DC generated
between pins
2 (blue) and 4 (red)
of CN 10 when operated at high fan
speed during cooling?
Are pulses of approx. 33 Vp-p
generated at the collectors of Q901
in the fan operation mode? Are
collectors of Q903 approx.
0V?
Are microcomputer fan PWM
outputs (micro computer pins
45
)“Hi”
or are pulses output
in the fan operation mode?
Has the fan been stopped by
remote control?
Are microcomputer fan PWM
outputs micro computer pins
45
“Hi”?
Is 5 V DC generated between pins
2
(blue) and
1
(yellow) of CN10?
Is there 1 Ω or less between L901
and L902?
Replace indoor fan motor.
Check disconnection, etc of lead
wires.
Replace Q901.
Replace L901.
Replace Q903.
Replace micro computer.
Perform fi nal operation check.
Replace micro computer.
Replace Q903.
Replace Q901.
Replace micro computer.
Replace micro computer.
Replace the air de fl ector motor. Replace IC111.
Perform fi nal operation check.
Perform fi nal operation check.
Is there a voltage higher than 15V
across C114 (12 V line)?
Is pulse signal output to micro
computer pins
~ with air
de fl ector set to auto during cooling?
No
Yes
No
No
Are the collectors of Q903 approx
0V?
No
No
Yes
No
Yes
No
No
Yes Yes
No
Yes
Yes
Yes
3. Indoor fan speed does not change (other is normal)
4. Air de fl ector does not move (other is normal)
No
Yes
Yes
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