Hitachi RAF-25NH5 Instructions De Service page 308

* 1 Example of indoor P.W.B. checking method (when indoor unit 1 is displayed as broken)
einsert the connecting cord of indoor unit 1 (the indoor unit with a communications error) and indoor unit 2 (the indoor unit
where communications are possible) (turn off the power source before disconnecting and reinserting the connecting cord)
indoor unit 2 communications error
LD303 blinks twice
The indoor unit control
P.W.B. is broken.
* 2 This breakdown check assumes an indoor unit is connected to all four rooms (or all three rooms). If an indoor unit is not
connected to all four rooms (or all three rooms), note that there will be either blinking to indicate a communications error
for the unconnected indoor unit or three blinks when there is a communications error for the connected indoor units.
* 3 Indoor unit switch power source P.W.B. check method
No
Is the 3A fuse
broken?
Yes
The switch power source
P.W.B. is broken.
abnormally
The switch power source
P.W.B. is broken.
Install CN9A, and Normal
check the voltage
f o r B E N - 1 2 V - A
and BEN-5V-A.
abnormally
Check the
expansion valve.
Normal
There is a chance that
the switch power source
control P.W.B. is broken.
eplace the switch power
source control P.W.B.
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The indoor unit control P.W.B. is not broken.
Check the outdoor unit control P.W.B.
Normal
U s e I / F 0 V - A a s a
standard for checking
the voltage for 35V-A,
BEN-12V-A and BEN-
5V-A.
abnormally
emove CN8 and
CN9A, and check
the voltage for 35V-
A, BEN-12V-A and
BEN-5V-A.
Normal
I n s t a l l C N 8 , a n d
check the voltage for
35V-A, BEN-12V-A
and BEN-5V-A.
abnormally
There is a chance that the
control P.W.B. interface
relay, interface transistor,
NF coil or indoor unit 1,
indoor unit 2 is broken.
- 344 -
indoor unit 1 communications error
LD303 blinks once
Normal
U s e I / F 0 V - B a s a
s t a n d a r d f o r
checking the voltage
for 35V-B, BEN-12V-
B and BEN-5V-B.
abnormally
abnormally
emove CN8 and
CN9B, and check
the voltage for 35V-
B, BEN-12V-B and
BEN-5V-B.
Normal
Normal
Install CN8, and check
the voltage for 35V-B,
BEN-12V-B and BEN-
5V-B.
abnormally
There is a chance that the
control P.W.B. interface
relay, interface transistor,
NF coil or indoor unit 3,
indoor unit 4 is broken.
The switch
power source
P.W.B. is normal.
The switch power
source P.W.B. is
broken.
Install CN9, and
c h e c k t h e
voltage for BEN-
12V-B and BEN-
5V-B.
abnormally
Check the
expansion valve.
Normal
There is a chance that
t h e s w i t c h p o w e r
source control P.W.B.
is broken. eplace the
switch power source
control P.W.B.