Hitachi RAS-25WX8 Manuel De Maintenance page 154

4. Check the control P.W.B. (power circuit)
Is 35V being output at pin
relative to 0V at pin
CN3?
Is 12V being output
at (+) relative to 0V at (-) of
C114?
Is DC5V being generated?
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No
Check to see if the connection cables are
of disconnected or reversed.
If normal, check the outdoor unit P.W.B.
Yes
No
Is ICP1 normal?
Normal if it is less than 1 .
Blown (open) if it is 1 or more.
Yes
Yes
(Normal)
Has the terminal board
thermal fuse blown (open)?
No
Replace Q111 and IC111.
No
Yes
Perform final operation check.
manuals search engine
No
Replace ICP1. Check if the air
deflector motor is shorted, and
IC111, Q111, C114, ZD121 are
defective.
If shorted / defective, ICP1 will be
open again.
Yes
(Open)
Replace the terminal board.
Insert the connection cable
securely.
Replace IC121. Check if a short
occurs in the 5V line.
If the 5V line is shorted, ICP1 will
be open again.
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