Hitachi RAM-90QH5, Service Manual, Page: 69 / 83

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Inspection method 2
Check the number of times LD301 blinks.
Doesn’t blink
Is LD302 blinking?
The IPM board is broken.
Replace the IPM board. If the unit doesn’t work even after the IPM board is replaced, the drive circuit may be broken or
the CN34 cable may be cut. Check to see that an electrical current is flowing through the
CN34 cable.
Takes several minutes to restart.
Blinks twice
Yes
LD301: Blinks once
Reset stop
LD301: Blinks twice
Peak current cut
LD301: Blinks three times
Low speed
LD301: Blinks four times
Switch failure
The power source circuit is broken.
Replace the control P.W.B..
Check to see that the MAIN P.W.B. has 16V.
* Be sure to check the correct points for measuring.
Check to see the approximate length of time it takes for
the compressor to stop after switching on and operating
two or three times.
* Wait for three minutes or more before operating.
Check to see the approximate length of time it takes for the
compressor to stop after switching on and operating two or
three times.
* Wait for three minutes or more before operating.
The power source or some other reason may have caused the microcomputer
to reset. Replace the control P.W.B. if the LED blinks once and then stops
frequently during operation.
* The LED blinks once after the power source has been inserted.
There is the possibility that the cycle load has become heavy and the
compressor has come loose. Check the compressor.
* In this case the LED may blink three times before stopping.
There is the chance that the cycle load has become heavy and the
compressor has come loose. Check the compressor.
* In this case the LED may blink twice before stopping.
Yes
Yes
Yes
abnormally
Takes several minutes
to restart.
Restarts quickly
every time.
Restarts quickly every time.
No abnormally
The IPM board may be broken.
Replace the IPM board.
The IPM board may be broken.
Replace the IPM board.
Cable abnormally
Cable abnormally
Replace the CN34 cable.
The wire from the IPM board to the
compressor loose or broken, or has it been
connected improperly?
Check the connecting wire between
compressor - IPM board, Capa board.
IPM board and Capa board - Act module,
has it been connected properly?
Replace the MAIN P.W.B..
No cable abnormally
Doesn’t work
even after the
IPM board is
replaced.
Doesn’t work even after
the IPM board is
replaced.
Doesn’t work
even after the
IPM board is
replaced.
If the unit doesn’t work even after replacing the
IPM board, the position detection circuit may
be broken. Replace the MAIN P.W.B..
If the unit doesn’t work even after replacing the
IPM board, the drive circuit may be broken.
Replace the MAIN P.W.B..
The compressor switch fails if two or more compressor cables are loose (or
broken).
There is the possibility that the compressor will not operate if the compressor
cables have been connected improperly.
Replace the cable or rewire as appropriate.
In the case that one of the compressor cables has become loose (or
broken), the compressor may work even if it is missing a phase. The
compressor occasionally operates in reverse if one of the compressor
cables has been connected improperly. Replace the cable or rewire as
appropriate.
Cable abnormally
No abnormally
O.K. (15-17.5V)
No
No
No
No