Hitachi RAM-68NP3B, Service Manual, Page: 60 / 79

SELF CHECK
When it is difficult to judge whether the compressor or the electrical part is faulty resulting self
diagnosis lamp LD351 blink 2,3,4 or 5 times, please confirm first the compressor terminal insulation
by using mega ohm checker. If the insulation is normal, proceed to below self-check method.
■ Self-check diagnosis method
1. Switch OFF main power supply. (Wait until DC voltage fully discharged :15 minutes or more)
2. Un-insert jumper wire connector at CN30.
3. Switch ON main power supply. (LD352 will blink 1 time)
4. Press and hold TEST SWITCH for more than 1 second.
・ IPM and the compressor motor will activated and each IGBT inside IPM will be checked
internally by inverter microcomputer. Microcomputer will detect short-circuit and open-circuit
of the IPM to determine IPM condition either in good condition or already broken.
5. Self-check diagnosis result will appear.
・ The content of diagnosis result shall refer to below table.
■ Self-check diagnosis result
In case abnormality found at the checking result, please confirm the connecting cord having
problem or not before replace the defect part according to the table of self-check diagnosis
result.
In case no abnormality found at electrical part, insert back the jumper wire connector at CN30
as original condition before it can be use.
※ If forgot to insert back as per original condition, the system will operate as below table
condition after power restored.
Time after
power restored
Below than
3 minutes
3 ~ 6 minutes
Unit condition
Indoor timer lamp will 12 times blinking
(show error - outdoor communication circuit failure).
Can run as normal.
After 6 minutes Unit enter hibernation mode. Can run as normal.