Hitachi RAC-10SH3 Service Manual Download

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The cleaning unit drive circuit comes equipped with a current detection circuit. Normally it runs in silent mode. When the

load increases, however, it will switch to high-power mode and increase the torque of the cleaning unit driving motor.

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The peak motor current in silent mode is about 83 mA, with the peak motor current in high power mode being between

about 200 mA and 300 mA.

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Switchover is judged by recognizing changes in values entered into the microcomputer as the current detection circuit

smoothes the strains in the motor current waveform. At that time, mode switchover is conducted when the change ratio of
the microcomputer input is found to have exceeded about 30%.

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Normally, the product will not switch to high-power mode unless it is mechanically locked or under a similar large load or in

another special environment which may deteriorate the grease performance.

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If the cleaning wiper undergoes a mechanical lock heavy enough to make it unmovable even in high-power mode, the

product will detect the lock and cause the clean lamp to remain on for 4 seconds and to blink for 1 second, thereby
producing an error message to alert the user.

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Even when the product has entered an error-blinking state where the clean lamp remains on for 4 seconds and off for 1

second, the product will be trouble-free in normal operation (such as cooling and heating).

When product locking is detected, it may be in either of its 2 modes.
Firstly, when the wiper is mechanically locked while moving from the right leftwards, the current is detected to detect the
locking. At that time, the cleaning wiper moves rightwards from the locked position and stops at the initial position at the right
end.
Lock judgment is performed by the strains in the motor current waveform and recognizing the changes in the microcomputer
input by using the current detection circuit. At that time, the change ratio of the microcomputer input is recognized to have
exceeded the level of about 15%, and is then judged to have locked.
Secondly, when the wiper is mechanically locked when moving from the left rightwards, the product will detect that the wiper
does not reach the right-end limit switch even after a specified time limit and detects the lock.

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The mechanical lock mentioned above is referred to when the filter is not inserted as specified or when it has received non-

dust foreign matter.

However, such locking may go undetected depending on the way the filter has ejected or on the size of the foreign matter

involved. This is because the lock detection threshold is set to a high level to prevent erroneous detection.

Reference

When mechanical locking is detected and the clean lamp has entered a mode where it remains on for 4 seconds and off

for 1 second, and when attempts to remove the cause of the mechanical locking keeps failing because of the cleaning
wiper interfering, then remove the cause of the mechanical locking by doing the following:

If the left side of the cleaning wiper is responsible for the locking, then detach the power plug and reattach it. The

cleaning brush will then move rightwards.

If the right end of the cleaning wiper is responsible for the locking, detach the power plug and reattach the plug while

holding down the cleaning limit switch. The cleaning brush will then move leftwards.

Caution

When the cleaning wiper has increased in load or switched to high-power mode, it may become slightly noisy. But this is

not a sign of breakdown.

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