Hitachi RAS-10HRNM, Service Manual, Page: 205 / 482

8.1.2 Failure of the power supply to the indoor unit and the remote control switch
• The LED and the LCD are not indicated.
• Not operated
If the fuses are blown out or a breaker is activated, investigate the cause of the overcurrent and take the necessary action.
Phenomenon Cause Check item
Action
(Turn OFF the main switch)
Power failure or power is not ON
Measure the voltage by means of
the voltmeter
Supply the power
Blown out fuse or activation of the
breaker at the power source
Short circuit supplied between the
wires
Check for any uncovered part of the
wires
Remove the cause of the short
circuit and replace the fuse
Short circuit of the wires to earth Measure the insulation resistance
Remove the cause of the short
circuit and replace the fuse
Failure of indoor unit fan motor
Measure resistance between wires
and insulation resistance
Replace the fan motor and fuse
Blown out fuse at the control circuit
Short circuit supplied between the
wires
Check for any uncovered part of the
wires
Remove the cause of the short
circuit and replace the fuse
Short circuit of the control circuit to
earth
Measure the insulation resistance
Remove the cause of the short
circuit and replace the fuse
Failure of indoor unit fan motor Measure the insulation resistance
Remove the cause of the short
circuit and replace the fuse
Failure of the transformer at the indoor unit side
Measure the voltage at the
secondary side
Replace the transformer
Disconnected cable of the remote control switch Connect the cable
Replace the cable or repair the
cable
Insufficient contacting at the
connectors of the remote control
switch
Insufficient connection or incorrect
connection of the indoor unit PCB
Check the connectors Correctly connect the connector
Insufficient connection or incorrect
connection of the indoor unit PCB in
the remote control switch
Failure of the remote control switch
Check the remote control switch by
means of the self-check mode *1)
Replace the remote control switch if
it failed
Failure of PCB
Unconnected wires to PCB Check the connectors Correctly connect the wires
Failure of PCB
Check PCB by means of the self-
check mode *2)
Replace PCB if it failed
Incorrect wiring connection Take action according to the procedure that is displayed in "TEST RUN"
N O T E
• *1): Refer to section Self-checking of the remote control switch , see on page 301.
• *2): Refer to section Self-checking procedure of PCB by means of the Remote Control Switch , see on page
299.
8 Troubleshooting
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SMGB0060 rev. 1- 12/2010
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