16
4.2. Unit Faults and Countermeasures
Table 1
Control Unit Troubleshooting
Problem
Things to check
Countermeasure
Nothing is
displayed.
Cannot start, protector activated
Cannot start, protector did not activate
Can start, display faulty
Check short circuit of
heater
Replace power supply.
Replace the display.
The display is not
accurate.
Can start
Cannot start
Replace display module.
Replace the MAIN board.
The buzzer sounds
intermittently after
the Main switch is
turned ON.
The CPU board is faulty.
Replace the CPU board.
The START switch
does not work.
(RUN lamp not lit)
The other switches do not work, either.
The other switches work.
Replace the MAIN board.
Replace the panel switch
sheet.
The COOL switch
does not work.
(COOL lamp not lit)
The other switches do not work, either.
The other switches work.
Replace the MAIN board.
Replace the panel switch
sheet.
The MODE switch
does not work.
The other switches do not work, either.
The other switches work.
Replace the MAIN board.
Replace the panel switch
sheet.
Each shift key does
not work.
The other switches do not work, either.
The other switches work.
Replace the MAIN board.
Replace the panel switch
sheet.
The CHECK switch
does not work.
The other switches do not work, either.
The other switches work.
Replace the MAIN board.
Replace the panel switch
sheet.
The FUNCTION
switch does not
work.
The other switches do not work, either.
The other switches work.
Replace the MAIN board.
Replace the panel switch
sheet.
The RUN lamp
does not light.
The test operation is good.
Cannot start
Replace the PNL board.
Replace the MAIN board.
The COOL lamp
does not light.
Pressing the COOL switch starts the fan.
Replace the PNL board.
