Hitachi RAK-18QXB, Service Manual

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[ Situation ] The compressor will not run (the same state as the thermometer turned off), the product receives remote control
signals normally. The self-diagnosis lamp (LD301) of the outdoor unit blinks once or becomes turned off.
[ Estimated failure locations ] Room temperature thermistor, heat exchanger thermistor
Microcomputer peripheral circuit
[ Diagnosis flow ]
Initiating troubleshooting
3. Failure phenomenon: The compressor will not run.
Is the "timer lamp" (orange) of the indoor unit
blinking?
Yes
Yes
Yes
No
No
No
Check for failures according to the self-
diagnosis display.
Did the self-diagnosis lamp (LD301) of the outdoor
unit blink once or become turned off? Check for failures according to the self-
diagnosis display.
Remove the connector (CN4) of the room
temperature thermistor and heat exchanger
thermistor and measure the thermistor resistance.
Did the reading roughly agree with the resistance
values indicated in the right-hand figure? Replace the "room temperature and heat
exchanger thermistors".
Thermistor characteristics (resistance)
Ther
mistor resistance
Thermistor temperature
Replace the "indoor electrical parts".
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