Hitachi RAC-18SX8 Service Manual page 223

12. Timer lamp blinking: blinking 9 times
[Situation] The timer lamp blinks 9 times and the product will not run.
[Estimated failure location] ・Loose connector, wire break, or short-circuit in the room temperature
[Cautions] ・Starting the product by remote control will initiate failure detection.
(Merely turning on the power will not activate the failure detection function.)
・The humidity sensor will not detect failures if more than 30 minutes has elapsed after
power-on.
[Diagnosis flow]
Initiating troubleshooting
Are the room temperature thermistor, heat exchanger
thermistor connector (CN4), and switching board
connector (CN17) securely inserted?
Detach the connector (CN4) from the room
temperature thermistor and heat exchanger
thermistor and measure the thermistor resistances.
Did the resistances almost agree with those indicated
in the right-hand figure?
The product will begin detecting failures if it is
close to a wire break or short-circuit.
Breathe gently onto the humidity sensor, then turn on
the power and press the START button on the remote
control unit.
After that, did the timer lamp blink 9 times again?
Replace the "switching board."
thermistor, heat exchanger thermistor, or humidity sensor
Yes
Yes
Yes
No
Correct the connectors.
No
Replace the room temperature and
heat exchange thermistor.
Thermistor characteristics (resistance)
40
30
20
10
0
0
※These cases are extremely rare in
terms of circuit configuration. If the
above troubleshooting procedure
fails to solve the problem, "replace
the indoor electrical installation."
– 256 –
10 20 30 40
Thermistor temperature
（℃）
50