Hitachi RAK-18QXB, Service Manual

Page: 87 / 92

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.
0 10 20 30 40 50
10
20
30
40
䋨 㷄䋩
䋨
k
㱅䋩
0
Are the room temperature thermistor, heat exchanger
thermistor connector (CN4)
[Situation] The timer lamp blinks 9 times and the product will not run.
[Estimated failure location]
䊶
Loose connector, wire break, or short-circuit in the room temperature
thermistor, heat exchanger thermistor.
[Cautions]
䊶
Starting the product by remote control will initiate failure detection.
(Merely turning on the power will not activate the failure detection function.)
[Diagnosis flow]
Initiating troubleshooting
Yes
Yes
No
No
Correct the connectors.
Replace the room temperature and
heat exchange thermistor.
Replace the "indoor control P.W.B".
Thermistor characteristics (resistance)
Ther
mistor resistance
Thermistor temperature
securely inserted?
10 . Timer lamp blinking: blinking 9 times
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