MXS Service Manual

Troubleshooting for Outdoor Unit SiUS121736EA
203 Service Diagnosis
7.17 Thermistor or Related Abnormality (Outdoor Unit)
Error Code H9, J3, J6, J8, J9, P4
Outdoor Unit LED
Display
A j 1 i 2 i 3 h 4 h 5 h
Method of Error
Detection
This fault is identified based on the thermistor input voltage to the microcomputer.
A thermistor fault is identified based on the temperature sensed by each thermistor.
Error Decision
Conditions
 The voltage between both ends of the thermistor is above 4.96 V or below 0.04 V with the power
on.
 J3 error is judged if the discharge pipe temperature is lower than the heat exchanger
temperature.
 The system is shut down if all the units are judged as the J8 error.
Supposed
Causes
 Disconnection of the connector for the thermistor
 Defective thermistor(s)
 Defective heat exchanger thermistor in the case of J3 error (outdoor heat exchanger thermistor
in cooling operation, or indoor heat exchanger thermistor in heating operation)
 Defective outdoor unit PCB
Troubleshooting In case of P4
Replace the outdoor unit PCB (main PCB).
P4 : Radiation fin thermistor
Caution
Be sure to turn off the power switch before connecting or disconnecting
connectors, or parts may be damaged.