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SiUS091601EA
Troubleshooting for FDMQ Series
Part 6 Service Diagnosis
144
Reference
6.6 Thermistor or Related Abnormality
Error Code
C4
,
C5
,
C9
Method of Error
Detection
The temperatures detected by the thermistors determine thermistor errors.
Error Decision
Conditions
The thermistor is disconnected or shorted while the unit is running.
Supposed
Causes
Disconnection of connector
Defective thermistor(s)
Breaking of wires
Defective indoor unit PCB
Troubleshooting
If the cause of the problem is related to the thermistors, the thermistors should be checked prior to
changing the indoor unit PCB.
To check the thermistors, proceed as follows:
1. Disconnect the thermistor from the indoor unit PCB.
2. Read the temperature and the resistance value.
3. Check if the measured values correspond with the values in the table of thermistor resistance
check.
C4
: Indoor heat exchanger thermistor 1 (liquid pipe) (R2T)
C5
: Indoor heat exchanger thermistor 2 (R3T)
C9
: Room temperature thermistor (R1T)
Check No.01
YES
(R24056)
NO
Check No. 01
Check the thermistor resistance
value.
YES
NO
Caution
Correct the connection.
Replace the defective
thermistor(s).
Replace the indoor unit PCB
(control PCB).
Normal?
Normal?
Check the connection of
connectors.
Be sure to turn off the power switch before connecting or disconnecting
connectors, or parts may be damaged.
Summary of Contents for FTX-N Series
Page 18: ...SiUS091601EA 13 Part 2 Specifications 1 Specifications 14 Part 2 Specifications...
Page 198: ...Check SiUS091601EA 193 Part 6 Service Diagnosis 18 24 class R24538 1 2 3 4 Multimeter...
Page 201: ...SiUS091601EA Check Part 6 Service Diagnosis 196 18 24 class R24539 DC DC W V U...
Page 229: ...SiUS091601EA Piping Diagrams Part 8 Appendix 224 RXL15QMVJU RXL18UMVJU 3D100007 3D123368...
Page 230: ...Piping Diagrams SiUS091601EA 225 Part 8 Appendix RXL24UMVJU 3D107985A...