Troubleshooting for FFQ Series
SiUS121632EA
152
Service Diagnosis
6.5
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:
C4
: Indoor heat exchanger thermistor 1 (liquid pipe) (R2T)
C5
: Indoor heat exchanger thermistor 2 (R3T)
C9
: Room temperature thermistor (R1T)
Note:
When replacing the defective thermistor(s), replace the thermistors as ASSY.
Check No.01
Refer to P.190
Step
Action
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.
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.
