Thermistor Or Related Abnormality - Daikin RMXS-L Series Service Manual

Troubleshooting for FFQ Series
5.5

Thermistor or Related Abnormality

C4, C5, C9
Error Code
Method of Error The temperatures detected by the thermistors determine thermistor errors.
Detection
Error Decision The voltage between the both ends of the thermistor is 4.96 V and more or 0.04 V and less during
compressor operation.
Conditions
Supposed
Causes
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.
Refer to Thermistor Resistance/Temperature Characteristics table 1 on page 267.
212
Disconnection of connector
Thermistor corresponding to the error code is defective.
Defective indoor unit PCB
Step Action
1 Disconnect the thermistor from the indoor unit PCB.
2 Read the temperature and the resistance value.
Check if the measured values correspond with the values in the table of thermistor
3
resistance check.
Be sure to turn off the power switch before connecting or disconnecting
Caution connectors, or parts may be damaged.
Check the connection of
connectors.
Normal?
YES
Check the thermistor resistance
value.
Normal?
YES
NO
NO
SiUS181631EA
Correct the connection.
Replace the defective
thermistor. (Replace the indoor
unit PCB (control PCB).)
Replace the indoor unit PCB
(control PCB).
(R22250)
Troubleshooting