Thermistor Abnormality - Daikin RXSQ24TAVJU Service Manual

Troubleshooting by Error Code

4.22 Thermistor Abnormality

C4, C5, C9, CA
Error Code
Applicable
C4, C5: All indoor units
C9: except FXTQ-TA and CXTQ-TA models
Models
CA: FXMQ-PB models only
Method of Error
The error is determined by the temperature detected by the thermistor.
Detection
Error Decision
The thermistor becomes disconnected or shorted while the unit is running.
Conditions
Supposed
Causes
Troubleshooting
∗1. Error code and thermistor
Notes:
∗2. Refer to page 191 for C9 for FXTQ-TA and CXTQ-TA models.
CHECK 11
187
Defective thermistor
Defective indoor unit PCB
Disconnection of connector
Broken or disconnected wire
Be sure to turn off the power switch before connecting or disconnecting
Caution
connectors, or parts may be damaged.
Remove the thermistor from
the indoor unit PCB. Then,
insert the connector again.
Is the thermistor
normal?
NO
Remove the thermistor from
the indoor unit PCB, and then
make resistance measurement
of the thermistor using a
multimeter.
CHECK 11
5 to 90 kΩ
YES
Error Code
C4
Heat exchanger liquid pipe thermistor
C5
Heat exchanger gas pipe thermistor
C9
Suction air thermistor
CA Discharge air thermistor
Refer to page 266.
YES
NO
Thermistor
Normal (The error is caused by
defective contact.)
Replace the thermistor. (∗1)
Replace the indoor unit main
PCB (A1P).
Except
FXMQ-PB,
FXMQ-PB
FXTQ-TA,
CXTQ-TA
R2T R2T
R3T R3T
R1T R1T
— R4T
SiUS331708EA
FXTQ-TA,
CXTQ-TA
R1T
R2T
∗2
—
Service Diagnosis