Thermistor Abnormality - Daikin RXYQ-TA Series Service Manual

SiUS341615E

3.18 Thermistor Abnormality

C4, C5, C9, CA
Error Code
Applicable
C4, C5: All indoor units
C9: except FXTQ-TA models
Models
CA: FXMQ-PB models only
Method of Error
The error is detected by temperature detected by thermistor.
Detection
Error Decision
The thermistor becomes disconnected or shorted while the unit is running.
Conditions
Supposed
Causes
Troubleshooting
∗1. Error code and thermistor
Note:
∗2. Refer to page 204 for C9 for FXTQ-TA models.
Service Diagnosis
Defective thermistor
Defective indoor unit PCB
Defective connector connection
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.
5 kΩ to 90 kΩ
CHECK 11
YES
Error Code
C4
Heat exchanger liquid pipe thermistor
C5
Heat exchanger gas pipe thermistor
C9
Suction air thermistor
CA Discharge air thermistor
CHECK 11 Refer to page 299.
YES
NO
Thermistor
Troubleshooting by Error Code
Normal (The error is caused by
defective contact.)
Replace the thermistor (∗1).
Replace the indoor unit main
PCB (A1P).
Except
FXMQ-PB and FXMQ-PB
FXTQ-TA
R2T R2T
R3T R3T
R1T R1T
— R4T
FXTQ-TA
R2T
R3T
∗2
—
200