Thermistor Abnormality - Daikin REYQ-XA Service Manual

SiUS371901E

3.22 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 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
Notes:
Error Code
∗2. Refer to page 282 for C9 for FXTQ-TA and CXTQ-TA models
Service Diagnosis
Defective thermistor
Defective indoor unit control 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 control PCB. Then,
insert the connector again.
Is the
thermistor normal?
NO
Remove the thermistor from
the indoor unit control PCB,
and then make resistance
measurement of the thermistor
using a multimeter.
CHECK 11
Normal?
YES
C4
Indoor heat exchanger liquid pipe thermistor
C5
Indoor heat exchanger gas pipe thermistor
C9
Suction air thermistor
CA Discharge air thermistor
CHECK 11 Refer to page 385.
YES
NO
Thermistor
Troubleshooting by Error Code
Normal (The error is caused by
defective contact.)
Replace the thermistor (∗1).
Replace the indoor unit
control PCB (A1P).
Except
FXMQ-PB and
FXMQ-PB
FXTQ-TA,
CXTQ-TA
R2T R2T
R3T R3T
R1T R1T
— R4T
FXTQ-TA,
CXTQ-TA
R2T
R3T
∗2
—
278