Daikin FTX25JVEA9 Service Manual page 271

Troubleshooting - SkyAir Indoor Unit
2.6.6 Malfunction of Heat Exchange Temperature Sensor System
C4
Remote
Controller
Display
Applicable All indoor unit models
Models
Method of Malfunction detection is carried out by temperature detected by heat exchanger sensor.
Malfunction
Detection
Malfunction When the heat exchanger thermistor becomes disconnected or short-circuited while the unit is
running.
Decision
Conditions
"
Supposed
"
Causes
"
"
Troubleshooting
Note: Measure the resistance while referring to the thermistor temperature and resistance conversion table.
Thermistor temperature and resistance conversion table.
Temperature Suction, heat exchanger(indoor)
258
Failure of the sensor itself
Broken or disconnected wire
Failure of electronic circuitry (indoor unit PC board)
Failure of connector contact
Be sure to turn off power switch before connect or disconnect connector,
Caution
or parts damage may be occurred.
Disconnect the heat exchange
sensor (R2T) from X18A on
the indoor unit PC board and
measure the resistance.
Is the thermistor
normal?
(See note)
YES
outdoor air, outdoor unit suction
pipe sensor (kΩ)
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
22.0
24.0
26.0
NO
Temperature Suction, heat exchanger(indoor)
90.8 28.0
81.7 30.0
73.5 32.0
66.3 34.0
59.8 36.0
54.1 38.0
48.9 40.0
44.3 42.0
40.2 44.0
36.5 46.0
33.2 48.0
30.2 50.0
27.5 52.0
25.1 54.0
23.0 56.0
21.0 58.0
19.2
Si18-201
Heat exchanger senser
replacement
If contact is OK, replace
outdoor unit PC board.
(MF016)
outdoor air, outdoor unit suction
pipe sensor (kΩ)
17.6
16.2
14.8
13.6
12.5
11.5
10.6
9.8
9.1
8.4
7.8
7.2
6.9
6.2
5.7
5.3
Service Diagnosis