SiBE12-933_A
Troubleshooting
Service Diagnosis
181
4.5
Thermistor or Related Abnormality (Indoor Unit)
Remote
Controller
Display
C4
,
C9
Method of
Malfunction
Detection
The temperatures detected by the thermistors are used to determine thermistor errors.
Malfunction
Decision
Conditions
When the thermistor input is more than 4.96 V or less than 0.04 V during compressor
operation
∗
.
∗
(reference)
F(A)TXS20-50G, F(C)(A)TXG25-50E, FDK(X)S25/35EA, FDK(X)S50C, FLK(X)S25-50BA,
FVXS25-50F
When above about 212°C (less than 120
Ω
) or below about –50°C (more than 1,860 k
Ω
).
ATX20-35G
When above about 105°C (less than
C4
: 1,070
Ω
/
C9
: 829
Ω
) or below about –30°C (more than
C4
:
331
Ω
/
C9
: 88 k
Ω
).
Note:
The values vary slightly in some models.
Supposed
Causes
Faulty connector connection
Faulty thermistor
Faulty PCB
Troubleshooting
Check No.06
Refer to P.215
C4
: Heat exchanger temperature thermistor
C9
: Room temperature thermistor
(R7134)
Check the connector connection.
Caution
Be sure to turn off power switch before connect or disconnect connector,
or parts damage may be occurred.
Is it normal?
Check No. 06
Check the thermistor resistance
value.
Is it normal?
YES
NO
YES
NO
Correct the connection.
Replace the thermistor.
(Replace the indoor unit PCB.)
Replace the indoor unit PCB.