Check code
5110
(U4)
Heat sink temperature thermistor(TH8) open/short
Abnormal points and detection methods
Causes and checkpoints
If TH8 (Internal thermistor) detects to be open/short.
Open: −34.8°C [−30.6°F] or less
Short: 102°C [215.6°F] or more
TH8:
Thermistor <Heat sink>
1.
Disconnection or contact failure of connectors
2. Characteristic defect of thermistor
3. Defective outdoor multi controller circuit board
●Diagnosis of defects
Make sure to turn the power OFF before connecting/disconnecting
any connectors, or replacing boards.
Diagnosis
Remedy
outdoor
The black square (■) indicates a switch position.
SW1 Setting
ON
OFF
Display on LED1, 2
Unit
−99.9–999.9
:
4
1 2
5 6 7 8
3
No
Yes
Yes
Yes
No
No
Yes
No
Is there any abnormality such
as disconnection, looseness or
breakage?
Is the detected resistance normal?
Is the detected temperature normal?
Connect the wiring/connector properly.
Replace it in the case of breakage.
Replace the thermistor.
Replace the outdoor multi controller circuit
board (Malfunction of thermistor circuit).
No abnormality
(A connector contact failure is suspected.)
Check the wiring and connector connection of TH8.
Disconnect the connector to check the
resistance of TH8 using a multimeter.
Check the temperature of TH8.
The detected temperature of thermistor (TH8)
can be displayed by an operation of SW1 on the
outdoor multi controller circuit board.
The detected temperature of TH8 can be displayed by an
operation of SW1 on the outdoor multi controller circuit board.
Is it a model with internal
thermistor?
76
77
OCH668G
