OCH790 _58
5105 (U4): Outdoor liquid pipe temperature thermistor (TH3) open/
short
Abnormal points and detection methods
TH3 is found to be open/short.
(The open/short detection is disabled for 10 seconds to 10
minutes after compressor starts, during defrosting opera
-
tion, or for 10 minutes after returning from the defrosting
operation.)
Open:
−40 [−40°F] or less
Short:
90 [194°F] or more
TH3:
Thermistor <Outdoor liquid pipe>
Causes and checkpoints
• Disconnection or contact failure of connectors
•
Faulty thermistor
•
Defective outdoor multi controller circuit board
The black square (■) indicates a switch position.
Diagnosis of failure
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
TH3.
Disconnect the connector to check the resis-
tance of TH3 using a multimeter.
Check the temperature of TH3.
The detected temperature of TH3 can be displayed by an
operation of SW1 on the outdoor multi controller circuit board
ON
OFF
1 2 3 4 5 6 7 8
SW1 Setting
Display on LED1, 2
Unit
–99.9–999.9
°C
Is there any abnormality such as
disconnection, looseness or break-
age?
Is the detected resistance normal?
Is the detected temperature normal?
Yes
No
No
Yes
Yes
No
