Abnormal points and detection methods Causes and check points
Abnormal if TH4 detects to be open/short.
(The open/short detection is disabled for 10 minutes after compressor
starts, during defrosting operation, or for 10 minutes after returning from
the defrosting operation.)
Open: 37.4°F [3 ] or less
Short: 422.6°F [217 ] or more TH4: Thermistor <Compressor>
Disconnection or contact failure of connectors
Characteristic defect of thermistor
Defective outdoor multi controller circuit board
●Diagnosis of defectives
Make sure to turn the power OFF before connecting/disconnecting
any connectors, or replacing boards.
Diagnosis Remedy
5101
(U3)
Compressor temperature thermistor (TH4) open/short
The black square (■) indicates a switch position.
<Detected in outdoor unit>
No
Yes
Yes
Yes
No
No
Is there any abnormality such
as a disconnection, looseness or
breakage?
Is the detected resistance normal?
Is the detected temperature normal?
Connect the wiring/connector properly.
Replace the connector in case of a
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 TH4
Disconnect the connector to check the
resistance of TH4 using a tester.
Check a temperature of TH4.
The detected temperature of TH4 can be displayed
by an operation of SW1 on the outdoor controller
board.
SW1 Setting
ON
OFF
Display on LED1, 2
Unit
−99.9–999.9
°F
41 2 5 6 7 83
80
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