MXZ-SM36NAMHZ Service Manual

82
OCH789
Check code
Abnormal points and detection methods Causes and checkpoints
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. The detection is also disabled when the outdoor
temperature is 41°F [5°C] or less in cooling operation, and −4°F [−20°C] or
less in heating.)
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 controller board
●Diagnosis of defects
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 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 breakage.
Replace the thermistor.
Replace the controller 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 multimeter.
Check the 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