Suction Pipe Temperature Thermistor (Th6) Open/Short - Mitsubishi Electric MXZ-4C36NAHZ Service Manual

Check code

Suction pipe temperature thermistor (TH6) open/short

5102
<Detected in outdoor unit>
Abnormal points and detection methods
Abnormal if TH6 detects to be open/short.
(The open/short detection is disabled during 10 seconds to 10 minutes.
after compressor starts, during defrosting operation, or for 10 minutes after
returning from the defrosting operation.)
Open:−40°F [−40 ] or less
Short: 194°F [90 ] or more
●Diagnosis of defectives
Make sure to turn the power OFF before connecting/disconnecting
any connectors, or replacing boards.
Check the wiring and connector connection of TH6.
Is there any abnormality such
as a disconnection, looseness or
breakage?
Disconnect the connector to check the
resistance of TH6 using a tester.
Is the detected resistance normal?
Check a temperature of TH6.
Is the detected temperature normal?
OCH573
TH6: Thermistor <Suction pipe>
Diagnosis
No
Yes
Yes
Causes and check points
Disconnection or contact failure of connectors
Characteristic defect of thermistor
Defective outdoor controller board
The black square (■) indicates a switch position.
Connect the wiring/connector properly.
Yes
Replace it in case of a breakage.
No
The detected temperature of TH6 can be displayed by
an operation of SW1 on the outdoor controller board.
SW1 Setting
Display on LED1,2
ON
−99.9–999.9
OFF
1 2 3 4 5 6 7 8
Replace the controller board
No
(Malfunction of thermistor circuit).
No abnormality
( A connector contact failure is suspected).
72
Remedy
Replace the thermistor.
Unit
°F