Piping Temperature Thermistor Open/Short - Mitsubishi PUMY-P60NKMU Technical & Service Manual

Check code
Piping temperature thermistor (TH3) open/short
5105
Abnormal points and detection methods
Abnormal if TH3 detects to be open/short.
(The open/short detection is disabled during 10 sec. to 10 min. after
compressor starts, during defrosting operation, or for 10 min. after
returning from the defrosting operation.)
Open: -40 [-40°F] or less
Short: 90 [194°F] 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 TH3.
Is there any abnormality such
as a disconnection, looseness or
breakage?
Disconnect the connector to check the
resistance of TH3 using a tester.
Is the detected resistance normal?
Check a temperature of TH3.
Is the detected temperature normal?
OCH502C
TH3: Piping temperature thermistor
Diagnosis
Yes
No
No
Yes
No
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
Replace it in case of a breakage.
Replace the thermistor.
The detected temperature of TH3 can be displayed by an
operation of SW1 on the outdoor controller board
SW1 Setting
Display on LED1,2 Unit
ON
-99.9 999.9 °F
OFF
1 2 3 4 5 6 7 8
Replace the controller board
(Malfunction of thermistor circuit).
No abnormality
( A connector contact failure is suspected).
60
Remedy