Compressor Temperature Thermistor (Th4) Open/Short; 5101 - Mitsubishi Electric PUMY-P250YBM Technical & Service Manual

Check code

Compressor temperature thermistor (TH4) open/short

5101

(U3)
<Detected in outdoor unit>
Abnormal points and detection methods
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: 3°C or less
Short: 217°C or more TH4: Thermistor <Compressor>
●Diagnosis of defects
Make sure to turn the power OFF before connecting/disconnecting
any connectors, or replacing boards.
Check the wiring and connector connection of TH4.
Is there any abnormality such
as disconnection, looseness or
breakage?
Disconnect the connector to check the
resistance of TH4 using a multimeter.
Is the detected resistance normal?
Check the temperature of TH4.
Is the detected temperature normal?
OCH760
Diagnosis
No
Yes
Yes
Causes and checkpoints
Disconnection or contact failure of connectors
Characteristic defect of thermistor
Defective outdoor multi controller circuit board
The black square (■) indicates a switch position.
Connect the wiring/connector properly.
Replace the connector in the case of
Yes
breakage.
No
The detected temperature of TH4 can be displayed
by an operation of SW1 on the outdoor multi
controller circuit board.
SW1 Setting Display on LED1, 2
ON
−99.9–999.9
OFF
1 2 3 4 5 6 7 8
Replace the outdoor multi controller circuit
No
board (Malfunction of thermistor circuit).
No abnormality
( A connector contact failure is suspected.)
65
Remedy
−99.9–999.9
Replace the thermistor.
Unit
°C