Mitsubishi Electric PUMY-P112VKM3 Technical & Service Manual page 81

Check code
Heat sink temperature thermistor(TH8) open/short
5110
(U4)
Abnormal points and detection methods
Abnormal if TH8 (Internal thermistor) detects to be open/short.
P112/125/140V model <Internal thermistor>
Open: 170.3 [338.5°F] or more
Short: −35.1 [−31.2°F] or less
2P112/125/140Y model
Open: 102 [215.6°F] or more
Short: −34.8 [−30.6°F] or less
TH8: Thermistor <Heat sink>
●Diagnosis of defectives
Make sure to turn the power OFF before connecting/disconnecting
any connectors, or replacing boards.
Is it a model with internal
Yes
thermistor?
Check the wiring and connector connection of TH8.
Is there any abnormality such
as a disconnection, looseness or
breakage?
Disconnect the connector to check the
resistance of TH8 using a tester.
Is the detected resistance normal?
Check a temperature of TH8.
Is the detected temperature normal?
OCH632A
Diagnosis
No
Yes
No
No
Yes
No
Yes
Causes and check points
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 it in case of a breakage.
Replace the thermistor.
The detected temperature of thermistor (TH8)
The detected temperature of TH8 can be displayed by an
can be displayed by an operation of SW1 on the
operation of SW1 on the outdoor multi controller circuit board.
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
board (Malfunction of thermistor circuit).
No abnormality
(A connector contact failure is suspected.)
81
Remedy
outdoor
Unit
: