Ground - Mitsubishi Electric City Multi PUMY-SP112VKM Technical & Service Manual

Check code
Outdoor liquid pipe temperature thermistor (TH3) open/short
5105
(U4)
Abnormal points and detection methods
Abnormal if TH3 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 [−40°F] or less
Short: 90 [162°F] or more TH3: Thermistor <Outdoor liquid pipe>
●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?
OCH668B
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.
Yes
Replace it in case of a breakage.
No
The detected temperature of TH3 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.)
75
Remedy
Replace the thermistor.
Unit
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