Mitsubishi Electric PUMY-P36NKMU2-BS Technical & Service Manual page 76

Check code
Outdoor liquid pipe temperature thermistor (TH3) open/short
5105
(U4)
Abnormal points and detection methods
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°F [−40 ] or less
Short: 194°F [90 ] or more
●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 TH3.
Is there any abnormality such
as disconnection, looseness or
breakage?
Disconnect the connector to check the
resistance of TH3 using a tester.
Is the detected resistance normal?
Check the temperature of TH3.
Is the detected temperature normal?
OCH695B
TH3: Thermistor <Outdoor liquid pipe>
Diagnosis
No
Yes
Yes
Causes and checkpoints
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 breakage.
No
The detected temperature of TH3 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).
76
Remedy
Replace the thermistor.
Unit
°F