Mitsubishi Electric PUMY-P112VKM3 Technical & Service Manual page 80

Check code
HIC pipe temperature thermistor (TH2) open/short
5109
(U4)
Abnormal points and detection methods
Abnormal if TH2 detects to be open/short.
Open: −40 [−40°F] or less
Short: 90 [162°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 TH2.
Is there any abnormality such
as a disconnection, looseness or
breakage?
Disconnect the connector to check the
resistance of TH2 using a tester.
Is the detected resistance normal?
Check a temperature of TH2.
Is the detected temperature normal?
OCH632A
TH2: Thermistor <HIC pipe>
Diagnosis
No
Yes
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.
Yes
Replace it in case of a breakage.
No
The detected temperature of TH2 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
board
No
(Malfunction of thermistor circuit).
No abnormality
(A connector contact failure is suspected.)
80
Remedy
Replace the thermistor.
Unit
°C