Mitsubishi Electric CITY MULTI PUMY-P112VKM6 Service Manual page 56

5101 (U3): Compressor temperature thermistor (TH4) open/short
Abnormal points and detection methods
TH4 is found 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 [37.4°F] or less*
Short:
217°C [422.6°F] or more
TH4:
Thermistor <Compressor>
* -10°C [14°F] or less when PEFY-P·VMH(S)-E-F is connected.
Diagnosis of failure
Check the wiring and connector connection of
TH4.
Is there any abnormality such as
disconnection, looseness or break-
age?
Disconnect the connector to check the resis-
tance of TH4 using a multimeter.
Is the detected resistance normal?
Check the temperature of TH4.
Is the detected temperature normal?
OCH790 _56
<Detected in outdoor unit>
Yes
No
No
Yes
The detected temperature of TH4 can be displayed
by an operation of SW1 on the outdoor multi
controller circuit board.
SW1 Setting
ON
OFF
1 2 3 4 5 6 7 8
No
Yes
Causes and checkpoints
• Disconnection or contact failure of connectors
• Faulty 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 breakage.
Replace the thermistor.
Display on LED1, 2 Unit
–0.99–999.9 °C
Replace the outdoor multi controller circuit board
(Malfunction of thermistor circuit).
No abnormality
(A connector contact failure is suspected.)