Mitsubishi Electric CITY MULTI PUMY-P112VKM5 Technical & Service Manual page 70

Check code
4400
(U8)
Abnormal points and detection methods
If no rotational frequency is detected, or detected a value outside the
specified range during fan motor operation.
●Diagnosis of defects
Make sure to turn the power OFF before connecting/disconnecting any connectors, or replacing boards.
Check the fuse on the outdoor multi
controller circuit board.
Has the fuse melted?
Check the fan motor connector (CNF1 and
CNF2) for disconnection or looseness.
Is there any abnormality such
as disconnection, looseness or
breakage?
1 While the breaker is OFF, disconnect the compressor
wirings (U/V/W) from the outdoor power circuit board.
2 While the breaker is OFF, disconnect the fan motor
connector CNF1 and CNF2.
3 When 5 minutes have passed since turning ON the
breaker, turn SW7-1 ON.
4 Check the voltage of the outdoor multi controller circuit board.
Test points are;
· VDC approx. 310 to 380 VDC (fan connector 1–4)
· VCC approx. 15 VDC (fan connector 5–4)
· VCC approx. 0–6.5 VDC (fan connector 6–4)
Is the voltage normal?
Note: Set SW7-1 OFF after the troubleshooting completes.
OCH740
Fan trouble (Outdoor unit)
Diagnosis
(Melted)
No (Not melted)
No
Yes
Causes and checkpoints
Malfunction of fan motor
Disconnection of CNF connector
Defective outdoor multi controller circuit board
• Replace the outdoor multi controller circuit board.
Yes
• Replace the defective fan motor.*
*For the detail, refer to ˝Check method of DC
fan motor (fan motor/outdoor multi controller
circuit board)˝ in chapter 8-7.
Connect the wiring/connector properly.
Yes
Replace it in the case of breakage.
Replace the outdoor multi controller circuit board
No
(Malfunction of thermistor circuit).
No abnormality
(A connector contact failure is suspected.)
70
Remedy