Check output waveform between the air mix door motor (driver side) harness connector and ground with the oscilloscope.
(+)
| (−)
| Output waveform
|
Air mix door motor (driver side)
| —
|
Connector
| Terminal
|
M252
| 3
| Ground
|

|
Is the inspection result normal?
YES
>>GO TO 3.
NO
>>Repair the harnesses or connectors.