Diagnosis
Not haunted. This is the 'dry fan' feature. It runs for 2-3 minutes after the compressor stops to dry out the internal coils and prevent mold/mildew.
How to Fix It
It's automatic and cannot be disabled. When you press the power button to turn the unit 'off,' the compressor stops immediately, but the fan will continue to run for a short, preset period. It will stop on its own. Do not unplug the unit while this is happening.
If That Didn't Work
If the fan runs for longer than 5 minutes after shutdown, or runs continuously when the unit is supposedly off and unplugged (impossible), then you're misremembering the sequence. For a true fault, it would be a stuck relay, but that's exceedingly rare on these.
Heads Up
This feature is good for the unit's lifespan and air quality. Let it complete its cycle. Constantly yanking the plug during the dry fan phase can cause electrical stress over time.