I doubt the extractor will do a lot, as the only place where you want more airflow is exactly at the damp spot; the extractor will suck out air from all over the place.
There is also a limit to the effective use of air movement; the top layer of damp soil will only give off so much water per day, and the damp will have to come up from below the top few mm.
Increasing the existing ventilation under the floor a bit is probably the only thing that will have effect without going into serious work.
There is also a limit to the effective use of air movement; the top layer of damp soil will only give off so much water per day, and the damp will have to come up from below the top few mm.
Increasing the existing ventilation under the floor a bit is probably the only thing that will have effect without going into serious work.