intermittent fan blower in cockpit

Hi Folks,
reading other posts on here I have a feeling my question might be a bit low key, but hey ho…nothing ventured, nothing gained.

The demister fan / blower inside the car seems to have a mind of its own. The good news is that it does work…but only sometimes. The actual temperature inside or out doesn’t seem to affect it, nor does the distance or bumpiness of the drive. Is this something as simple as a loose wire? If so, any idea where and how I start looking for it?

The problem is inside my 55 plate S2 Exige. My other problem sits next to me sometimes.

Cheers,
Lester.