Citroen C4 Grand Picasso 2015 fan issue

[92kaz]

Hi all any help with this I'd really appreciate it. I have a Citroen C4 Grand Picasso 2015 model diesel
After a drive yesterday evening. I turned the car engine off, but the car blower fan, not the radiator fan, it's the fan inside dashboard.
It takes 5 minutes or so to go off, but as soon as i unlock the car The fan comes on again. have the car 3 years this has never happened before.
I even disconnected the battery for the night and as soon as i reconnect the battery the fan is back on again.

Thanks

[RichardW]

Mk 1 or mk 2 car? Is it blowing on full all the time?

[92kaz]

It's MK2, if I don't lock the car the fan will stay on all the time, but once I lock the car, after 3 to 4 minutes it will turn off, as soon as I open a door the fan will come back on. And stay on