Replacing my shower fan motor problems

Hi
I have just purchased a new fan unit for my shower, to replace a not very good one.
The problem I have is that the fan works fine untill I turn the light off!! When I turn the light off the fan continues very slowly and the light does not go out but is very dim.
I disconnected the old fan unit and wired in the new unit the same way (I think) I tried moving the wires around but still no good. If I disconect the light switch the fan still works.
Any help would be appreciated.
Just tried one more thing now the light goes off but the fan starts.
My old fan had N L S/L the new fan has L N1 N2
Rick

Are you sure on those connections - they sound really odd for a bog standard timer fan which your old one was?
What make and model is the new fan?

Hi Yes the old one was a timer fan but the new one has no timer, it is a Manrose 100 mm inline Fan only not a kit.
Cheers
Rick

You do not need to connect the permanent live at all on that fan, place it in a piece of terminal block and tuck it out of the way in the fan enclosure.
The SW/L goes to the L terminal, the N to whichever N terminal it says in the instruction book.
Earth to the earth terminal if fitted.

Thank you very much!
Rick