Kenwood KFF2DW14 – Changed Fan Motor and…….

So….. the fan motor was rattling like mad as the shaft was worn but the fridge seemed to be working fine as far as I can remember – changed out the fan motor and now the fridge is 12 deg at the top and around -6 at the bottom (think my little thermometer gives up around that temp). I’m stumped, as there’s only a grill at the bottom, so it makes sense that the freezing air from the coil behind the freezer compartment would come through that, but it has always worked fine. There’s what’s listed online as an air damper at the top of the fridge, but I’m not sure exactly what this is meant to do? What’s got me baffled is what senses the temperature in the fridge, as there’s no thermostat as such that I can see, only a thermostat cable tied to the coil behind the freezer?

I would have posted images, but the upload dialog tells me I’ve only got a maximum on 19.5kb to upload, so virtually impossible to get them down to that size!

Any help/suggestions most welcome – TIA