How can i fix my Hotpoint FF92P Fridge Freezer?

I have a problem with the fridge section on my Hotpoint FF92P, the temperature keeps creeping up to 16degrees. I have linked out the fan(so it runs continiously) in the freezer which feeds the fridge to prove that the compressor brings the temp down. As soon as i remove the link and let the temperature be controlled it creeps up to 16 degrees. I have been reccomended to change the thermisters, exactly which ones are they as there are about four in total when you look at the spares list on the net?

Thanks in advance

Leigh Harrison, February 2007

Evaporator thermistor part no 2601683

airkool@hotmail.co.uk, February 2007