Hi Tony,
Thank you very much, as the fridge freezer was under warranty at the time, the new sensor that was fitted was fitted by the engineer for Liebheer, im not surprised its not the correct one as the engineer was leaving when the freezer was still not working properly until i told him, he had not the connections in the wee round connectors correct in that they were not tight. the sensor that was replaced was (the the coil sensor ends the defrost and enables the fan to come on once the coil is at temperature) freezer is sitting at -18 today as I reconnected the joints myself on the replaced sensor.
I think to keep things right I will order the correct sensor.
Once again thank you very much for your help and reply
Declan