zanussi 71921/8ffa fridge frezzer

Hi there we have problems with this fridge frezzer the fridge is pipe wall linding and the frezzer is frost free .its the frige where the problem is it keeps frezzing everthing the back wall does not look like its got a leak as its genraly does not have lots of froze on it or any build up in any one place ie the top right or left .So i thought it may have a probe in the frige as the frezzer is ok and it does but on the bad drawings it looks like its in the linding and as there is no cage in the fridge does any one know if you can get to the probe with out cutting the back out and if this could be the problem with out changing the pcb which sits in the transome and help please cheers pod