Whirlpool ARC7410 Fridge/Freezer – Not switching on??

Hi all,

I had the Whirlpool ARC7410 now for 3 years and had no problems with it so far but now?? The fridge will reach its desired temp and then switches off, like it is suppose to do. After this my fridge will not come back on (after becoming warmer inside off course) until I turn the fridge settings dial to OFF, wait 5 seconds and then back to the desired setting. After this she will come on again.
On older fridges this would be the thermostat that needs replacing, but on these fridges there is no thermostat as such. The dial inside for setting the desired temp is just a potentiometer and then there is a ‘SPACE 4’ sensor thing on the inside of the fridge, don’t know what that is doing though?As far as I know then there is a BI-Metal strip on the back of the fridge as well?

Any thoughts on what could be the problem or which part I should start to changfe out first.

Apperciate any help here.