My father in law has an under worktop integrated fridge, the sort that slides into and is fixed to a standard 600mm wide base unit and the kitchen cupboard door is screwed to the fridge door hinge mechanism. Anyway the fridge does not get any lower than 10 degrees C, even with the temp dial turned right up, (or down??) to 5. We took the fridge out at the weekend and drilled some holes through the worktop to increase airflow, but this hasn't really helped. When we had the fridge out we noticed it didn't have the 'normal' radiator thingie on the back as you would find on a free standing model, presumably because a built in fridge doesn't need one. Also the plate at the back (inside) frosts up quite badly. What is the likely cause of the lack of coldness and is it worth fixing or is it junk? The fridge is approx 5 years old and has worked OK except for the last few weeks.
TIA
John