I have a 14 year old De Dietrich 7451.B fridge/freezer. It is built into a fitted kitchen, using the correct De Dietrich kit.
I notice that the compressor runs nearly all the time and barely keeps the fridge compartment below 6C. On a hot day it struggles to keep it at 8C. The compressor isn't excessively noisy - in fact, it's quite quiet. The fridge/freezer is defrosted and the kitchen is ambient temperature is normally below 22C. The vents at the bottom and rear aren't blocked.
I don't recall the compressor running so much when it was new and think the problem may have been getting progressively worse over the years.
Any ideas? Low refrigerant? Compressor fault? Either way it doesn't sound like a DIY job. Any idea how much it might cost to fix?