Hi,

I'm having temperature issues on my upright Freezer. The freezer will freeze down to any temperature I set on the display but intermittently, and only on the superfrost setting, which led me to suspect the thermostat, however the display indicates a temperature the freezer is currently at. However if it is -18c and I have the door open for less than a minute the temperature can change to -15c which it never used to change by wide a variance if at all. It can also drop to -1c and then take an hour to achieve -5c when prior to being at -1c after the door had been opened it was at -22c.
Some months ago I had herd a grating sound coming from within the freezer compartment as if a fan blade was catching but I haven't located a fan inside the unit and suspect that perhaps the frost free function requires a fan and that is faulty and causing this issue.
The freezer is freezing but I haven't as yet put a probe inside to double check the displayed temperature tallies with the actual temperature, but there is a clear difference from -10c and -22c for example.

I'm a domestic engineer myself in the gas and oil industry so I'd like to fix this problem myself if practical to do so, but in any event I would like to know some idea of the potential issue and cost of repair if I were to embark on having a refrigeration engineer attend from Liebherr for example, particularly if the fault is relatively simple and easy to fix. If it a compressor/ refrigerant side then I will require an engineer but not if the cost is close to the cost of a new freezer!
Many thanks for taking the time to read this.