Fridge/freezer fridge not getting down to temperature

[Russell]

Seasons greetings!

We have a Siemans frost free fridge freezer that has a single compressor.  The fridge is cooled by a fan blowing air from the freezer into the fridge compartment.  The fan is triggered by the door being closed (and maybe at other times as well).  The fan runs for a period of time and there is a knob helpfully marked cold to eco that controls the length of time the fan runs for.  There may be a thermostat in the mix as well, at least I hope so!

The air coming out of the vents can go down to very low single figures but the fridge space is often up in double figures.

Has anyone any experience of these devices and what might be wrong?

R

[Asterix, the former Gaul.]

We'd a fridge that needed to kept in an ambient temperature above a certain level.  When the ambient temperature was too low the fridge decided it didn't need to do anything and let the freezer stop working.

In other words we had to move it out of the garage.

[Canardly]

Is the freezer compartment still operating ok?

[Russell]

It's in the kitchen so at 18-20 deg ambient and the freezer is fine.

We have located the contents to the garage for now, it's 8 deg in there.

Now it's empty we can see that the fan runs for quite a while after door closure and the temp in the fridge does drop to 6-7 deg.  But then creeps up to 10-12.  It's almost as if the thermostat (if there is one) is not cutting in to maintain temp if the door does not trigger the cooling cycle.

[Diver300]

My guess is that there is a thermostat and it’s not working. The running of the fan each time the door closes is a secondary function so that the fridge recovers from the door opening faster, but now that’s all you’ve got.

[rafletcher]

A quick google suggests that if you can adjust the temperature of the freezer, then you’ll have 2 ‘stats. If you can’t, you’ll still have one for the fridge, with the freezer being a fixed -18C. So broken ‘stat seems probable.

[Russell]

We can adjust the freezer in 2 deg steps withing a range of -16 to -22 so 2 'stats and one not working is the diagnosis.

Thanks, I'll look to see what I can find.

[Canardly]

There may be a plug in thermostat temp sensor which has packed up.

[Russell]

Cannot see anything obvious here.  There are two thermostats but it's not obvious which one does what.

https://www.siemens-home.bsh-group.com/uk/supportdetail/product/KG30NVI20G/01#/Tabs=section-spareparts/Togglebox=tb0159/Togglebox=tb0307/

[Thor]

Do you know that the fridge temperature is high, independently of the appliance's indicator? Cos that could be wrong. With some of these, the dial in the fridge compartment controls how much Very Cold Air can flow up from the freezer. So, two further possibilities :- 1. the duct running up from the freezer is blocked or impeded 2. The fridge temperature gauge is lying to you.

[Russell]

It didn't feel cold to start with so we put an indoor outdoor thermometer in the fridge.

The duct seems fine because when the fan runs following a door closure the duct temp rapidly drops to close to zero with noticible cold airflow.