Mold problem in new kitchen - how to prevent it in the future?

In our kitchen, which was completely renovated in mid-2020, there is a problem with mold:

It became noticeable when water suddenly ran out from under the refrigerator. At first, I thought it was a device defect, but apparently, it is not. We have a built-in refrigerator and removed the cabinet in which it was installed, and behind it was the horror: Mold in the lower corner of the room and on the wall next to the refrigerator (see picture). There was even mold between the refrigerator and the built-in cabinet (picture 2). The entire right side wall of the appliance was covered with water droplets (picture 3).

Known craftsmen (tilers and plasterers) looked at it and said it was condensed water from the humidity in the air. The air cannot circulate properly around this cabinet, causing this problem. Additionally, the refrigerator is placed directly in the corner of the room against two exterior walls (northeast).

How should this problem be approached? Removing the mold and drying everything well at first is logical.

The tiler suggested that I install an air ventilation system in the wall above the refrigerator to regulate the moisture. I also find that quite plausible, but I am concerned that because the cabinet on the right stands directly against the wall (max. 0.5 to 1 cm gap), condensate will continue to form there despite ventilation.

Are there any additional measures that could be taken here – possibly to fill the small cavity somehow?

Thanks in advance for tips.

N

Here is a picture where the refrigerator is in place.
Additional information: The exterior wall is 30cm masonry without further insulation. (Year of construction early 70s)

I would measure the temperature of the exterior wall at that spot. If it is colder than the surrounding exterior walls, you do not have a problem due to lack of circulation, but a problem with the insulation of the wall. Otherwise, in my opinion, it is a planning error. You shouldn't place a refrigerator against two exterior walls, or was it different? Btw nice and very tasteful kitchen

Otherwise, in my opinion, it is a planning mistake. You shouldn't place a refrigerator on two exterior walls, right, or how was that?

How do you come to that statement, or where can one find this information? I have never heard that before.

I can already imagine the reason for this: a refrigerator emits heat, an exterior wall can be particularly cold. A large temperature difference between the appliance and the wall results in condensation - just like in my case. Therefore, my question is what can possibly still be done to the wall here to prevent this in the future. Regardless of whether one should do this or not - it was not possible otherwise in our kitchen, see picture. On the opposite side are two doors (pass-through room). There is no other usable location for such a tall cabinet.

The only thing that helps there - besides ventilating - is insulating. However, you probably lack the space inside for that, and on the outside you would then of course have to insulate on a larger scale.