The fan is malfunctioning.

[Talentrews]

Upon returning to my mini, I saw that the fan's speed has decreased. However, there are instances when it operates at full speed intermittently.
I had heard of the hedgehog resistor, but I cannot see one on my device.
Aside from the extensive labour involved in removing the fan housing, is it just a matter of accepting and tolerating the situation?

[RacingNight]

Require a diagnostic scan to identify any problem codes. If there are no fault codes, it is probable that the issue is related to the diesel particulate filter (DPF) regeneration process. However, if the problem occurs often, it is possible that the DPF is significantly obstructed by soot. In such cases, some fault codes will activate the fan.

[Talentrews]

Apologies for the confusion. I was referring to the interior fan, not the engine fan.

[Ledgerciao]

The presence of corrosion on a connection is causing a fluctuation in the circuit's resistance due to temperature changes. Alternatively, the blower resistor may be deteriorating.

[Ledgerciao]

The hedgehog is situated posterior and inferior to the heater controls, perhaps next to the clutch (if the proper side has been identified).

[Talentrews]

I have conducted a thorough search for a hedgehog resistor, but unfortunately, I have been unable to locate one. It seems that locating a corroded connection will prove to be a challenging and unpleasant task.

[Ledgerciao]

Take a look at RealOEM - it is identified as a blower regulator on some websites.

The resistor is located right below and in front of the motor, specifically labelled as M30/X630.

[Talentrews]

It seems to need a significant amount of disassembly, which may be best done over the winter.