The air conditioning in the 8er consists of 3 or 4 components.
The heating sword regulates the fan speed and is installed behind the air conditioning box and can be reached from the footwell of the passenger.
The climate control unit is used to adjust the temperature and is actually rarely faulty. It contains only a few important parts.
Mostly only the lighting is bad because the light guide goes blind.
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Another very rare error within the control panel is a switch that completely shuts off the water valve as in "Defrost", ie opens.
The problem can be measured with a multimeter. Middle pin on the plug, ground on the body. No 12Volt -> Climate control unit.
The so-called IHKA is the control of the complete air conditioning and is also installed behind the air box and can be accessed from the footwell of the passenger and the driver. Here are often mistakes. Air conditioning does not regulate, do not fold, control unit does not go to sleep mode (water valve still clinking), battery is draining quickly.
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Some vehicles still have the "auxiliary ventilation". This is controlled by a small relay box which is installed under the dashboard on the right side of the passenger side.
So running, for example, the fan even though the ignition is off, this relay box is faulty and must be repaired or disconnected, otherwise the battery is relatively quickly empty.
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best to pack everything and send. I can then test everything and thus better locate the error.
