IKHA module on 2002 BMW 540i ?

when you remove the module in case there might be a defect, usually they can be resoldered/repaired. Also have a look at the connections where the 4 arrows are, which sometimes get loose or have a short connection.

Inside the IHKA module there is the CPU for the temperature feelers, stepper motors, heater valves, which only carries out the orders (settings) thru the control panel in front of the driver and just acts according to the programs (which you select by pushing the buttons) selected by you.
So the module is the heart of the whole system or better to say the brain.