To remove the heater blower motor, start by taking off the heater motor cover plate and lifting out the mesh grid over the heater blower assembly. Disconnect the cable connectors and remove the screws that secure the motor mounting to the housing, then pull the unit out diagonally upwards. Release the retaining clips and pull the motor from its mounting, ensuring not to separate the blower from the motor shaft as they are balanced as a matched assembly; if the motor is faulty, both components must be replaced together. For refitting, reverse the removal process, pressing the shorter ends of the clips over the motor mounting during installation. Regarding air conditioning systems, it is crucial not to remove or dismantle any components due to the risk of refrigerant leakage, which can cause immediate freezing and serious injury upon contact; thus, any work on these systems should be performed by a qualified BMW service station. For compressor drive belt tensioning, the correct tension allows for a deflection of 5 to 10mm when pressed at the center points between the pulleys. To adjust, loosen the upper bolt on the compressor swivel plate and the lower bolt in the slotted mounting link, pull the compressor away from the engine to achieve the correct tension, then tighten the bolts and recheck the tension. To remove the belt, loosen the bolts and push the compressor towards the engine until the belt can be taken off the pulleys, then reassemble in reverse order while ensuring the belt is correctly tensioned.