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M57/M67 – A/C compressor activation

Activation and deactivation of the air-conditioning compressor depends on a number of vehicle and control-unit states. When high torque is needed for brief period (pulling away from rest, accelerating) the air-conditioning compressor control logic shuts down the air-conditioning compressor to ensure that sufficient engine torque is available.

Activation comprises two subfunctions:
• Air-conditioning compressor logic
• A/C compressor activation

Air-conditioning compressor logic

The logic checks all conditions which prevent activation of the air-conditioning compressor:
• Pulling away from rest (vehicle speed, accelerator pedal, engine speed)
• Acceleration (change in accelerator pedal position, vehicle speed, engine speed)
• Oil temperature
• Coolant temperature
• Engine starting procedure
• System fault (defect in road-speed sensor or accelerator pedal faulty)
• A dummy value is used if the oil temperature sensor or the coolant temperature sensor is faulty

A/C compressor activation
Activation drives the output as a function of:
• Air conditioning request via CAN and
• A/C compressor logic

Idle-speed increase is not implemented.