Bus messages, A/C

Bus messages, A/C

For a detailed description of the car's bus system, see bus and diagnostics communication, detailed description .

Bus messages	Unit	Transmitter	User	Description
A/C compressor request	On/Off	ACC	ECM	The ACC requests A/C compressor engagement if the ambient temperature exceeds 0°C and A/C OFF is not selected. The ECM activates the compressor if the pressure is sufficient and the engine is running.
A/C compressor request	On/Off	BCM	ECM	The A/C command travels via a separate lead to BCM, which requests that the A/C compressor be activated. ECM activates the compressor if there is sufficient pressure and the engine is running.
A/C idle speed increase request	On/Off	BCM	ECM	The purpose of the function is to improve cooling properties when the engine is idling and the ambient temperature is high. At temperatures higher than 28°C when the A/C is active, the BCM will request an idle speed increase from the engine management system.
A/C compressor clutch active	On/Off	ECM	ACC, BCM	If the A/C compressor is not activated, recirculation will be selected in order to improve cooling properties. Recirculation is prevented if there is an A/C function fault. The BCM uses the information to increase the idle speed when the compressor is active and the ambient temperature is high.