GF83.40-P-0005FQ Automatic Air Conditioning, Function

GF83.40-P-0005FQ Automatic Air Conditioning, Function
MODEL 218

Function requirements, general
^ Operating functions: circuit 15 On
^ Climate control: Engine running
^ Residual heat: Circuit 15C ON or circuit 15R ON (with code (581) Comfort automatic air conditioning)
Status of circuit 15 is sent by electronic ignition lock control unit (N73) via interior CAN (CAN B).
The "Engine running" signal is sent by the CDI control unit (N3/9) (with diesel engine) or by the ME-SFI [ME] control unit (N3/10) (with gasoline engine) via chassis CAN (CAN E) and sent by the front SAM control unit with fuse and relay module (N10/1) via interior CAN.

Automatic air conditioning, general
Two different automatic air conditioning versions are installed:
- Automatic air conditioning with 2-zone temperature control (without code (581) comfort automatic air conditioning )
- Automatic air conditioning with 3-zone temperature control (with code (581) Comfort automatic air conditioning)
Regulation and control are performed by the automatic air conditioning control and operating unit (N22/7).
The automatic air conditioning without code (581) Comfort automatic air conditioning is equipped with a separate temperature control for the left and the right half of the vehicle. Blower control takes place with 1 zone and can be operated manually or controlled automatically.
The automatic air conditioning with code (581) Comfort automatic air conditioning is equipped with a separate temperature control for the left and the right half of the vehicle and for the rear compartment.
The front blower control can be manually or automatically operated.
Manual operation is only possible in the rear using a separate rear automatic air conditioning operating unit (N22/4).
The blower is controlled in 2 zones (front and rear)
The automatic climate control function comprises the following subfunctions:
^ Heating circuit function sequence
^ Residual engine heat utilization function sequence (with code (581) Comfort automatic air conditioning)
Further subfunctions are described in separate documents:
^ Automatic air conditioning refrigerant circuit, function
^ Ventilation system, function
^ Regulation of Automatic air conditioning, function

Heating circuit function sequence
Driven by the coolant pump, the coolant circulates in the engine cooling circuit. In the process, it absorbs engine heat. The heated coolant passes through the heater heat exchanger, which dissipates heat to the air blowing by.
In addition, at low engine speed or when the engine is stopped (with code (B03) ECO start/stop function), the coolant circulation pump (M13/5) (with code (581) Comfort automatic air conditioning or code (B03) ECO start/stop function) is actuated to ensure that the flow rate is sufficient that is required for heating the blowby air. The coolant circulation pump is actuated by the front SAM control unit on request of the control and operating unit.

Additional function requirements for residual engine heat utilization (with code (581) Comfort automatic air conditioning)
^ Circuit 15C ON or circuit 15R ON (provided by electronic ignition lock control unit)

Residual engine heat utilization function sequence (with code (581) Comfort automatic air conditioning)
The function is switched on when the "REST" button on the control and operating unit is pressed. The control and operating unit sends the request via interior CAN to the front SAM control unit, which directly actuates the coolant circulation pump. The coolant circulation pump delivers the still warm (residual heat) coolant through the heat exchanger.
At the same time, the control and operating unit sends the request to ventilate to the blower regulator (A32n1), which then actuates the blower motor (A32m1) at the lowest blower setting. The air drawn in by the blower motor is routed along the heater heat exchanger and thus heated up.
The function is terminated after a time of t = 30 min. has elapsed or when the on-board power supply voltage drops below a certain value.