GF83.40-P-0005CW Automatic air conditioning, function

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

Two different versions of the automatic air conditioning 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)

The regulation and control are taken care of by the automatic air conditioning control and operating unit (N22/7).

Scope of functionality without code (581) Comfort automatic air conditioning
The automatic air conditioning has separate temperature control for the left and right sides of the vehicle. The blower control is single-zone and can be operated manually or controlled automatically.

Scope of functionality with code (581) Comfort automatic air conditioning
The automatic air conditioning has separate temperature control for the left and right sides of the vehicle and for the rear compartment. The front blower control can be operated manually or controlled automatically. In the rear, only manual operation is possible via the separate rear automatic air conditioning operating unit (N22/4).
The blower control is 3-zone.

The automatic air conditioning function consists of the following subfunctions:
^ Ventilation
^ Control
^ Heating circuit
^ Refrigerant circuit

Also in vehicles with code (581) Comfort automatic air conditioning, not (United States of America):
^ Residual engine heat utilization system

Ventilation
The ventilation system prevents windows from misting up, supplies air to the occupants and ensures that uniform and pleasant temperatures in the interior are reached quickly. The aeration is controlled with the aid of the blower motor (A32m1).

Control
Electronic control of the temperature and the air distribution in the interior takes place depending on the settings selected at the control and operating unit and the marginal conditions recorded via various sensors (e.g. interior temperature, outside temperature, coolant temperature, vehicle speed).

Heating circuit
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.
Additionally, at low engine rpm, the coolant circulation pump (M13/5) is actuated to ensure that the flow volume needed to heat up the air blowing by is adequate.

Refrigerant circuit
The refrigerant compressor (A9) driven by the engine compresses the refrigerant vapor which is cooled down in the condenser. As it cools down, the refrigerant liquefies. The liquid refrigerant is then injected via the expansion valve into the evaporator where it evaporates. It cools down during the evaporation process and withdraws heat from the air blowing by, cooling it down. The refrigerant compressor aspirates the refrigerant which has turned gaseous on account of the heat absorption and then compresses it yet again.

Engine residual heat utilization system

Function requirement
^ Circuit 15R or circuit 15C ON

Residual engine heat utilization function sequence
The function is enabled by pressing the Rest button on the control and operating unit. The control and operating unit relays the request via the interior CAN to the front SAM control unit with fuse and relay module (N10/1), which actuates the coolant circulation pump directly.

The coolant circulation pump transports the coolant, which is still warm (residual heat) through the heater heat exchanger. At the same time, the control and operating unit relays the ventilation request via the climate control LIN to the blower regulator (A32n1), which then actuates the blower motor at slow speed. The air drawn in by the blower motor is routed along the heater heat exchanger and thus heated up.
The function stops after a fixed, stored time or when the on-board power supply voltage drops below a certain value.