In addition to the automatic function, the driver and passenger have available three manual air distribution programs. They are used to open and close the defrost, ventilation and footwell flaps independent from each other on the driver's and passenger's side and independent of the set temperature value.
With the aid of these programs, cooled air can be blown out of the defroster and footwell ducts in A/C mode and warm air can be blown out of the ventilation grilles in winter mode.
In this way situations are covered in which the automatic program no longer fulfils the set requirements.
A fresh air/recirculated air flap is fitted on either side for the recirculated air function.
Backpressure compensation is achieved by means of a separate flap. This flap reduces the increase in the air throughput in the heating/air conditioning system as the road speed increases.
5 electric servodrives and 1 high-speed motor are fitted in the system for infinitely variable actuation of the air-outlet flaps for the IHKA. They consist of stepper motors and step-down gear systems.
A stepper motor with 4-pin connection driven at 500 Hz operates the fresh air/recirculated air flaps. Bus-controlled motors are used to operate all other flaps. Each of these motors features its own electronic circuitry and is electrically coded, i.e. the motor must be installed in its intended position.
The design of several components in the electronic circuitry of the motors has made it possible to reduce the size of the control electronics to such an extent that it can be housed in the operating unit. An additional control unit is therefore no longer necessary.
A further advantage is that up to 5 motors can be connected to a common 3-core branch. Two motor variants are used with the connectors on the electronic section brought out to the left or right.