IHKS Principle of Operation

IHKS Principle of Operation
Blower
When KL15 is switched ON, the blower is activated in linear progression from 0 to 8 Volts (depending on the selected blower speed). When the blower is switched OFF (zero position) the IHKS is deactivated in addition to the following:
^ Blower switched off
^ Fresh air/recirculating air flap closed
^ Mixed air flap closed (to ensure the heat exchanger does not unnecessarily heat up the heater/air conditioner)
^ Compressor switched off

Note: Rear window defogger can still be activated

Temperature Control





Warm and cold air are mixed for temperature control. The requested temperature is set by the rotary knob on the control panel/control unit. The outlet temperature is set by a stepper motor coupled to the mixed air flap.
The temperature is controlled by mixing:
^ Outside air that flows through the evaporator = cold air
^ Outside air that initially flows through the evaporator and then through the heat exchanger (reheat) = warm air

Note: Changes in engine rpm do not trigger any temperature adjustments.

Air Distribution





The individual setting for the air distribution is requested with the rotary knob on the control panel. The main flap settings are: The central kinematics stepper motor adjusts the cam disc for air distribution.

Air Volume Control
The air volume is controlled based on the position of the fresh air/recirculating air flap and blower speed. There is 1 flap at the fresh air inlet and 2 flaps for recirculating air control. The actuator for the fresh air/recirculating air flap adjusts these 3 individual flaps by a coupling linkage.
The system assumes recirculating air mode after pressing the recirculating air button. The fresh air inlet is closed and the recirculating air channel opened. The actuator for the fresh air/recirculating air flap is not a stepper motor. Its position is determined based on the activation of 4 phases.