Blower With Blower Output Stage IHKA
Blower With Blower Output Stage IHKA
Blower with blower output stage IHKA
This functional description covers the blower and blower output stage of the integrated automatic heating / climate control. The IHKA is a heating and air conditioning system regulated on the on air side. The interior temperature is picked up by two independent temperature sensors. The sunlight level is picked up by the solar sensor.
Brief description of components
The blower output is set by turning the air-volume control wheel.
The blower output can also be set automatically by the control unit (automatic mode of the IHKA, function LED AUTO is switched on). Here, the blower output, the temperature stratification as well as the air distribution are automatically activated by the IHKA. Depending on the set nominal temperature, these adjusting values are used to regulate the vehicle interior temperature. Interference variables, e.g. sunlight, are compensated for in the automatic mode.
If a manual air distribution position is selected in the automatic mode of the IHKA, the blower output continues to be regulated automatically.
System functions
Blower function
The blower creates the necessary air-mass flow. The blower is fitted after the fresh air recirculated-air flap in the heater/air conditioning system (pressing blower arrangement). The blower draws the air in depending on the flap position of the fresh air recirculated-air flap via the following paths:
- via the filters and fresh-air duct
- or via the fresh air recirculated-air flap
- or via both.
The blower output stage is mounted directly at the housing of the blower motor. The blower output stage is activated by the IHKA control unit with a pulse-width modulated signal (PWM signal). The blower output stage is not self-diagnosable. The set blower speed is shown in the display of the IHKA controls in a bar gauge.
Defrost function
The defrost function assumes a higher-level position in the air distribution and control calculation in the mode. The defrost function is activated using the defrost button. Operating the button for defrost again disables the defrost function. Here, the IHKA switches into the previously set operating mode.
The DEFROST function has the highest priority after the OFF function. On activating of the defrost function, all function LEDs are switched off (except for the rear window and windscreen heating). The air distribution flap is set to the top position (defrost position) and the blower output is set to the maximum level. In addition, the heated windscreen (if fitted) is activated. The DEFROST function is relevant to safety and always operates at maximum blower speed. The blower output can be lowered manually.
Backpressure compensation
Without dynamic pressure compensation, as the driving speed increases, the air volume at the fresh air inlet duct also increases disproportionately. This effect can be compensated for in that the blower output is adapted depending on the driving speed.
Raising and reducing the blower output
The blower output is raised or lowered under certain circumstances:
In order to be able to cool down or heat up the interior rapidly in the case of extreme interior temperatures, the blower output is raised automatically depending on the setting value. The maximum blower value is limited depending on the coolant temperature.
If the vehicle voltage drops below a certain limit value, the power module initiates a reduction in the blower output (via the body CAN). In order to relieve the load on the car battery during the starting sequence, the blower is disabled.
No liability can be accepted for printing or other errors. Subject to changes of a technical nature