Integrated Automatic Heating/Air Conditioning (IHKA)
Integrated Automatic Heating/air Conditioning (IHKA)
IHKA (integrated automatic heating / air conditioning system)
This functional description covers the integrated automatic heating and air conditioning system. 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. The IHKA is used to adapt the in-car climate to the individual needs of the passengers. Information is exchanged between the vehicle components involved via the body CAN data bus.
There are no differences for left-hand drive and right-hand drive vehicles. The control unit with operating unit is always fitted in the same position in the vehicle.
The control unit has the following functions (see also individual functional descriptions):
- Temperature control
- Air distribution
- Air flow control
- Automatic recirculated air control / recirculated air mode
- Heated windscreen and rear window
Brief description of components
Control unit with operating unit
The IHKA control unit records the signals of the IHKA components and controls/regulates the heating and air conditioning process. The control unit is at the same time the operating unit of the IHKA.
The IHKA control unit also contains the bank of switches. The bank of switches can be used to operate the seat heating (if installed), the heated windscreen and heated rear window, as well as the electrical power windows. The center lock button as well as the switches for the fog lamps and rear fog lamp are also built in.
Heater/air conditioner
The IHKA heater/air conditioner is fitted underneath the instrument cluster in the centre, at the front bulkhead. The heater/air conditioner performs the tasks:
- Generation and regulation of air quantity
- Air distribution, air mixture (stratification) and air dehumidification
- Transfer of refrigerating output generated by the cooling circuit
- Transfer of heat output delivered by the refrigerant circuit
The heater/air conditioner is composed of the following components:
- Evaporator
The evaporator plates are cooled by the coolant evaporating inside. The air-mass flow supplied by the blower is guided over the cool evaporator plates. The air is cooled and dried and guided into the vehicle interior.
- Heat exchanger for heating system and heating system heat exchanger sensor
The heating system heat exchanger sensor is fitted directly behind the heat exchanger for the heating system. The heating system heat exchanger sensor measures the temperature of the heat exchanger for the heating system.
- Flaps with drive and mechanical system
The flap motors are connected directly to the IHKA control unit. Three flap motors are fitted in the IHKA. The flaps serve to distribute the air and to mix hot and cold air.
Fresh air recirculated-air flap: the amount of clean air drawn in by the blower is regulated with this flap.
Air distribution flap: The air distribution flap mechanical system mechanically adjusts the air distribution flaps. The air distribution flap mechanical system is driven by the air distribution flap motor. The air distribution flap motor has the task of setting the air distribution by means of a cam disk. The air distribution flap motor has no detection of the actual position. In order to ensure unique positioning of the cam disk nonetheless, there are 2 cams of different widths on the cam disk. The micro-switch signals to the IHKA control unit that the cams have been passed over. This mechanism achieves reliable and rapid positioning of the cam disk.
Temperature mixing flap: The air-mass flow is guided through the evaporator. The air-mass flow is cooled and dried in the evaporator (when the air conditioning system is switched on). Subsequently, the temperature mixing flap guides the air-mass flow (depending on the set desired temperature value in the IHKA controls) fully or partially over the heat exchanger for the heating system and the electrical auxiliary heater (diesel engine).
- Blower with blower output stage
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 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 diagnosis-capable.
- Electrical auxiliary heater
The electrical auxiliary heater based on the PTC principle (positive temperature coefficient) is fitted in the heater/air conditioner. The electrical auxiliary heater directly heats up the air to adjust the temperature of the vehicle interior. The electrical auxiliary heater is only fitted in diesel engines.
Radiator fan
The radiator fan and the engine cooling are also required for cooling the condenser. The radiator fan is activated by the Digital Engine Electronics (DME).
Signal path:
IHKA control unit -> K-CAN -> Junction box electronics -> PT-CAN -> DME -> Radiator fan
A/C compressor
The air-conditioning compressor compresses the refrigerant taken in by the evaporator. The refrigerant is pressed towards the condenser. The air-conditioning compressor is switched by the compressor coupling. Activation is initiated by the IHKA control unit.
Condenser with integrated drier flask
In the condenser, gaseous refrigerant is converted into liquid refrigerant. In the integrated downstream drier flask, any water present in the refrigerant circuit is bound. The drier insert can be replaced.
Sensors
- Internal temperature sensor
The internal temperature sensor is built into the IHKA control unit. The internal temperature sensor measures the temperature in the control unit. This measured temperature is used by an integrated mathematical model to calculate the value for the interior temperature.
The internal temperature sensor is not force-ventilated. This means that no internal temperature sensor fan is fitted in the IHKA control unit.
- Solar sensor
The solar sensor consists of a photo diode. The solar sensor picks up external light or heat sources (e.g. sunlight). The solar sensor provides the IHKA control unit with an analog signal depending the intensity of the sunlight in each case.
Adaptation to the sunlight is only active in the automatic program. The solar sensor is fitted in the centre of the instrument panel.
- Sensor for automatic recirculated air control
The AUC sensor is fitted on the micro-filter compartment. The AUC sensor detects the following pollutant emissions:
- Hydrocarbons (CH)
- Carbon monoxide (CO)
- Nitrogen oxides (nitrogen monoxide NO, nitrogen dioxide NO2)
The junction box supplies the AUC sensor with voltage. The junction box electronics evaluate the data of the AUC sensor. This evaluated data is sent via the K-CAN to the IHKA control unit.
- Evaporator temperature sensor
The evaporator temperature sensor measures the outlet temperature of the air at the evaporator to prevent freezing over. The evaporator temperature sensor is directly connected to the IHKA control unit.
- Ventilation temperature sensor
The ventilation temperature sensor is integrated in the solar sensor. The ventilation temperature sensor measures the delivery temperature directly at the upper ventilation air vents.
- Coolant pressure sensor
The coolant pressure sensor is fitted in the pressure line between the condenser and the evaporator. Depending on the sensor signal, the air-conditioning compressor is regulated by the IHKA control unit in the event of excessive refrigerant pressure. The junction box supplies the coolant pressure sensor with voltage. The data is evaluated in the junction box electronics. The prepared data is sent across the body CAN (K-CAN) to the IHKA control unit.
Microfilter
A microfilter with activated carbon is built into the IHKA. The activated carbon filter makes an additional contribution to cleaning the fresh air that enters of gaseous pollutant emissions. There is no detection of the state of the filter.
Notes for Service department
Observe the following information for service:
General information
The following general data is provided for servicing the IHKA:
Running in the air-conditioning compressor
IMPORTANT: After replacement, allow the air-conditioning compressor to run in.
After replacement of the air-conditioning compressor or refilling the refrigerant circuit, the air-conditioning compressor must be run in. Running in is required to ensure lubrication (oil distribution). Running in can only be carried out using the BMW diagnosis system.
For this running in, the air-conditioning compressor must be operated within the specified engine speed range. Here, the oil volume filled by the manufacturer mixes evenly with the liquid refrigerant.
IMPORTANT: Do not exceed the specified engine speed.
If the engine speed exceeds the specified engine speed range, running in is aborted automatically. The running-in procedure must then be repeated in its entirety.
Replacement of the electrical auxiliary heater
The electrical auxiliary heater can be replaced in service (the heater/air conditioner must be completely removed).
Coding and programming
Coding
When coding the vehicle-specific data, the following details (among others) are taken into account:
- Engine variant (diesel engine or petrol engine)
- Version of the control unit (IHKA)
Programming
Flash programming of the IHKA control unit via the K-CAN is possible.
Personal Profile
Almost all functions of the Personal Profile are set in the vehicle itself (see Owner's Handbook at "Personal Profile": personal settings for a maximum of 3 remote controls via the display in the instrument cluster or the Central Information Display).
Country-specific versions
The temperature display can be switched to °C or °F using the on-board computer function.
No liability can be accepted for printing or other errors. Subject to changes of a technical nature