Integrated Automatic Heating and Air-Conditioning System (IHKA)
Integrated Automatic Heating And Air-conditioning System (IHKA)
The integrated automatic heating/air-conditioning system (IHKA) with left right separation is a water-regulated heating and air conditioning system.
The following equipment specifications are available:
- Integrated automatic heating and air conditioning system in basis version (IHKA Basis)
The IHKA Basis is an automatic air-conditioning system with 2.5 zone control. That means: Left right separation for driver's and passenger's side and control in the rear (without left right separation)
- Integrated automatic heating and air conditioning system in High version (IHKA High) with rear automatic rear air-conditioning system (FKA)
The IHKA High with FKA is an automatic air-conditioning system with 4-zone control. In addition to the separate settings for the driver and front-passenger sides, the FKA also enables separate settings for the left and right sides in the rear.
- Integrated automatic heating and air conditioning system in High version (IHKA High) with rear automatic rear air-conditioning system (FKA) and automatic rear air conditioning (HKA)
The IHKA High with FKA and HKA is an automatic air-conditioning system with 4-zone control. The HKA with left right separation means that the air supply and air temperature (only cooling possible) in the rear is additionally regulated via the roof air vent.
The major new features of the integrated automatic heating and air conditioning system (IHKA) are:
- Control panel for IHKA is a unit with the control panel for audio
- Fresh air and recirculated air fan of the heating and air conditioning system positioned in the engine compartment
- Ionizer to prevent bacteria growth in the IHKA
Differences between the heating and air conditioning systems (F01, F02):
Brief description of components
The following components are described for the heating and air conditioning system:
- IHKA control unit with integrated control panel
- FKA control unit with integrated control panel
- IHKA control unit and control panel
- Blower with blower output stage
- Ionizer
- Electric auxiliary heater
- Electric auxiliary heater in the heating and air-conditioning unit (only vehicles with diesel engines)
- Electric auxiliary heater rear left and electric auxiliary heater rear right (only IHKA High with FKA)
- Flap motors
- Stratification control wheel
- Limit-position switch
- Sensors
- Internal temperature sensor (IHKA and FKA)
- Refrigerant pressure sensor
- Evaporator temperature sensor (IHKA and HKA)
- Rain-light-solar-condensation sensor
- Sensor for automatic recirculated air control (AUC sensor)
- Heat exchanger sensor
- Ventilation temperature sensor
- Rear-cabin footwell-temperature sensor
- Roof air vent temperature sensor
- Dual water valve
- Refrigerant shut-off valve at front and rear
- Air conditioning compressor
- Condenser with integrated drier flask
- Expansion valve
IHKA control unit with integrated control panel
The control panel and control unit together form a single component. The control panel of the IHKA forms a unit with the audio control panel.
The IHKA is operated using the operating elements shown in the illustration. The nominal temperature is set on the control panel separately for the driver's and passenger's side. The control unit regulates the climate control to the desired temperature. In doing so, the control unit picks up the sensor signals and continuously adapts the adjusting values for delivery temperature and fan output. The seat heating and active seat ventilation (if fitted) are also operated using buttons in the control panel.
FKA control unit with integrated control panel
The control panel and control unit together form a single component. The automatic rear air-conditioning system (FKA) control panel / control unit is fitted in the rear of the centre console. The FKA is operated using the operating elements shown in the illustration. The nominal temperature is set on the control panel separately for the driver's and passenger's side, rear. The control unit regulates the climate control to the desired temperature. In doing so, the control unit picks up the sensor signals and continuously adapts the adjusting values for delivery temperature and fan output. The rear seat heating and rear active seat ventilation (if fitted) are also operated using buttons in the control panel.
HKA control unit and control panel
The control panel and control unit are installed separately. The control unit of the automatic rear air conditioning (HKA control unit) is installed on the rear air conditioner. The HKA control unit activates the mixed-air flap motors, the air-distribution-flap motors, the LEDs, as well as the fan of the rear air conditioner by means of an output stage.
The left right separation means that the rear air conditioner has 2 control panels (left-hand control panel on the rear air conditioner and right-hand control panel on the rear air conditioner). A control panel is installed each roof air vent.
The control panels regulate the air supply and air temperature (only cooling possible) in the rear via the two roof air vents.
The left-hand operating unit on the rear air conditioner is connected directly via a plug-in connection to the righthand operating unit on the rear air conditioner. This means that all the settings for the left-hand operating unit on the rear air conditioner are picked up and digitized in the electronics of the right-hand operating unit on the rear air conditioner. The right-hand operating unit on the rear air conditioner sends the signals on the LIN bus to the HKA control unit.
Blower with blower output stage
The fan consists of the fan motor, the fan wheel, the fan output stage and the housing.
Depending on the equipment variant, the following fans and fan output stages are installed:
- Fan with fan output stage (IHKA)
The fan creates the necessary air-mass flow in the heating and air conditioning system. At the fan output stage, the control unit of the integrated automatic heating / air-conditioning system (IHKA control unit) specifies the voltage for the fan motor. The nominal voltage is output by the IHKA control unit as a signal on the LIN bus. The activation of the blower motor via the blower output stage takes place depending on this control signal.
- Rear compartment fan with output stage for the rear compartment fan motor (FKA)
The rear compartment fan is installed in the centre console; it generates an additional air-mass flow for the rear air conditioning/heating. At the output stage, the control unit of the rear automatic heater / air conditioner (FKA control unit) specifies the voltage for the rear compartment fan motor. The nominal voltage from the automatic rear air-conditioning system control unit is to be output to the output stage as a pulse-width modulated signal. The activation of the blower motor via the blower output stage takes place depending on the control signal.
- Fan with fan output stage (HKA)
The fan creates the necessary air-mass flow in the rear air conditioner. At the fan output stage, the control unit of the automatic rear air conditioning (HKA control unit) specifies the voltage for the fan motor. The nominal voltage is output by the rear air conditioner control unit as a signal on the LIN bus. The activation of the blower motor via the blower output stage takes place depending on this control signal.
Ionizer
The ionizer treats the air upstream of the evaporator. The ionizer contains a ceramic plate covered with toughened glass. Electrical conductors are attached to the front and back. An AC voltage of approx. 3 kV is applied to the electrode by the control electronics circuit. The application of a device-internal high voltage leads to partial ionization of the air. The reaction generates hydrogen peroxide. The hydrogen peroxide produces a chemical reaction that removes bacteria for the most part from the evaporator and other components of the automatic air-conditioning system.
The ionizer is controlled depending on the automatic program as well as the operating state of the vehicle. The IHKA control unit activates the ionizer by means of a pulse-width modulated signal (PWM signal).
Electric auxiliary heater
The electric auxiliary heater using the PTC principle (resistance with positive temperature coefficient) heats the air flow to adjust the temperature of the vehicle interior. The electric auxiliary heater accelerates the heating of the vehicle interior, especially at low ambient temperatures and during the cold-start phase. In principle, the electric auxiliary heater works like an electric radiator.
The heating elements in the electric auxiliary heater are PTC resistors. The heating elements are made up of individual ceramic semiconductor resistors. As of a certain temperature, the resistance of the heating element has a positive temperature coefficient. That means: The warmer the heating elements become, the higher their resistance. When the electric auxiliary heater is switched on, a high level of current flows. With increasing heat, this level of current falls. This limits the maximum power consumption. These electrical characteristics of the resistors enable a temperature of approx. 120 °C in the area of the heating elements that presents no problem for the heating and air conditioning system. This "physical" over-temperature protection is ensured even in the event of a blower failure.
The following electric auxiliary heaters are installed:
- Electric auxiliary heater in the heating and air-conditioning unit (only vehicles with diesel engines)
The electric auxiliary heater is a separate component and is installed in the heater/air conditioner. The electric auxiliary heater is activated by the control unit of the integrated automatic heating and air-conditioning system (IHKA control unit). Depending on different signals (e.g. temperature signal from the rear footwell temperature sensor, signals from energy management), a percentage power request for the electric auxiliary heater is generated in the IHKA control unit and sent on the LIN bus The maximum electrical power output of the electric auxiliary heater depends on the resources of the vehicle network. As a general principle, only the surplus power output of the alternator is available to the electrical auxiliary heater.
- Electric auxiliary heater in rear left and rear right (only IHKA High with FKA)
The electrical auxiliary heaters are part of the rear automatic rear air-conditioning system (FKA) with left right separation. An electric auxiliary heater is installed In every footwell ventilation duct.
Depending on different signals (e.g. temperature signal from the rear footwell temperature sensor, signals from energy management), a percentage power request for the electric auxiliary heater is generated in the FKA control unit and sent by means of a pulse-width modulated signal (PWM signal).
Flap motors
The flap motors are activated and supplied with voltage and earth across the LIN bus by the corresponding control unit (IHKA control unit, HKA control unit). In the idle state, the control unit switches the power supply off.
The flap motor is fitted with an integrated circuit. This circuit controls the coil of the flap motor. The circuit has bus- and diagnosis capabilities. After activation of the flap motor, the integrated circuit sends a position message (actual position) to the control unit. The flap motors communicate across the LIN bus with the HKA control unit. The flap motors are switched in series on the LIN bus. Each flap motor is assigned a certain address. The address determines what function the flap motor assumes in the composite system. This address tells e.g. the rear right footwell-flap motor that messages are being addressed to it (e.g. 'open flap'). This address tells e.g. the IHKA control unit which flap motor has sent it a fault message.
Stratification control wheel
The selected potentiometer setting is implemented on the flap position of each flap motor.
Limit-position switch
With the help of the limit-position switch, the ventilation flap picks up the following positions:
- Ventilation flap open (contact in the limit-position switch closed)
- Ventilation flap closed (contact in the limit-position switch open)
The limit-position switches are switched on and off mechanically via eccentric washers. The IHKA control unit evaluates the information from the limit-position switch. If the ventilation flap is closed manually, the IHKA control unit activates the corresponding ventilation flap motor in the IHKA on the basis of the signals from the limit-position switch. This completely blocks the air flow to the air vents in the ventilation grille.
Sensors
The following sensors are installed in the heating and air conditioning system:
- Interior-temperature sensor
A force-ventilated interior temperature sensor with interior temperature sensor blower is fitted in the integrated automatic heating / air conditioning system and automatic rear air-conditioning system control panel. The interior temperature sensor measures the temperature of the air drawn in from the vehicle interior by the integrated interior temperature sensor blower.
- Refrigerant pressure sensor
The refrigerant pressure sensor is located in the pressure line between the condenser and the evaporator. Depending on the sensor signal, the output of the air-conditioning compressor is reduced via the control unit of the integrated automatic heating / air-conditioning system (IHKA control unit) if the refrigerant pressure is too high. The junction box supplies the coolant pressure sensor with voltage. The data are evaluated in the junction box electronics (JBE). The prepared data is sent across the body CAN (K-CAN) to the IHKA control unit.
- Evaporator temperature sensor
The evaporator temperature sensor picks up the outlet temperature of the cooled air at the evaporator to prevent freezing of the evaporator. The evaporator temperature sensor of the integrated automatic heating / air-conditioning system (IHKA) is directly connected to the IHKA control unit. The evaporator temperature sensor of the rear air conditioner is directly connected to the HKA control unit ("HKA" stands for "automatic rear air conditioning").
- Solar rain/light fogging sensor
The solar sensor and condensation sensor are parts of the rain light solar condensation sensor. The solar sensor enables the integrated automatic heating and air conditioning system (IHKA) to take account of solar radiation. The solar sensor measures the sunlight on the vehicle. The sunlight on the driver's side and front passenger side are detected separately. Sunlight compensation is only active in the automatic program.
The condensation sensor enables the IHKA to detect window condensation at an early stage, even before the driver can detect it. Countermeasures (programme for the prevention of condensation) can be made in good time without requiring any action from the driver. The condensation sensor provides the following information:
- Temperature on inside of the windscreen
- Air humidity on inside of the windscreen
The sensor data are processed in the electronic evaluation unit of the rain light solar condensation sensor. The rain light solar condensation sensor provides the data via the LIN bus. The junction box electronics (JBE) adopts the signals into the corresponding CAN message and sends them. The IHKA control unit is equipment attached to the bus on the K-CAN. If the rain and/or condensation sensor system fails, a fault entry is made in the junction box electronics (JBE).
- Sensor for automatic recirculated air control (AUC sensor)
The AUC sensor is a metal oxide sensor. This sensor is highly sensitive to various smells and pollutants that are typical of traffic.
The AUC sensor is fitted on the microfilter compartment. The AUC sensor evaluates the concentration of carbon monoxide and nitrogen oxides in the intake fresh air. The AUC sensor converts the detected air quality (also referred as air grade) into an electrical signal. To simplify processing of the information, the air quality in 10 levels:
- Level 0 to Level 10 (clean to severely contaminated)
The AUC sensor sends the corresponding level as a digital signal on the LIN bus to the junction box electronics (JBE). The junction box electronics send the digital signal on the CAN bus to the IHKA control unit. If the automatic air recirculation control sensor has an emission level that is too high, then the integrated automatic heating / air conditioning system control unit (IHKA control unit) in the air recirculation function is automatically switched to (prerequisite: IHKA in the automatic mode).
- Heat exchanger sensor
Two sensors are installed in the integrated automatic heating / air-conditioning system (IHKA), as the delivery temperature at the heat exchanger for the heating system is registered separately for the driver's and passenger's side. The sensors are directly connected to the IHKA control unit.
- Ventilation temperature sensor
Two sensors are installed in the integrated automatic heating / air-conditioning system (IHKA), as the delivery temperature at the middle ventilation flap is registered separately for the driver's and passenger's side. In the rear air outlet in the centre console, 1 sensor is installed (no left-right separation in the rear passenger compartment). The 3 sensors are connected to the IHKA control unit. The left right separation means that 2 sensors are installed (on the right-hand and left-hand footwell vent outlets) in the footwell vent outlet in the centre console IHKA High with rear automatic rear air-conditioning system (FKA). The sensors are connected to the FKA control unit. The FKA control unit evaluates the signals from the sensors. The signal is sent as a message on the CAN bus. The IHKA control unit uses this message to regulate the corresponding flap motor.
- Rear footwell temperature sensor
The left right separation means that 2 sensors are installed on the rear automatic rear air-conditioning system (FKA). One sensor is attached to each of the left and right footwell air vents. The sensors are directly connected to the FKA control unit. The FKA control unit evaluates the signals from the sensors. The signal is sent as a message on the CAN bus. The IHKA control unit uses this message to regulate the corresponding footwell-flap motor.
- Roof air vent temperature sensor
The two roof air vents are only installed in conjunction with the rear air conditioner. The left right separation means that a roof air vent temperature sensor is installed in each roof air vent.
The signals of the 2 sensors are picked up and digitized in the control panel of the rear air conditioner on the right. The control panel sends the signals on the LIN bus to the HKA control unit. The HKA control unit evaluates this information and activates the air-distribution-flap motors and mixed-air flap motors.
Dual water valve
The dual water valve is an electromagnetic valve that meters the coolant flow volume to the heat exchanger for the heating system with left right separation in line with requirements. This determines the air temperature used for heating the vehicle interior. The junction box electronics (JBE) control the dual water valve.
Refrigerant shut-off valve at front and rear
The automatic rear air conditioning (HKA) is connected to the chiller circuit of the integrated automatic heating / air-conditioning system (IHKA) and is supplied from the same air-conditioning compressor. The two refrigerant circuits are separated by 2 refrigerant shut-off valves (front and rear) which are only fitted together with the HKA. The front refrigerant shut-off valve is integrated in the expansion valve of the IHKA and it blocks the pressure line to the front evaporator. The rear refrigerant shut-off valve is integrated in the expansion valve of the HKA and it blocks the pressure line to the rear evaporator. The connection and control operation of the HKA for the refrigerant circuit of the IHKA is designed in such a way that independent operation is possible. If both systems are in operation, clocking the 2 refrigerant shut-off valves can regulate both systems independently of one another. However, at least one refrigerant shut-off valve must always be opened.
The HKA control unit activates the refrigerant shut-off valves (front and rear). Without current, the refrigerant shutoff valves are closed.
Air conditioning compressor
The air-conditioning compressor compresses the refrigerant taken in by the evaporator. The refrigerant is pressed towards the condenser.
The air-conditioning compressor driven by the engine by means of a belt drive. The air-conditioning compressor is switched on and off via a magnetic clutch.
Infinitely variable power control is possible in the air-conditioning compressor. Within the A/C compressor, the delivery volume and thus the pressure in the refrigerant circuit is generated by pistons. The piston stroke is controlled by a swash plate. The electric control valve on the A/C compressor influences the balance of forces on the swash plate and thus the adjustment of the displacement. The junction box electronics (JBE) control the control valve with a clocked voltage. The IHKA control unit prompts the actuation. For the purpose of load reduction, only the refrigerating output that is directly needed is generated.
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.
Expansion valve
The expansion valve controls the injection quantity into the evaporator. Only as much liquid refrigerant enters the evaporator as the evaporator is able to completely evaporate. Drops of liquid that have not been evaporated would cause damage in the A/C compressor.
System functions
The following system functions are described for the integrated automatic heating and air conditioning system IHKA rear automatic rear air-conditioning system:
Functional networking
- IHKA Basis and IHKA High
The following illustration shows the functional networking for the integrated automatic heating and air conditioning system in the Basis version (IHKA Basis) and High version (IHKA High). The rear automatic rear air-conditioning system (FKA) is part of the IHKA High, but for reasons of space it is shown separately.
- Automatic rear air-conditioning system (FKA)
The following illustration shows the functional networking for the rear automatic rear air-conditioning system (FKA). The rear automatic rear air-conditioning system (FKA) is part of the IHKA High, but for reasons of space it is shown separately.
- Automatic rear air conditioning (HKA)
The following illustration shows the functional networking for the automatic rear air conditioning (HKA).
Notes for Service department
General notes
Running in A/C compressor
After replacement of an 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. 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.
Encoding the rain, light and precipitation solar sensor
Coding of the rain light solar condensation sensor is required after replacement of the windscreen or replacement of a rain light solar condensation sensor.
Encoding of the heating and air conditioning system
When coding the vehicle-specific data, the following details (among others) are taken into account:
- Engine type (diesel or spark-ignition)
- Version of the heating and air conditioning system (IHKA Basis or IHKA High with FKA or IHKA High with FKA and HKA)
If, for example, an HKA is installed, the IHKA must be coded to "HKA is fitted" (IHKA control unit is the master controller; the HKA control unit is a slave). Otherwise the built-in refrigerant shut-off valves (front and rear) remain closed and have no function.
No liability can be accepted for printing or other faults. Subject to changes of a technical nature