Part II

Integrated Automatic Heating / Air Conditioning System (IHKA)

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 air temperature drawn in from the passenger compartment by the integrated interior temperature sensor blower.

- Refrigerant pressure sensor
The refrigerant pressure sensor is located in the pressure line between the capacitor 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 refrigerant 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 icing 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").

- Rain-light-solar-condensation 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 irradiation. 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. Counter-measures (program for the prevention of condensation) can be taken in good time without the need for driver intervention. The condensation sensor provides the following information:
- Temperature on inside of the windscreen
- Air humidity on inside of the windscreen

The sensor data is processed in the evaluation electronics 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 bus user on the K-CAN. If the rain and/or condensation sensor system fails, a fault entry is made in the junction box electronics (JBE).

- Automatic air recirculation control sensor (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 automatic air recirculation control sensor evaluates the concentration of carbon monoxide and nitrogen oxides in the intake fresh air. The automatic air recirculation control 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 divided into 10 stages:
- Grade 0 to 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 blow-out temperature at the heat exchanger for the heating system is registered separately for the driver's and front passenger 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 blow-out temperature at the middle ventilation flap is registered separately for the driver's and front passenger 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 rear air outlet) in the rear air 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-cabin 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 outlets. 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 rear 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 mixing flap drives.

Dual water valve
The dual water valve is an electromagnetic valve that meters the coolant flow rate 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 passenger compartment. The junction box electronics (JBE) controls the dual water valve.

Refrigerant shutoff valve at front and rear
The rear automatic air conditioning (HKA) is connected to the refrigerant 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 shutoff valves (front and rear) which are only fitted together with the HKA.
The front refrigerant shutoff valve is integrated in the expansion valve of the IHKA and it blocks the pressure line to the front evaporator. The rear refrigerant shutoff 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, pulsing the 2 refrigerant shutoff valves can regulate both systems independently of one another. However, at least one refrigerant shutoff valve must always be opened.
The HKA control unit activates the refrigerant shutoff 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 capacitor.
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 coupling.
Stepless 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) controls the control valve with a clocked voltage. The IHKA control unit prompts the activation. For the purpose of load reduction, only the cooling power that is directly needed is generated.

Condenser with integrated dryer flask
In the capacitor, gaseous refrigerant is converted into liquid refrigerant. In the integrated downstream dryer 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 basic 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 the air-conditioning 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
Encoding 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 encoding the vehicle-specific data, the following details (among others) are taken into account:
- Engine version (diesel engine or petrol engine)
- 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, a rear air conditioner is installed, the integrated automatic heating /air conditioning system must be encoded to "rear air conditioner is fitted" (IHKA control unit is the master controller; the rear air conditioner control unit is a slave). Otherwise the built-in refrigerant shutoff valves (front and rear) remain closed and have no function.

We can assume no liability for printing errors or inaccuracies in this document and reserve the right to introduce technical modifications at any time.