Part 1
64 01 03 (006)
Integrated automatic heating / air-conditioning system (IHKA), Basic and High
E60, E61, E63, E64
Introduction
The integrated automatic heating/air conditioning system (IHKA) is available in the versions Basic and High (option 534).
- E60 and E61
Standard equipment: IHKA Basic (IHKA High on 545i)
- E63 and E64
Standard equipment: IHKA High
The automatic air conditioning system High has separate ranges of adjustment for the driver' side and for the front-passenger side.
[system overview ...]
New features of the IHKA:
- An electric auxiliary heater working on the PTC principle (positive temperature coefficient) is installed on vehicles with diesel engines
The electric auxiliary heater is a component of the heat exchanger for the heating system. Electric heating elements made of aluminium have been added to the fins in the coolant flow of the heating system heat exchanger. The air drawn in is directly heated by these heating elements and fed into the vehicle interior through the air vents. In principle, the electric auxiliary heater works like an electric fan heater.
- Condensation sensor
The condensation sensor detects an imminent misting up of the windscreen, before condensation actually forms. To prevent the windows from misting over, the IHKA control unit starts to work through a table of measures as soon as a certain level of humidity is detected at the windscreen.
- LIN bus (Local Interconnect Network bus)
The LIN bus serves to actuate flap motors, the electric auxiliary heater and the blower motor in the heating/air-conditioning system.
- Convertible program (E64 only)
When the convertible top is opened and the air-conditioning system is in automatic mode, the convertible program is automatically activated.
The convertible program adapts the air-conditioner settings (blower, airflow, temperature) to the conditions created by the open top. The settings do not have to be changed when the top is opened or closed.
The convertible program is stored in the IHKA control unit.
Differences between IHKA Basic and IHKA High:
Differences/modifications from E39:
- New IHKA controls with additional functions: OFF button, temperature and airflow are set with rotary switches. On the IHKA Basic, the manual air distribution is set with the IHKA controls. On the IHKA High, the manual air distribution is set with the controller on the CID (Central Information Display).
- Revised display concept
The scale on the rotary switch for the blower setting has a 9-element LED display. The manually blower speed setting is shown by the corresponding LEDs lighting up. In automatic mode, the display remains off (IHKA High only).
The LCD display from earlier versions has been discontinued. Additional air-conditioning functions such as air stratification or independent heater (option 536) are selected and activated in the Central Information Display (CID) using the controller.
- The flap drives are only operated by flap motors.
- Separate left/right-hand footwell flaps, (IHKA High only)
- Separate ventilation flaps, (IHKA High only)
- Intake fan arrangement in the heating/air-conditioning system
The fan is located after the evaporator.
- On vehicles with diesel engine, a heating system heat exchanger is installed with integrated electric auxiliary heater. The same heating system heat exchanger is used for both Basic and High versions.
- Clutchless, externally actuated a/c compressor with regulated performance
- Sensor for automatic air-recirculation control (AUC sensor, IHKA High only)
- Solar sensor for taking external light/heat sources into account, which could affect the air conditioning in the vehicle interior (IHKA High only).
Benefits of system:
- The efficiency and functionality of the IHKA has been improved compared to the predecessor model. Despite this, the size is some 1/3 smaller than on the E39.
- The electric auxiliary heater accelerates the heating of the vehicle interior, especially at low ambient temperatures and during the cold-start phase. This clears the windows of condensation more quickly.
- The condensation sensor automatically prevents/eliminates condensation on the inside of the windscreen, before it becomes visible.
- The variable evaporator control extracts less humidity from the air. This reduces the risk of mucous membranes drying out.
Brief description of components
Sensors:
- Interior temperature sensor
The forced-ventilated sensor with interior temperature sensor fan is fitted in the IHKA controls. The sensor measures the temperature of the air drawn in from the vehicle interior by the integrated interior temperature sensor blower.
- Solar sensor (IHKA High only)
The solar sensor is located in the middle of the dashboard. (The installation position of the solar sensor in the E63/E64 has been turned through 180°.) This sensor is only active in automatic mode. The solar sensor takes external sources of light or heat (e.g. direct sunlight) into account, which could affect the air conditioning of the vehicle interior.
The sensor consists of 2 photoresistors. The sensor supplies the IHKA control unit with analogue signals for the driver's and front-passenger sides. The signal depends on the intensity of sunlight.
- Sensor for automatic air-recirculation control (IHKA High only)
The AUC sensor is installed at the top of the fan cowl. The sensor is exposed to the sideways downwind from the auxiliary fan. The AUC sensor detects the following pollutant emissions from spark-ignition and diesel engines:
- Hydrocarbons (HC)
- Carbon monoxide (CO)
- Nitric oxides (nitrogen monoxide NO, nitrogen dioxide NO2)
- Condensation sensor (IHKA High only)
The sensor is located under the rain/light sensor. In IHKA automatic mode, the sensor measures the humidity in the vehicle interior and on the inside of the windscreen. The sensor detects an imminent misting up of the windscreen, before condensation actually forms. The condensation sensor is not active in the convertible program.
- Heating system heat exchanger sensor
The sensor is integrated in the heating/air-conditioning system. On the IHKA Basic, the sensor measures the delivery temperature on the drivers side, directly on the delivery side of the heating system heat exchanger. On the IHKA High, 2 sensors are installed as the delivery temperatures are measured separately at the heating system heat exchanger for the drivers side and for the front-passenger side.
- Evaporator temperature sensor
The sensor measures the outlet temperature of the refrigerant at the evaporator to prevent icing from occurring.
- Ventilation temperature sensor (IHKA High only)
A sensor is integrated in the air duct to measure the ventilation temperatures. This sensor measures the delivery temperature directly in the middle of the ventilation grille.
- Refrigerant pressure sensor
This sensor is located in the pressure line between the condenser and the evaporator. Depending on the sensor signal, the A/C compressor is switched off by the IHKA control unit in the event of excessively high system pressure.
Control unit:
- IHKA controls / control unit
The IHKA controls and the IHKA control unit are combined in a single component. The Basic and High versions have different IHKA controls.
Actuators:
- Electric auxiliary heater
The heating elements of the electric auxiliary heater are integrated into the heating system heat exchanger and directly heat the air drawn in to control the temperature of the air inside the vehicle.
- Flap motors
On the IHKA Basic, 6 flap motors control the ventilation flaps. The IHKA High has 9 flap motors due to the left/right separation for the drivers side and the front-passenger side and because of the additional rear compartment flap.
- Blower with blower output stage
The blower generates the necessary airflow. The blower is installed after the evaporator in the heating/air-conditioning system (suction fan) and is equipped with 2 blower wheels.
The blower output stage is fitted directly on the blower motor housing. The blower output stage is capable of self-diagnosis. The blower output stage is actuated by the IHKA control unit (via the LIN bus). The blower output stage controls the blower motor with a pulse-width modulated signal (PWM signal).
- A/C compressor
The A/C compressor compresses the refrigerant drawn in from the evaporator and presses it to the condenser. The A/C compressor used is clutch-free. That means that the A/C compressor always runs with the engine. A swash plate in the A/C compressor allows the output to be smoothly regulated. To reduce load, only the cooling output actually needed is generated.
Note: A/C compressor with magnetic coupling
Measures for reducing CO2 emissions: Depending on the engine version and national version, an A/C compressor with magnetic coupling supersedes the A/C compressor previously installed with electric control valve.
- Evaporator
The evaporator plates are cooled by the refrigerant that has been evaporated inside the evaporator. The airflow generated by the blower is fed over the cooled evaporator plates. The air is cooled and dried and fed into the vehicle.
- Additional coolant pump
The additional coolant pump serves to make sure that the coolant flow rate needed in the heater circuit is maintained, even at low engine speeds.
On vehicles with diesel engine and independent heating (option 536), there is no additional coolant pump in the engine compartment. Its job is assumed by the independent heater's additional coolant pump and is controlled by the independent heating control unit.
- Water valve
The water valve operates electromagnetically and meters the coolant flow rate to the heating system heat exchanger as it is needed. This determines the temperature of the air used for heating the vehicle interior.
On the IHKA High, a dual water valve is used for the left/right separation of the heating system heat exchanger.
- Switchover valve
The switchover valve is only installed if the vehicle is equipped with independent heating (option 536).
The switchover valve regulates the inlet to the independent heating as follows:
- From the radiator and the additional coolant pump
or
- From the return flow from the heating system heat exchanger
The switchover valve is actuated by the independent heating control unit.
- Auxiliary fan
The auxiliary fan is standard on all vehicles with IHKA. Besides the engine cooling, the auxiliary fan is also needed for cooling the condensers.
- Condenser with integrated drier flask
Refrigerant is converted from gas into liquid in the condenser. In the integrated drier flask, which is installed downstream of the condenser, any water that may be present in the refrigerant circuit is collected. The drier element can be exchanged.
- Expansion valve
The expansion valve is directly on the evaporator in the heating/air-conditioning system. The valve regulates the injection rate in the evaporator. Only as much liquid refrigerant is permitted to enter the evaporator as the evaporator is able to completely evaporate. Drops of liquid that have not been evaporated could cause damage in the A/C compressor.
Additional components:
- Microfilter
On the IHKA Basic, fresh air for interior ventilation is fed through a system of microfilters. On the IHKA High, a microfilter with activated carbon is fitted. The activated-charcoal filter helps to provide additional purification of the incoming fresh air from gaseous pollutant emissions. When a filter replacement is needed, this will be indicated by the Condition Based Service (CBS) display.
- Rear air-stratification flap (IHKA High only)
The selected potentiometer setting is transposed into the rear compartment flap motor position.
- LIN bus
The IHKA control unit controls the following components via the LIN bus:
- Electric auxiliary heater
- Flap motors
- Blower with blower output stage
- Control and display functions via controller and Central Information Display
The following control and display functions are selected and activated on the CID (Central Information Display) with the controller (move controller to left in start menu):
- Temperature control (IHKA Basic)
The temperature for the driver's and front-passenger sides are centrally set on the IHKA controls. The temperature can be increased or decreased from this central setting using 3 selectable settings (warmer, neutral, colder).
- Temperature control (IHKA High)
The temperature can be increased or decreased separately on the drivers side and front-passenger side in 4 increments.
- Independent heater (optional)
Select between direct operation and programming with timer.
- Independent ventilation (IHKA High only)
Select between direct operation and programming with timer.
- Air distribution (IHKA High only)
The airflow for the drivers and front-passenger sides are centrally set on the IHKA controls. Deviating from these central setting, the airflow can be adjusted separately for the footwell and upper body (driver's and front-passenger sides).
The driver-side setting applies for both sides in the area of the windscreen.
> E64
When the convertible program is active, air distribution is switched to the upper body and head. Airflow to the footwell is throttled.
- A/C program
The A/C program is called up as follows:
1. - Press the controller in the start menu (5. menu)
2. - Select "Vehicle settings" and press controller.
3. - Select "A/C settings" and press controller.
4. - The following settings are available in the menu level "automatic program":
- low
- medium
- high
- convertible program (selection only possible when convertible top is open)
The selection of low, medium and high is not possible when the convertible program is active.
When the convertible program is deactivated, the air-conditioning system acts as if the convertible top were closed (selection of low, medium and high is again possible).
The following control unit is also active in the IHKA:
- Convertible top module (E64 only)
The convertible top module (CVM) provides the IHKA control unit with the signal whether the convertible top is open or closed. The convertible top module is connected to the K-CAN.
The convertible top module is installed under the rear left side trim.
Continued in Part 2