Part II
System functions
The IHR/IHKR/IHKA comprises the following functions:
- Temperature control
- Evaporator control (IHKR/IHKA only)
- Air distribution
- Air flow control
- Sunlight adaptation (solar sensor)
- MAX cooling (IHKA only)
- Residual heat (IHKA only)
- Defrost function (IHKA only)
- AUTO function (IHKA only)
- Heated rear window
- OFF
- Air recirculation function
- Automatic air recirculation control (IHKA only)
- Program for preventing condensation on the window surfaces (IHKA only)
- Central kinematics actuation (IHR, IHKR only)
- Convertible program (E93 only)
- Auxiliary heater operation (optional equipment 536)
- Automatic rear air-conditioning system (optional equipment 4NB, E7x only)
- Additional heating/ventilation in 3rd row seats (optional equipment 4NC, E7x only)
- Seat heating and active seat ventilation (E7x only)
- Steering wheel heating
- Electric steering column adjustment
Temperature control
- E8x, E9x: Air-controlled heating and air conditioning systems
The temperature for the best possible interior climate is regulated with a blending flap in the heating and air-conditioning unit.
The air mass flow is fed through the evaporator (IHKR, IHKA only). As this happens, the air mass flow is cooled and dried (providing the air-conditioning system is switched on). The blending flap then feeds the air mass flow completely or in part over the heating system heat exchanger and the electric auxiliary heater (depending on the desired nominal temperature value set at the IHR/IHKR/IHKA control panel). Subsequently, the air flows mix once again. The air mass flow is then fed through the ventilation flaps and into the passenger compartment. On the IHKA, the air ducts for the driver and front passenger are separate. Due to the separate settings for the left and right sides for the driver and front passenger there are 2 mixing flaps.
- IHR, IHKR
Temperature control is based on the set point value set and a calculated actual value The set point value is set at the temperature selector wheel on the IHR/IHKR control panel. The actual value is calculated from the temperatures measured by the ventilation temperature sensor and the footwell temperature sensor.
With the IHR, temperature control below the ambient temperature is not possible.
- IHKA
Control is based on the set point values set and the calculated actual value The set point values are set using 2 temperature selector wheels on the IHKA control panel (separate settings for left and right sides). The actual value is calculated from the temperatures measured by the ventilation temperature sensor and the footwell temperature sensor.
The reference variable is calculated from the comparison between the actual value for the interior temperature and the corrected set point value (calculated from customer request and ambient temperature). Compared to the set set point value, the interior temperature is raised in the cold so that a comfortable level is achieved even at negative temperatures, despite the temperature setting being unchanged. The ambient temperature is transmitted to the IHKA control unit via the body CAN (body Controller Area Network).
- E7x: Water-controlled heating and air conditioning systems
Within the heating/air-conditioning systems, the air mass flow is first fed through the evaporator. As this happens, the air mass flow is cooled and dried (providing the air-conditioning system is switched on). The air mass flow is then fed over the heating system heat exchanger and the electric auxiliary heater,where it is heated up to the required set point value (depending on the desired temperature value set at the IHKA control panel). The air mass flow is then guided via the air flaps into the passenger compartment. The IHKA High has separate air ducts for the driver and front passenger. The separate settings for the driver and front passenger side means that the heating system heat exchanger also has separate settings for the left and right sides.
- IHKA Basic
The temperature in the heating system heat exchanger is controlled with the help of the heating system heat exchanger sensor and a clocked water valve in the heater circuit. The water valve is actuated with a pulse-modulated signal (PWM signal) by the IHKA control unit. A characteristic map for the heating system heat exchanger determines the opening times for the water valve, depending on the engine speed.
Control is based on the set point value set by the vehicle occupants at the temperature selector wheel and the calculated actual value. The set point values are set via a temperature selector wheel on the IHKA control panel.
The actual value is calculated from the temperatures measured by the interior temperature sensor, the ventilation temperature sensor and the heating system heat exchanger sensor.
The reference variable is calculated from the comparison between the actual value for the interior temperature and the corrected set point value (calculated from customer request and ambient temperature). Compared to the set set point value, the interior temperature is raised in the cold so that a comfortable level is achieved even at negative temperatures, despite the temperature setting being unchanged.
The ambient temperature is transmitted to the IHKA control unit via the body CAN (body Controller Area Network).
- IHKA High
The separate temperature setting for the drivers side and the front passenger side affects:
- Heating system heat exchanger with left/right separation
- 2 heating system heat exchanger sensors
- 2 ventilation temperature sensors
- Dual water valve
Evaporator control (IHKR, IHKA only)
The evaporator temperature is regulated with the help of the evaporator temperature sensor and the expansion valve. The evaporator temperature is adjusted to the specified set point value of 2 C. Lower temperatures are not possible due to the risk of icing.
If the "variable evaporator control" function has been encoded, the set point evaporator temperature is calculated between 2 and 7 C. The specification depends on the ambient temperature, the ventilation temperature and the refrigerant pressure. A variable evaporator control reduces dehumidification. This reduces the risk of mucous membranes drying out.
Air distribution
For the best possible operation of the air distribution, it is important for the manually adjustable air vents to be open.
- IHR, IHKR
Air distribution selection is only possible manually with the air-distribution control wheel.
- IHKA
Occupants have the possibility of allowing the air distribution to be decided by the automatic program (AUTO button).
Alternatively, individual, personal air distribution is possible through manual selection (defrosting, ventilation, footwell).
If the relevant vehicle equipment is fitted to the vehicle, it is also possible to make a fine adjustment via the CID (Central Information Display) in the submenu Air distribution. Compared to manual selection, fine adjustment offers the additional possibility of further individualisation of the air distribution.
- E7x: IHKA Basic
With the IHKA Basic, the air distribution can only be set manually with the controller.
The menu provides the following settings:
- 4 different pre-adjustments and
one individually configured setting
The vehicle occupants can effect individual air distribution/stratification of hot and cold air inside the vehicle at the same temperature setting.
- E7x: IHKA High
In addition, air distribution can also be set at the IHKA control panel.
The menu provides the following settings:
- Driver's side:
4 different pre-adjustments and
one individually configured setting
- Passenger side:
3 different pre-adjustments and
one individually configured setting
Settings for ventilation temperature (stratified temperatures) can also be made in this menu. With the IHKA High, separate stratification can be set for the left and right sides in the front. Stratification is also possible in the rear.
- E7x: IHKA High with automatic rear air-conditioning system
With the IHKA High with automatic rear air-conditioning system, stratification can be set separately for the left and right sides in the rear.
Air flow control
The air flow control is dependent on the following settings and control actions:
- Manual blower setting
- Automatic blower and flap setting (IHKA only)
The automatic blower and flap functions are activated when the AUTO button is pressed.
- Ram air pressure compensation
The air mass at the air intake grilles increases disproportionately with increasing driving speed. This effect is compensated for by the opening angle of the fresh air flap being reduced as speed increases (ram air pressure compensation).
The opening angle is controlled according to a defined characteristic curve.
- Blower control
If necessary, the power management system will assign priority levels to reduce the blower output (via K CAN).
- Effect of terminal 50
When the engine is being started (terminal 50 ON), the electric auxiliary heater and blower are switched OFF to reduce the load on the car battery.
Sunlight compensation (solar sensor)
- E7x IHKA High and E8x, E9x IHKA
The following functions are modified when automatic mode is activated (depending on the intensity of sunlight):
- Blower output is increased or reduced
- Nominal temperature value is increased or reduced
E7x
The influence on IHKA control by the solar sensor is assigned separately to the driver's side and to the front passenger side.
- E8x, E9x IHKA
How the solar sensor affects the IHKA control on the driver's side and on the front passenger side is not programmed separately.
MAX cooling (IHKA only)
The MAX button makes it possible for the user to select maximum cooling with just one press of a button at the IHKA controls.
When the MAX button is pressed, all functions, including the defrost function, are deactivated. The air-conditioning function is activated (if it was not already activated) and defined settings are selected (e.g. temperature control is deactivated, ventilation flaps are fully opened).
Residual heat (IHKA only)
The residual heat function allows the waste heat from the engine to be used to heat up the passenger compartment when the engine is not running (e.g. during a stop at a level crossing). The residual heat function is only possible for a certain run-down period (15 minutes from terminal 15 OFF). The auxiliary water pump is activated to circulate the water.
Switch-on conditions:
- Terminal 15 OFF
and
- Run-down period active (up to 15 minutes after terminal 15 OFF)
and
- REST button* in IHKA controls ON
and
- Ambient temperature below 25 °C
and
- Engine temperature at some point above 60 °C
and
- Vehicle voltage over 11.4 volts
Condition for switch-off condition:
- Terminal 15 ON
or
- Residual heat ON (15 minutes) expired
or
- REST button* in IHKA control panel OFF
or
- OFF condition activated with residual heat active (terminal R)
or
- Prompt from power management to switch off auxiliary consumers
or
- Vehicle voltage less than 11 volts
* The residual heat button is omitted in the X5. The function of the REST button is integrated into the blower speed button.
Defrost function (IHKA only)
When the defrost function is activated, the defroster flap (on the inside in front of the windscreen) is opened fully. The fresh air/recirculated air flaps move to the "fresh air" position. All other flaps are closed. The blower is run up to maximum output.
- E7x with automatic rear air-conditioning system
The blower in the rear is switched off.
AUTO function (IHKA only)
When this button is pressed, all IHKA functions are set to automatic mode. If one or more automatically controlled functions are manually set, automatic control for the functions concerned will be cancelled. All other functions remain automatically controlled.
Heated rear window
The heated rear window is switched on when the button in the IHR/IHKR/IHKA control panel is pressed. The function indicator light in the button lights up.
The heated rear window is switched off by pressing the button again or automatically after the heating period has elapsed.
E8x
- Defrosting phase (1st heating period)
When terminal 15 is switched ON, the first time the system is switched on, the time span for the heated rear window is defined as follows:
Ambient temperature down to -15 °C: heating period: 20 minutes
Ambient temperature below -15 °C: heating period: 30 minutes
- Pulsing
After the defrosting phase, the heating phase (30 minutes with pulsed heat output (on-off cycle: 40 seconds ON, then 80 seconds OFF).
The function indicator light in the button is off during pulsing.
- 2nd heating period
After the 1st heating period has expired, each subsequent time the button is pressed will cause the heated rear window to be switched on for a further 30 minutes (defrosting phase).
After the 2nd heating period has expired, output is again pulsed.
- E7x, E9x
- Defrosting phase (1st heating period)
When terminal 15 is switched ON, the first time the system is switched on, the time span for the heated rear window is defined as follows:
Ambient temperature down to -15 °C: heating period: 10 minutes
Ambient temperature below -15 °C: heating period 17 minutes
- Pulsing
After the defrosting phase, the heating phase (25 minutes with pulsed heat output (on-off cycle: 40 seconds ON, then 80 seconds OFF).
The function indicator light in the button is off during pulsing.
- 2nd heating period
After the 1st heating period has expired, each subsequent time the button is pressed will cause the heated rear window to be switched on for a further 30 minutes (defrosting phase).
After the 2nd heating period has expired, output is again pulsed.
OFF
The IHR/IHKR/IHKA control panel is switched off when the blower speed is set to 0 (The control panel/control unit continues to run in the background.)
Air recirculation function
In the recirculated air mode, in the event of a high pollutant load, e.g. in a traffic jam, the supply of fresh air can be blocked. The air in the passenger compartment is permanently circulated. To ensure sufficient fresh air supply, the air recirculation function is limited to a certain duration (30 minutes air recirculation function -> 30 seconds partial fresh-air mode -> 30 minutes air recirculation function -> etc.)
Automatic air recirculation control (AUC)
- E8x, E9x IHKA only
- E7x IHKA High only
If the AUC sensor detects an increased level of pollutants in the environment from spark-ignition and diesel engines, the IHKA control unit will automatically switch to air-recirculation mode.
To ensure adequate fresh-air supply, the recirculated air mode has a time limit:
- at ambient temperatures below 0 C:
2 minutes air recirculation function -> 1 minute fresh air mode (as from 03/2005: 20 seconds) -> 2 minutes air recirculation function -> etc.
- at ambient temperatures of 0 °C to 6 °C:
3 minutes air recirculation function -> 1 minute fresh air mode (as from 03/2005: 20 seconds) -> 3 minutes air recirculation function -> etc.
- during operation without air conditioning function at ambient temperatures above 6 C:
4 minutes air recirculation function -> 1 minute fresh air mode (as from 03/2005: 20 seconds) -> 4 minutes air recirculation function -> etc.
- during operation with air conditioning function at ambient temperatures above 6 C:
12 minutes air recirculation function -> 1 minute fresh air mode (as from 03/2005: 20 seconds) -> 12 minutes air recirculation function -> etc.
When the engine is started and the AUC function activated, fresh-air mode is always selected for approx. 40 seconds due to the warming phase of the AUC sensor.
Program for preventing condensation on the window surfaces (IHKA only)
The following conditions must be satisfied for measures against condensation on the windscreen to be effected:
- Engine running
and
- The IHKA must be in automatic program
The IHKA control unit evaluates condensation sensor signal (air humidity). If condensation on the windscreen is imminent, the following measures are initiated in sequence to prevent condensation from forming.
If a measure proves to be ineffective, the next measure is initiated.
Once successful, the measures previously performed are reversed step-by-step in reverse order.
Measures if the windscreen threatens to mist over:
- Open defroster flaps further
- Switch from air recirculation function/AUC/automatic air recirculation function to partial fresh-air mode
- Switch from partial fresh-air mode in air recirculation function/AUC/automatic air recirculation function to fresh air
- Increase air mass with the blower
- Reduce air mass for the footwell
- Increase nominal temperature value
Central kinematics actuation (IHR, IHKR only)
The air distribution flap motor has the task of setting the air distribution over a cam disc. The air distribution flap motor has no way of recognising the actual position. To allow the cam disc to be unambiguously positioned despite this, there are two cams of different widths on the cam disc. The microswitch signals to the IHR/IHKR control unit when the cams pass. This mechanism achieves reliable and rapid positioning of the cam disk.
Convertible program (E93 only)
The convertible program is activated in the factory. (this factory setting can be deactivated in the "Personal Profile".)
Switch-on conditions:
- Terminal 15 ON
- Soft top open
The convertible program comprises the following functions:
- The condensation sensor is switched off
- The blower speed increases with increasing driving speed
- Air distribution is switched to the upper body and head, airflow to the footwell is throttled.
- Ram air pressure compensation is changed, i.e. as driving speed increases, the air mass fed into the vehicle through the fresh air grille increases.
- Solar sensor control variables are changed
When the soft top is open, the solar sensor evaluates the ambient brightness (darkness to intense sunshine) more strongly. For this reason, the solar sensor has a stronger effect on the IHKA controls when the soft top is open.
In the convertible program, the blower speed can be changed manually at the IHKA controls. The automatic flap control remains active (no change to flap position).
If the convertible program is active and the flap positions are changed with the CID and controller, the convertible program will be deactivated. This means that manual settings will be assumed, unchanged settings will revert to those that the air-conditioning system had before the soft top was closed.
The convertible program can be completely reactivated by pressing the AUTO button.
Auxiliary heater operation (optional equipment 536)
The auxiliary heater operation is activated either via the Central Information Display (CID) or via Telestart (through the Car Access System (CAS)). There are 2 ways of switching the system on via the CID:
Direct operation or programming using the timer.
[for more information, please refer to SI Technology (SBT) 64 01 05 135]
Automatic rear air-conditioning system (optional equipment 4NB, E7x only)
The automatic rear air-conditioning system provides for separate temperature and blower settings for the left and right sides in the 2nd row of seats.
[more ...]
Additional heating/ventilation in 3rd row seats (optional equipment 4NC, E7x only)
A rear compartment blower draws air in under the seats in the 3rd row of seats and blows it out through the ventilation outlet between the seats in the 3rd row of seats.
[more ...]
Seat heating and active seat ventilation (E7x only)
Seat heating and active seat ventilation in front
If the seat heating/active seat ventilation button is pressed, the IHKA control unit sends the status as a K CAN message.
Depending on the equipment specification of the seat, the message is received either by the seat modules or by the Junction Box electronics (JBE).
- Message direct to the seat modules:
The seat heating and the active seat ventilation are actuated by the respective seat module according to the operating logic at the IHKA control panel.
- Message via Junction Box electronics:
The Junction Box electronics transmits a message to the seat modules in the form of a pulse-width modulated signal (PWM signal). The seat heating is actuated by the respective seat module according to the operating logic at the IHKA control panel.
If the energy management system requires a reduction in output, the heater and blower output may be reduced in 3 stages or switched off completely:
1. Heating and blower output are reduced from level 3 to level 2
2. Heating and blower output are reduced to 50 percent of level 2
3. Seat heating and active seat ventilation are switched off
Seat heating in rear without automatic rear air-conditioning system
When the seat-heating switch for the rear is pressed (2 levels), the seat heating is directly actuated.
If the energy management system requires a reduction in output, the seat heating in the rear may be switched off by a relief relay.
Seat heating in rear with automatic rear air-conditioning system
The seat-heating switches are located in the FKA control panel.
The status of each seat-heating switch is transmitted to the respective seat module (rear seat, driver's side and rear seat, passenger side) by means of a pulse-width modulated signal (PWM signal). If the energy management system requires a reduction in output, the heater output may be reduced in 3 stages or switched off completely.
Steering wheel heating (E7x only)
The steering wheel heating is integrated in the steering column switch cluster (SZL). The IHKA control unit transmits the signal for the steering wheel heating to be switched off (power down command).
Electrical steering column adjustment (E7x only)
The electrical steering column adjustment enables the driver to set the optimised position of the steering wheel. There is a switch on the left of the steering column for operation. The inclination and length of the steering column are adjusted electrically. Power for the electrical steering column adjustment is provided via terminal 30 switched.
The IHKA control unit actuates the electric steering column adjustment. When the steering column is adjusted, a hall effect sensor on the steering column adjustment motor sends a signal the IHKA control unit. The position of the steering column is registered and stored by the IHKA control unit.
For the key memory, this means that the position of the steering column can be called up. To support entry and exit, the tilt adjustment moves to the highest position.
For Easy Exit, the steering column adjustment is automatically activated under the following conditions:
- Terminal R OFF
- Terminal R ON and driver's door opened (signal via door contact)
- Terminal 15 OFF with driver's door open (signal via door contact)
The steering column memory is activated under the following conditions:
- One of the two memory buttons is pressed (from terminal R ON).
- Another identification sensor is used (personalisation). Condition: The selection "Last seat position after unlocking" is activated in the "Settings" menu in the Central Information Display (CID).
In both cases, the steering column memory only moves to the corresponding memory position after terminal 15 On.
Notes for Service department
Observe the following information for service:
- General information: [more ...]
- Diagnosis: ---
- Encoding/programming: [more ...]
National-market version
Temperature display in °C (Celsius) or °F (Fahrenheit) can be selected with an on-board computer 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.