Part 3

64 01 04 (090) Integrated Heating Control And Air-Conditioning System

Temperature control
- E81, E82, E87, E90, E91, E92, E93: Heating and air-conditioning system controlled on the air side

The temperature for the best possible interior climate is regulated with a mixer flap in the heater/air conditioner.

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 mixer 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 temperature value set at the IHR/IHKR/IHKA control panel). The air flows are subsequently mixed again. The air-mass flow is then fed through the ventilation flaps and into the vehicle interior.

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 nominal value set and a calculated actual value (The nominal 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 nominal values set and the calculated actual value (The nominal 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 interior temperature sensor and the footwell temperature sensor).

The lead parameter is calculated from the comparison between the actual value for the interior temperature and the corrected nominal value (calculated from temperature request and ambient temperature).
Compared to the set specification, 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).

- E70: Heating and air-conditioning system controlled on the water side
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 nominal value (depending on the desired temperature value set at the IHKA control panel). The air-mass flow is then fed through the ventilation flaps and into the vehicle interior.

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 pulsed water valve in the heater circuit. The water valve is actuated with a pulse-modulated signal (PWM signal) by the IHKA control unit. A map for the heating system heat exchanger determines the opening times for the water valve, depending on the engine speed.

Regulation is based on the nominal value set by the vehicle occupants at the temperature selector wheel and the calculated actual value.
(nominal 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 and the heating system heat exchanger sensor).

The lead parameter is calculated from the comparison between the actual value for the interior temperature and the corrected nominal value (calculated from temperature request and ambient temperature).
Compared to the set specification, 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 by means of the evaporator temperature sensor and the expansion valve. The evaporator temperature is set to the predefined specification of 2 °C. Lower temperatures are not possible due to the risk of icing.

If the "variable evaporator control" function has been encoded, the nominal 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 setting
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 settings are possible through manual selection (defrost, ventilation, footwell).

If the relevant 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.

- E70: 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 presettings 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.

- E70: 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 presettings and one individually configured setting
- Passenger side:
3 different presettings and one individually configured setting

Settings for ventilation temperature (temperature stratification) 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.

- E70: IHKA High with automatic rear air conditioning
With the IHKA High with automatic rear air conditioning, stratification can be set separately for the left and right sides in the rear.

Airflow control
The airflow 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.
- Dynamic pressure compensation
The air volume at the air inlet grilles increases disproportionately with increasing road speed. This effect is compensated for by the opening angle of the fresh-air flap being reduced as speed increases (dynamic pressure compensation).
The opening angle is regulated according to a defined map.
- 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)
- E70 IHKA High and E81, E82, E87, E90, E91, E92, E93 IHKA

The following functions are modified when automatic mode is activated (depending on the intensity of sunlight):
- Blower output is increased or reduced
- Desired temperature value is increased or reduced

- E70 High
The influence on IHKA regulation by the solar sensor is assigned separately to the driver's side and to the front-passenger side.

- E81, E82, E87, E90, E91, E92, E93 IHKA
How the solar sensor affects the IHKA regulation 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 vehicle interior 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
- On-board supply voltage over 11.4 volts

Condition for switching off:
- 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
- On-board supply voltage less than 11 volts

* On the E70, there is no REST button (residual heat button). 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/ air-recirculation flaps move to the fresh air position. All other flaps are closed. The blower is run up to maximum output.

- E70 with automatic rear air conditioning
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 lamp in the button lights up.

The heated rear window is switched off by pressing the button again or automatically after the heating time has expired.

- E81, E82, E87
- 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, 80 seconds OFF).
The function indicator lamp 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.

- E70, E90, E91, E92, E93
- 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, 80 seconds OFF).

The function indicator lamp 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 mode
In recirculated-air mode, the flow of outside air can be stopped to prevent pollution from entering the vehicle, e.g. in traffic congestion. Air inside the vehicle is continually recirculated.
To make sure that there is a sufficient supply of fresh air, air-recirculation mode is only available for a limited time (30 minutes air recirculation - 30 seconds partial fresh air - 30 minutes air recirculation - etc.)

Automatic air recirculation control
- E81, E82, E87, E90, E91, E92, E93 only IHKA
- E70: 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 make sure there is still an adequate supply of fresh air, air recirculation is only available for a limited time:
- At ambient temperatures less than 0 °C:
2 minute recirculated air mode -> 1 minute fresh air mode (from 03/2005: 20 seconds) -> 2 minute recirculated air mode -> etc.
- At ambient temperatures from 0 °C to 6 °C:
3 minutes air recirculation mode -> 1 minute fresh air mode (from 03/2005: 20 seconds) -> 3 minutes air recirculation mode -> etc.
- Operation without air-conditioning function at ambient temperatures greater than 6 °C:
4 minutes air recirculation mode -> 1 minute fresh air mode (from 03/2005: 20 seconds) -> 4 minutes air recirculation mode -> etc.
- Operation with air-conditioning function at ambient temperatures greater than 6 °C:
12 minutes air recirculation mode -> 1 minute fresh air mode (from 03/2005: 20 seconds) -> 12 minutes air recirculation mode -> 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 mode

The IHKA control unit evaluates condensation sensor signal (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 defrost flaps further
- Switch from air recirculation/AUC/automatic air-recirculation mode to partial fresh-air mode
- Switch from partially fresh air in air-recirculation/AUC/automatic air-recirculation mode to fresh air
- Increase air volume with the blower
- Reduce air volume for the footwell
- Increase desired 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 ensures that the cam disc is reliably and promptly positioned.

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
- Convertible top open

The convertible program comprises the following functions:
- The condensation sensor is switched off
- The blower speed increases with increasing road speed
- Air distribution is switched to the upper body and head, airflow to the footwell is throttled.
- Dynamic pressure compensation is changed, i.e. as road speed increases, the volume of air fed into the vehicle through the fresh air grille increases.
- Solar sensor control variables are changed
When the convertible top is open, the solar sensor evaluates the surrounding brightness (darkness to intense sunshine) more strongly. For this reason, the solar sensor has a stronger effect on the IHKA controls when the convertible 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 convertible top was closed.

The convertible program can be completely reactivated by pressing the AUTO button.

Independent heater (option 536)
The independent heating function 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 further information, please refer to SI Technology (SBT) 64 01 05 135]

Automatic rear air conditioning (option 4NB, E70 only)
The automatic rear air conditioning provides for separate temperature and blower settings for the left and right sides in the 2nd row of seats.
[more ...]

Additional heating/ventilation for 3 rd row of seats (option 4NC, E70 only)
A rear compartment blower draws air in under the seats in the 3rd row of seats and blows it out through the ventilation air outlet between the seats in the 3rd row of seats.
[more ...]

Seat heating and active seat ventilation (E70 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 version 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 control 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 control 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
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
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 (E70 only)
The steering wheel heating is integrated in the Steering Column Switch (SZL). The IHKA control unit transmits the signal for the steering wheel heating to be switched off (power-down command).

Electric steering column adjustment (E70 only)
The electric steering-column adjustment allows the driver to set the steering wheel to the best possible position. This is done with a switch on the left-hand side of the steering column. The tilt and the fore-and-aft setting of the steering column can be electrically adjusted.
Power for the electric steering column adjustment is provided via terminal 30g.

The IHKA control unit actuates the electric steering column adjustment. When the steering column is adjusted, a Hall 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.

The position of the steering column can be stored for the Key Memory.
The tilt adjustment moves to the highest possible position to make it easier to get in and out of the vehicle.

For the easy-access facility, 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 ID transmitter 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 will not move the steering column to the stored position until terminal 15 is switched ON.

Notes for service staff
Service staff should note the following points:
- General notes: [more ...]
- Diagnosis: ---
- Encoding/programming: [more ...]

National versions
Temperature display in °C (Celsius) or °F (Fahrenheit) can be selected with an on-board computer function.
Subject to change.