Ihka Automatic Heating & Air Conditioning System - Overview - E65 & E66: Overview BMW 7 series E65/E66 facelift

System Overview

The heating and air conditioning system spans the entire vehicle. The major component locations including the optional rear air conditioner (E66) with cooler box is shown below.

Scheme 205

Overview Of System Components

Refrigerant System: The refrigerant system components include the following

Scheme 206

The layout includes two shutoff valves (one at the front for IHKA and one at the rear for E66 IHKA) and an additional evaporator with expansion valve. R134a refrigerant is used in the E65. The system capacity is 1.78 +/-.02 lbs (810 +/- 10 grams).

Heating System: Components of the heating circuit (coolant) with the N62 engine include

Scheme 207

Air Ducts: Air ducts refers to all components that distribute the air supplied by the fan to the outlets. The ends of the air ducts are fitted with directional grilles.

Scheme 208

Heater and Air Conditioner Housing: The IHKA housing is secured to the middle of the engine compartment bulkhead, underneath the instrument panel. The blower is mounted inside the passenger compartment offset to the passenger's side (in front of the glovebox).

The IHKA housing is the central unit in the heating and air conditioning system, it performs the following functions

1. Create and control air flow
2. Distribute the air
3. Mix the air (air stratification)
4. Dehumidify the air
5. Convert the energy supplied by the cooling system
6. Transfer the refrigeration power of the refrigerant system

Layout of the IHKA major components (as viewed from the back

Scheme 209

Control Panel/Control Module: The control panel is a dashboard insert with integrated electronic controls. The electronic circuits monitor and control the entire IHKA system. The control panel provides the essential basic controls. Precision adjustments are made using the Controller and the Control Display menu settings.

IHKA control panel front view

Scheme 210

There are also controls for the hazard warning lights and central locking (Centerlock) functions (not part of IHKA system, only for location convenience).

Scheme 211

Additional Sensors and Actuating Components: The system includes other components in addition to those previously listed.

1. AUC-2 sensor for automatic recirculated air control
2. One solar sensor for each side
3. One temperature sensor on each side in the center vent outlets
4. One potentiometer on each side in the rear center outlets (for adjusting air stratification)
5. One limit position switch on each side in the rear compartment center outlets

AUC-2 Sensor: The AUC-2 sensor provides an input to the IHKA module that will automatically activate recirculation mode when excessive ambient pollution is detected. This sensor detects pollutant gases emitted by gasoline and diesel engines that include the following

1. Hydrocarbons
2. Carbon monoxide
3. Nitrogen oxides

The heating and electronic analyzer (and software) are integrated into the sensor (located on the fan shroud). The sensor signal is pulse width modulated (PWM) to the IHKA control module.

The sensor is self diagnosable. Within the first minute of operation it determines if there is a fault in the sensor electronics. A fault will be set in the IHKA control module when a fault is detected.

Scheme 212

Solar Sensor: The solar sensor is mounted on the dashboard top center grille. The black cap is visible which masks the diffuser and two (left and right) photo resistors. The cap only allows infrared light to pass through.

The solar sensor supplies the control module with a separate signal for left and right. These signal levels depend on the intensity of the sunlight striking the sensor. The solar sensor influences

1. Blower output
2. Opening angle of the ventilation flaps
3. Air stratification temperature

Scheme 213

Temperature Sensors: The various temperature readings used by the IHKA control module are supplied from the following sensors

Initial Operation After Replacing The Refrigerant Compressor

When the compressor is operated for the first time (after replacement) it must be run in to ensure proper lubrication (oil distribution)!

Procedure

1. Set all air vents in the instrument panel to "OPEN".
2. Start the engine and wait until it stabilizes at a constant idle speed.
3. Set the speed blower to at least 75% of the maximum output.
4. Switch on the A/C system and allow it to operate for at least 2 minutes at idle speed (risk of damage at higher speed).

Note. The engine speed must not exceed 1200 rpm. If it does, the procedure will automatically abort and must be repeated.

Consult the Repair Information (in TIS) for the correct compressor oil filling procedure and the Running In phase that allows thorough and uniform mixing with the refrigerant.

Function Operations Based on Ignition Switch Positions

Terminal 30 (Ignition OFF)

1. Residual heat (Rest function)
2. Parked-car ventilation

Terminal R (Accessory Position)

1. Residual heat (Rest function)
2. Parked-car ventilation
3. AUTO (residual heat/parked-car ventilation)
4. OFF (residual heat/parked-car ventilation are deactivated when "OFF" is selected)

Terminal 15

1. Parked-car ventilation
2. AUTO Driver
3. AUTO Front passenger
4. AC
5. DEFROST
6. MAX AC
7. Recirculating air
8. AUC
9. HHS (rear window defroster)
10. OFF

Principle Of Operation

There are a number of ways to select the air distribution mode

1. Automatic program - selectable by the button on the control panel or the air conditioning menu on the Control Display.
2. Prioritized programs - selectable by the buttons on the control panel.
3. Manual air distribution programs - selectable by the air conditioning menu on the Control Display.
4. INDIVIDUAL settings (no program) - selectable by the DUAL function in the air conditioning menu on the Control Display (future).

The air distribution status is always transmitted to the Control Display for the flap range from 0% (flap closed) to 100% (flap open).

The IHKA will operate features (when programmed) to enhance cabin comfort based on exiting heating and air conditioning systems and components. The IHKA Stationary Functions include: Residual Heat (rest) and Parked-car Ventilation.

The rear window roller blind is controlled by K-CAN messages sent by one of the door modules. The IHKA distinguishes between short and long actuation of the button.

Short actuation of the button (< 750 ms) will cause the rear window roller blind to be activated. If the button is pressed longer, a request is sent to the door modules to move the side window roller blinds in the same direction as the rear window roller blind.

When the motor of the rear window roller blind is stopped short, the motor will move in the opposite direction (OPEN or CLOSE), depending on the previous detected limit position. The direction of motor rotation is reversed when the button is pressed while the motor is in operation. The motor continues to receive the drive signal until it stops.

The first time the button is pressed after the engine is started (and KLR active), the motor will attempt to move the roller blind down, because the current position is not known. If the motor immediately blocks, the direction of rotation is reversed. To protect the motor, the drive signal is cancelled after 15 seconds (or current draw exceeds 8 amps).

Control Module Identification

The data written into the memory chip for control module identification is

1. BMW part number
2. BMW control module version number
3. BMW coding index
4. BMW diagnosis index
5. BMW variant number
6. Manufacturer's date of production
7. Manufacturer's catalogue of messages
8. Manufacturer's software version
9. Manufacturer's standard core version
10. Manufacturer's reserve
11. BMW change index
12. BMW test stamp

Overview of BMW control module versions

BMW CONTROL MODULE VERSIONS