IHKA E36 Control Panel/Module

IHKA E36 Control Panel/Module




The E36 control panel and control module is integrated into one unit. IHKA E36 control panel/module features are listed below.

NOTE: When the IHKA E36 system is "Off," pressing any button on the control panel/module turns it on again.

Air Distribution Buttons: The E36 control panel/module air distributions are the same as E38, except there is only one set of buttons, which control air distribution on both sides.







If the "up arrow" button is pressed, air flows from the windshield defroster outlets.







Pressing the "right arrow" button causes air to flow from the face vent outlets.







When the "down arrow" is pressed, air flows from the footwell outlets (front and rear).







If the "AUTO" button is pressed, the control module automatically selects the appropriate flap positions for the sensed conditions. When cooling is required, air flows from the face vents. When heating is required, air flows from the footwells and the windshield defroster outlets.




LCD Display: The E36 control panel/module has a backlit LCD display where left and right desired temperatures and blower speed are shown. Display brightness varies according to ambient light levels when the headlamps and parking lamps are "off." With the lamps "on," brightness depends on dimming rheostat thumbwheel position.




Interior Temperature Sensor: As on all previous IHKA systems, an interior temperature sensor is located inside the control panel/module. also as on previous systems, the sensor has its own electric fan to ensure adequate air flow over the sensor.

Photocell: The photocell, located just below the interior temperature sensor grille, monitors ambient light levels to influence LCD display brightness (as on E38s).




Temperature Selection Rocker Switches: The temperature selection rocker switches (left and right), function the same as those on E38 vehicles.




Blower Rocker Switch: Blower speed is selected using a rocker switch. Speed is increased by pressing the "+" end of the switch and decreased by pressing the end.

When the system is at the lowest blower speed (speed "1"), pressing the "-" end turns the system "Off.




Maximum Defrosting Button: This button functions the same as the one on E38, except that the mixing flaps are not affected (they are cable operated). When pressed:

- the fresh air flaps are opened and
- the recirc. flaps are closed and
- the windshield defrost flaps are opened and
- all other distribution flaps are closed and
- the blower runs at maximum speed and
- the rear window defroster switches on.

The A/C compressor does not turn on automatically, but will run if the "snowflake" button is pressed.




A/C Compressor "snowflake" Button: Pressing the "snowflake" button causes the control panel/module to signal the engine control module (ECM) that A/C compressor operation is desired.

The ECM then energizes a relay to run the compressor.




Recirculating Air Button: This button controls air intake location as on previously covered IHKA systems.

On IHKA E36, though, recirculating air mode has no time limit. Once activated, it continues until the button is pressed again.




Rear Window Defroster Button: Pressing the rear window defroster button activates the rear window heating for about 17 minutes.




Viewed from the bottom, the IHKA E36 control panel/module has the following features:

IHKA E36 Control Panel/Module Functions

The control panel/module handles all the functions necessary to operate the IHKA system;

- Blower speed
- Heater core temperatures
- Auxiliary cooling fan
- Evaporator temperature
- Air intake flaps (fresh/recirculating)
- Special programmed functions
- Air distribution flaps (face vent, foot-well, defroster)
- Rear window defrost timing

And, like the E38 control panel/module, the E36 version has an EEPROM for fault code storage. The module can go into "sleep mode" to reduce power consumption when the ignition is switched "off," but still retain control panel settings and fault code information.

Another feature, unique to the E36 control panel/module, is that temperature sensor readings, "Y-factor" values, software version and other information can be displayed on the panel face for diagnosis. Refer to "Special Functions" later in this Handout for more information.


NOTE: If the control module is replaced it must be coded.


Substitute Value Operation

If an input potentiometer or sensor (or its circuit) fails, the control panel/module will ignore the faulty input and, in its place, use a replacement value which has been programmed into its memory for just this purpose. The replacement value, typically a mid-scale value for a particular input, allows the system to operate as normally as possible, despite the fault.

Substitute values for IHKA E36 components are:

- Desired temperature value (left or right) 72°F (22°C)
- Interior temperature sensor 75°F (24°C)
- Heater core temperature sensor (left or right) 130°F (55°C)
- Evaporator temperature sensor 23°F (-5°C)
- Ambient temperature sensor 32°F (0°C)

The substitute value for the evaporator temperature sensor is significantly below the A/C compressor cycling point (1-3°C). Therefore, if the evaporator temperature sensor signal is not possible, the substitute value will switch the refrigeration system off.