IHKA - E39

CONTROL PANEL/MODULE







All heater/ air conditioner operation is controlled from the button and rocker switches located on the control panel The control module is integrated into the control panel and contains all of the control electronics except the final stage for the blower motor control

The control module contains a fault memory in a non volatile RAM and incorporates a sleep mode when the ignition is switched off. The control module will switch to the sleep mode 16 minutes after the ignition is switched off. The control panel consists of the following:

Air Distribution Buttons: Manual distribution buttons with selection for:







- Defrost - air to the windshield without maximum defrost.







- Air distribution to the face vents.







- Air distribution to the footwell outlets.

The defrost, face vent and footwell buttons can be selected in any order for distribution to the desired vents.







Auto: Overrides the manual buttons and provides distribution based on the control module settings as with other systems.







Temperature Selection Buttons: For the driver and passenger's side with digital temperature readout in the LCD.







There is one LCD panel for the display of both the left/right side temperature selections and the blower speed.







Rest Button: For activation of the residual heat feature.







Air Volume Control Rocker Switch: The air volume can be adjusted through 16 steps using the rocker switch. The selected volume is displayed as a wedge on the LCD panel.







Front Windshield Defrost: - Maximum defrost to the front windshield is provided by pressing this button. This over rides the other distribution button settings and switches on the rear defroster simultaneously.







Air Conditioning Button: - Pressing the snowflake is the A/C on request input to the control module.







Recirculation/Automatic Recirculation (AUC) Button:

The button allows switching between:
- Fresh/Recirculated air flap activation
- Automatic control of Fresh/Recirculated air flaps.

The AUC system incorporates a sensor that reacts to the levels of oxidizable gasses in the ambient air. When the levels exceed a set value stored in the IHKA control module, the system switches automatically to the recirculation air mode.







Rear Defroster Button: - When pressed, the rear defroster is switched on for:

- 10 minutes with the outside temperature > 14°F.
- 17 minutes with the outside temperature < 14°F.

After the initial timed duration, each subsequent pressing of the button will switch the defroster on for 5 minutes.







Interior Air Temperature Sensor: The sensor includes the integral blower fan which continuously draws interior air over the sensor. This helps the system to stabilize the output of the system to match the desired settings on the control panel.

Changes To 5 Series (E39) IHKA Control Panel







The operation and appearance of the IHKA on the E39 as of 9/96 production has changed only slightly:

On the LCD display the new "AUTO-symbol" replaced the tan symbol, indicating activation of the automatic blower speed program.

The lit LED on the "AUTO-button" indicates activation of the automatic air distribution.







NOTE:From 9/96 to 3/97 Production:


When in the automatic blower speed mode, the "AUTO-symbol" and the blower wedge silhouette will be displayed







After 3/97 Production:
When in the automatic blower speed mode, the "AUTO- symbol" and the actual blower speed indicated by the bars, will be displayed. The number of bars will automatically change as the auto control of the blower takes place.







If the plus or minus tan speed button is pressed when in the auto mode, the "AUTO-symbol" in the display will be turned off and the manual blower speed control takes place. Blower speed is indicated by the bars.

At the same time the automatic air distribution program is still active and the LED in the "AUTO-button" will be:

1. turned off - from 9/96 to 3/97 production

2. turned on - after 3/97 production

If one of the air distribution buttons is pressed when in the auto mode (1), the air distribution will come out of the automatic program, however; the automatic blower speed program will remain active and the "AUTO-symbol" will continue to be displayed in the LCD panel.


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