Control Panel

IHKA E32 CONTROL PANEL







Cabin climate control functions are controlled using the buttons and thumbwheels on the control panel. The E32 control panel also houses the rear window defroster button and the interior temperature sensor.

Control panel features are covered briefly below. Detailed descriptions for each feature appear in the appropriate section, later in this Handout.







Rear Window Defroster Button: used to activate the rear window defroster; this button is a "momentary-contact type" button. The rear window defroster button works whether the IHKA system is on or off.

Several different defroster operating strategies are used on E32 vehicles. These are discussed later in this Handout.







Left/Right Desired Temperature Thumbwheels: Separate thumbwheels allow independent temperature regulation on the driver and passenger sides of the cabin.

The numbers that appear on the thumbwheels do not indicate actual cabin temperature - they correspond to a general comfort level.







Left/Right Air Distribution Buttons: Separate air distribution buttons allow the driver and passenger to select different air discharge locations. From left to right, the buttons are: Up/Down, AUTO, and Down.

The air distribution buttons are "opposing arrest" buttons - only one button in each three-button set can be depressed at any one time. Pressing an "extended" button causes the button already depressed to pop out.

If no buttons are depressed, the system will operate in "AUTO" mode by default.












Up/Down Button: For most operating conditions, this button provides the most evenly-distributed air flow since some air is discharged from all air distribution outlets (face vents, console rear outlet, footwells, windshield defrosting).

Some flap positions are modified when the A/C compressor is switched on, and the console rear outlet flap position depends upon rear seat switch position. Other flap positions depend upon Y-factor.

When up/down mode is selected, however, the face vent flaps are always fully open and the footwell flaps are always at least half open.







Automatic Button: When the "AUTO" button is pressed, the control module operates all the air discharge flap motors according to Y-factor.

If cooling is needed, the face vent and console rear outlet flaps are fully opened, while the windshield defroster and footwell flaps are fully closed. If heating is called for, the face vents and console rear outlet flaps are closed, and the footwell and windshield defroster flaps are fully opened For some mid-range Y-factor values (e.g. 40%) all air distribution flaps are partially open.







Down Button: Pressing this button limits air discharge to the windshield defroster and footwell air distribution outlets.

When down mode is selected, the face vent and console rear outlet flaps are always fully closed, and the footwell flaps are always fully opened.

The windshield defroster flap positions depend on whether the A/C compressor is switched on, and Y-factor values. The defroster flaps are, however, always half open when the Y-Factor is above 30%.

Detailed information about each of these three buttons appears later in this Handout under "IHKA E32 Air Distribution."







Blower Speed Thumbwheel: The blower speed thumbwheel is linked to a potentiometer inside the control panel, and performs several functions:
- The thumbwheel is the "master controller" for the IHKA system - rotating it fully to the left ("0" position) turns off the system.
- Rotating the thumbwheel to the right from "0" turns the system on and activates the blower. Blower speed increases the further the thumbwheel is rotated.
- On early versions of IHKA E32, the blower speed thumbwheel also influences fresh air inlet flap position.







Maximum Defrosting Button: Pressing this button overrides all current system modes and functions, and activates the maximum defrosting mode:
- The fresh air intake flaps are fully opened (recirc. mode, if active, is overridden).
- The windshield defrosting flaps are fully opened.
- All other air distribution flaps are fully closed.
- The blower runs at near-maximum speed.
- The A/C compressor is turned on (control module software version 1 only, up to 9/87 production).
- The water valves are opened fully for maximum coolant flow through the heater cores. (At ambient temperatures above 32 °F (0 °C), the water valves are pulsed to regulate heater core temperature.)
- The rear window defroster is activated.

The maximum defrosting button works whether the IHKA system is turned on or off.







A/C Compressor Button: Pressing the "snowflake" button sends an A/C compressor "on" request to the IHKA control module (so long as the blower speed thumbwheel is not in position "0").







Recirculating Air Button: Pressing this button tells the control module to close the fresh air intake flaps and open the recirculating air flaps. It also sends an A/C compressor "on" request to the control module.







Interior Temperature Sensor: The interior temperature sensor is located behind an air intake grille on the control panel face.
A small electric fan, mounted on the back of the control panel, draws air over the sensor to avoid sampling "stale" cabin air.
The sensor fan runs whenever the ignition is turned on, whether the IHKA system is on or off.

Viewed from the back, the IHKA E32 control panel has the following features: