Control Unit

The control unit is located in center console and comprises a temperature dial (3), a push-button switch unit (4) and blower switch (5).

The temperature dial serves for stepless adjustment of in-car temperature between the two end detent positions "MIN" = not heating and "MAX" = fully heating.

Set to "MAX" means full, uncontrolled heating capacity; set to "MIN" means full, uncontrolled cooling capacity, each time in 5th blower stage. These functions apply only for push-button "b", "c" and "d", as well as for blower switch in position "AUTOM". The temperature set with temperature dial is attained as quickly as possible and will then remain constant.






6 Temperature sensor for heat exchanger (up to 12/80)

To prevent undesired temperature fluctuations the temperature, once set, should be corrected in small steps only. Rotation of temperature dial will adjust a potentiometer. Together with in-car temperature sensor (7),





7 In-car temperature sensor (up to 06/81)

as well as sensor (6) for heat exchanger, the potentiometer indicates the nominal value for temperature control.





6 Temperature sensor for heat exchanger (starting January 1981)






6 Layout temperature sensor for heat exchanger






7 In car temperature sensor (starting July 1981)






1 Layout in-car temperature sensor (starting July 1981)






The push-button switch unit (4) provides 5 functions (a to e), the blower switch (5) 3 (f. g, h,); all are included in control unit.






3 Temperature dial
4 Push-button switch unit with 5 functions
5 Blower switch

Function selection "e" (Off):
Selecting this function will switch off the air supply through main air flap into inside of vehicle. (e.g., in the event of unpleasant outside dust or odors).

The electronic system continues to operate while driving and the monovalve (11) remains closed. Blower is not operating.

Function selection "d" (refrigerant compressor off)

EC (ECONOMY.- refrigerant compressor is off). System operates with fresh air only.

In heating range, tempered air will flow out of footwell and side nozzles, with a leak air share from defroster nozzles. The windshield will be provided with lust enough air to remain free of fog during normal weather conditions.

In venting range, air is routed to air inlets in center of instrument panel and to lateral vents only. The minimum in-car temperature depends on outside temperature and on solar radiation.

At low outside temperatures, the air supply and the blower remain in off position until the engine is heated to approx. 35 °C by the coolant. The blower operates in stages 3 to 5 at "AUTOM".

We recommend the above function selection at outside temperatures, at which no cooling of fresh air is required (to save fuel).






Function selection "C" (normal adjustment):
Function selection "c" corresponds to function selection "d", but with a cooling effect.

The refrigerant compressor of the air conditioning system is switched on at outside temperatures above +4°C.

If the vehicle in-car temperature is higher by approx. 4 °C than the preselected temperature on temperature dial, the blower will start immediately. At "AUTOM" the blower operates in stages 2 to 5.

In heating range, tempered air will flow Out of leg footwell and side nozzles with a leak air share from defroster nozzles.

In cooling range, cooled air will come out of center and side vents only. The mode changes automatically; overlapping is possible, that is, footwell and center nozzles can be opened simultaneously.

The compressor is added, the evaporator temperature is held to approx. 0 °C. If the system moves to "full cooling", the main air flap is automatically switched to recirculated air and the diverter flap will be opened at the same time. Opening of diverter flap will route a large portion of the air volume from evaporator directly to center and lower side nozzles. Less air will then flow through heat exchanger.






3 Temperature dial
4 Push-button switch unit with 5 functions
5 Blower switch with 3 functions

Function selection "b" top and bottom (overall ventilation):
Blower starts after approx. 10 seconds, also below 35 °C coolant temperature. In position "AUTOM" in stages 3 to 5. Refrigerant compressor is switched on. If function selection "a" or "b" is pressed with the ignition switched on, and the system is then switched to "c" or "d", the blower remains in operation even at coolant temperatures below 33 °C.

In heating range air is routed to windshield, to side vents and to footwell; in coaling range additionally to air inlets in center of instrument panel.

The interior of the vehicle is extensively cooled free of draft, the footwell is cooled more intensively. This function serves the purpose of removing fog, if any, on glass during damp, cold weather conditions.






3 Temperature dial
4 Push-button switch unit with 5 functions
5 Blower switch with 3 functions

Function selection "a" (defrosting):
With the ignition switched on, the blower will start immediately and operates in 6th blower stage only.

Max. heated air is routed to the windshield regardless of the setting of the temperature selector.

The recirculating pump always runs at the same time and the refrigerant compressor is switched on.

Blower switch (5):
The blower operates in 6 stages.






At function selection "b", "c" and "d", the air volume can be set as required.






During "AUTOM" operation in functions "b, c and d" the blower will start in 2nd blower stage after the system has been switched on, with a delay of approx. 10 seconds and remains constant for approx. 10 seconds (on vehicles up to 12/80 approx. 30 seconds). If required, blower switches up to 5th blower stage.