Control Assembly: Description and Operation

CONTROL UNIT

Control Unit:

- The control unit is located in the center console and comprises a temperature dial (3), a pushbutton switch unit (4) and a blower switch (5).
- The temperature dial serves for stepless adjustments 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 pushbuttons "b" and "c"; "d" for uncontrolled heating only, as well as for blower switch in position "AUTOM".

Temperature Sensor (6) For Heat Exchanger:

In Car Temperature Sensor (7):

- 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 sensor (7) and sensor (6) for heat exchanger, the potentiometer provides the nominal value for temperature control.

Control Unit:

- The pushbutton switch unit (4) has 5 functions (a to e), the blower switch (5) has 3 (f, g, h); all are included in control unit.
- The temperature dial (3) and the blower switch can be individually removed from control unit.

Function Selection "e" (Off)

Main Air Flap (42) Arrows Show Inlet For Fresh Air:

- Selecting this function will reduce the air supply through main air flaps inside of vehicle to approx. 20 % (e.g. in the event of unpleasant outside dust or odors).

Monovalve (11), Recirculating Pump (30):

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

Function Selection "d" (cooling system off)
- EC (ECONOMY = refrigerant compressor is off), system operates with fresh air only.
- In heating mode, tempered air will flow out of legroom and side nozzles, as well as leak air from defroster nozzles. In such a case, the windshield will be provided with just enough air to remain free of fog during normal weather conditions.
- In venting mode, air is routed to air inlet 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 switched off until the engine coolant has been heated to approx. 33 °C. The blower operates in stages 3 to 5 at "AUTOM".
- This function selection is recommended when 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 cooling.
- The refrigerant compressor of the air conditioning system is in switched-on condition at outside temperatures above + 2 °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 mode, tempered air will flow out of legroom, center and side nozzles, as well as leak air from defroster nozzles. Simultaneously, the tempered air is guided to the doors.
- In cooling mode, cooled air will come out of center and side nozzles only. The mode change is automatic; overlapping is possible, that is, legroom and center nozzles can be open at the same time.
- The refrigerant compressor is added at outside temperatures above + 2°C, the evaporator temperature is held to approx. 0 00. If the system moves to full "cooling", the main air flaps will automatically switch to recirculating air.

Function Selection "b" (top and bottom)
- The blower starts after approx. 10 seconds, also below 33°C coolant temperature. In position "AUTOM" in stages 3 to 5.
- The refrigerant compressor is in switched-on condition at outside temperatures above + 2°C.
- In heating and cooling mode, air is routed to windshield, to center and side nozzles, as well as to legroom and doors.
- The interior of the vehicle is widely free of draft - the legroom is cooled more intensively. This function serves the purpose of removing fog, if any, on glass during damp, cold weather conditions.

Function Selection "a" (defrosting)
- With the ignition switched on, the blower will start immediately and operate in 6th blower stage only.
- Independent of temperature dial adjustment, max. heated air will be routed to windshield and side nozzles.
- The recirculating pump is always running along and the refrigerant compressor is switched on at outside temperatures above + 2°C. If, with the ignition switched on, function selection "a" or "b" is pushed, followed by switching to "c" or "d", the system remains in operation also below 33°C coolant temperature.

Blower Switch (5)
- The blower operates in 6 stages.
- At function selection "b", "c" and "d" the air volume can be set as required.

Switch: Air Volume: Blower Stage:
f (top) max. 6 (12 V)
h (bottom) min. 1 (4 V)
g (center) automatic 2-5 (5-10 V)

- 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 there for approx. 10 seconds. If required, the blower will switch up to 5th blower stage.