Heating System Control, Functional Description

A. Control of water circulation
The heater valve is pneumatically adjusted (vacuum) into position "open" or "closed". It is located under air intake grille adjacent to blower.












The vacuum control proceeds by way of two vacuum switches, which are integrated in the two heater switches. Both vacuum switches are similar in design.

Example:
In position "heater closed" (heater switch left and right in position "closed") both vacuum switches are releasing the vacuum. During this process, a vacuum element on heater valve is attracted via vacuum line.

In position "heater open" (min. 1 heater switch is slightly opened)the vacuum element on heater valve is connected to atmosphere via vacuum line and vacuum switches. The heater valve is opened by spring force.

NOTE: In the event of a defect on vacuum system, the heater valve is opened by spring force. The layout of the mixed air flaps permits that in spite of an open heater valve in position "heater closed" only a slight volume of warm air will flow out of heating system. Only the heat exchanger will be getting warm.







Function diagram, switch position: Heater open
1 Intake manifold
2 Check valve
3 Heater switch left
4 Heater switch right
5 Vacuum element
6 Heater valve

Color code of vacuum lines
a gray
b dark red-green
c red-white
d red

B. Control and distribution of the air







The air enters at air intake grille below windshield and flows via blower into vehicle interior. The main air flap is located between blower and heater box. As a result, the supply can be centrally closed in the event of dust and unpleasant odors from outside.

The temperature can be steplessly and separately regulated for each vehicle side by means of the two mixed air flaps.







1 Heater switch for lefthand vehicle side.
2 Heater switch for righthand vehicle side. Switched on by turning to the right. The heater output is increased up to stop of heater switch.
3 Switch for air volume

By moving lever from end detent position "mm" to the right, the main air flap will be opened and the four-stage blower will be added.

For perfect ventilation of interior, the blower should always be switched on- Depending on operating conditions, set lever to blower stage "I", "II"," III" or MAX.

In the event of dust and unpleasant odors from outside, the air supply into vehicle can be switched off (moving lever into end detent position "mm".

4 Air distribution switch
The closer the switch is turned in direction of the following symbol, the more air will flow into respective range. The 12 detents also permit intermediate steps in addition to the four switch positions named on control unit.
- Air toward windshield
- Air toward windshield, as well as toward driver's and rear compartment legroom
- Air toward driver's and rear compartment legroom (max. rear compartment ventilation)
- Air only out of swivelling inserts 6 and 8

5 Lever for not heatable fresh air (stepless adjustment)
lever at top = open
6 Swivelling inserts for not heatable fresh air
7 Lever for lateral ventilation (stepless adjustment)
lever at top = open
8 Swivelling inserts for lateral ventilation (heatable)