Auxiliary Water Pump (From 09/99)

Temperature Control

Temperature control
The required temperature in the passenger compartment (setpoint temperature) is set by means of the selector wheel with potentiometer on the operating panel. The interior (footwell), heat exchanger, evaporator, outside and coolant temperatures are evaluated for the purpose of temperature control together with the driving speed and engine speed signals.

Heater operation is based on the reheat principle. The air is cooled down by the evaporator and then heated up again to the required temperature by the heat exchanger. The temperature of the heat exchanger is controlled by a clocked water valve. In this way, the control unit calculates the valve opening times dependent on the above-specified input variables. The valve opening times are 0 ms at max. COLD and 3600 ms at max. WARM.