Temperature Demand Switch

Temperature Demand Switch

In-car temperatures are selected by the temperature demand switch (Fig. 1).

The switch is coupled to a 590 ohm potentiometer (Fig. 2) supplied with +5 volts from pin 43 of the ECM. The output voltage is from zero to 2.885 volts which represents a range of temperatures from 16 to 38°C. Rotation of the switch is restricted mechanically to 180° of travel.

Face Level Differential Controller

The face level differential control alters the temperature of the air distributed through the face level vents. The switch is coupled to a 10 K ohm potentiometer supplied with +5 volts from pin 43 of the control module (Fig. 3). Temperature, from the face vents, is decreased by moving the switch anticlockwise and increased by moving it clockwise.