Page 183 - 05. Subyek Teknik Mesin - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

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Engine systems 167

The distribution of air inside the vehicle is provided by a series of ducts and
outlets. These are positioned on the underside of the fascia, at fascia level, and
adjacent to the front and side screens (and in the doors on some cars). The
outlets can be selected by operating the controls to the required positions
( Fig. 2.174 ). The controls are connected to fl aps in the heater air box by a cable,
a vacuum system or an electrical actuator. The fl ap position directs air to the
appropriate outlet.
On older vehicles, temperature selection was achieved by regulating the coolant
fl ow through the heater, by means of a valve. More often now it is by a fl ap in
the heater air box that directs how much air fl ows through the heater matrix
( Fig. 2.175 ). The fl ap is controlled in the same way as the air direction fl aps.
Thermostatic devices are used to control air temperature on some vehicles.
A blower motor in the air-intake duct boosts air fl ow through the heater system
( Fig. 2.176 ). The motor may be fi tted with a series of resistors or be electronically
controlled to provide a range of speeds.
Most modern heaters are linked with an air conditioning system. This is covered
in Chapter 3.

Figure 2.174 Air fl ow and heater controls

Figure 2.175 Heater control with fl aps Figure 2.176 Heater motor fan