Page 182 - 05. Subyek Teknik Mesin - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

2
166 Automobile mechanical and electrical systems

Many vehicles, particularly those fi tted with air conditioning, have two-speed fan
circuits. These have a control circuit to switch the motor (or motors) to half speed
Key fact
at 95°C, and full speed at 100°C. This arrangement can be also be operated by
Many vehicles, particularly those the engine management system.
fi tted with air conditioning, have
two-speed fan circuits. Cooling system hoses are manufactured from fabric-reinforced rubber, and are
moulded to suit the vehicle application. Connectors are cast, or formed, with a raised
lip on the pipes leading into, and out of, other components. The hoses are held with
round clips that can be drawn tight to give a watertight seal (e.g. jubilee clips).

2.3.3 Interior heater

The vehicle interior heater is made from an air box with a heat exchanger inside.
The heat exchanger, called a heater matrix or a heater radiator ( Fig. 2.172 ), is
very similar to the cooling radiator in that it consists of a similar series of tubes
and fi ns. Hot coolant from the engine fl ows through the matrix, thus heating the
tubes and fi ns. Air fl ows across the outside and collects some of the heat for
distribution inside the vehicle.

Air is drawn into the heater through ducts on the vehicle exterior. The design of
the ducts provides a dust and water trap, and usually the ducts have an outlet
hose for water drainage. Many vehicles have a pollen fi lter fi tted in the air-intake
ducts ( Fig. 2.173 ). The fi lter is a microporous paper element that traps pollen and
dust particles.

Figure 2.172 Heater radiator

Figure 2.173 Heater intake with pollen fi lter