Motor Vehicle Air Conditioning
The air conditioning systems of a motor vehicle are similar to those of a home or building, the principles involved are the
same as is the science behind the functioning of the units although the components are slightly different and the interfaces for the user are
integrated into the vehicles electronic systems, these are usually aesthetically designed by the vehicle manufacturer to compliment the both the
interior and facia designs and incorporate the latest technological and electronic advances for efficiency and utilisation of the space
A motor vehicle air conditioning system needs to function in the same way as a home system would but because of the space restriction for the
components the manufacturers have had to make many of them much smaller than you would find in a home or building unit. These components consists
of a compressor mounted on the engine and usually driven by a belt from the crankshaft pulley, a condenser located at the front of the vehicle in
front of the cooling radiator and that has an electric fan or fans mounted on it to assist in drawing air through it for cooling purposes, there
is a receiver/drier that is usually mounted in the engine compartment and close to the condenser, an expansion valve and an evaporator and fan,
the evaporator is located inside the vehicle usually within the heater unit mounted on the bulkhead behind the facia.
The refrigerant is compressed and pumped through the condenser by the compressor to the receiver/drier that removes any moisture that may be
present in the refrigerant, it then passes to the expansion valve and through the evaporator where warm air is passed by the in car fans over the
evaporator removing the heat from the air and then the refrigerant goes back through the compressor to begin the cycle once again. This process
allows for the change in state of the refrigerant from gas to liquid to gas as the airflow over the condenser and evaporator alters its
temperature and the expansion valve makes sure it is in the correct state as it enters the evaporator.
A basic motor vehicle air conditioning system diagram showing the components and direction of refrigerant travelling through the system. With
constant changes in temperature within the evaporator condensation is formed and pipes are fitted to the unit leading outside the vehicle
(usually underneath) and the water that accumulates is allowed to leave the unit through these. On hot days when the air conditioning is used
constantly there can be quite a lot of condensation formed and it may seem that a leak has appeared under the vehicle when it is stood but it is
the natural release of the water formed on the evaporator.
Modern day vehicles have numerous different systems ranging from a basic cold air delivery to complex climate control systems
that maintain the temperature inside the vehicle set by the driver or user to the individual’s preference. Luxury and high-end vehicles have
different controls for different parts of the vehicle to allow for maximum passenger and driver comfort and allows for different temperatures in
different areas of that vehicle. The facia controls reflect the adjustments and the complexity of the system for any particular vehicle and where
basic cooling of an air conditioning alone is not enough; climate control systems have sensors around the interior that constantly monitor the
temperature and then automatically alter the heat or cooling and the fans speeds to maintain a constant interior temperature. The advance in
electronics and computer technology has made this ability much easier and cost effective and climate control is now becoming available on lower
specification vehicles as a standard fitment where just a few years ago only high priced and luxury vehicles had this type of system.