Introduction to Air Conditioning and Climate Control

Climate Control Systems are no longer considered to be a luxury item Why? Tests carried out by WHO (World Health Organisation) show that ones ability to concentrate are impaired by stress The best temperature for the driver is between 20°C and 22°C  

Control of the Vehicle Interior Air Conditioning Heating & Ventilation Climate Control Automatic Climate Control

Air Conditioning Principle of Operation States of existence Water can exist in 3 different states depending on its temperature. Below 0°C – Solid(Ice) 0°C - 100°C – Liquid(Water) Above 100°C – Gas(Steam)

Sensible Heat As heat is applied to water, increases in temperature can be measured using a thermometer. As the influence of the heat can be measured, it is referred to as ‘SENSIBLE HEAT’

Latent / Hidden Heat When water reaches 100°C it boils and starts to change state from liquid to a gas. To ensure this change of state occurs, heat still has to be applied although the temperature of the water does not increase To enable the change of state to take place, energy is required This energy / heat is known as ‘LATENT’ or ‘HIDDEN HEAT’

Using LATENT Heat If a suitable gas / Refrigerant is compressed into a liquid and then forced through a restricted orifice It changes back into a gaseous state In order for it to be in a gaseous state energy is required This energy is absorbed from the surroundings, hence cooling them

Refrigerants Refrigerants must have a low boiling point In normal atmospheric conditions it exists as a gas Traditionally a gas known as Freon12 (R12) has been used This gas is a chlorinated hydrocarbon (CFC) and harmful to the environment

R 134A This is now the most common refrigerant used It replaced R12 in the early 1990’s, as R12 is only permitted to be used to top up older vehicles R134A destroys a fraction of the Ozone compared to R12

HEALTH & SAFETY Only suitably trained personnel should attempt to repair an Air conditioning System Protective gloves MUST be worn to prevent possible Frostbite burns, as escaping refrigerant will be approx. –26 degrees Celsius

HEALTH & SAFETY Due to the possibility of a leak of Refrigerant under extreme pressure eye protection MUST be worn

HEALTH & SAFETY All Refrigerants are classified as TOXIC, it is therefore illegal to dispose of them without a license If R134A is allowed to occupy a non ventilated room, there is a severe risk of suffocation

HEALTH & SAFETY R134A refrigerant is not highly flammable but if it were to be exposed to high temperatures, the resulting Toxic gas would be highly dangerous.

Component Layout On switch Relief Valve Radiator fan Pressure sensor Coolant temp. sensor Fan thermo switch Evaporator temp. sensor Fan Engine ECU Magnetic clutch

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