INTRODUCTION

As a result of primary and secondary physiologial processes involving the activities of human beings, the air in the environment in which they live is altered with an increase in the rate of carbon dioxide, a decrease in the percentage of oxygen, the

emission of aromatic substances (e.g. from smoking) and an increase in the concentration of pathogenic bacteria; this all makes a closed environment less healthy, especially if a small area is involved.

One of the solutions for improving these conditions is the use of an air conditioning system.

An efficient air conditioning system fitted in the vehicle should control the main environmental factors which determine the physiological conditions for the well-being of people, namely:

the temperature;

the humidity;

the speed of the air;

the purity of the air in the passenger compartment.

The variation in the temperature and the humidity of the air in the passenger compartment is achieved by the following two systems:

manually operated climate control system, which is fitted as standard on the vehicle.

automatically controlled temperature (twin zone) and ventilation climate control system, available as an option of vehicles with higher specification levels.

The two systems described below, jointly as far as the systems which they share, such as for example the refrigerating cycle, are concerned and separately for all the different components, such as for example the systems for regulating and controlling

the temperature of the air are concerned because in one the operating logic for the temperature (heating/mixing/cooling) in two distinctly different areas of the passenger compartment is far more sophisticated than in any manually operated system.