Volkswagen Polo Service & Repair Manual: Physical Principles

Volkswagen Polo Service & Repair Manual / Refrrigerant R134a Servicing / A/C System, General Information / A/C Technology Basic Principles / Physical Principles

The four known states of water also apply to air conditioning system refrigerants.

1 -	gaseous (invisible)

2 -

vapor

3 -

fluid

4 -

solid

Physical Principles

When water is heated in a vessel (heat absorption), water vapor can be seen to rise. If the vapor is further heated through heat absorption, the visible vapor turns into invisible gas. The process is reversible. The warmth is extracted from gaseous water, vapor forms first, then water and then ice.

A -	Heat absorption

B -	Heat emission

Physical Principles

Heat Transfer

Every substance consists of a mass of moving molecules. The fast moving molecules of a warmer substance give off some of their energy to the cooler and thus slower molecules. As a result, the molecular motion of the warmer substance slows down and that of the colder substance is accelerated. This process continues until the molecules of both substances are moving at the same speed. They are then at the same temperature and no further heat exchange takes place.

A/C Technology Basic Principles

...

Pressure and Boiling Point

The boiling point given in tables for a liquid is always referenced to an atmospheric pressure of 1 bar (14.5 psi). If the pressure acting on a fluid changes, its boi ...

Other materials:

Overview of the front passenger side
Fig. 9 Overview of the front passenger side (left-hand drive vehicles). The controls are mirrored in right-hand drive vehicles Key for : Vent , Location of front passenger front airbag in the dash panel Key-operated switch in the stowage compartment for switch ...

Changing the bulbs in the tail light cluster
Fig. 184 On the side of the luggage compartment: removing the tail light cluster Fig. 185 Tail light cluster: removing the bulb holder First read and observe the introductory information and safety warnings The steps should only be carried out in the specified order. Removing the tail li ...

Extraction and Charging System Safety Regulations
Make sure the shut-off valves are closed before connecting the charging system to the air conditioning system. Make sure the process is finished before disconnecting the charging system from the A/C system. This prevents any refrig ...