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

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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:

Identification
There are several specifications located on the rim. The following examples shows the rim identification: Replacement parts number: 6E0 601 027 A Size of disc wheel: 6 J x 15 6 - Rim width in inches J - Shape of rim flange 15 - Rim diamete ...

Checking with Expansion Valve and Receiver/Dryer, with Internally Regulated A/C Compressor
Note Connecting service station. Refer to → Chapter „Connecting Service Station“. Observe test requirements. Refer to → Chapter „Pressures, Checking“. – ...

Decorative Trims, Replacing, Bolted Decorative Trims
These disc wheels are equipped with replaceable decoration elements. Note the following when installing. – Clean the thread in the disc wheel before screwing in the new bolts. ...