VW Polo manuals

Volkswagen Polo Service & Repair Manual: 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:

Replacing Reservoir, No Contaminants, No Loss of Refrigerant
  Discharge the refrigerant circuit. –  Replace the restrictor depending on the vehicle. –  Remove receiver or accumulator. –  Remove dirt from receiver or res ...

Run-Flat Tire, General Information
Run-flat tires have a reinforced sidewall in comparison to standard tires. This reduces the tendency for the sidewall to roll when there is a loss of pressure and prevents the sides of the tire from being pinched. This allows the vehicle to be driven whi ...

A/C Service Station, Connecting for Measuring and Testing
  Caution If it is suspected that chemicals were added to the refrigerant circuit to seal leaks, do not connect the A/C service station and do not extract the refrigerant. ...

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