Volkswagen Polo Service & Repair Manual: Critical Point

Volkswagen Polo Service & Repair Manual / Refrrigerant R134a Servicing / A/C System, General Information / Refrigerant R134a / Critical Point

Vehicle air conditioning systems make use of the vaporization and condensation process. In this case, one works with a substance which boils easily, designated as refrigerant.

The refrigerant employed is tetrafluoroethane R134a, which boils at -26.5 °C (-15.7 °F) at a vapor pressure of 1 bar (14.5 psi).

The critical point (critical temperature and critical pressure) is that above which there is no longer a boundary between liquid and gas.

A substance above its critical point is always in the gaseous state.

At temperatures below the critical point, all types of refrigerant in pressure vessels exhibit both a liquid and a gas phase, i.e. there is a layer of gas above the liquid.

As long as there is still gas present in the container next to the fluid, pressure is dependent on ambient temperature. Refer to → Chapter „Refrigerant R134a Vapor Pressure Table“.

Note

Different types of refrigerant are never to be mixed. Only the refrigerant designated for the corresponding A/C system may be used.

Refrigerant R134a Physical Data

Vehicle air conditioning systems make use of the vaporization and condensation process. In this case, one works with a substance which boils easily, designated as ref ...

Refrigerant R134a Environmental Information

Vehicle air conditioning systems make use of the vaporization and condensation process. In this case, one works with a substance which boils easily, designated as ref ...

Other materials:

Refrigerant Circuit with Expansion Valve and Evaporator
1 - Evaporator 2 - Expansion Valve 3 - Valve for extracting, filling and measuring 4 - Receiver/dryer with dryer bag/dryer cartridge ...

Adhesive/Sealant
Definition: Adhesive/Sealant -D 511 500 A2-, gray Adhesive/Sealant -D 511 510 A2-, black Edition 04/2009 Product Description Adhesive/Sealant -D 511 50 ...

Socket in the vehicle
Fig. 106 Front centre console: 12-volt socket First read and observe the introductory information and safety warnings Maximum power rating Electrical socket Maximum power rating 12-volt 120 watts The maximum power rating of the sockets may not ...