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:

Lifting the vehicle with the jack
Fig. 168 Jacking points for the vehicle jack (mirrored on the right-hand side of the vehicle) Fig. 169 Vehicle jack at the rear left-hand side of the vehicle First read and observe the introductory information and safety warnings The jack may be applied only at the jacking points shown (m ...

Preserving Wax
Definition: Preserving Wax -AKR 321 M15 4- Preserving Wax -AKR 321 M16 10- Edition 04/2009 Product Description Preserving Wax -AKR 321 M15 4- and Prese ...

Using the cruise control system
Fig. 123 On the left of the steering column: button and switch for the CCS First read and observe the introductory information and safety warnings Function Switch position, switch control Action Switching on the CCS. Switch ② i ...