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:

Structuring Component
Definition: Structuring Component, Fine -ALN 775 108- Edition 04/2013 Product Description The Structuring Component, Fine -ALN 775 108- is a component for the two-part HS top ...

Overview of the driver door
Fig. 4 Overview of the controls in the driver door (left-hand drive vehicles) The controls are mirrored in right-hand drive vehicles Key for : Door release lever Central locking button for locking and unlocking the vehicle Switch for adjusting the exterior mirrors: ...

Tyre lettering
Fig. 149 International tyre lettering First read and observe the introductory information and safety warnings Tyre lettering (example) Meaning ① Product name Individual tyre lettering from manufacturer. ② DO ...