Critical Point

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The critical point (critical temperature and critical pressure) means the substance has gone above the point when 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 reservoirs exhibit both a liquid and a gas phase meaning there is a layer of gas above the liquid.

As long as there is still gas present in the cylinder next to the fluid, pressure is dependent on ambient temperature. Refer to REFRIGERANT VAPOR PRESSURE TABLE .

NOTE:

The refrigerants used in vehicles must not be mixed. Only the refrigerant designated for the corresponding A/C system may be used.

The vapor pressure of both refrigerant R1234yf and R134a are very similar across a wide temperature range; therefore, it is not possible to differentiate between both refrigerants. Refer to REFRIGERANT VAPOR PRESSURE TABLE and A/C System, General Information . Differentiating is only possible using sensors that can analyze the chemical composition of the refrigerants. Refer to REFRIGERANT R1234YF ANALYSIS .