Auto A/C Terms - Glossary
Boiling Point

Typically we think of boiling as hot. That is because when we think boiling, we are usually thinking about water. We know that water boils at 212F or 100C. Yes, that is hot. However, consider that other substances like refrigerant actually boil at temperatures below zero. As an example, R134a which is the most common automotive refrigerant today, boils at minus 15.3 degrees F. That is the temperature that the liquid refrigerant changes to vapor refrigerant at sea level.

Therefore, it is important to understand that boiling does not always have to be hot. The boiling point is simply the temperature that a liquid substance changes state to become a vapor.

In physics, this point is defined as the temperature at which the vapor pressure of a water is equal to the pressure of the atmosphere on the liquid, which is equal to 212F or 100C at sea level.