Before 1994, most manufacturers used which refrigerant?

Before 1994, the predominant refrigerant used by most manufacturers in air conditioning and refrigeration systems was R-12. This refrigerant, also known as dichlorodifluoromethane, became widely used because of its effective thermodynamic properties, which allowed for efficient heat transfer in cooling systems.

However, by the early 1990s, concerns regarding R-12's potential to deplete the ozone layer led to increased regulatory pressure, culminating in the Montreal Protocol's phase-out of ozone-depleting substances. This transition away from R-12 paved the way for the development and adoption of more environmentally friendly refrigerants, such as R-134a, which gained popularity after 1994.

Understanding the historical context of refrigerant use illustrates the shift in industry standards and environmental considerations that have shaped modern practices in HVAC systems.