The gas used in most air conditioning systems is called refrigerant. Refrigerants are chemicals specifically designed for their thermodynamic properties, allowing them to efficiently absorb and release heat as they undergo phase changes between liquid and vapor states.
In the past, a common refrigerant used in air conditioners was chlorofluorocarbon (CFC) known as R-22, also called Freon. However, due to its detrimental effects on the ozone layer, its production has been phased out as part of international environmental agreements like the Montreal Protocol. As a result, newer air conditioners now use more environmentally friendly refrigerants.
Today, the most commonly used refrigerants in residential and commercial air conditioning systems are hydrofluorocarbons (HFCs), such as R-410A (Puron) and R-32. These HFC refrigerants have lower ozone depletion potential, but they still have high global warming potential. In recent years, there has been a growing emphasis on developing and adopting even more environmentally friendly refrigerants, such as hydrofluoroolefins (HFOs), including R-1234yf and R-1234ze.
It's worth noting that the specific refrigerant used in an air conditioner depends on the system's design, age, and regional regulations. Therefore, it's always important to consult the manufacturer's guidelines or seek professional assistance to determine the correct refrigerant for a particular air conditioning unit.