The gas used in most air conditioning systems is called refrigerant. There are various types of refrigerants used in air conditioners, and the specific one depends on the age and type of the system.
Historically, chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) were commonly used as refrigerants, with R-22 (also known as Freon) being a well-known example. However, these refrigerants have been phased out due to their harmful impact on the ozone layer.
Today, the most commonly used refrigerants in air conditioners are hydrofluorocarbons (HFCs), such as R-410A (Puron) and R-32. HFCs have significantly lower ozone depletion potential but are still greenhouse gases contributing to climate change. Efforts are being made to develop and adopt even more environmentally friendly refrigerants with lower global warming potential.
It's worth noting that the specific type of refrigerant used in an air conditioner depends on the manufacturer, model, and the regulations or standards applicable in the region where the air conditioner is installed.