The AC system has many key components: compressor, condenser, receiver dryer, evaporator, and hoses. For an AC system to work, it needs a gas or liquid substance called refrigerant (R-12 in older cars, R-134a in 1995 and newer cars). The job of an AC compressor is to control the temperature and pressure of the refrigerant in the AC system before being passed to the condenser for cooling. Some important information for selecting the correct AC coompressor is the type of part needed; fitment position, required oil and refrigerant, mounting type and date limitation of the unit. As car manufacturers regularly update certain peripherals and design of their models, some compressors will only be suitable for particular models of certain years.