This unit describes the skills and knowledge required to retrofit automotive air conditioning systems, including heating, ventilation and air conditioning (HVAC) systems, fitted to a range of vehicles and machinery. It involves preparing for the task, selecting the correct de-gas procedure, carrying out the retrofit and associated modifications, performing post-retrofit testing, and completing workplace processes and documentation. Air conditioning systems may contain a mixture of both natural and flammable synthetic refrigerants that are difficult to accurately identify and safely recover. To minimise the possibility of ignition, the procedures and equipment used when recovering refrigerants must be those required for flammable refrigerants.