Most people go to TAFE after Year 10, but many refrigeration apprentices now complete Year 12, usually majoring in STEM subjects. Refrigeration is a science so Year 11-12 science can be a useful foundation.

You have a choice of several levels depending on what type of work you want to do. You can get a Cert II to install split system air conditioners and heat pumps, or a Cert III to become an Air Conditioning and Refrigeration Technician. Or you can move into engineering with a Diploma or Advanced Diploma. 

Most auto air conditioning technicians have an existing qualification, usually as an auto electrician or auto mechanic. They then need to do additional units of competency or the full Cert II course in automotive air conditioning to add air con to their skillset – the level of tr5aining is determined by your existing experience and knowledge. 

Yes, refrigeration technicians are needed in aviation, marine, mining, manufacturing and other specialised sectors in addition to the more usual stationary and automotive areas. They can even work in Antarctica.