It depends on how long ago you purchased the vehicle and its age. It applies to vehicles less than ten years old. Full statutory warranty information (VIC) can be found here: http://www.consumer.vic.gov.au/motor...car/warranties
In Queensland you used to get three months statutory warranty on (dealer) used vehicles and air con was definitely covered. If your vehicle is in the shop for repairs for five days, you get a five day statutory warranty extension (QLD). I argued this with a car dealer years ago who refused these terms. They were very surprised when I quoted the legislation and thereafter complied with my request.