AMBient ie outside temp. The sensor is on the driver's side, just in front of the radiator, below the headlamp. Unless you are in FNQ or Darwin or Alice Springs, then the temp being shown is quite possibly in error. Run a diagnostic on the A/C (there's a thread somewhere about it).
If it needs regassing, then it probably wouldn't work at all, as it has a pressure switch to prevent operation when gas pressure is low.