It probably takes about 5 mins for a car to start to cool down after being parked in the sun all day - the dashboard where the evaporator sits probably heats up to over 60C and has to cool down before it can cool the rest of the car. You will probably find the compressor in a Falcon is identical to the Commodore (Sanden) and most cars are RS on 40C days unless they've been parked in the shade.
There are a few ways you can make the car cooler apart from making sure it is fully charged with R134a - use a sunshade when parking in the sun - place a light coloured towel over the steering wheel to keep sun off drivers area - disconnect or bypass the heater hoses so that there is no chance of the heater feeding hot air to the A/C (common on Execs when tap control fails...climate control may also leak hot air).
My Commodore - Exec, has never been regassed since new and air coming from the vents on low setting is about 7C with ambient temp at 34C. A really good A/C will pump air out at 3C on low setting.
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