The best solution is to just turn your AC off. When driving 60 KMH or less, roll down your window and enjoy a bit of fresh air. (Wise dogs have known the pure joy of fresh air for years.) At speeds above 60 KMH, keep a comfortable airflow moving by using the fan to bring in fresh air and keeping a window or sunroof open just a crack to let it out.
On really hot days when that's not enough, alternate the AC on and off to get just the amount of cooling you need. Just remember: it costs you every time you turn it on.
Brought to you by Carl Duivenvoorden
Though, not that you need an air conditioner now that the cool weather is back again?