2003 Ford Ranger

A/C works by removing heat, the hotter the interior, the longer it will take to feel cold, so try rolling the windows down a few inches while parked in the sun. Also a proper charge of R134a is critical, this is best done by getting an A/C service at a shop with a charging station, they vacuum out the old, hold vacuum for a while, if it holds vacuum, the system is then recharged to exact amount of freon. This will help.