Opening a window could help, or putting the air conditioner on. You can also open the doors, the sunroof/moonroof, put the convertible top down, turn the heater on, or open a vent.
Recharging any air conditioner unit is not a DIY job. To be able to do it safely - without endangering your own life or anyone else's - you need a licence to do the work. To get a licence you need to...