If you vehicles AC works OK and you want the vehicle to get colder, have the window tint added by a company that does it every day. Then ask the local dealerships who they use for interior work. Go to the interior person and have them add as much additional insulation to the vehicle as posable. Or do it you self. Most hardware stores sell the bubble wrap with silver side insulation. You will have to put in in the doors, and all around the sides. Then pull the seats and put it under the carpet.