Automobile air conditioners work by absorbing heat inside your car and releasing it to the outside air using a special type of compressed gas. The air inside your car becomes cooler as more heat is absorbed. Three major parts compose the air conditioning system: the compressor, the condenser, and the evaporator. All of these parts need to be in good working order for your air conditioner to function properly. Since failure of any one of the components could lead to expensive repairs, you may want to have them checked periodically by a qualified mechanic. Air conditioners may substantially reduce the fuel economy of your car since they require the engine's power to operate. Overheating may also result if you're driving in traffic with the air conditioner on when it's extremely hot outside. Air conditioners require periodic recharging. If your car was made before 1993, it may have to be converted to the new and environmentally safer refrigerant used in today's automobiles. Contact a qualified mechanic in your area for more information on your air conditioning system.