Car air conditioner is designed to move heat from inside of your car to outdoors.
Become familiar with the major components to auto air conditioning:
The Compressor: which compresses and circulates the refrigerant in the system. The refrigerant, which carries the heat and the condenser, which changes the phase of the refrigerant from gas to liquid and expels heat removed from the car.
The Expansion Valve: which is somewhat of a nozzle and functions to simultaneously drop the pressure of the refrigerant liquid, meter its flow, and atomize it
The Evaporator: which transfers heat to the refrigerant from the air blown across it, cooling your car
The Receiver/Dryer: which functions as a filter for the refrigerant/oil, removing moisture and other contaminants
Following are some of the possible reasons of your Car a/c is not functioning properly: