Although most of us do own an air conditioner we hardly have an understanding on how it works. May be we have given it a thought but didn't quite know where to look for an answer, or even if we tried we found the explanation too technical to make proper sense. Or we just didn't care. What we will attempt here is to describe the process of air conditioning, specifically car air conditioning, and that in a simple and lucid manner so that even a novice can make sense of what we are talking about.

It should be understood that the basic working principle of all air conditioners, be it a window air conditioner or an auto air conditioner, is the same. There are four fundamental processes in physics that we have all read of in our schools which are involved in the working of an air conditioner. The four processes are - evaporation, condensation, compression and expansion.

Let us now go to the details of the workings of an auto air conditioner. We will take it component by component.

Compressor: This is like the heart of the air conditioning unit. When you turn on the air conditioner in your car the compressor kicks in and pumps the refrigerant vapor to the condenser. The vapor at this stage is under extremely high pressure.

Condenser: This is the device which converts the high pressure refrigerant vapor into a liquid. Since the vapor is condensed into a liquid a lot of heat is generated. This extra heat is removed from the condenser by the air that flows out.

Receiver: The liquefied refrigerant next moves to the receiver also referred to as the drier at times. It is like a small reservoir and here any excess moisture that has escaped into the refrigerant is removed. This is because if moisture is allowed to escape it can severely damage the unit with ice crystals being formed causing blockages.

Expansion Valve: The refrigerant, now free of any moisture, next flows into the expansion valve where the high pressure on the refrigerant is removed and it again changes from the liquid state to vapor.

Evaporator: Here the refrigerant vapor absorbs the heat from the air inside the car. On the other hand the blower fan inside the passenger compartment pushes the air across the outside of the evaporator and hence cold air is circulated inside the car.