The first automobile air conditioner was introduced in 1940s. The car air conditioning system works on the same process found in windows air conditioning unit. Car air conditioning system has undergone much change over the years.
The sketch of a Car Air Conditioning System
To understand the function of the automobile air conditioning system, you need to know about the different components of the air conditioning system. Compressor is the large central part from which high pressure and low pressure hoses are coming out. These hoses lead to the condenser and an evaporator. Dryer and expansion valves are also part of the system. Expansion valves are meant to regulate the temperature of the air and also control the flow of refrigerant through the system. Antifreeze agent (coolant, a condensed gas) runs through these valves.
Process of cooling
Automotive air conditioning system never produces the cold air rather it takes the heat out of air already present in the car. The coolant or a chemical compound often used in the automotive air conditioning system is called Freon. The process starts in the compressor where refrigerant is compressed to high temperature gas. This high temperature gas then travels to the condenser through high pressure channels. In the condenser the fresh air and the gas comes into contact and air absorbs all the heat from the high temperature gas. In a result the refrigerant takes the liquid form. Once it becomes liquefy it flows into the dryer chamber. The dryer makes the liquid gas free from all impurities and pushed the purified gas through expansion valve into the evaporator. The heat in the air is absorbed by the liquid gas and it evaporates. Fan or blower blows the air across the evaporator and finally into the interior cabin of the car. The process repeats again and again.
Fixing the Air Conditioning system
Fixing the leakage is relatively a tough job rather than spotting the leak. It is important to check for certain leakage regularly. The leak of refrigerant certainly reduces the performance of the air conditioning system. Leakage in the system means there is nothing left to take away the heat.
To check whether compressor is working fine or not, turns on the engine and make sure that the AC switch is on. Open the bonnet and in the central part look out for the pump like structure surrounded by hoses. Examine the compressor carefully. If you find no movement in it, then there must be a problem with compressors switch. There can be many reasons behind it. For instance, wiring problem, bad fuse, or a broken AC switch and in some cases the low level of refrigerant also cause this problem. Locate the fault and act accordingly.
In some cases the system does its work normally but the cooling is not up to the mark. This is due to the refrigerant. It is important to use the refrigerant recommended by the manufacturer for your vehicle type.
You might also want to learn how to diagnose a PT cruiser AC problem and also how do I change the cabin air filter on my 2003 Honda Accord?