Two Types of Auto Air Conditioning

by Adam Benks
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Automotive air conditioning is considered a necessity for most people. Consequently, we have come a long way in revolutionizing the air conditioners in our cars. The latest upgrades to this useful invention include the ability to set a desired temperature and have the system adjust automatically. Automotive air conditioners may be of two types. The main difference between the two types lies in the device that lowers the refrigerant pressure. Each has advantages and disadvantages.


The main shared components of the two types of car air conditioning include the compressor, condenser, evaporator, orifice tube, thermal expansion valve, receiver-drier and accumulator. The orifice tube may be replaced by a thermal expansion valve, thus the two types of automotive air conditioning.


The compressor pulls low-pressure refrigerant from the evaporator and compresses it into high-pressure refrigerant vapor that is moved to the condenser. During this process, the temperature of the refrigerant is increased. While the high-pressure refrigerant is in the condenser, it is cooled down by fans blowing across the condenser fins. The refrigerant is then collected by the receiver-drier, which is filtered and dried.

As a result of this process, liquid refrigerant builds up at the bottom of the receiver-drier, with the vapor at the top. The expansion valve then allows a certain amount of the liquid refrigerant to enter the evaporator. During its final stage, the refrigerant leaves the evaporator as a gas by absorbing the heat inside the car. As the warm air from inside the automobile is forced onto the evaporator fins, it is cooled by the refrigerant and released back to the car's interior. The moisture from the warm air after the cooling process is drained away.

Orifice Tube System

The orifice tube systems are commonly found in General Motors (GM) and Ford models. The orifice tube is located in the inlet tube of the evaporator or in the liquid line. The orifice tube is no longer than 3 inches. It is made up of small brass tubes surrounded by plastic, covered with a filter at each end.

Disadvantages of the orifice tube system include clogging caused by debris and high costs of repairing or replacing the tube. To avoid the clogging of debris in the orifice tube system, install a larger pre-filter in front of the orifice tube.

Expansion Valve System

The expansion valve system is generally used on after-market systems. This system is efficient at regulating refrigerant to the evaporator. It is located at the firewall, between the evaporator inlet and outlet tubes and the liquid and section lines. It may clog with debris. Additionally, the valve contains small moving parts that may stick together or malfunction because of corrosion.

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