Car Air Conditioning System

By 16 March 2015

Before we look at the individual components of an automotive air conditioning system, it’s important to keep in mind that all air conditioning systems have a “high” and a “low” side. The dividing line for the two sides always occurs at the same point in the system.

The high side is the portion of the system in which high pressure, and high temperature, exists. The high side stretches from the outlet or discharge side of the compressor, through the condenser and, if equipped, the receiver drier, to the expansion valve or orifice tube.

The compressor raises the pressure (and the temperature) so the refrigerant can condense and release heat as it moves through the condenser. A “pressure differential” is created at the expansion valve or orifice tube – the dividing point on the front side of the system. We will explain the expansion valve and orifice tube in detail later in this chapter.

The low side is the other half of the system. On this side, from the expansion valve, through the evaporator and accumulator (if equipped) to the inlet (suction) side of the compressor, the refrigerant is in a low pressure, low temperature state. This allows heat to be transferred from inside the vehicle to the “colder” refrigerant, which then carries it away.

Keeping these two concepts in mind, let’s consider the hardware in a typical air conditioning system.