In the previous section of this two-part series, we learned about the three primary components that make up a vehicle’s air conditioning system. In this section, we shall look at the secondary components without which the system would be incomplete.


When the refrigerant exits the condenser, it does so in a liquid form. However, in order for the evaporator to do its job properly, the liquid refrigerant needs to be free of any water molecules and this is where the receiver/drier module comes into play. The unit resembles a small reservoir of water-absorbing granules called ‘desiccants’.

When the refrigerant liquid passes through the receiver/dryer it is stripped of any moisture contained in it. This is required so as to prevent the formation of ice crystals that could damage the A/C system.

Thermal Expansion Component

This is the stage between the receiver/drier and the evaporator where the high-pressure liquid refrigerant is allowed expand thus reducing its pressure. This component can be a valve capable of sensing the pressure and the regulating the flow of the liquid coolant into the evaporator.

Yet in other vehicles, the thermal expansion valve may be replaced with an orifice tube to serve the same purpose of regulating coolant flow. However, unlike the valve, the orifice tube has no moving parts, meaning it will face wear and tear issues. However, it can get clogged over time with debris transported by the refrigerant.


In vehicles, whose A/C system employs orifice tubes, there’s is a compensation component called an accumulator that is positioned between the evaporator and the compressor. The accumulator’s job is to trap any excess liquid from the gaseous refrigerant before feeding it into the compressor.

This is because the compressor can only compress the coolant in its gaseous state and not in its liquid state. Furthermore, the accumulator also removes humidity from the air inside the cabin, which in turn gives you that ‘cool effect’ of the A/C.