Air Conditioning System

DESCRIPTION
The A.R.A. air conditioning system comprises four major units:

A/C Components:

1. An engine-mounted compressor.
2. A condenser mounted in front of the radiator.
3. A receiver/drier unit located in the engine compartment.
4. An evaporator unit mounted behind the dashboard.

The four units are interconnected by hoses carrying refrigerant, and the evaporator is linked into the vehicle ventilation system.

Refrigeration Cycle
The function of the refrigeration circuit is to cool the evaporator.

Compressor--The compressor draws vaporized refrigerant from the evaporator. It is compressed, and thus heated, and passed on to the condenser as a hot, high pressure vapor.

Condenser--The condenser is mounted directly in front of the vehicle radiator. It consists of a refrigerant coil mounted in a series of thin cooling fins to provide the maximum heat transfer in a minimum amount of space. Airflow across condenser is induced by vehicle movement and is assisted by two electric condenser fans. The refrigerant enters the inlet at the top of the condenser as a heat laden high pressure vapor.

As this vapor passes down through the condenser coil, heat will follow its natural tendency and flow from the hot refrigerant vapor into the cooler air flowing across the condenser coils and fins.

When the refrigerant vapor reaches the temperature and pressure that will induce a change of state, a large quantity of latent heat will be transferred to the outside air. The refrigerant will change from a high pressure HOT VAPOR to a high pressure WARM LIQUID.

Receiver drier--This unit filters, removes moisture, and acts as a reservoir for the liquid. To prevent icing inside the system, extreme precautions are taken during servicing to exclude moisture. The receiver drier should be considered as a second stage insurance to prevent the serious consequences of ice obstructing the flow.

NOTE: A sight glass provided in the unit top enables a visual check to be made of the high pressure liquid flow.

Expansion valve and evaporator--High pressure liquid refrigerant is delivered to the expansion valve. A severe pressure drop occurs across the valve and as the refrigerant enters the evaporator space at a temperature of approximately -6°C(21 °F) it boils and vaporizes. As this change of state occurs, a large amount of latent heat is absorbed. The evaporator is therefore cooled and as a result heat is extracted from the air flowing across the evaporator. The air flow is controlled by two evaporator fans regulated by the air conditioner fan control.

Second cycle
Low pressure vaporized refrigerant is drawn from the evaporator by the compressor and a second cycle commences.